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Anaesthesia, 2009, 64, pages 625–631 doi:10.1111/j.1365-2044.2008.05859.x .....................................................................................................................................................................................................................

Prehospital airway management on rescue helicopters in the United Kingdom M. Schmid,1 H. Mang,1 K. Ey2 and J. Schu¨ttler1 1 Department of Anesthesiology, University Erlangen-Nuernberg, Erlangen, Germany 2 Department of Anesthesiology, Municipal Hospital of Nuernberg, Nu¨rnberg, Germany Summary

Adequate equipment is one prerequisite for advanced, out of hospital, airway management. There are no data on current availability of airway equipment on UK rescue helicopters. An internet search revealed all UK rescue helicopters, and a questionnaire was sent to the bases asking for available airway management items. We identified 27 helicopter bases and 26 (96%) sent the questionnaire back. Twenty-four bases (92%) had at least one supraglottic airway device; 16 (62%) helicopters had material for establishing a surgical airway (e.g. a cricothyroidotomy set); 88% of the helicopters had CO2 detection; 25 (96%) helicopters carried automatic ventilators; among these, four (15%) had sophisticated ventilators and seven (27%) helicopters carried special face masks suitable for non-invasive ventilation. We found a wide variation in the advanced airway management equipment that was carried routinely on air ambulances. Current guidelines for airway management are not met by all UK air ambulances. . ......................................................................................................

Correspondence to: Dr Markus Schmid E-mail: [email protected] Accepted: 4 December 2008

Prehospital airway management in the critically ill patient is one of the key tasks performed by rescue personnel. This setting remains challenging for several reasons: the incidence of the difficult to manage airway is higher in the prehospital setting [1] than in the hospital environment, even for experienced physicians. Prehospital availability of alternative airway equipment is often limited [2] and advanced airway management often has to be performed by inadequately trained staff. In the UK, mostly paramedics are the primary healthcare providers on ground and helicopter ambulance services and are therefore responsible for prehospital airway management, usually without the attendance of an experienced physician. Presently, there are no data on incidence and success rates of prehospital airway interventions by UK paramedics but data from other countries reveal high intubation failure rates [3, 4]. In view of this, there was a recent change in prehospital airway management guidelines for UK paramedics [5]: intubation is no longer recommended and instead supraglottic airway devices should be used. Apart from adequate skills in airway management, the availability of sufficient equipment is a central prerequisite to treat the emergency patient according to current airway guidelines [6], but there are 2009 The Authors Journal compilation 2009 The Association of Anaesthetists of Great Britain and Ireland

no uniform guidelines for airway management equipment on UK rescue helicopters. There are already data on the availability of equipment for airway management on UK ambulances [2, 7] but information is lacking on current equipment on UK rescue helicopters. In order to show existing differences between the bases and to detect possible inadequacies of the equipment, we conducted a questionnaire survey of all UK air ambulance bases. Methods

An internet search identified 27 air ambulance bases in the UK and a questionnaire was mailed to all these bases. If no response was received after 2–4 weeks, further attempts e.g. by telephone calls, were made to acquire the data for each helicopter. The questionnaire was designed to determine which equipment is available to the crews for airway management. Results

We finally received replies from 26 helicopter bases (96%). Six (23%) helicopters always have a physician on board and the breakdown of medical staff is shown in 625

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M. Schmid et al. Airway management on UK rescue helicopters Anaesthesia, 2009, 64, pages 625–631 . ....................................................................................................................................................................................................................

Table 1 Physician staffing on UK rescue helicopters.

Item

Number (%) n = 26

Helicopters with a physician always on board

6 (23) n = 67

Emergency physicians Anaesthetists Surgeons Internists Other specialties (not specified)

30 (45) 25 (37) 3 (4) 1 (1) 8 (12)

Table 4 Equipment to confirm tracheal intubation.

