Background
Prehospital emergency anaesthesia (PHEA) is one of the most important interventions we deliver in the pre-hospital setting. Over the years, the technique of RSI has been adapted to the prehospital setting, and there are now very good guidelines and governance structures around its delivery. However, while substantial literature focuses on preparation and induction of PHEA, the maintenance phase—that involves uninterrupted sedation, analgesia, and haemodynamic stability—has received relatively little attention. This week we have a study that seeks to address the variability in maintenance practices and governance across prehospital and retrieval services in Australia, New Zealand, and the UK. The paper abstract is below, but as always we recommend you read the full paper yourself and come to your own conclusions. Whilst this paper is about pre-hospital post RSI sedation, I think the principles apply just as well to emergency department anaesthesia/sedation *(where I perhaps see even greater variability in practice), and so this is relevant to a broad range of clinicians
Abstract
Background: Literature on prehospital anaesthesia predominantly focuses on preparation and induction, while there is limited guidance on anaesthesia maintenance. The hypothesis of this study was that for prehospital trauma patients, protocols and practice for anaesthesia maintenance may vary considerably between services. Hence, we sought to describe the practice of prehospital anaesthesia maintenance for trauma patients in Australia, New Zealand, and the UK.
Methods: An online practice survey of prehospital and retrieval services in Australia, New Zealand, and the UK was conducted from May to September 2022. Branching logic of between five and 140 questions covered services’ background information, protocols relating to anaesthesia maintenance, and perceived effectiveness and governance.
Results: Forty-two services were approached with an 81% response rate. While most services (88%) had some form of maintenance protocol, only 14% had one specific for trauma patients. Most services (61%) used a combination of intermittent boluses and continuous infusions. Ketamine and midazolam were the favoured hypnotics, and fentanyl the favoured opioid. However, there was considerable variation in drug selection and dosing, and in the detail contained within protocols. There was high self-reported confidence in effectiveness and governance of anaesthesia maintenance practices.
Conclusions: Protocols for anaesthesia maintenance in prehospital trauma patients show considerable variation in content and detail across the surveyed services. Further consideration of pharmacokinetics and the specific aims of anaesthesia maintenance is warranted. More research is needed to establish the optimal choice of drugs, dosing, de- livery, and adjustment criteria for anaesthesia maintenance in prehospital trauma patients.
Sheridan, B., & Perkins, Z. (2025). Maintenance of prehospital anaesthesia in trauma patients: inconsistencies and variability in practice. BJA Open, 13(C), 100366.
What Kind of Study Is This?
This is a cross-sectional multinational practice survey conducted between May and September 2022. Using the REDCap electronic data capture tool, the survey targeted clinical directors of prehospital and retrieval services performing PHEA for trauma patients. Following pre-testing and iterative refinement, the survey was distributed to 42 services, achieving an 81% response rate. The methodology adhered to the CROSS (Consensus-based Checklist for Reporting of Survey Studies) guidelines.
Tell Me About the Who was Included?
Although this was a survey of service practices rather than a direct study of patients, the survey focused on trauma patients undergoing PHEA following RSI. The typical patient population includes those with severe injuries necessitating intubation and anaesthesia during prehospital care. Notably, the study acknowledged significant heterogeneity in patient presentations, such as haemodynamic instability, ongoing pain, and altered physiology.
It’s a little uncertain how the services themselves were recruited and so this may be a biased sample (as the authors admit) of services accessible to the UK authors and with a strong anglophile engagement. Similarly, there was little opportunity to delve into how paediatric practice may differ. From a purely critical appraisal perspective, this is a convenience sample rather than a systematic approach.
What Were the Measured Outcomes in This Study?
The study aimed to describe current practices in the maintenance of anaesthesia post-RSI, with specific attention to:
- Presence and specificity of maintenance protocols.
- Drug selection, dosing, and administration methods.
- Timing and adjustments of maintenance regimens.
- Clinician-reported effectiveness and governance practices.
What Are the Main Results?
- Protocol Availability:
- 82% of responding services have protocols for anaesthesia maintenance.
- 4% had protocols specifically tailored to trauma patients.
- Methods of Maintenance:
- 61% used a combination of intermittent boluses and continuous infusions.
- 21% relied solely on continuous infusions, while 18% used only intermittent boluses.
- Drug Selection:
- Ketamine and midazolam were the most commonly used hypnotics.
- Fentanyl was the preferred opioid, with morphine used less frequently.
- Rocuronium was the sole neuromuscular blocking agent mentioned.
- Perceived Effectiveness:
- Most services rated their protocols as effective or very effective.
- Governance:
- The majority of services reported spending some time discussing maintenance practices in governance meetings.
Can we believe the findings?
I think we can believe that there is variability, and to a large extent that is the main point of the paper. As to whether the specific data is representative of UK and/or international practice then we can be less certain.
