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for airway management in prehospital emergency medicine
Hichem Chenaitiaa, 
, 
, Valéry Soulleiheta, Horace Massab, Jacques Bessereaua, Jeremy Bourennec, Pierre Micheleta and Jean-Pierre 
Auffraya
Securing the airway in emergency is among the key requirements of appropriate prehospital therapy. The Easytube (Ezt) is a relatively new device, which combines the advantages of both an infraglottic and supraglottic airway.
Our goal was to evaluate the effectiveness and the safety of use of Ezt by emergency physicians in case of difficult airway management in a prehospital setting with minimal training.
We performed a prospective multi-centre observational study of patients requiring airway management conducted in prehospital emergency medicine in France by 3 French mobile intensive care units from October 2007 to October 2008.
Data were available for 239 patients who needed airway management. Two groups were individualized: the “easy airway management” group (225 patients; 94%) and the “difficult airway management” group (14 patients; 6%). All patients had a successful airway management. The Ezt was used in eight men and six women; mean age was 64 years. It was used for ventilation for a maximum of 150 min and the mean time was 65 min. It was positioned successfully at first attempt, except for two patients, one needed an adjustment because of an air leak, and in the other patient the Ezt was replaced due to complete obstruction of the Ezt during bronchial suction.
The present study shows that emergency physicians in cases of difficult airway management can use the EzT safely and effectively with minimal training. Because of its very high success rate in ventilation, the possibility of blind intubation, the low failure rate after a short training period. It could be introduced in new guidelines to manage difficult airway in prehospital emergency.
Keywords: Easytube; Prehospital emergency medicine; Difficult airway management
The European Resuscitation Council Guidelines for Cardiopulmonary Resuscitation 2005 recommend that tracheal intubation should be attempted only by trained personnel with adequate ongoing experience, and in cases of failure to intubate the trachea using an endotracheal tube (ETT), the Combitube is an acceptable alternative [2].
The Easytube (Ezt, Teleflex Medical Ruesch) is a 0relatively new device (Fig. 1). It is a sterile, disposable airway device, approved by the European Union in 2003 and by the U.S. Food and Drug Administration in 2005. The Ezt is a two-lumen tube with a pharyngeal proximal cuff and a distal cuff. One lumen of the Ezt opens at the distal end and the other lumen serves as a supraglottic ventilation aperture between the two cuffs. It is latex free and available in two sizes to be used in patients with a height of 90–130 cm (size 28 Fr [French]) or over 130 cm (size 41 Fr). The distal end of the Ezt is designed like a standard ETT with a tip diameter of 7.5 mm (size 41 Fr) or 5.5 mm (size 28 Fr). It includes a Murphy eye at its tip. The design of the pharyngeal aperture allows insertion of a flexible fiberoptic bronchoscope, bougie or suction catheter with a maximum external diameter of 3.9 mm into the trachea.
| Full-size image (26K) |
Easytube (EzT; Teleflex Ruesch, Research Triangle Park, NC) 28 Fr for patients with a height of 90–130 cm (left) and EzT 41 Fr for patients greater than 130 cm (right).
It is fairly similar to the Combitube. Both the Combitube and the Ezt can be used as infraglottic or supraglottic airways. They enable sufficient ventilation whether they are inserted into the oesophagus or the trachea [3], [4]and [5]. The Ezt was developed for in-hospital and out-of-hospital use in all patients with anticipated or unanticipated airway difficulties [1], [2], [3], [4] and [5].
The French prehospital Emergency Medical System (EMS) is based on a national phone number (15 or 112). A physician screens each call. In cases of vital distress, a mobile intensive care unit (MICU) consisting of an emergency physician, a nurse and an ambulance driver is sent to the scene within minutes.
The aim of this study was to evaluate the effectiveness and the safety of use of Ezt by emergency physicians in case of difficult airway management in a prehospital setting with minimal training.
This study was a prospective multi-centre study of patients requiring airway management conducted in a French prehospital EMS (SAMU 13) in the city of Marseille, by 3 French MICUs over a 12-month period.
The primary outcome measurement was airway management success. Our hypothesis was that emergency physicians would be able to successfully perform prehospital airway management using the Ezt in cases of difficult airway management with minimal training.
In order to evaluate the Ezt, all emergency physicians used the same algorithm for airway management (Fig. 2). It included 3 MICUs distributed in different parts of the city.
| Full-size image (23K) |
The airway management protocol during the study period. BVM: Bag valve mask; BURP maneuver: backward, upward and rightward pressure maneuver; DI: difficult intubation; DL: direct laryngoscopy; ETI: endotracheal intubation; Ezt: Easytube; ICU: intensive care unit.