Item Capnometry Colour CO2 – detection Capnometry or colour CO2 – detection Both items (capnometry and colour CO2 – detection) No means of CO2 – detection

Number (%) n = 26 22 14 23 13

(85) (54) (88) (50)

3 (12)

Table 5 Available ventilator types and non-invasive ventilation

masks. Table 2 Available tracheal intubation aids.

Item Macintosh blade Straight blade McCoy blade Only one blade available Macintosh blade and at least one alternative blade (straight or McCoy) All three blades GlideScopeTM Bronchoscope Regular stylet Eschmann stylet or ‘gum elastic bougie’ At least one of both stylets Both stylets Suxamethonium

Number (%) n = 26 26 (100) 17 (65) 8 (31) 7 (27) 19 (73) 6 (23) 3 (12) 1 (4) 24 (92) 18 (69) 26 (100) 16 (62) 11 (42)

Table 1. Availability of tracheal intubation aids is outlined in Table 2. Among alternative supraglottic airway devices, 24 bases (92%) had at least one of the items mentioned in Table 3 and seven (27%) bases had at least two or more different items. Two (8%) helicopters had no alternative supraglottic device. Sixteen (62%) helicopters had the material for establishing a surgical airway. Confirmation of correct Table 3 Alternative supraglottic airway management devices.

Item

Number (%) n = 26

Laryngeal masks ProSealTM laryngeal masks Intubation laryngeal masks CombitubeTM Laryngeal tube Easy tube At least one of the items above Just one of the items above Two ore more of the items above None of the items above

19 (73) 4 (15) 2 (8) 1 (4) 5 (19) 1 (4) 24 (92) 16 (62) 7 (27) 2 (8)

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Item

Number (%) n = 26

Ventilator available paraPACTM paraPACTM 200D ventiPACTM PneupacTM OxylogTM 1000 OxylogTM 2000 OxylogTM 3000 Ventilator available (type not specified) Masks for non-invasive ventilation

25 (96) 7 (27) 1 (4) 3 (12) 1 (4) 1 (4) 1 (4) 4 (15) 7 (27) 7 (27)

Table 6 Available methods for increasing FIO2 in ventilation

bags.

Item (Oxy-)demand valve O2 – reservoir bag (Oxy-)demand valve and O2 – reservoir bag Only direct O2 – inlet into the bag ⁄ no means of O2 – concentration

Number (%) n = 26 14 (54) 23 (88) 12 (46) 1 (4)

tracheal intubation via CO2 detection was available on 88% of all helicopters (Table 4). All helicopters, except one, carried automatic ventilators (96%) (Table 5). Equipment for increasing inspired oxygen fraction in ventilation bags is shown in Table 6. Discussion

We found wide variations in airway management equipment carried on UK air ambulances, which is not surprising as different operators with different skill levels run the bases and there is presently no common standard for the equipment. This survey showed that most UK helicopters (77%) do not have a physician on board at all times. That could 2009 The Authors Journal compilation 2009 The Association of Anaesthetists of Great Britain and Ireland

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Anaesthesia, 2009, 64, pages 625–631 M. Schmid et al. Airway management on UK rescue helicopters . ....................................................................................................................................................................................................................

