Article Text

Should non-anaesthetists perform pre-hospital rapid sequence induction? an observational study
  1. J N Fullerton1,
  2. K J Roberts1,2,
  3. M Wyse1,2
  1. 1University Hospital Coventry and Warwickshire NHS Trust, Coventry, UK
  2. 2Warwickshire and Northamptonshire Air Ambulance, Princethorpe, Warwickshire, UK
  1. Correspondence to Dr James Fullerton, 39 Westhill Close, Selly Oak, Birmingham B29 6QQ, UK; james.fullerton{at}doctors.org.uk

Abstract

Introduction The use of rapid sequence induction and tracheal intubation (RSI) in the pre-hospital environment is controversial. Currently, it is felt that competence to perform RSI should be defined by skills in anaesthesia not by the primary speciality of a practitioner. This aim of the study was to evaluate the tracheal intubation success rate of doctors drawn from different clinical specialities performing RSI in the pre-hospital environment.

Method Retrospective review of all RSI performed by doctors operating on the Warwickshire and Northamptonshire Air Ambulance over a 5-year period. Tracheal intubation failure rates were calculated and analysed for proportional differences between groups by χ2 and, where appropriate, Fisher's exact test.

Results 4362 active missions were flown. RSI was performed in 200 cases (4.6%, 3.1/month). Successful intubation occurred in 194 cases, giving a failure rate of 3% (6 cases, 95% CI 0.6 to 5.3%). While no difference in failure rate was observed between emergency department (ED) staff and anaesthetists (2.73% (3/110, 95% CI 0 to 5.7%) vs 0% (0/55, 95% CI 0 to 0%); p=0.55), a significant difference was found when non-ED, non-anaesthetic staff (GP and surgical) were compared to anaesthetists (10.34% (3/29, 95% CI 0 to 21.4%) vs 0%; p=0.04). There was no significant difference associated with seniority of practitioner (p=0.65).

Conclusions Non-anaesthetic practitioners have a higher tracheal intubation failure rate during pre-hospital RSI. This likely reflects a lack of training opportunities and infrequency of clinical experience. Strategies to improve pre-hospital airway management are required.

  • Helicopter emergency medical services
  • airway management
  • intubation
  • rapid-sequence induction
  • airway
  • anaesthesia
  • RSI
  • prehospital care
  • prehospital care
  • doctors in PHC

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Rapid sequence induction and tracheal intubation (RSI) utilising sedative and muscle-relaxant drugs may represent a life-saving procedure in the pre-hospital environment. In cases of severe acute illness and injury, the provision of a secure airway, adequate oxygenation and ventilation may be achieved, and patient analgesia, stabilisation and transport are facilitated. RSI is not without risk, however, and concerns over attendant morbidity persist. Reports of transient hypoxia and pulse lability, and more seriously, failed, missed oesophageal or right-main bronchus intubation have raised questions about who should perform RSI1 2 and even whether it has a role in pre-hospital care.3–6

In the UK, RSI may only be performed by medically qualified practitioners. In order to reduce the procedure-associated risk, recommendations stipulating minimum skill and experience requirements for those practicing pre-hospital anaesthesia have recently been established by the Association of Anaesthetists of Great Britain and Ireland (AAGBI)7 and generic guidelines to aid the management of the difficult airway and failed intubation formulated.8 Reported data suggest a failed intubation rate ranging from 0.1–3% in the pre-hospital environment dependant on practitioner experience and definition.9–11 Currently, it is not felt that the primary speciality of the medical practitioner should determine RSI competence.7

The Warwickshire and Northamptonshire Air Ambulance (WNAA) attends a full-range of pre-hospital emergencies either as a primary responder or to back-up a crew already on-scene. Doctors flying with WNAA are drawn from a range of clinical specialities but all conform to established criteria (see appendix 1which can be accessed online only) and follow standard operating protocols (online only appendix 2; WNAA RSI protocol). The service thus offers a paradigm to directly evaluate and compare the performance of RSI by doctors from different primary specialities.

Methods

A retrospective review of continuous WNAA activity over a 64-month period (October 2003 to January 2009) was conducted. Mission data were recorded contemporaneously on a central Microsoft Access® database. All cases of RSI were identified, extracted and subjected to analysis. Patients who did not receive an induction agent or muscle relaxant were excluded.

