British Journal of Anaesthesia

All editorial communications should be addressed to: Professor Hugh Hemmings, Weill Cornell Medical College, New York, NY, USA; E-mail: [email protected]

Aims and Scope
The British Journal of Anaesthesia (BJA) publishes high-impact original work in all branches of anaesthesia, critical care medicine, pain medicine and perioperative medicine including fundamental, translational and clinical sciences, clinical practice, technology, education and training. In addition, the Journal publishes review articles, important case reports, correspondence and special articles of general interest.

Manuscripts
For guidance, the requested size for articles is:
Clinical investigations: up to 3000 words, 40 references, and 6 tables or figures.
Laboratory investigations: up to 3000 words, 40 references, and 6 tables or figures.
Review articles: up to 5000 words, 150 references and 6 tables or figures.
Editorials: up to 2500 words, 25 references and 2 tables or figures. Include a 3-4 sentence summary. The Editorial should include: a brief introduction to the paper, a brief background to the paper, a succinct overview of the paper, a balanced evaluation of the paper?s strengths and weaknesses, a discussion of the importance of the work and its potential or real translational impact, and a discussion of future directions. Consider an illustration explaining the key concepts if it helps support the Editorial.
Special articles: Articles that do not fit one of the other article types (such as guidelines, and articles about history and education) must be approved by the Editorial Office (please contact [email protected]) prior to submission. Special articles have up to 4000 words, 150 references and 4 tables or figures, and include an unstructured Abstract up to 250 words.
Case reports: up to 1500 words, 15 references and 1 table or figure.
Correspondence: up to 1000 words, 10 references and 1 table or figure.
Book Reviews: 600-800 words approximately.
The word count refers to the main body of text, excluding the title page, abstract, references etc. Submissions that do not follow this guidance on word count or numbers of tables and figures may be returned without being reviewed. Authors wishing to submit manuscripts with tables and figures in excess of the recommended number should justify this in the cover letter.

For clinical and laboratory investigations, review articles and case reports it is possible to include supplementary material (such as expanded tables of results or additional figures for investigations or additional references for reviews) for on-line only publication. Authors should specify in their submission letter which files are to be considered for on-line only publication, and clearly refer to the on-line material in the main article text.

The BJA will also consider guidelines and position papers for publication. Authors interested in publishing such items should contact the Editor-in-Chief directly to discuss this possibility.

Please note that the BJA does not typically publish unsolicited obituaries.

Review Articles
The BJA welcomes review articles on clinical and scientific subjects. Authors are advised to contact the Editor-in-Chief before preparing or submitting a review to ascertain the appropriateness of the subject for the Journal and to prevent duplication of reviews that have been commissioned or published recently.

Narrative reviews should cover all aspects of a subject and avoid being opinion based. Narrative reviews should follow a logical structure, but the Introduction, Methods, Results, Discussion format is not required. The Abstract should not be structured but should give a clear indication of the objectives and findings of the review.

Systematic reviews should be presented in the "Introduction, Methods, Results, Discussion" format and must include a structured Abstract. These reviews must follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines (http://prisma-statement.org/). Systematic reviews must be pre-registered with the International Prospective Register of Systematic Reviews (PROSPERO) (https://www.crd.york.ac.uk/prospero/), and the registry number must be cited in the Methods and under the Abstract. Additionally, authors must state in the Methods section whether a protocol exists for review and, if so, indicate where this protocol can be accessed. The objective of systematic reviews must be to produce an evidence-based conclusion. Authors should note that if there are few randomised controlled trials available (e.g., only 4 studies with a total of 200 patients), the value of the review will be limited as the level of evidence is inadequate. Meta-analysis of inadequate evidence will have a low priority for publication (e.g. studies with a high risk of bias, retrospective studies, small number of total subjects).
Forest plots - please include full details in the reference list for all studies mentioned the Forest plot. Any studies not already cited in the main text of the manuscript must be cited in the figure caption.

Case Reports
The BJA welcomes case reports that describe new clinical problems or new approaches to established clinical problems. Case reports must be novel, important and impactful, and provide a significant learning point for other anaesthetists. Just because a case is clinically challenging does not mean that it is appropriate to publish it as a case report. The acceptance rate for case reports is considerably lower than for clinical and laboratory investigations. Authors are referred to an editorial on this subject (British Journal of Anaesthesia 2008; 100: 744) for further background.

The BJA requires permission from the patient or patient's relatives for submission of the case report for potential publication. This must be obtained before submission of the manuscript and must be stated in the cover letter. If photographs of the patient (in any form) are used, a specific signed permission from the patient or patient's relatives must be obtained and a copy of this submitted with the manuscript. Click here to download a Patient Consent Form. Failure to comply will result in rejection of the manuscript.

Book Reviews
Book reviews are by request only, which would be sent via the BJA Editorial Office. Once the book is received, the review is required to be completed within six weeks (please inform the Editorial Office should an extension be required). The book review is to be uploaded via Editorial Manager, selecting 'Book Review' as the manuscript type. Book reviews are usually about two sides of A4 (double-spaced), 600-800 words approximately. Please ensure that the book details are added to the main document. These details are included in the letter, which accompanies the book.

Submission Declaration and Verification
Submission of an article implies that the work described has not been published previously (except in the form of an abstract, a published lecture or academic thesis, see Multiple, redundant or concurrent publication for more information), that it is not under consideration for publication elsewhere, that its publication is approved by all authors and tacitly or explicitly by the responsible authorities where the work was carried out, and that, if accepted, it will not be published elsewhere in the same form, in English or in any other language, including electronically without the written consent of the copyright-holder. To verify originality, the article may be checked by the originality detection service Crossref Similarity Check.

Preprints
Please note that preprints can be shared anywhere at any time, in line with Elsevier's sharing policy. Sharing of preprints (e.g. on a preprint server) will not count as prior publication (see 'Multiple, redundant or concurrent publication' for more information). The BJA requests that submitting authors update their preprint with a footnote to confirm that their paper is under review at BJA to inform readers as to the manuscript status. After acceptance in BJA, this footnote should be updated to include a link to the final published article.

Authorship
The BJA follows the ICMJE criteria for authorship (see this link). All authors should have made substantial contributions to all of the following: (1) the conception and design of the study, or acquisition of data, or analysis and interpretation of data, (2) drafting the article or revising it critically for important intellectual content, (3) final approval of the version to be submitted, and 4) all authors must agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

For large, multicentre studies, the group of investigators should identify individuals who accept direct responsibility for the manuscript. These individuals should fully meet the criteria for authorship. If the author list includes a group name, then all members of the group must meet the full criteria for authorship as described above. If all members of a group do not meet all authorship criteria, a group must designate one or more individuals as authors or members of a writing group who meet full authorship criteria. Other group members who are not authors may be listed as collaborators (sometimes called non-author contributors). These will be listed on PubMed as collaborators rather than authors. In order to be indexed as collaborators, the names of the group members should be listed in an Appendix in the main text document, before the Reference list. The group should also be included in the main author list. There should be a note associated with the author list clearly stating that the full list of author and collaborator names appears elsewhere in the paper. Collaborator names are searchable on PubMed in the same way as authors. PubMed rules for this can be found here. For an example of a previously published paper in BJA which lists collaborators in the correct format, please see this article.

Changes to authorship
Authors are expected to consider carefully the list and order of authors before submitting their manuscript and provide the definitive list of authors at the time of the original submission. Addition, removal or rearrangement of author names in the authorship list can be made only before the manuscript has been accepted and only if approved by the handling Editor. To request such a change, the corresponding author must provide the Editor with: (a) the reason for the change in author list and (b) written confirmation (e-mail, letter) from all authors that they agree with the addition, removal or rearrangement. In the case of addition or removal of authors, this includes confirmation from the author being added or removed. In exceptional circumstances the Editor will consider the addition, removal or rearrangement of authors after the manuscript has been accepted. While the Editor considers the request, publication of the manuscript will be suspended. If the manuscript has already been published in an online issue, any requests approved by the Editor will result in a corrigendum.

Copyright
Upon acceptance of an article, authors will be asked to complete a 'Journal Publishing Agreement' (see more information on this). An e-mail will be sent to the corresponding author confirming receipt of the manuscript together with a 'Journal Publishing Agreement' form or a link to the online version of this agreement. Please note that the 'Crown Copyright' copyright status typically only applies to authors who are direct employees of the Government in the United Kingdom, Canada or Australia. For example, National Health Service (NHS) employees are not usually direct Government employees. If in doubt authors should consult their employer prior to submission to ascertain the correct copyright status.