imply that on those helicopters, it would make no sense to carry any equipment that paramedics are not allowed to use. However, five bases reported to have doctors on board on some flights, which could justify the presence of these items e.g. suxamethonium, to be used by physicians whenever they join the team. Intubation without drugs has been a core competence for UK paramedics for many years. Data form other countries show tracheal intubation failure rates as high as 50% in paramedic-based rescue systems [3]. There is growing evidence that current initial training of UK paramedics is insufficient and lack of intubation practice leads to overall bad intubation skills [8], which may worsen the patient’s outcome. Therefore, the Joint Royal Colleges Ambulance Service Liaison Committee (JRCALC) airway working group has recently published [5] new recommendations on airway management in prehospital care. One key statement is that intubation without drugs by paramedics should be abandoned in favour of establishing an airway with supraglottic airway devices (SAD). Current airway guidelines [5, 7] are aimed at physicians in the clinical environment and cannot easily be transferred to the prehospital situation, as staff (e.g. paramedics) and available equipment are often quite different. In view of this, the Association of Anaesthetists of Great Britain and Ireland (AAGBI) published a position statement: ‘Prehospital anaesthesia’ [9] with recommendations and standards for personnel skills and necessary equipment for those who are performing prehospital anaesthesia and airway management. Rapid sequence induction (RSI), using sedative and rapid acting neuromuscular blocking drugs like suxamethonium to facilitate immediate tracheal intubation, is the method of choice for patients with intact airway reflexes in the prehospital setting when skilled personnel are available [10]. In our survey, 11 helicopters (42%) had suxamethonium on board. Among these were the six helicopters which are permanently staffed with doctors. Another five bases also carry suxamethonium, supposedly to have the option if a physician joins the team (on an irregular basis) or is present at the scene, because UK paramedics are not allowed to use narcotics, sedatives or neuromuscular blocking drugs to facilitate tracheal intubation. All helicopters had the Macintosh blade, while a straight blade was available on 17 (65%) of all bases and eight (31%) bases had the McCoy blade. Straight blades and the McCoy blade may improve glottic view [11, 12] and are recommended as alternative blades in current guidelines for difficult airway management [6]. A survey of UK ambulance services [2] showed an even lower availability of straight blades for adults. Use of alternative laryngoscope blades needs to be practiced in routine 2009 The Authors Journal compilation 2009 The Association of Anaesthetists of Great Britain and Ireland

intubation before it can be recommended with confidence for difficult cases. To date, there is no evidence that either of the two alternative blades can significantly improve intubation success rates by paramedics in the prehospital setting. For difficult visualisation of the larynx, optimal shaping of the tracheal tube, with or without stylet or introducer (‘bougie’), is recommended in current airway guidelines [6, 9]. Twenty-four helicopters (92%) had a ‘regular’ stylet and 18 bases (69%) had the Eschmann tracheal tube introducer or gum elastic bougie. In contrast, 37% of all UK ambulances [2] had neither item, while 42% had a stylet only and 8% had bougies only. One clinical study showed that the bougie may be more effective than the stylet when the view of the larynx is Cormack grade 3 [13]. Data on prehospital use of the bougie by paramedics is limited, but one study showed no significant benefit of the bougie in comparison to a regular stylet [14]. Paramedics can successfully use this device after only a brief introduction on a manikin model [15]. To ensure oxygenation and ventilation after failed intubation, bag-valve-mask (BVM) ventilation is the basic technique for all health care providers, but requires considerable skill and may be difficult to perform. Supraglottic airway devices (SAD) such as the laryngeal mask (LMA) usually allow better ventilation than BVM [16] and may reduce the risk of gastric inflation and aspiration [17]. Current airway management [6, 18] and resuscitation guidelines [19] recommend the use of SADs as a backup rescue airway to ensure ventilation when routine measures fail. Currently, 92% of all UK air ambulances have at least one alternative supraglottic device and seven (27%) have more than one item (Table 3). The laryngeal mask (LMA) is the most popular device on UK rescue helicopters: 88% had a ‘standard’ or ProsealTM LMA available. Although the LMA is recommended as an alternative supraglottic airway adjunct for adults and children in current JRCALC guidelines [20], two surveys, in 2001 [21] and 2004 [2], showed a low availability of LMA on UK ambulances of 26% and 39% respectively. Prehospital use of supraglottic aids by adequately trained paramedics and nurses is mostly safe and efficient [22–24]. Presently, there are no data showing that one supraglottic item is superior in the prehospital setting when users are adequately trained and skills are updated on a regular basis. In a recent JRCALC position paper on prehospital airway management by paramedics, intubation was abandoned and SADs now have become the standard airway [5]. Maximising inspiratory oxygen fraction (FIO2) in the ventilation bag is mandatory and can be achieved mainly by three methods: the (oxy-) demand valve, any kind of reservoir (tube or bag), or in the absence of a reservoir, by 627