Population and setting

WNAA is based in the UK, serving a mixed urban and rural population in excess of 1.2 million. WNAA operates one helicopter operating 10 h a day, 7 days a week during daylight hours. The flight crew consists of a pilot, paramedic and usually a doctor. When a doctor is not available, the second crewmember is a paramedic. Allocation of crew-mix and medical practitioner is dependant on availability of staff rather than a mission category specific basis. RSI is not performed by double paramedic crews in the absence of a doctor.

Over the study period, 15 doctors operated on WNAA. These were predominantly drawn from anaesthetics (8) and emergency medicine (5). One surgical trainee and military general practitioner (GP) were also active. All the doctors on the unit were considered RSI competent. This was based on either having current and ongoing hospital or pre-hospital exposure to RSI or they were placed through a period of operating theatre-based training followed by supervised practice in the field.

Standard operating protocol

WNAA standard operating protocols act as guidelines indicating which patients are suitable for RSI and what pharmacological agents should be employed (see online only appendix 2). They aim to standardise practice, facilitate audit and ensure universally high-quality care is provided.

The protocol suggests that those with a Glasgow Coma Score level ≤8, actual or impending airway difficulty, likely ventilatory failure, severe shock or burns and/or injuries causing severe agitation or distress such that transport and clinical management would be impaired, should be considered eligible for RSI. Etomidate and suxamethonium represent the principle induction agent and short-term muscle relaxant, with morphine and midazolam or propofol being used to maintain sedation and rocuronium to maintain relaxation. Routine monitoring of vital signs is obligatory. The equipment provided for intubation included Macintosh size 3 and 4 blades and a single use bougie for all intubations, immediately available to the operator were a Miller blade (straight) and a single use McCoy blade. A range of single use supra-glottic airways (LMA Unique) were available as first-line back-up devices and the equipment to perform a surgical cricothyroidotomy was available for the cannot intubate cannot ventilate scenario.

Despite the existence of standard operating protocols, it is recognised that no two clinical scenarios are the same. While encouraging comparable practice between practitioners, the decision to perform RSI and how to achieve it are at the discretion of the attending clinician.

Outcome and analysis

The main outcome measure was successful tracheal intubation. Correct endotracheal tube (ETT) placement was confirmed by the presence of three criteria—observation of chest movement, auscultation of axillae and epigastrium and either end-tidal carbon dioxide monitoring or in the event of equipment failure or unavailability, colourimetric capnography12 (Nellcor Easy Cap II©, Tyco, Boulder, Colorado, USA). Failure to intubate was declared if >2 successive attempts were required to achieve intubation or a ETT could not be placed correctly necessitating the use of an alternate airway. Data were self-reported after cross-checking with team members. It was assumed that the attending WNAA doctor performed the tracheal intubation and was successful on the first attempt if not explicitly stated otherwise.

Differences in failure rates between groups of practitioners, as defined by primary speciality and seniority, were subsequently assessed. Groups were divided in terms of speciality into anaesthetists, ED doctors and other specialities (GP and surgery) and by speciality into career grade (consultants and staff grades) and trainees (specialist registrars). An additional heterogeneous group of all practitioners for whom anaesthetics was not their primary speciality (ED, GP and surgery) was also used as a comparator. Proportional differences between discrete variables were tested for by χ2 and Fisher's exact test13 as appropriate with significance being accepted as p≤0.05. A qualitative appraisal of failed cases was conducted including a review of morbidity as determined by vital signs and mission narrative. Demographic information was collated.

The same dataset was previously interrogated regarding intubation success at out of hospital cardiac arrests.14 Overlap exists in seven cases where RSI occurred as part of post-cardiac arrest management. No failures to intubate were reported in this group. Ethical approval was not sought for the study as it conforms to a service evaluation definition.15

Results

Incidence of RSI and failure rate

Four thousand, three hundred and sixty-two active missions were flown over the study period. RSI was performed in 200 (4.59%) cases, with a frequency of 3.1/month. The average age of those requiring RSI was 42.8 years (range 4 to 88 years), with 69.6% being men.

Successful intubation occurred in 194 cases, giving a failure rate of 3% (6 cases, 95% CI 0.6 to 5.3%). In three cases, >2 attempts to pass an ETT were required, and in three, there was an absolute inability to intubate necessitating an alternative airway. A laryngeal mask airway (LMA) was employed in one case (0.5%) and surgical airways utilised in the remaining two (1%). No primary surgical airways were reported.