Subscribers may reproduce tables of contents or prepare lists of articles including abstracts for internal circulation within their institutions. Permission of the Publisher is required for resale or distribution outside the institution and for all other derivative works, including compilations and translations. If excerpts from other copyrighted works are included, the author(s) must obtain written permission from the copyright owners and credit the source(s) in the article. Elsevier has preprinted forms for use by authors in these cases.

For gold open access articles, upon acceptance of an article, authors will be asked to complete an 'Exclusive License Agreement' (more information). Permitted third party reuse of gold open access articles is determined by the author's choice of user license.

Author rights
Authors (or their employers or institutions) have certain rights to reuse their work. See more information on author rights.

Elsevier supports responsible sharing
Information about responsible sharing of research published in Elsevier journals is available here: share your research published in Elsevier journals.

Funding body agreements and policies
Elsevier has established a number of agreements with funding bodies that allow authors to comply with their funder's open access policies. Some funding bodies will reimburse authors for the gold open access publication fee. Details of existing agreements are available online.

Open access
The BJA offers authors a choice in publishing their research. Regardless of how authors choose to publish their articles, the Journal will apply the same peer review criteria and acceptance standards.

Subscription

• Articles are made available to subscribers as well as developing countries and patient groups through our universal access programs.
• No open access publication fee is payable by authors.
• Authors are entitled to post the accepted manuscript in their institution's repository and make this public after an embargo period (known as green open access). The published journal article cannot be shared publicly, for example on ResearchGate or Academia.edu, to ensure the sustainability of peer-reviewed research in journal publications. The embargo period for the BJA is 12 months.

Gold open access

• Articles are freely available to both subscribers and the wider public with permitted reuse.
• A gold open access publication fee is payable by authors or on their behalf, e.g. by their research funder or institution. For gold open access articles, permitted third party (re)use is defined by the following Creative Commons user licenses:

Creative Commons Attribution (CC BY)
Creative Commons Attribution lets others distribute and copy the article, create extracts, abstracts, and other revised versions, adaptations or derivative works of or from an article (such as a translation), including in a collective work (such as an anthology), text or data mine the article, even for commercial purposes, as long as they credit the author(s), do not represent the author as endorsing their adaptation of the article, and do not modify the article in such a way as to damage the author's honour or reputation.

Creative Commons Attribution-NonCommercial-NoDerivs (CC BY-NC-ND)
For non-commercial purposes, this attribution lets others distribute and copy the article, and to include it in a collective work (such as an anthology), as long as they credit the author(s) and provided they do not alter or modify the article.
The open access fee for this journal is $3,200, excluding taxes (USD). Learn more about Elsevier's pricing policy.

Green open access
Authors can share their research in a variety of different ways and Elsevier has a number of green open access options available. We recommend that authors refer to our green open access page for further information. Authors can also self-archive their manuscripts immediately and enable public access from their institution's repository after an embargo period. This is the version that has been accepted for publication and which typically includes author-incorporated changes suggested during submission, peer review and in Editor-author communications. For subscription articles, an appropriate amount of time is needed for journals to deliver value to subscribing customers before an article becomes freely available to the public. This is the embargo period and it begins from the date that the article is formally published online in its final and fully citable form. Find out more here. After acceptance, open access papers will be published under a non-commercial license. Authors requiring a commercial CC BY license can apply after their manuscript is accepted for publication.

Plan S Authors
If you are an author funded by a signatory to Plan S and have any questions about publishing with the BJA, and what options you have please contact the Elsevier Open Access team at the following address: [email protected].

Elsevier Researcher Academy
Researcher Academy is a free e-learning platform designed to support early and mid-career researchers throughout their research journey. The "Learn" environment at the Researcher Academy offers several interactive modules, webinars, downloadable guides and resources to guide you through the process of writing for research and going through peer review. Feel free to use these free resources to improve your submission and navigate the publication process with ease.

Language (usage and editing services)
Please write your text in good English (the house style of BJA and BJA Education is UK English). Please see here for a guide to preferred spellings. Authors who think that their English language manuscript requires editing to eliminate spelling or grammatical errors and to conform to correct scientific English may wish to use the English Language Editing service available from Elsevier's WebShop.

Reporting sex- and gender-based analyses

Reporting guidance
For research involving or pertaining to humans, animals or eukaryotic cells, investigators should integrate sex and gender-based analyses (SGBA) into their research design according to funder/sponsor requirements and best practices within a field. Authors should address the sex and/or gender dimensions of their research in their article. In cases where they cannot, they should discuss this as a limitation to their research's generalizability. Importantly, authors should explicitly state what definitions of sex and/or gender they are applying to enhance the precision, rigor and reproducibility of their research and to avoid ambiguity or conflation of terms and the constructs to which they refer (see Definitions section below). Authors can refer to the Sex and Gender Equity in Research (SAGER) guidelines and the SAGER guidelines checklist. These offer systematic approaches to the use and editorial review of sex and gender information in study design, data analysis, outcome reporting and research interpretation - however, please note there is no single, universally agreed-upon set of guidelines for defining sex and gender.

Definitions
Sex generally refers to a set of biological attributes that are associated with physical and physiological features (e.g., chromosomal genotype, hormonal levels, internal and external anatomy). A binary sex categorization (male/female) is usually designated at birth ("sex assigned at birth"), most often based solely on the visible external anatomy of a newborn. Gender generally refers to socially constructed roles, behaviors, and identities of women, men and gender-diverse people that occur in a historical and cultural context and may vary across societies and over time. Gender influences how people view themselves and each other, how they behave and interact and how power is distributed in society. Sex and gender are often incorrectly portrayed as binary (female/male or woman/man) and unchanging whereas these constructs actually exist along a spectrum and include additional sex categorizations and gender identities such as people who are intersex/have differences of sex development (DSD) or identify as non-binary. Moreover, the terms "sex" and "gender" can be ambiguous?thus it is important for authors to define the manner in which they are used. In addition to this definition guidance and the SAGER guidelines, the resources on this page offer further insight around sex and gender in research studies.

Submitting your article
Please submit your article via https://www.editorialmanager.com/bja/default1.aspx.

Please suggest potential reviewers for this submission and provide specific reasons for your suggestion in the comments box provided for each person. Authors should not suggest reviewers with whom they have an actual, perceived, or potential conflict of interest. Moreover, authors should not suggest reviewers with whom they share a personal or professional connection if there is potential for that relationship to introduce bias into the evaluation of the manuscript. Please note that the editors may not use your suggestions, but your help is appreciated and may speed up the selection of appropriate reviewers.

Your Paper Your Way
This enhanced submission feature is designed to facilitate the submission of new manuscripts. We now differentiate between the requirements for new and revised submissions. You may choose to submit your manuscript as a single Word or PDF file to be used in the review process. Only when your paper is at the revision stage, will you be requested to format your paper for final acceptance and provide necessary items for the publication of your article. To find out more, please visit the Preparing Your Manuscript section below.

NEW SUBMISSIONS
Submission to this journal proceeds totally online and you will be guided through the creation and uploading of your files. The system automatically converts your files to a single PDF file, which is used in the peer-review process.
As part of the Your Paper Your Way service, you may choose to submit your manuscript as a single file to be used in the refereeing process. This can be a PDF file or a Word document, in any format or lay-out that can be easily used by referees to evaluate your manuscript. While we do not insist that the format meet all detailed requirements for acceptance, it should follow the general requirements regarding sections, length, figure numbers etc. (see below). The file should contain figures of sufficient quality for peer review. If you prefer to do so, you may still provide some or all of the source files at the initial submission. Please note that individual figure files larger than 10 MB must be uploaded separately.

References
There are no strict requirements on reference formatting at submission. References can be in any style or format provided that the style is consistent. Article titles must be included and if missing, submissions will be returned to authors to correct. Where applicable, author(s), journal/book title, chapter title, year of publication, volume number/book chapter and the article number or pagination must be present. The inclusion of article DOI is highly encouraged.

Formatting requirements
There are no strict formatting requirements, but all manuscripts must contain the essential elements needed to facilitate peer review, including (where applicable) abstract, keywords, introduction, methods, results, conclusions, artwork and tables with captions. Ensure that the article is divided into clearly defined sections.
If your article includes any videos and/or other supplementary material, this should be included in your initial submission for peer review.

Figures and tables embedded in text
Please ensure the figures and the tables included in the single file are placed next to the relevant text in the manuscript, rather than at the bottom or the top of the file. The corresponding caption should be placed directly below the figure or table.