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attaching an oxygen hose directly to the oxygen inlet nipple of the unit. In this survey, 14 helicopters (54%) had a demand valve, 23 (88%) had a reservoir and only one base just had a direct oxygen – inlet into the bag without any kind of reservoir. There are no data on the availability of these items in UK ambulances but, in a survey of physician staffed ambulance cars in Germany, 77% had a reservoir and 39% had a demand valve [25]. FIO2 in ventilation bags depends on several variables such as the type of bag, use and type of attached reservoir, and O2 flow and minute-ventilation [26, 27]. While demand valves provide a consistent FIO2 of 1.0, reservoir systems can be equally effective [28]. There is no doubt that without any type of reservoir, FIO2 will not reach adequate levels [28]. Although demand valves are more effective than reservoirs in terms of saving oxygen and the resulting FIO2 is independent of ventilatory technique, their high cost may result in a lower availability compared to reservoirs in prehospital use. Confirmation of correct tube placement after intubation is mandatory since unrecognised oesophageal intubation can be rapidly fatal. In the prehospital setting, a difficult and noisy environment, clinical signs such as breath sounds are unsafe and can be misleading [29]. Measurement of end-tidal CO2 after intubation is a minimum monitoring standard for peri-operative monitoring during anaesthesia [30]. Current JRCALC [5] and AAGBI guidelines [9] on prehospital airway management strongly recommend the availability of prehospital capnometry. To date, there is no evidence that capnometry is superior to colourimetric methods in detecting correct tracheal tube placement in the prehospital setting, but colourimetry is probably less sensitive than capnometry in detecting oesophageal intubation [31]. CO2 detection is not always the method of choice; during cardiac arrest, the oesophageal detector device (ODD) [32] has a higher sensitivity in determining correct tube position [33]. In this survey, capnometry was available on 85% and colour CO2 detection on 54% of all rescue helicopters. Many (50%) had both items and 12% had no device for CO2 detection. None of the bases stated that an ODD is available on their helicopters. One survey of all UK ground ambulance services in 2002 [7] showed availability of CO2 detection of 14% (capnometry). Data from 2004 [2] revealed that 76% of all ambulance trusts had no means of tracheal tube verification. On German physician staffed ambulances, the availability was 74% [34] and 32% [25] in two different provinces. Implementation of prehospital continuous end-tidal CO2 measuring as part of an airway management protocol can help to improve outcome and save lives as it decreases the number of unrecognised, misplaced tracheal tubes [35] and is associated with a decrease in inadvertent severe hyperventilation in patients 628

with severe head injury [36]. Continuous verification of correct tracheal tube position by CO2 monitoring may reduce the risk of accidental displacement due to frequent movement of the patient’s head and neck during rescue and transport. Sixteen (62%) of all UK helicopter bases had available equipment for establishing a surgical airway (e.g. cricothyroidotomy set). Among these were all six permanently physician staffed helicopters. In a survey of UK ground ambulance services, a needle cricothyroidotomy set was available on 45% of all ambulances [2]. In contrast, 70% [25] of all physician staffed ambulance cars in Germany had equipment for surgical airway management. Cannot intubate ⁄ cannot ventilate (CICV) situations in the clinical setting are supposed to be very rare (two in 10 000 cases) [37] while, in the prehospital setting, the incidence is difficult to determine as it depends on multiple factors such as airway skills of the personnel (e.g. paramedic vs trained physicians) leading to different intubation skills and different levels of training with alternative airway devices. Nevertheless, the incidence of invasive airway interventions seems to be higher. In a recent prehospital survey with trained anaesthetists [1], one cricothyroidotomy was done in 1106 tracheal intubation attempts (0.09%) while need for cricothyroidotomy performed by paramedics can reach 15% [38]. Current UK airway guidelines for management of the CICV situation recommend surgical cricothyroidotomy as the first line procedure [6] and in current JRCALC guidelines [20], needle cricothyroidotomy is the only mentioned surgical airway allowed for paramedics in the UK. For effective ventilation of the emergency patient, an automatic ventilator should be standard because manual ventilation may lead to greater fluctuation of ventilatory parameters, resulting in respiratory alkalosis, pulmonary barotrauma and haemodynamic complications [39, 40]. All but one UK air ambulance had an automatic ventilator. Eighteen bases (69%) specified the type of the available ventilator. The majority of ventilators on UK helicopters fulfil basic requirements by providing time ⁄ volume cycled ventilation for adults and depending on the type for children (Table 5). These ventilators work adequately in adults with normal lungs but in children and patients with abnormal compliance and resistance, performance can decrease significantly [41] and may lead to hyper- or hypo-ventilation. Four helicopters had an advanced emergency ventilator with additional modes such as BIPAP and pressure support ventilation. These ventilators may better meet future demands for inter hospital transfer of critically ill patients and small children who need more sophisticated ventilation modes and because of the possibility to use these ventilators for prehospital non-invasive ventilation (NIV). 2009 The Authors Journal compilation 2009 The Association of Anaesthetists of Great Britain and Ireland