The most common mechanisms of injury were road traffic collisions (RTC; driver/passenger 99 (49.3%), pedestrian 13 (6.5%)) and falls from height (22 (10.9%)). Traumatic aetiology in total accounted for 155 cases (77.5%), with medical pathology (collapse, post-cardiac arrest, respiratory distress, seizure, overdose) representing the remainder. No significant difference in failure to intubate was observed between traumatic and medical cases (3.2% (5/155) vs 2.2% (1/45); p=1).

Practitioner speciality and seniority variability

The majority of RSI were performed by ED staff (55%, 110), followed by anaesthetists (27.5%, 55). Other specialities accounted for 14.5% (29) of cases. In six cases, the identity of the practitioner was not identified (see table 1).

Table 1

Speciality and grade of the practitioner performing RSI

No significant difference in failure of intubation was observed between either ED staff and anaesthetists (2.73% (3/110, 95% CI 0 to 5.7%) vs 0% (0/55, 95% CI 0 to 0%); p=0.55) or ED staff and other specialists (2.73% vs 10.34% (3/29, 95% CI 0 to 21.4%); p=0.11). The same was true of anaesthetists in comparison with combined other specialities (non-anaesthetists; 0% vs 4.32% (6/139, 95% CI 0.9 to 7.7%); p=0.19). However, when the performance of non-ED, non-anaesthetist staff (GP and surgical) were compared to anaesthetists, a significantly higher failure rate was seen (10.34% vs 0%; p=0.04). While career grades had a lower failure rate than trainees, no significant difference was apparent (2.78% (4/144, 95% CI 0.1 to 5.5%) vs 4.0% (2/50, 95% CI 0 to 9.4%); p=0.65).

No mortality was associated with RSI in the study group. Morbidity was best judged from individual case narratives, it often being impossible to delineate pathology from pharmacological side effects by analysis of observations alone. Successful intubation was associated with post-procedural hypotension (to <90 mmHg systolic) in 1% (2) of cases. ETT cuff failure was reported in a further 1% and monitoring failure secondary to climatic conditions occurred in another (one case, 0.5%). Morbidity was reported in two cases where failed intubation occurred, including one case of oesophageal intubation (see table 2).

Table 2

Cases of failed intubation

Discussion

Our data, if taken as representative, indicate that RSI is performed relatively infrequently by provincial air ambulance services and in response to a multitude of pathologies in contrast to trauma-focused centres.10 Individual pre-hospital practitioner exposure to tracheal intubation is thus limited and varied, unless forming a core part of their regular practice. We report an overall failure to intubate rate of 3%. This is directly comparable with other pre-hospital groups10 11 16 yet remains considerably higher than RSI in the anaesthetic room (0.1–0.4%) or emergency department (1%).17 18

Several factors have been shown to independently influence difficulty of intubation in the pre-hospital setting,9 and it has been demonstrated that through the use of standardised procedures and expertly-trained staff, it is possible to reduce the RSI intubation failure rate dramatically, potentially to near-zero.9 19 With growing concerns about the role of RSI in the pre-hospital environment, this should be considered the minimum acceptable standard.

The effects of speciality

The AAGBI have recently suggested that the ability of pre-hospital practitioners to perform RSI should be defined by their skills in anaesthesia, not by the primary speciality of the individual.7 Unfortunately, it is hard to see how the two are not inextricably linked.

Previous studies have shown that non-anaesthetic practitioners report a much higher incidence of ‘difficult’ intubations (up to 65% in trauma patients20), with worse laryngoscopic views.10 They are less likely to utilise intubation aides,10 cannot reliably anticipate a difficult airway11 and have been shown to have a higher intubation failure rate.10 Our study is the first to examine the performance of doctors whose primary speciality is outside of ED or anaesthetics and shows a likely extension of these trends.

Despite all doctors operating in WNAA receiving mandatory training and being regarded as clinically proficient, analysis of our run records indicated a significant difference in intubation failure rate between non-ED/non-anaesthetic staff (GP and surgical) and anaesthetists, and a higher, but non-significantly so, failure rate by ED doctors compared to anaesthetists. While it is impossible to state the root cause of the observed discrepancy, it is likely that the technical difficulties reported by other authors are at fault and that the higher failure rate of non-anaesthetists in our series reflects operator experience, infrequency of skill utilisation and lack of educational opportunities.9 11 17 Despite this, other factors must be considered.