REVISED SUBMISSIONS
Please note that Your Paper Your Way applies to new submissions only. You are required to follow the journal-specific instructions for formatting of the manuscript for the submission of revisions.

Preparing Your Manuscript
The standard layout of a manuscript is:

• Title page
• Abstract including Keywords (see further guidance on when to use a Structured Abstract)
• Introduction
• Methods
• Results
• Discussion
• Details of authors' contributions
• Acknowledgements
• Declaration of interests
• Funding
• Appendices (if applicable)
• References
• Tables (including a title and legend, with any essential abbreviations defined)
• Legends to figures

The pages should be numbered in the top right-hand corner, the title page being page one. Each section should start on a separate page. Different types of studies (e.g. randomised controlled trial, matched cohort study) will contain different elements. Guidance on each type of study can be found on the EQUATOR (Enhancing the QUAlity and Transparency Of health Research) Network website (http://www.equator-network.org/), along with appropriate checklists. There are checklists available for each type of study on the EQUATOR Network. You are strongly encouraged include the appropriate checklist (e.g. STROBE, CHEERS, AGREE) with your submission to the BJA. A CONSORT checklist is required for clinical trials (see below). It is also advisable to include the ethics committee approved protocol with clinical trial submissions.

Title Page
Titles should provide a reasonable indication of the contents of the paper. Avoid enigmatic or vague titles such as 'An unusual cause of hypotension'. Titles in the form of a question, such as 'Is propofol epileptogenic?', or which draw conclusions about the research ('Propofol causes seizures') are discouraged. The Editors reserve the right to edit the title. The title page should include the name(s) and institutional affiliation(s) including city and country of all author(s). No postnominals. Note that it is the house style of the BJA for full author names to be spelled out (i.e. please do not use initials for your first name). Do not include street address and city code for institutional affiliation, just institutions, city and country. It should be made clear which affiliation refers to which author by use of numerical superscripts following each author. Details of the authors' qualifications and post (e.g., consultant, senior lecturer) are not included. An author's present address, if it differs from the address at which the work was carried out, should be given as a footnote on the title page and referenced at the appropriate place in the author list by superscript numbers (^{1 2 3} etc.). The corresponding author and email should be indicated with an asterisk. A Twitter handle can also be included for the corresponding author.
A short running title containing not more than 50 characters (including spaces) should be included on the title page.

If a preliminary account of the results has been given in a published abstract, it is customary to refer to this on the title page.

Abstract
The Abstract will be printed at the beginning of the paper. It should be on a separate sheet, in structured format (Background, Methods, Results and Conclusions) for Clinical Investigations, Laboratory Investigations and Systematic Reviews. Abstracts are not required for Editorial, Book Reviews and Correspondence. For Narrative Reviews and Special Articles, the Abstract (label as Summary) should not be structured. The Abstract should give a succinct account of the study or contents in up to 250 words, with rare exceptions granted by the Editor. The Results section should contain primary outcomes with relevant statistics. Effect sizes and confidence intervals should be included in addition to P values or confidence intervals. Exact P values should be included, unless the P value is <0.001. It is important that the results and conclusion given in the Abstract are the same as in the Article, as the Abstract may be used, as it stands, by abstracting journals. References are not included in this section. Avoid use of nonstandard abbreviations in the Abstract.

Keywords
Five to eight keywords should be included on the title page of all manuscripts under the heading Keywords. They should be in alphabetical order, and with UK English spelling. Please consider repeating any important terms from the title of the article in both the keywords and in the Abstract, to ensure maximum discoverability of your article online. Avoid keywords that are only one word or are too general (e.g. "anaesthesia"); keywords that are too short will render the search unspecific, whereas keywords that are too long may filter articles to such a great extent that your paper could be excluded.
For advice on choosing keywords and improving the discoverability of your manuscript please visit https://www.elsevier.com/connect/authors-update/top-tips-making-your-article-visible-with-seo.

Introduction
The recommended structure for this section is;

• Background to the subject
• What is known / unknown about it
• Hypothesis
• Aim of your study

As a rule, the Introduction should be covered in a maximum of 1.5 pages double-spaced. The introduction should give a concise account of the background of the problem and the objectives of the investigation. It should state what is known about the problem to be studied at the time the study was started. Previous work with a direct bearing on the present problem should be quoted. The final paragraph should clearly state the primary and, if applicable, secondary aims of the study.

Methods
The Methods section should give a clear but concise description of how the study was conducted. Subjects covered in this should include:

• Ethics approval / licence (including date and administering institution)
• Registration (including date) (if applicable)
• Patient population
• Inclusion / exclusion criteria
• Conduct of the study
• Measurements and data handling
• Primary and secondary endpoints
• Sample size calculation
• Statistical analyses

Ethics approval/licence
Please see our information pages at https://www.elsevier.com/publishingethics and https://www.elsevier.com/journal-authors/ethics.

Regardless of the country of origin, all clinical investigators describing human research must abide by the Ethical Principles for Medical Research Involving Human Subjects outlined in the Declaration of Helsinki, and amended by the World Medical Association (https://www.wma.net/policies-post/wma-declaration-of-helsinki-ethical-principles-for-medical-research-involving-human-subjects/). Investigators are encouraged to read and follow the Declaration of Helsinki. Clinical studies that do not meet the Declaration of Helsinki criteria will be denied peer review. If published research is subsequently found to be non-compliant it will be withdrawn or retracted.

On the basis of the Declaration of Helsinki, the BJA requires that manuscripts reporting clinical research state in the first paragraph of the Methods section that:

• The study was approved by the appropriate Ethics authority.
• Written informed consent was obtained from all subjects, a legal surrogate, or the parents or legal guardians for minor subjects, or that the requirement for written informed consent was waived by the ethics committee, or that the research was conducted under a national, regional or institutional process that obviated the need for approval.
• In countries where formal ethics committee approval is not mandatory for a non-interventional study, evidence should be provided that the study was submitted to the ethics committee and deemed exempt from review and/or consent from the patient or patient's relatives. The name of the committee and the study reference number should be cited in the Methods.

Human subjects must not be identifiable. Do not disclose patients' names, initials, hospital numbers, dates of birth, or other protected personal or healthcare information. Keep copies of ethics approval and signed consent forms. In unusual circumstances the Editors may request blinded copies of these documents to address questions about ethics approval and study conduct. For more information, please review Elsevier Policy on the Use of Images or Personal Information of Patients or other Individuals. Unless you have written permission from the patient (or, where applicable, the next of kin), the personal details of any patient included in any part of the article and in any supplementary materials (including all illustrations and videos) must be removed before submission.

Drugs
When a drug is first mentioned, it should be given by the international non-proprietary name (INN), followed by the chemical formula in parentheses if the structure is not well known, and (if relevant) by the proprietary name (with an initial capital letter) and the manufacturer with location. A figure giving the molecular configuration of the drug is necessary only in the case of the earliest reports of a new drug. Drug dosages are normally given by the name of the drug followed by the dose (e.g. propofol 2.5 mg kg^-1). Use the SI system of units. Dose, route, and frequency of administration must be provided. Do not confuse drug dose with concentration.

Multiple Publications of Human or Animal Trials
In the interest of minimising the risk to human and animal subjects, as well as promoting efficient use of scarce research funds, investigators sometimes pose several questions and make multiple measurements in a single study with the intent of publishing multiple manuscripts. Division of data from a single research study into multiple manuscripts is acceptable, provided three requirements are met:

1. The cover letter for every paper derived from the study explains the need for dividing the study into multiple manuscripts. This applies even if only one of the submissions is to the BJA. It is essential that the cover letter states that other parts of the study are currently under consideration or in press with another journal. The Journal will consider the appropriateness of the division as part of the review process. Any manuscripts related to the same study should be submitted for consideration by the reviewers as a supplementary PDF file through ScholarOne Manuscripts.
2. In all manuscripts after the first, the investigator must disclose that the data have been previously reported, with appropriate citation to the first manuscript. This practice is essential for scientific continuity. For example, should a question arise about the conduct of the study in one manuscript, readers should be able to identify all manuscripts based on the same experimental data.
3. Measurements must not interfere with each other. Such interference may happen in ways that are not evident at the time of the study. For example, measurements of pain thresholds may make it impossible to measure sedative effects. The potential for interfering measurements may not be evident if the pain thresholds and sedation effects are reported in separate manuscripts that are not appropriately cross-referenced.

