Introduction
Prehospital care within the United Kingdom (UK) encompasses both Helicopter Emergency Medical Service (HEMS) and British Association for Immediate Care (BASICS), a predominantly road-based service. Both services provide physician-delivered care and are involved in prehospital rapid sequence induction (RSI) and anaesthesia. 1 , 2
Muscle relaxation in RSI has been traditionally undertaken with the use of suxamethonium, due to its rapid onset and short duration; however, it can be associated with potentially life-threatening side effects, including hyperkalaemia, bradycardia, and malignant hyperthermia.Reference Orebaugh 3 Rocuronium, a nondepolaring neuromuscular blocker with a longer duration of action, at higher doses has comparable intubating conditions to suxamethonium without the associated side effects, and is therefore a useful alternative.Reference Larsen, Hansen and Jacobsen 4 - Reference Andrews, Kumar and van den Brom 9
The aim of this survey was to establish how many prehospital services in the UK are now using rocuronium as first line in RSI.
Methods
A database was constructed of all UK providers of prehospital care in 2013. All BASICS providers throughout the UK were identified through their web site, and air ambulance services in the UK were identified through the UK HEMS web site. 1 - 2 The lead clinician for each service was contacted via email to complete the survey on behalf of their service. The survey was constructed using online questionnaire SurveyMonkey (SurveyMonkey; Palo Alto, California USA). 10 Questions related specifically to the choice of first-line neuromuscular blocker (rocuronium or suxamethonium) in prehospital RSI. If suxamethonium was answered, then the survey ended at that point; however, if rocuronium was answered, four further questions regarding dose, use of sugammadex, contraindications to use, and difference in intubating conditions were asked (Table 1).
Table 1 Survey Questions Sent to All Prehospital Services
Abbreviations: BASICS, British Association for Immediate Care Society; HEMS, Helicopter Emergency Medical Services; RSI, rapid sequence induction.
Results
Nineteen regional air ambulance services were identified throughout the UK, of which, 15 delivered physician-based prehospital care. Thirty organized BASICS schemes were identified across the UK, of which, 16 services routinely delivered physician-based care able to provide prehospital anaesthesia. This gave a total of 31 services providing prehospital anaesthesia, and all were contacted. No reply was obtained from one service. A total of 30 responses were obtained (96.8%); however, one was incomplete resulting in 29 full responses (93.5%).
First Line Neuromuscular Blocker
Suxamethonium was used as first line by 17 prehospital services routinely (58.6%), and rocuronium was used first by 12 services (41.4%).
Dosage
In 11 services, a dose of 1 mg/kg of rocuronium was used at induction (91.7%).
In only one service, a dose of 1.2 mg/kg was used (8.3%). No service used any other dose.
Contraindications to First Line Use of Rocuronium
This question allowed a free-text answer and services could specify many reasons, if required (two services gave more than one reason). In nine services, if there was a very high probability of difficult airway being experienced, then careful consideration would be given to whether rocuronium should be used (75%). Previous anaphylaxis or allergy was a contraindication to use in three services (25%); however, it was recognized that in the prehospital setting, this information was unlikely to be available. In two services, no contraindications to first-line use of rocuronium were documented (16.7%).
Sugammadex Use
In all 12 services using rocuronium for induction, none routinely carried sugammadex (0%).
Difference in Intubating Conditions
In five services, slower relaxation time was found with use of rocuronium (41.7%), and in seven services, no difference in intubation conditions were noted (58.3%).
Discussion
Recent studies have shown high-dose rocuronium (1-1.2 mg/kg) is comparable to suxamethonium in RSI.Reference Larsen, Hansen and Jacobsen 4 - Reference Andrews, Kumar and van den Brom 9 Previous surveys of UK prehospital anaesthesia found that 32% of prehospital services carry rocuronium.Reference Cowan, Burton and Newton 11 Use of rocuronium as a first-line muscle relaxant is on the increase, and almost half the services contacted in this survey have converted from suxamethonium. In theory, rocuronium should not be used in a difficult airway due to the increased risk of failed intubation; however, the nature of all prehospital RSIs necessitate all intubations to be difficult and waking the patient up is usually not an option. In a study of 402 prehospital intubations by London HEMS, three cricothyroidotomies were performed, two as primary and one as a rescue procedure.Reference Harris, Ellis and Foster 12 In this study, 98.8% were intubated on first or second attempt, which illustrates the benefits and importance of adequate training and a clear failed-intubation drill.Reference Harris, Ellis and Foster 12 The longer duration of action of rocuronium can be an advantage when a failed intubation has occurred and a rescue technique is required. The patient will remain paralyzed without a second dose of suxamethonium needing to be administered, which can be associated with life-threatening bradycardia.Reference Orebaugh 3 This is particularly the case with children. If physicians have concerns regarding rocuronium and they anticipate a very difficult airway, consideration should be given to the prehospital use of sugammadex. However, this may not be feasible with the high cost and short shelf life (after first opening and dilution, it requires to be stored at 2°C to 8°C and used within 24 hours). 13 Intubation conditions obtained by high-dose rocuronium and suxamethonium are similar.Reference Larsen, Hansen and Jacobsen 4 - Reference Andrews, Kumar and van den Brom 9 There is a tendency towards quicker relaxation time with suxamethonium, but this appears clinically insignificant.Reference Larsen, Hansen and Jacobsen 4 , Reference McCourt, Salmela and Mirakhur 5 , Reference Andrews, Kumar and van den Brom 9 The mixed views within this survey have echoed these results.
Conclusion
Use of rocuronium as a first-line muscle relaxant in prehospital RSI is increasing. Continued auditing of practice will be important to ascertain which services have adopted this change and identify if complications of failed intubation increase as a result.