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Seven (27%) helicopters had masks for NIV while just four (15%) bases had suitable ventilators for NIV (providing e.g. pressure support ventilation). Clinically, NIV is a well established procedure in the management of acute respiratory failure [42], reducing the need for intubation and mechanical ventilation leading to fewer complications and a reduced stay in both ICU and hospital [43]. While being well established clinically, prehospital use of NIV currently is not a standard procedure in the UK. One reason for reluctant use of NIV on helicopters may be the fact that patients requiring ventilatory support are always at risk of deterioration in flight. This would lead to emergency intubation in the small helicopter cabin or the need for immediate landing, neither ideal. In order to avoid this, suitable patients for NIV must be cautiously selected prior to flight by experienced physicians who know the limitations of the method. There are currently no data concerning the availability of NIV on UK ambulances. Most studies on prehospital use of NIV primarily used CPAP systems such as the Boussignac device [44], because sophisticated ventilators for non-invasive pressure support ventilation (NIPSV) use are still rare. Prehospital CPAP showed positive results including a reduced need for intubation and improved oxygenation in severe pulmonary oedema [45, 46]. When the availability of small, portable, sophisticated ventilators increases, NIPSV will be another option for prehospital use. Weitz et al. [47] compared standard medical treatment with standard treatment plus prehospital NIPSV in patients with pulmonary oedema. In the NIPSV group, the oxygen saturation improvement was significantly faster and oxygen saturation was higher at the time of hospital admission; however, need for intensive care treatment did not differ between the two groups. To date, prehospital use of CPAP and NIPSV can be regarded as an additional treatment option for some patients. Before becoming a standard treatment option in prehospital routine, larger controlled studies are needed to demonstrate that NIV is superior to standard medical therapy alone. This survey shows differences in available airway management equipment and in the medical crew on UK rescue helicopters. While most helicopters have sufficient equipment, on some bases important items are not available, meaning that advanced airway management according to current guidelines is not possible. Defining minimum standard equipment for all UK rescue helicopters could help to create a common level. Carrying a large variety of equipment on the helicopter is unreasonable as limitation of medical equipment to just a few items that can be properly handled by the team is the basis of efficient decision making and helps to improve patient safety. At least one reliable means of CO2 detection for 2009 The Authors Journal compilation 2009 The Association of Anaesthetists of Great Britain and Ireland

tracheal tube verification, one supraglottic alternative airway device, a stylet, a reservoir for the ventilation bag and a cricothyroidotomy set should be available on every helicopter to meet demands of modern prehospital advanced airway management. NIV must prove its efficacy in larger studies before becoming a standard procedure in prehospital treatment. A uniform patient record for all helicopter bases and a central database for all air rescue missions in the UK could be a first step to acquire relevant data e.g. to compare both paramedic and physician-based systems. A quality difference in patient treatment between the two systems must be avoided as it might have a detrimental impact on patient outcome. Airway training at regular, obligatory intervals for those who rarely practice airway management will help to maintain an appropriate skill level. Acknowledgement

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