- Geographic and System Limitations: The survey’s focus on English-speaking countries (Australia, New Zealand, and the UK) limits generalisability to other regions and healthcare systems.
- Self-reported Data: Perceptions of effectiveness and governance are subjective and susceptible to social desirability bias.
- Heterogeneity in Responses: Wide variability in dosing, timing, and methods of administration suggests inconsistent application of pharmacokinetic principles.
- Lack of Direct Patient Data: While informative, the survey does not provide clinical outcomes to validate perceived effectiveness.
Should We Change Practice Based on This Study?
This study highlights considerable variability in the maintenance of prehospital anaesthesia, which may suggest that we need greater standardisation and evidence-based guidelines. However, the lack of direct patient outcome data limits the ability to draw definitive conclusions about optimal practices. So at the moment, there is not enough here to definitively state that we should change practice to a specific regime, but it would be reasonable for services to critically appraise their own protocols, ensuring they consider both pharmacokinetic and pharmacodynamic principles while prioritising individualised patient care.
It appears that the authors are in favour of infusions to maintain anaesthesia in trauma patients. There are some interesting graphs looking at the pharmacodynamics of ketamine and midazolam with and without infusion that lend weight to an argument for ongoing maintenance with infusions (likely ketamine), and there are some strong arguments against intermittent bolus anaesthesia with it’s resulting peaks and troughs of plasma drug concentration.
It’s also worth reviewing how we adjust drugs against actual, ideal, and lean body weight. LITFL have a good article on this that you can read here. For our most common emergency anaesthesia drugs LITFL suggests the following.
- Fentanyl – Dose on LBW at induction
- Midazolam – TBW for induction, then IBW for infusion
- Rocuronium – IBW
Interestingly Ketamine is not listed in that table and is also not in many of the guidelines I have seen. A quick twitter ask revealed this paper which suggests that we should use an ideal or adjusted body weight is suggested.
Of course all of this is predicated on us knowing the weight of the patient, which if course we usually don’t and so all drugs are probably a little vague.

Summary
This paper shows the significant variability in protocols for maintaining prehospital anaesthesia in trauma patients. While most services report confidence in their practices, there is a lack of specific, evidence-based guidelines to support this. However, what’s really lacking is some patient related outcomes for research in this area. There are opportunities to do so, looking at awareness and cardiovascular stability might be good places to start.
References and further reading
- Sheridan, B., & Perkins, Z. (2025). Maintenance of prehospital anaesthesia in trauma patients: inconsistencies and variability in practice. BJA Open, 13(C), 100366.
- Crewdson, K., et al. (2019). Best practice advice on pre-hospital emergency anaesthesia. Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine, 27, 6.
- McQueen, C., et al. (2015). Prehospital anaesthesia performed by physician/critical care paramedic teams. Emergency Medicine Journal, 32, 65-69.
- Hodkinson, M., & Poole, K. (2023). Induction of pre-hospital emergency anaesthesia: a national survey of UK HEMS practice. BMC Emergency Medicine, 23, 126.
- Erstad, B.L., Barletta, J.F. Drug dosing in the critically ill obese patient—a focus on sedation, analgesia, and delirium. Crit Care 24, 315 (2020). https://doi-org.manchester.idm.oclc.org/10.1186/s13054-020-03040-z
- Devlin, J. W., et al. (2018). Clinical practice guidelines for the prevention and management of pain, agitation, and delirium in critically ill adults. Critical Care Medicine, 46, e825-e873.
- Sharma, A., et al. (2021). A consensus-based checklist for reporting of survey studies (CROSS). Journal of General Internal Medicine, 36, 3179-3187.
- Morton S, Spurgeon Z, Ashworth C, Samouelle J, Sherren PB.Scand J Trauma Resusc Emerg Med. 2024 Feb 12;32(1):12. doi: 10.1186/s13049-024-01183-4.PMID: 38347604
- Predictors of post-intubation hypotension in trauma patients following prehospital emergency anaesthesia: a multi-centre observational study.
- Price J, Moncur L, Lachowycz K, Major R, Sagi L, McLachlan S, Keeliher C, Steel A, Sherren PB, Barnard EBG.Scand J Trauma Resusc Emerg Med. 2023 Jun 2;31(1):26. doi: 10.1186/s13049-023-01091-z.PMID: 37268976
- The Prehospital Emergency Anaesthetic in 2022.
- Morton S, Dawson J, Wareham G, Broomhead R, Sherren P.Air Med J. 2022 Nov-Dec;41(6):530-535. doi: 10.1016/j.amj.2022.08.003. Epub 2022 Sep 22.PMID: 36494168
- Pre-hospital emergency anaesthesia in trauma patients: An observational study from a state-wide Australian pre-hospital and retrieval service.
- Maclure P, Gluck S, Kerin K, Boyle L, Ellis D.Emerg Med Australas. 2022 Oct;34(5):711-716. doi: 10.1111/1742-6723.13969. Epub 2022 Mar 30.PMID: 35355423