Human Subjects
Data on the age (mean with range), weight (kg), sex, height (m), criteria for selection, etc. (patient characteristics, not demographics) should be presented. Authors of clinical investigations should report the 'sex' of participants and use the words 'sex', 'male' and 'female' in their manuscripts, unless the 'gender' of participants is relevant to their hypotheses. The numbers and percentages of both male and female patients (and other sexes/genders as appropriate) should be reported in the text and/or tables. If appropriate, the incidence of primary outcome should be reported in males and females (and other sexes/genders as appropriate), and sex/gender should be considered as covariates in multivariable models, or the reason for exclusion explained. These recommendations are consistent with existing advice for preclinical and clinical research.

The sex/gender, age, weight, height, and eligibility criteria should be presented, with an indication of the general state of health of participants (e.g., ASA physical status) and types of operations being undertaken. More complex information is best be presented as a table. When patient or next-of-kin consent was required by the ethics committee, this should be indicated.

Clinical Trials
In accordance with the Clinical Trial Registration Statement from the International Committee of Medical Journal Editors, all clinical trials in BJA must be registered in a public trials registry available in English at or before the onset of participant enrolment. This requirement applies to all clinical trials that begin enrolment after 1 January 2009. Research is considered to be a clinical trial if it involves prospective assignment of human subjects to an intervention or comparison group to study the relationship between a health-related intervention and a health outcome. Further details of which clinical trials are covered by this policy are in the updated ICMJE guidelines (http://www.icmje.org). The registry must be accessible to the public at no charge, searchable, open to all prospective registrants, available in English, and managed by a not-for-profit organisation. The registry must include the following information: a unique identifying number, a statement of the intervention(s), study hypothesis, definition of primary and secondary outcome measurements, eligibility criteria, target number of subjects, funding source, contact information for the principal investigator, and key dates (date of ethics approval, registration date, start date/date of first subject enrolled, and completion date). The following registries are recommended by ICMJE: Clinical Trials, ISRCTN Register, UMIN Clinical Trials Registry, Australia New Zealand Clinical Trials Registry, Nederlands Trial Register.

In accordance with the ICMJE's recommendation, the BJA will also accept registration of clinical trials in any of the primary registries that participate in the World Health Organization's (WHO) International Clinical Trial Registry Platform (http://www.who.int/ictrp/en/). Primary registries are WHO selected registers managed by not-for-profit entities that will accept registrations for any interventional trials, delete duplicate entries from their own registry, and provide data directly to the WHO. Please note that registration in any WHO partner registry is insufficient.
Authors are requested to provide the exact URL and unique identification number for the trial registration at the time of submission on the title page of their submission. This information will be published in the article.

Clinical trial reports should also comply with the Consolidated Standards of Reporting Trials (CONSORT) and include a standardised flow diagram presenting the enrolment, intervention allocation, follow-up, and data analysis with number of subjects for each (visit here for more information on CONSORT and here for the required template diagram). Please also refer specifically to the CONSORT Checklist of items to include when reporting a randomised clinical trial.

Results posted in the same clinical trials registry in which the primary registration resides will not be considered prior publication if they are presented in the form of a brief abstract (500 words or less) or a table.

Statistical analysis plan reporting and HARKing (Hypothesising After Results are Known)
Publication of a time-stamped statistical analysis plan prior to data analysis is strongly recommended for both interventional and observational studies. In the absence of a publicly available statistical plan, we strongly encourage authors to report that their statistical analysis plan was approved by the authors before analyses began or acknowledge that their submission is based on testing a hypothesis after the main study results were known (for example: "Based on striking patterns in the dataset, we conducted the following post hoc analysis...The results of this analysis should be regarded as hypothesis-generating.").

Reporting checklists must be provided as supplementary data. An appropriate flow diagram should be included in the manuscript, as recommended by the following guidelines:
Randomised controlled trials (RCTs): CONSORT checklist, flow diagram, and CONSORT Checklist for Reporting of Harms in RCTs should be provided. Customized CONSORT checklists are available for trials with parallel group design, cluster-randomised trials, noninferiority and equivalence randomised trials, pragmatic trials and trials of nonpharmacological treatment.

Non-randomised studies: guidelines described in Transparent Reporting of Evaluations with Nonrandomized Designs (TREND) should be provided.

Observational studies: STROBE statement reporting checklists must be provided. Please check the STROBE statement website for up-to-date information concerning specific study types, including observational studies in epidemiology, genetic association studies, cohort studies, case-control studies, and cross-sectional studies.

Diagnostic accuracy studies: for studies where the performance of two or more diagnostic tests are compared, submissions must include the STARD checklist and STARD Flowchart of Diagnostic Test Results.

Translational human studies: We are particularly keen to receive manuscripts that undertake innovative clinical and translational research in humans. In addition to adhering to, and providing, STROBE (or other appropriate) checklists, we refer authors to two articles (PMID:22029804, 21677197) that provide helpful guidance on justification of sample size calculations in this type of submission.

Research Using Animals

Institutional approval
All animal studies must have been conducted within the guidelines of the appropriate national body as well as be approved by institutional review board(s), and accompanied by a specific declaration of such approval and number in the Methods. Authors must submit a supplementary file detailing compliance with ARRIVE (Animal Research: Reporting of In Vivo Experiments) guidelines for reporting on animal studies. For animal models, the genotype, strain, source, number of backcrosses, sex, and age of animals studied must be provided in the manuscript.

Studies that involve the use of animals must clearly indicate that Institutional approval was obtained and state the UK Home Office Licence number or equivalent code that the studies were performed under. European studies with animals should follow the EU directive 2010/63 and provide a national and/or institutional approval number. It is recognised that animal welfare legislation can vary between countries. The BJA uses the UK standards as a baseline and reserves the right to reject manuscripts judged not to meet these standards, even when local approval has been granted.

ARRIVE guidelines
The contribution of animal research in enabling better health for humans and animals is incontrovertible and the BJA is committed to the publication of research studies that use animal models. This demands the same rigorous attention to detail as in clinical trials. Failure to describe research methods and to report results appropriately has scientific and ethical implications for the entire research process and the reputation of those involved. Experiments involving animals should be appropriately designed, correctly analysed and transparently reported to increase validity of the results and maximise the scientific gain including use of blinding, randomisation, etc. A minimum amount of relevant information must be included to ensure that the methods and results of a study can be reviewed, analysed and repeated. It is strongly encouraged that animal studies are accompanied by the ARRIVE guidelines.

Anaesthesia
The methods of anaesthesia and analgesia for research studies involving animals should be the best available to ensure the welfare of the animals involved. Submissions that ignore this guidance may be returned without being assessed. Reducing the potential for pain and distress is a significant refinement and provision of safe and effective anaesthesia that does not interfere with specific research objectives also reduces the numbers of animals used. Authors must also state how they assessed and monitored the adequacy of anaesthesia. Some anaesthetics have interactions that are important to certain areas of research. Whichever agents are used, an appropriate plane of anaesthesia for the intervention must be assessed and achieved. This is particularly important when neuromuscular blocking agents are used. Information on potentially suitable anaesthetic regimens can be obtained from a variety of sources, including the veterinary advisor at your research institution, specialist laboratory animal anaesthesia and general veterinary anaesthesia textbooks.

Analgesia
Every effort should be made to minimise pain or distress in research studies that are conducted using animals. Not only is this important for ethical reasons, but also because pain is a source of stress that can cause undesirable effects on the outcome of research projects. Provision of effective pain relief can only be done by assessing the degree of pain experienced by the animal involved. Animal pain assessment is difficult and time-consuming to implement effectively, so that it is tempting to simply give all animals a "standard dose" of analgesic. Often, all that is possible is to use doses that have been established to be safe and effective in some of the tests used in rodents during early drug development. Provided these limitations are appreciated, some strategies for pain management that make best use of our existing knowledge include:

• If methods of pain assessment have been developed for the species used, these should be adapted to the requirements of the particular research procedure
• If methods of pain assessment are not available, consider devoting resources to developing some form of scoring system
• If pain scoring is not possible, determine the analgesic protocol based on experience with other surgical procedures in that species
• If possible, use doses that have been established using studies that have employed pain scoring systems
• Attempt to evaluate the efficacy of the analgesic regimen selected using clinical assessment (your veterinary advisor will be able to help you to recognise pain in laboratory animals)
• Prepare a rescue analgesia protocol and an immediate euthanasia protocol for animals which appear to be in severe pain

Use of animal models of pain to investigate analgesia techniques is a particular challenge for journals in the field of anaesthesia. Such studies must be conducted with extremely careful regard to animal welfare. Rarely will this journal publish studies where an analgesic agent has been compared to a placebo in an animal model of severe pain. The book 'Laboratory animal anaesthesia' by P. Flecknell (4th Edition, 2015, Academic Press) provides a helpful introduction for safe, effective and appropriate anaesthesia and analgesia in animals used in research studies.