Pre-hospital care demands a wide variety of technical, cognitive and team working competencies, spanning a number of medical specialities. RSI requires technical skills in performing laryngoscopy, cognitive skills in predicting potentially difficult airways, determining who requires intubation and what agents are to be used and leadership skills in bringing a diverse team on scene together to assist with the procedure. In the individual cases where intubation failed, it is impossible to demonstrate what element(s) were at fault. While technical skills in non-anaesthetists may represent the problem, it is plausible that differences in the clinical situation, decision making and/or leadership played just as much a role. Within the UK, no standardised training or assessment package delivers all the above pre-requisites for pre-hospital practice. WNAA practitioners, as in many other units, rely on anaesthetic skills gained in hospital and refined through supervised practice operationally. This may be insufficient in providing one or more of the necessary skills to perform RSI.

Should non-anaesthetists perform RSI?

The Cochrane review on emergency intubation concludes that ‘the skill level of the operator may be key in determining (the) efficacy’ of the procedure.3 Given the significantly higher intubation failure rate observed in non-anaesthetic/non-ED practitioners is likely of clinical significance,10 our data may go some way to explaining the divergence in RSI success rates witnessed between hospital practice, where RSI is most commonly performed by anaesthetists and pre-hospital practice.

If standards in pre-hospital airway management are to improve, then various options are available.

First, as suggested by the AAGBI, it may be accepted that ‘most pre-hospital practitioners cannot and should not practise pre-hospital anaesthesia’.7 Only those with sufficient resources and skills should perform RSI, and the use of simple airway manoeuvres and supra-glottic devices should be encouraged by others. While representing an intrinsically safe position, this may not provide best possible care for patients21 and is going against the operational philosophy of advanced pre-hospital care services. It may also lead to monopolisation of clinical procedures by speciality groups to the detriment of others.22

As an alternative, the status-quo may be allowed to continue, with focus being placed on the improvement and standardisation of training and protocols and regular performance of RSI being required in order to maintain competency.17 23 24 It is accepted that pre-hospital anaesthesia is always likely to throw up challenges; the priority being to put in place guidance on how to manage them a priori, not to exclude individuals or restrict practice prophylactically. The question is how such training time and clinical experience will be afforded and whether this would risk on-going sub-optimal performance of RSI.

A further option we suggest is a fundamental alteration in practice, with an emulation of the in-hospital setting. Patient management could be provided by two or more doctors with varying sub-speciality expertise. Mixed helicopter emergency medicine service (HEMS) crews, incorporating an anaesthetist and a clinician drawn from a separate field, would deliver a broader skill mix with greater experience, potentially contributing to superior clinical outcomes. This may be especially relevant in pre-hospital scenarios where the environment, physiological state of the patient, limited staff availability and the potential for multiple casualties add to procedural complexity. Such an arrangement may afford greater protection for patients and practitioners and would facilitate the sharing of knowledge, improved training and mutual development of skills without loss of clinical exposure. Further work investigating the feasibility and benefit of dual-doctor HEMS composition would be required before the instigation of this team structure.

Study limitations

Despite the benefits of observing clinical performance over a long period, the information presented above must be interpreted in light of certain difficulties. The numbers involved are small, and intubation difficulty was assumed to be randomly distributed among cases. The data are retrospective and self-reported and run records were completed to varied standards, with the consequence that repeat intubations and RSI related morbidity may be under-reported. Outcome data on individual cases were unavailable, and information on parameters such as the use of intubation aides and laryngoscopic views was not recorded in the majority of cases. Most importantly, the study examines the practice of a small group of doctors and thus individual skills represent those of specialities. As the event rate is small in all groups, it is important that future work utilises larger series in order to validate the results described here.

It is also recognised that the overall safety and clinical effectiveness of pre-hospital airway management relies on a much wider scope of practice than intubation success alone. Failures or deficits in decision-making regarding whether to intubate, timing of intubation, drug-use in specific clinical situations and in other domains would not be identified in this study. The establishment of a national database of pre-hospital RSI employing the recently established Utstein-style template25 would be beneficial in this regard, facilitating suitably powered studies with greater external validity to accurately delineate the factors contributing to successful and unsuccessful airway management.

Conclusions

Non-anaesthetic practitioners have a higher tracheal intubation failure rate during pre-hospital RSI. This is likely to reflect the infrequency of clinical exposure to intubation. Strategies to improve pre-hospital airway management are required.

Acknowledgments

We would like to thank Nick Parsons for his help with the statistical analysis. WNAA is a registered charity (No: 1098874) and relies entirely on voluntary donations; we thank them for access to run data.

References

Supplementary materials

  • Online only appendix

Footnotes

  • Competing interests None.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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