Euthanasia
Animals used for research are usually euthanised at the end of a study for the purpose of sample collection or post-mortem examination. Animals may also be killed because they are experiencing severe pain or distress. The method of killing the animal after the experiment is completed should be chosen carefully and must be detailed in the Methods. The method used should be appropriate to the species and should not confound any objective of the research - veterinary advice should be sought. The conduct of euthanasia for those working with laboratory animals in the UK is quite straightforward. Either the Code of Practice for the Humane Killing of Animals under Schedule 1 to the Animals (Scientific Procedures) Act 1986 is followed or a project and personal licence authorisation is obtained to use a technique not covered by this Code. An updated code of practice for schedule 1 killing has been published by the Animal Procedures Committee and is available online at: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/662364/Guidance_on_the_Operation_of_ASPA.pdf. The use of carbon dioxide for killing is a subject of much debate and is not suitable for rabbits. For rodents, use of carbon dioxide is permitted but other methods are preferable.

Laboratory Studies

Cell lines
Authors must describe the source of all cell lines utilized, including information on testing for mycoplasma contamination.

Antibodies
Detailed description of all antibodies used for flow cytometry, immunoblotting, immunoprecipitation and immunohistochemistry must be included in tabular form in Supplementary Methods, providing the source and catalogue/clone number for commercial antibodies or a description/reference to a description of the generation of custom antibodies. Evidence for antibodies having been validated either by the authors, previous publications or manufacturers should also be provided in the table.

Flow cytometry
Authors should adhere to the Minimum Information about a Flow Cytometry Experiment (MIFlow Cyt; PMID 18752282), which establishes criteria for recording and reporting information about the flow cytometry experiment overview, samples, instrumentation and data analysis. Gating strategy should be demonstrated in supplementary data, together with raw data provided as an example for each experiment. For figures in the main manuscript, key flow cytometry data are sufficient (e.g. histograms, density plots).

ELISA
Details on intra- and inter-assay variability, lower limits of detection and linearity-of-dilution assessment for ELISAs should be provided in Supplementary Methods and referred to in Methods.

Large datasets
Large datasets for gene expression microarrays, SNP arrays, and high-throughput sequencing studies must be deposited in a public repository. Microarray data must be deposited in a MIAME-compliant public database. High-throughput sequencing data must be deposited in a MINSEQE-compliant public database. Provide the relevant accession numbers in the text of the main manuscript. Deposition of other types of large datasets in a public repository is strongly encouraged. Datasets should be made available to any interested reader on the publication date from the authors directly. Researchers who encounter a persistent refusal by an author of a paper to comply with these guidelines should contact the Editor-in-Chief.

Software
Commercially available software should be referenced, detailing software version number, company and location) Additionally, custom-written software should report the source code in the Supplemental Methods or detail how the software can be obtained.

Statistical Analysis
Many scientific manuscripts have flaws in design and statistical analysis. Statisticians should be involved in the design, analysis and reporting of most studies. Investigators should commit in writing to the statistical analysis plan prior to conducting a study. Certainly, this should be done prior to conducting analyses. Pre-publication of research protocols helps to promote rigour and allows other scientists to attempt replication or refutation. It is helpful to submit a date-stamped, ethics committee-approved protocol, containing the statistical analysis plan, together with your submission. Specialist statistical expertise will be sought at editorial discretion, including, where applicable, to re-analyse original data. Authors must describe all statistical tests used in the Methods. Complete details of the statistical analyses should be reported in full in the Results section. Examples for reporting main statistical analyses are:
"…odds ratio, 1.22; 95% confidence interval, 1.06-1.39; P=0.005."
[Note: abbreviations for odds ratio (OR) and 95% confidence interval (95% CI) are acceptable provided they are defined in text/abstract].
"…lidocaine-group: 48 (23) mg (mean (SD)) vs placebo-group: 51(19) mg, P=0.22."
"…hazard ratio (HR) 0.65, 95% CI 0.49-0.84, P=0.001."
The distribution of data must meet the assumptions of the statistical test used. Authors must specify whether statistical tests are one-sided or two-sided. When making multiple comparisons on a single data set, authors should choose statistical tests that account for multiple groups (one-way, two-way or repeated measures ANOVA). The statistical analysis should also correct for repeated measures when comparing multiple measurements between groups.
Statistical methods must be described with enough detail to enable a knowledgeable reader with access to the original data to verify the report and results. Findings should be quantified and presented with appropriate indicators of measurement error or uncertainty (such as confidence intervals). Confidence intervals and effect sizes provide more useful information for interpretation than a P value alone conveys. P values should be exact and provided to three decimal places (e.g. P=0.123) unless they are <0.001. P values between 0.05 and 0.005 can generally be interpreted as providing suggestive evidence, whereas P values <0.005 generally provide more compelling evidence.
A sample size calculation should be performed before starting the study to determine the number of subjects needed in each group to detect a given change. Please note that a sample size calculation based on the primary endpoint will not necessarily be applicable to secondary measures. It is important to choose sample sizes for studies based on biologically or clinically important and realistic effect sizes. One of the most important weaknesses of scientific studies is that they do not include enough patients (or non-human animals). On the other hand, studies that are very large might yield statistically significant but clinically unimportant findings. There should be a separate section for Statistics in the Methods; all statistical tests used should be described in this section. It is helpful to provide brief rationale for these choices.

Propensity Score Analyses
Methods

• Before an effect is estimated, it is important for researchers to think carefully about their estimand of interest which must be clearly specified.
• Provide a detailed explanation of the model used to estimate propensity scores, including the type of model, variables included and the presence of any non-linear and interaction terms.
• Describe the method used to select variables for inclusion in the propensity score model. When possible, this should be accomplished using clinical expertise and not through solely statistical methods.
• When using propensity score matching, explicitly describe the matching algorithm used, including the distance metric and ratio of matching. Describe the metric used to assess balance e.g. standardised mean difference, and indicate the threshold used for determining adequate balance.
• When using a matching approach, authors should also be aware that the causal effect estimated is the average effect in the treated/exposed (if unexposed individuals are matched to the exposed individuals), rather than the average causal effect.
• When using propensity score weighting, explicitly describe and provide justification for the type of weight used.
• When stratification by the propensity scores is implemented, provide justification for the strata chosen.
• Describe the methods used to examine the assumptions of propensity score methods, including examination for adequate overlap and the presence of extreme values to assess the balance of the groups on baseline factors after matching is done.
• Analyses in propensity-matched cohorts should incorporate the matched pairs or sets, by including a random effect for the matched sets.
• Propensity matched analyses should be conducted alongside a secondary analysis using a standard multivariable regression model for comparison.

Results

• When using matching, report the sample size of the pre- and post-matching cohorts.
• Describe the balance of variables across exposure groups both in the initial cohort and following matching or weighting. Comparison of balance should not utilize p-values; standardized mean differences are the preferred metric for assessing balance in this context.
• If not referenced in the methods section, provide visual representations of the distributions of propensity scores and/or weights; this may be included in the supplemental material.
• Provide estimates of the effect of interest using both standard multivariable regression models and the selected propensity score method (e.g., provide both unweighted and weighted estimates). Include measures of uncertainty (e.g., confidence intervals).
• Discuss the degree of unmeasured confounding that would be sufficient to alter conclusions (for example using, the e-value or a similar tool).

Discussion

• Provide cautious interpretation of estimates as evidence for causal associations, making sure to identify and discuss any issues encountered throughout the use of propensity score methods (e.g., residual imbalance, loss of sample size with matching, etc.). A single epidemiological study rarely provides proof of a causal relationship. Authors must be clear that propensity score analysis cannot replace a randomised trial in which unmeasured confounding is controlled.

Results
Results should be presented in a logical order related to the aims and design of the study with appropriate statistical reporting and any pertinent negative findings. Description of experimental results should be concise. It is often useful to present the results in the order described in the Methods section. Data should not be repeated unnecessarily in text, tables and figures (see below). Unwarranted numbers of digits (false precision) should be avoided (Example: the mean dose of propofol was 2.1 mg kg^-1 rather than 2.0897 mg kg^-1 ). Precision of most biological measurements does not allow significant digits over two; use of more than this can imply false precision. It may not be necessary to provide all data from a complex study: only those values essential to the communication should be given. However, results should be presented in a manner so that the reader can check the statistical inferences. If the data are so numerous that this is not possible, Supplemental Data can be submitted as a separate file for on-line publication only. For example, in a pharmacokinetic study, more extensive sets of data can be included as an Appendix with the on-line version of the article. If authors wish to make use of this facility, they should state this in the submission letter and upload the data as a separate file. The Editor has the right to request the original data collected. The Results section should not include discussion of the findings, which should be included in the Discussion. Similarly, the Discussion should not restate the Results. SI units must be used. Means must be accompanied by SD in brackets; medians must be accompanied by 25-75^th percentiles in brackets. Odds ratios (OR) must be accompanied by 95% confidence intervals (CI) in brackets. Negative index notation (e.g. mg kg^-1) must be used rather than solidus notation (e.g. mg/kg). Numbers in text and tables should always be provided if % is shown.

Tables and Figures
Tables and figures are often useful to present either complex or extensive data in a more easily understandable form. However, authors are cautioned against unnecessary use of tables and figures. A useful approach is to prepare the raw data in the form of tables and then decide which data are to be presented in the article. The author should then decide whether the essential data can be presented succinctly in the text. If not, the essential tables and/or figures should be prepared. To illustrate this with examples: a study outcome which compares two measurements in two groups can easily be presented as text, a comparison of arterial pressure and heart rate changes at five time points in two groups would be appropriate as a table and the same measurements in comparing three groups may be better as a figure.

Tables and figures are important communications and should be accompanied by a legend that makes them self-explanatory. However, the legend must not contain experimental details, which should be given in the Methods section. The use of a figure should be considered only where a figure presents the data more clearly than is possible in a table or when an important trend or comparison has to be made for which a graphic presentation is clearly superior to a table or text.
The authors should decide in which form they wish to present data. Please note the limitation given above on the number of figures/tables permissible for each article type. Data should not be duplicated by including it in a table and figure, or presentation in both a table and text.

Graphs
Graphs of quantitative data should be presented as dot plots for small data sets, with the mean and appropriate error bars indicated; or as box and whisker plots, with values defined in the legend (the bounds of the boxes, the lines within the boxes, the whiskers, and any outlying values). Presenting data as columns with error bars is generally not acceptable.

Images
Submissions that contain cropped gels/blots are required to submit a supplementary file that contains the entire unedited gel for all cropped gels in the submission. Each gel should be annotated as "Full unedited gel for Figure X," and the authors should highlight which lanes of the unedited gel correspond to those shown in the cropped images within the manuscript. This file can be provided as Supplemental Data and will be published as full uncut blot data if the submission is ultimately accepted.
No specific feature within an image should be enhanced, obscured, moved, removed, or introduced. The groupings of images from different parts of the same gel or from different gels or fields or exposures must be made explicit by using dividing lines and noted in the figure legend. Adjustments of brightness, contrast, or colour balance are acceptable provided they do not obscure or eliminate any information present in the original. Nonlinear adjustments (e.g., changes to gamma settings, curves, or input levels) must be disclosed in the figure legend. If original data cannot be produced, acceptance of the manuscript may be revoked. If images or datasets, including control data, are presented in multiple figure panels in the manuscript or supplement, an explanatory note must be included in the figure legend.

Tables
Please submit tables as editable text and not as images. Number tables consecutively using Arabic numerals in order of their appearance in the text, and place any table notes below the table body. Be sparing in the use of tables and ensure that the data presented do not duplicate results described elsewhere in the article. Please avoid using vertical rules and shading in table cells. Tables should be presented as individual, completed tables on a single page in the main text file after references. Tables should have brief titles.

Electronic Artwork
General points

• Make sure that you use uniform lettering and sizing of your original artwork.
• Embed the used fonts if the application provides that option.
• Use Helvetica or Arial font in preparing figures.
• Number the illustrations according to their sequence in the text; use a logical naming convention for your artwork files with panels indicated by lower case letters.
• Provide captions to illustrations separately.
• Size the illustrations close to the desired dimensions of the published version.
• Submit each illustration as a separate file.
• Include a key to denote any symbols used.
• Scale bars should be defined in figures, and reported in the figure legends.
• Avoid pairing red and green to improve legibility for colour-vision impaired readers.
• Whenever possible, do not place labels over any part of a colour figure.

A detailed guide on electronic artwork is available. Some excerpts from the detailed information are given here.

Formats
If your electronic artwork is created in a Microsoft Office application (Word, PowerPoint, Excel) then please supply the artwork in the native document format. Regardless of the application used other than Microsoft Office, when your electronic artwork is finalised, please 'save as' or convert the images to one of the following formats (note the resolution requirements for line drawings, halftones, and line/halftone combinations given below):
EPS (or PDF): Vector drawings, embed all used fonts.
TIFF (or JPEG): Colour or grayscale photographs (halftones), keep to a minimum of 300 dpi.
TIFF (or JPEG): Bitmapped (pure black & white pixels) line drawings, keep to a minimum of 1000 dpi.
TIFF (or JPEG): Combinations bitmapped line/half-tone (colour or grayscale), keep to a minimum of 500 dpi.
Please do not: Supply files that are optimised for screen use (e.g., GIF, BMP, PICT, WPG); these typically have a low number of pixels and limited set of colours; Supply files that are too low in resolution; Submit graphics that are disproportionately large for the content.

Colour Artwork
Please make sure that artwork files are in an acceptable format (TIFF (or JPEG), EPS (or PDF) or MS Office files) and with the correct resolution. If, together with your accepted article, you submit usable colour figures then Elsevier will ensure, at no additional charge, that these figures will appear in colour online (e.g., ScienceDirect and other sites) in addition to colour reproduction in print. Further information on the preparation of electronic artwork.

Figure captions
Ensure that each illustration has a caption. Supply captions separately, not attached to the figure. A caption should comprise a brief title (not on the figure itself) and a description of the illustration. Keep text in the illustrations themselves to a minimum but explain all symbols and abbreviations used.

• 200 word limit, including a short title and a brief explanation with sufficient detail to make the figure intelligible without reference to the main text.
• Describe in words the key used to denote any symbols.
• The exact number of samples (n) should be included for each figure panel presenting multiple samples. If bar charts are appropriate, number of samples may be embedded within each bar of the figure.
• The statistical test used should be indicated in each figure legend.

Discussion
This is an important part of the manuscript but it should not be too long, usually no more than three pages. The Discussion should normally follow the pattern below:
State main findings - This does not mean a repetition of all the results with their statistics. It should provide a concise overview of the study. For example, 'Drug X produced a greater haemodynamic change on induction of anaesthesia than occurred with drug Y, resulting in a greater fall in arterial pressure and a higher incidence of tachycardia'. Do not repeat data already presented in the Results, figures and tables.
Relation to previous studies - This section should relate directly to the statements made in the Introduction and qualify your findings in relation to previous studies of the subject. Mention any important uncertainties in the methods of measurement. In laboratory studies, try to relate the concentrations used to those encountered clinically.
Why are they different/same - Avoid excessive speculation or speculation beyond your results. It is quite reasonable to suggest possible explanations for your findings and any differences from previous studies, but the 'missing parts' of such reasoning must be acknowledged.
Additions to knowledge of the subject - Summarise previous sections by pulling together the implications of your main findings, studies by other workers and their combined contribution to our knowledge of the subject. This should not be just another repetition of the results and preceding discussion but more of an expanded conclusion. A meta-analysis incorporating the results of the new study as well as previous relevant studies could be included in this paragraph.
Weaknesses and strengths in study - This is the most important part of the Discussion. Acknowledge any limitations of your study at this point. Examples here could include the generalisability of the patient population, patients lost to follow-up, limitations of analytical test etc. Authors are advised to be honest but succinct in this section. It is also reasonable to comment briefly on the particular strengths of the study, especially in comparison to comparable studies.
Future studies - Identify future studies that would address some of the potential explanations and limitations discussed earlier. This section should be very brief.
Conclusions - The original contribution to knowledge from the present study should be stated. A common fault here is to overstate the findings from a study. It may be appropriate to give the implications of the conclusions for anaesthetic practice and the indications for further enquiry in this area of interest.

Acknowledgements
Collate acknowledgements in a separate section at the end of the article before the references and do not on the title page, as a footnote to the title or otherwise. List here those individuals who provided help during the research (e.g., providing language help, writing assistance or proof reading the article, etc.). The contributors, who do not meet the criteria for authorship, as determined by the ICMJE and given in the section on BJA Policies, should be listed in the Acknowledgements section. You may acknowledge contributors, who do not justify authorship, under headings such as 'clinical investigators', 'participating investigators', 'served as scientific advisors', 'critically reviewed the proposal', 'collected data', or 'provided care for study patients'. Individuals should be identified by first initial, surname, institution and city only.

Declaration of interests
Each manuscript must contain a declaration of interests from ALL authors. This should include all possible interests in the past five years. This is obviously most common in studies involving new equipment or drugs, but other areas such as advisory bodies are also relevant. For example: 'Dr A has received an honorarium from Company X. Dr B has received a travel grant from Company Y. Prof C is a member of the national advisory committee on Z.'
You are required to declare all authors' interests at the time of submitting your manuscript by completing and uploading the conflict of interest form, available to download here in Word or PDF format, along with your manuscript. Failure to do so will lead to delays in the processing of the manuscript. Please make sure that information from all authors has been included before uploading, even if there are no interests to be declared. A form must be submitted even if there is no conflict of interest. The corresponding author of an article acts as guarantor and must ensure that this criterion is fulfilled and a full conflicts of interest statement is supplied to the Journal. If there are no interests to declare then please state: 'The authors declare that they have no conflict of interest' (if there are multiple authors) or 'The author declares that they have no conflicts of interest' (if it is a single-authored paper). Simply stating 'None' or 'None declared' is not sufficient.

Declaration of Generative AI in scientific writing
The below guidance only refers to the writing process, and not to the use of AI tools to analyse and draw insights from data as part of the research process.

Where authors use generative artificial intelligence (AI) and AI-assisted technologies in the writing process, authors should only use these technologies to improve readability and language. Applying the technology should be done with human oversight and control, and authors should carefully review and edit the result, as AI can generate authoritative-sounding output that can be incorrect, incomplete or biased. AI and AI-assisted technologies should not be listed as an author or co-author, or be cited as an author. Authorship implies responsibilities and tasks that can only be attributed to and performed by humans, as outlined in Elsevier's AI policy for authors.

Authors should disclose in their manuscript the use of AI and AI-assisted technologies in the writing process by following the instructions below. A statement will appear in the published work. Please note that authors are ultimately responsible and accountable for the contents of the work.

Disclosure instructions
Authors must disclose the use of generative AI and AI-assisted technologies in the writing process by adding a statement at the end of their manuscript in the core manuscript file, before the References list. The statement should be placed in a new section entitled `Declaration of Generative AI and AI-assisted technologies in the writing process'.

Statement: During the preparation of this work the author(s) used [NAME TOOL / SERVICE] in order to [REASON]. After using this tool/service, the author(s) reviewed and edited the content as needed and take(s) full responsibility for the content of the publication.

This declaration does not apply to the use of basic tools for checking grammar, spelling, references etc. If there is nothing to disclose, there is no need to add a statement.

Funding
It is essential to acknowledge all sources of financial assistance, and any potential material benefit expected from publication of the work. Also, please describe the role of the study sponsor, if any, in study design, collection, analysis and interpretation of data, writing the report, and the decision to submit the report for publication. Details of all funding sources for the work in question should be given in a separate section entitled Funding. The following rules should be followed:

• The sentence should begin: 'This work was supported by …'
• The full official funding agency name should be given (one of the 27 institutes), i.e. 'National Institute for Academic Anaesthesia', not 'NIAA' or 'NCI at NIH' (full RIN-approved list of UK funding agencies).
• Grant numbers should be complete and accurate and provided in brackets as follows: '[grant number ABX CDXXXXXX]'.
• Multiple grant numbers should be separated by a comma as follows: '[grant numbers ABX CDXXXXXX, EFX GHXXXXXX]'.
• Agencies should be separated by a semi-colon (plus 'and' before the last funding agency).
• Where individuals need to be specified for certain sources of funding the following text should be added after the relevant agency or grant number 'to [author initials]'.

An example is given here: 'This study was funded by a small project grant from The Royal College of Anaesthetists (07/123) (AB). Equipment was provided by a project grant from British Journal of Anaesthesia/RCoA (06/321) (CD).'

Elsevier will deposit all NIH-funded articles in PubMed Central. Authors must ensure that manuscripts are clearly indicated as NIH-funded using the guidelines above.

Authors' contributions
All manuscripts submitted to the BJA must inform readers of the individual contributions of each author to the research and/or manuscript. Please give initials of the names of each author (i.e. RD, IKM), and against their initials list the contributions which they individually made to the work (i.e. RD: Study design and data analysis; IKM: Patient recruitment, data collection and writing up of the first draft of the paper). The BJA follows recommendations of the ICMJE. To comply with ICMJE recommendations, all the authors must meet all of the following four conditions:

• substantial contribution to conception and design, acquisition of data, or analysis and interpretation of data;
• drafting the article or revising it critically for important intellectual content;
• final approval of the version to be published; and
• agreement to be accountable for all aspects of the work thereby ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Footnotes
Footnotes should be used sparingly. Number them consecutively throughout the article. Many word processors can build footnotes into the text, and this feature may be used. Otherwise, please indicate the position of footnotes in the text and list the footnotes themselves separately at the end of the article. Do not include footnotes in the Reference list.

References
Except for review articles, long lists of references are usually inappropriate. Please avoid inappropriate and/or excessive self-citations. Appropriate self-citations are welcome.

• References must be numbered consecutively in the order in which they are first mentioned in the text.
• References in text, tables and legends should be identified by Arabic numbers appearing in the text in superscript, for example ⁵ or ^5-7 or ^{5, 16} for unrelated references.
• Papers that do not conform to the BJA style will be returned to the authors for re-typing. The scope for major printer's errors in attempting to rectify inappropriate schemes is considerable.
• References in the text. In general, it is not necessary to cite names of the authors of a study in the text (in addition to the identifying number) as it disrupts the flow of the text. If it is felt to be essential, up to two names should be cited (A; B and C). In the case of three or more authors, 'G and colleagues', 'G and co-workers', 'G and others' are acceptable. The expression 'et al. ' should not be used in the text.
• An informal reference to previous work (Z's study or Y's study) is permissible only in a paragraph that contains the reference cited formally.
• Abstracts that are more than two years old should not be used as references.
• Text references to 'unpublished observations' or 'personal communications' should not be included in the final list of references. Personal communications may be cited in the text as (Brown AB, personal communication, year). Authors are responsible for verifying that the wording of references to unpublished work is approved by the persons concerned. This should be provided in writing with the first submission of the manuscript.
• Papers that have been submitted and accepted for publication should be included in the list, with the phrase 'in press' replacing volume and page number. Authors should be prepared to give the volume and page number at the time of proof correction. Abstracts should also be sent with the original submission.
• Information from manuscripts submitted but not yet accepted should be cited in the text as unpublished observations.
• There should be a list of references at the conclusion of the paper, commencing on a new sheet.
• Journals. Names and initials of six authors (if more than six, list three followed by et al.), title of paper, approved abbreviated title of journal, year of publication, volume number, first and last page numbers:
  Myles PS, Chan MTV, Leslie K, Peyton P, Paech M, Forbes A. Effect of nitrous oxide on plasma homocysteine and folate in patients undergoing major surgery. Br J Anaesth 2008; 100: 780-6.
• Chapter in a book. The reference for an article forming part of a book should take the form:
  Wildsmith JAW. Local anaesthetic agents. In: Aitkenhead AR, Smith G, Rowbotham DJ, eds. Textbook of Anaesthesia. Edinburgh: Churchill Livingstone Elsevier, 2007; 52-63.
• Electronic source (web site/web page):
  Department of Health. Monthly Creutzfeldt-Jakob disease statistics 2002/0341 2002. Available from http://www.doh.gov.uk/cjd/stats/aug02.htm (accessed 30 March 2010).
• Online journal article:
  Lander JA, Weltman BJ, So SS. EMLA and amethocaine for reduction of children's pain associated with needle insertion. Cochrane Database Syst Rev 2006; 3: CD004236.
• Proceedings:
  O'Rourke K. Mixed means and medians: a unified approach to deal with disparate outcome summaries. Proceedings of the Symposium on Systematic Reviews: Pushing the Boundaries. Oxford: 2002; 49.
• Report:
  Royal College of Anaesthetists and Royal College of Radiologists. Sedation and Anaesthesia in Radiology. Report of a joint working party, London, 1992.
• Advance access article:
  Qiao D, Chen W, Stratagoules E, Martinez J. Bile acid-induced activation of activator protein-1 requires both extracellular signal-regulated kinase and protein kinase C signaling. J Biol Chem Advance Access published on May 19, 2000, doi:10.1074/jbc.M908890199.

It is a serious error to include in the list of references items that are not accurate or have been retracted. It is essential, therefore, that authors check the accuracy of all references listed. It is important also to check that the references listed do indeed appear in the text and vice versa.

Units, symbols and abbreviations
The BJA uses the SI system of units with a few notable exceptions (pH and intravascular and ventilatory pressure measurements, which should be given in units of calibration, e.g. mm Hg, cm H₂O). Blood-gas tensions and the partial pressures in the gas phase should be given in the appropriate SI unit (kPa for kilopascal). Readers are referred to Units, Symbols and Abbreviations. A Guide for Biological and Medical Editors and Authors, 6th Edn. Baron DN and Clarke HM, ed. (2008), CRC Press.
Avoid the use of the solidus (/) in favour of units of the expression set on one line. In the case of expressions 'below the line' superscript -1, -2, etc. as appropriate is given. Thus for drug dosage use mg kg ^-1 not mg/kg.

Gene nomenclature and style
Please refer to the NC-IUPHAR (the International Union of Basic and Clinical Pharmacology Committee on Receptor Nomenclature and Drug Classification) nomenclature guidelines at https://www.guidetopharmacology.org/nomenclature.jsp

Video
The BJA accepts video material and animation sequences to support and enhance your scientific research. Authors who have video or animation files that they wish to submit with their article are strongly encouraged to include links to these within the body of the article. This can be done in the same way as a table or figure by referring to the video or animation content and noting in the body text where it should be placed. All submitted files should be properly labelled so that they directly relate to the video file's content. In order to ensure that your video or animation material is directly usable, please provide the file in one of our recommended file formats with a preferred maximum size of 150 MB per file, 1 GB in total. Video and animation files supplied will be published online in the electronic version of your article in Elsevier Web products, including ScienceDirect. Please supply 'stills' with your files: you can choose any frame from the video or animation or make a separate image. These will be used instead of standard icons and will personalize the link to your video data. For more detailed instructions please visit our video instruction pages. Since video and animation cannot be embedded in the print version of the journal, please provide text for both the electronic and the print version for the portions of the article that refer to this content.

Research Data
The BJA encourages and enables you to share data that supports your research publication where appropriate, and enables you to interlink the data with your published articles. Research data refer to the results of observations or experimentation that validate research findings. To facilitate reproducibility and data reuse, the BJA also encourages you to share your software, code, models, algorithms, protocols, methods and other useful materials related to the project. Below are a number of ways in which you can associate data with your article or make a statement about the availability of your data when submitting your manuscript. If you are sharing data in one of these ways, you are encouraged to cite the data in your manuscript and reference list. Please refer to the "References" section for more information about data citation. For more information on depositing, sharing and using research data and other relevant research materials, visit the research data page.

Data linking
If you have made your research data available in a data repository, you can link your article directly to the dataset. Elsevier collaborates with a number of repositories to link articles on ScienceDirect with relevant repositories, giving readers access to underlying data that gives them a better understanding of the research described.
There are different ways to link your datasets to your article. When available, you can directly link your dataset to your article by providing the relevant information in the submission system. For more information, visit the database linking page. For supported data repositories a repository banner will automatically appear next to your published article on ScienceDirect. In addition, you can link to relevant data or entities through identifiers within the text of your manuscript, using the following format: Database: xxxx (e.g., TAIR: AT1G01020; CCDC: 734053; PDB: 1XFN).

Data deposit and linking
The BJA encourages and supports authors to share raw data sets underpinning their research publication where appropriate and enables interlinking of articles and data. More information on depositing, sharing and using research data.

Offprints
The corresponding author will, at no cost, receive a customized Share Link providing 50 days free access to the final published version of the article on ScienceDirect. The Share Link can be used for sharing the article via any communication channel, including email and social media. For an extra charge, paper offprints can be ordered via the offprint order form which is sent once the article is accepted for publication. Both corresponding and co-authors may order offprints at any time via Elsevier's Webshop. Corresponding authors who have published their article gold open access do not receive a Share Link as their final published version of the article is available open access on ScienceDirect and can be shared through the article DOI link.

Correspondence
Each issue of the Journal contains Correspondence (Letters to the Editor). We aim to publish Correspondence arising from papers in a recent issue online with the minimum of delay, and for this reason such Correspondence will be given priority. The Editor may change, delete or modify in any way all items of Correspondence. Correspondence unrelated to a published article can also be submitted. Correspondence must be submitted via the regular submission process using the online submission web site. This includes studies that have received a 'Submit as a letter' decision, Case Reports or topics of general interest. A corresponding author should provide a contact e-mail. When you submit an item of Correspondence, you agree to the following which may be amended from time to time:

• The Editor-in-Chief has absolute discretion whether to publish Correspondence or not. The Editor-in-Chief and Elsevier also reserve the right to edit Correspondence items before and after publication without consulting the author.
• Accepted Correspondence pieces are published online as part of a regular issue of the BJA and will be referenced in the table of contents for that issue.
• If patients could be recognised from your description or from any images in a Case Report or letter, you must obtain their written consent to publication before sending your comment and forward the original signed print version immediately to the Editor-in-Chief. It is highly unlikely that a case report will be accepted for publication without written consent. You should explicitly confirm in the body of your comment that such written consent has been obtained.
• If your Correspondence reports a research study, you must confirm in the body of the report itself that appropriate research approvals were obtained. Failure to do this will result in rejection of the comment.
• Your submission must be original and not infringe any third party's intellectual property rights.
• You must declare any competing interests (financial or otherwise).
• Once your Correspondence has been published in the print or online version of the journal, you will not have the right to have it removed or edited.
• Upon receipt of an accepted piece of Correspondence at Elsevier, authors will be invited to complete an online Journal Publishing Agreement.

Advertising
Editorial decisions of the BJA are taken separately from, and not influenced by, advertising or any related revenue. The Journal makes all possible efforts to refuse advertisements that are misleading. The publication of an article about a product, alongside an advertisement of the product, if it occurs, is purely co-incidental.

Complaints
Authors who may have a complaint against any of the aspects of their interaction with the BJA should, in the first instance, e-mail the Editor responsible for handling the manuscript. In case that does not resolve the issue, the complaint should be forwarded to the Editor-in-Chief. The Editors and Editor-in-Chief aim to acknowledge the complaint within 7 days after receiving it and will explain to the author the procedure that they will be undertaking to resolve the matter.

Corrections
If errors are noted in an article published in an issue, and these require publication of a correction, the corrections will appear on a numbered page and be listed in the Table of Contents as a Corrigendum.

Manuscripts authored by a member of Editorial Board
Manuscripts authored by Editors or members of Editorial Board are treated no differently to any other manuscript submitted to the BJA. All possible measures are undertaken to avoid any potential conflict of interest in handling of such manuscripts at all the stages including allocation of handling Editor, selection of reviewers, decision making and, if required, processing for publication.

Media release
Authors should not release stories related to their work prior to publication of their paper in the Journal. If authors and/or Editors consider particular work suitable for media release, they should discuss it among themselves and agree on a planned media release and publication. In case of agreed media release, the Editors will plan with the authors the way in which they can help the media in preparing accurate reports by providing news releases, answering questions, or referring reporters to relevant experts. This assistance will be contingent on the media's cooperation in timing the release of a story to coincide with publication of the article.

Misconduct/Retractions
All manuscripts submitted to the BJA undergo plagiarism check using commercial software. Based on the findings of the check, Editors may ask authors to address any minor duplication, or similarity, that the contents of their manuscript may have to any previously published work (even though it may be author's own previously published work). However, severe cases of plagiarism amount to 'misconduct', and these cases will be dealt with as such. The reviewers and the Editors initially assume that authors are reporting work based on honest observations. However, if substantial doubt arises about the honesty or integrity of work, either submitted or published, the Editor will inform the authors of the concern, seek clarification, and pursue the issue with the author's sponsoring body and/or employing authority. Consequently, if the sponsoring body and/or employers find a published paper to be fraudulent, the Journal will print a retraction. If, however, this method of investigation does not result in a satisfactory conclusion, the Editor may choose to conduct his or her own investigation, and may choose to publish an expression of concern about the aspects of the conduct or integrity of the work. The validity of previous work by the author of a fraudulent paper cannot be assumed. Editors may ask the author's institution to assure them of the validity of earlier work published in their journal or to retract it. If this is not done, Editors may choose to publish an announcement expressing concern that the validity of previously published work is uncertain. The BJA adheres to the COPE guidelines for publication ethics (https://publicationethics.org).

Author Enquiries
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