Emergency physicians were trained in the use of Ezt on manikins. Ten consecutive successful intubations were required for every physician before beginning the evaluation of Ezt.
The inclusion criteria were: all the patients with a height above 90 cm and an indication for prehospital airway management.
The exclusion criteria were a contraindication to the use of Ezt: patients with a height less than 90 cm, patients suffering from upper airway obstruction, and patients suffering from oesophageal diseases or ingestion of caustic substances.
During the study period, all patients were managed with the same airway management protocol (Fig. 2). Our protocol complies with the guidelines of the French Society of Anaesthesia and Resuscitation (SFAR) and received ethical approval from Marseille University Hospital's Emergency Committee.
The SFAR defines difficult intubation (DI) as more than two failed intubation attempts under direct laryngoscopy with an optimal head position.
We prospectively separated patients into 2 groups: “easy airway management”: less than 2 ETI attempts and “difficult airway management”: more than 2 ETI attempts or use of EZT in accordance with the protocol.
In our study, before ETI we also systematically evaluate predictive signs of DI (short neck, restricted mouthopening <3 cm, estimated thyromental distance <6 cm, morbid obesity with body mass index estimated more than 40 and cervico-facial trauma).
For a patient with vital distress on arrival of the prehospital medical team on-site and after evaluation of the situation, the emergency physician decides if intubation is necessary.
The patients were preoxygenated by Bag–Valve–Mask (BVM) with 100% oxygen for 3 min, except in the case of cardio-respiratory arrest or if there was an immediate indication of intubation.
During airway management, patients were monitored continuously by electrocardiogram, cutaneous pulse oximetry and non-invasive arterial pressure.
A Rapid Sequence Induction (RSI) with etomidate (0.3 mg/kg) and succinylcholine (1 mg/kg) was performed in patients with cardiac activity. Arrest patients were intubated without giving any medications.
If there was no predictive sign of DI, ETI was attempted with an ETT and by a direct laryngoscopy, with or without a stylet.
Whatever the attempted airway management, this is always limited to 40 s.
If ETI failed, ventilation by BVM with 100% oxygen was resumed, or in the event of a predictive sign of DI, an attempt at ETI was recommended but with measures taken to facilitate intubation: place the head in the modified Jackson position or “sniffing position”, if no cervico-facial trauma, bend the tube into a “hockey stick” shape with a stylet and have an assistant perform the BURP (backward upward rightward pressure) maneuver to move the larynx closer to the visual axis for intubation.
If ETI failed again, ventilation by BVM with 100% oxygen was resumed and a further attempt with Ezt was recommended, respecting any contraindications.
If a “cannot intubate, cannot ventilate” situation occurred and as no time could be wasted in further intubation attempts, immediate use of Ezt was allowed because the Combitube and the Ezt are listed as a rescue method in “cannot ventilate–cannot intubate” situations by the American Society of Anaesthesiologists [6].
Laryngoscopic insertion of Ezt is very similar to the use of a standard ETT, and if an ETI by Ezt is finally possible, the patient is ventilated through the transparent lumen.
If ETI is not possible, the tip of the EzT can be inserted into the esophagus under visual guidance with the help of a laryngoscope or blindly.
If it is inserted blindly, the patient's head must be in neutral position. Manually opening the patient's mouthand pressing the tongue gently toward the mandible, the tube is inserted parallel to the frontal axis of the patient until the proximal black ring mark is positioned at the level of the incisors. If the EzT is inserted blindly, the tip is likely to be positioned in the esophagus with a probability of more than 95% [3]. Ventilation of the patient should be performed using a colored lumen, and the transparent lumen can then be used to insert a gastric tube or to drain gastric contents.
The colored pharyngeal proximal cuff and the transparent distal cuff are subsequently inflated with 80 and 10 ml of air, using two pre-filled syringes in the package. Inflation of the pharyngeal cuff occludes theoropharynx and should prevent inhalation of blood or secretions from the oral or nasal cavity. The transparentdistal cuff seals the oesophagus and should prevent inhalation of gastric contents.
Correct insertion of Ezt was defined as efficient ventilation of the patient assessed by three square-wave capnograph traces during manual ventilation, symmetric auscultation with no audible gastric insufflations or air leak.
If all of these methods failed, ventilation by BVM with 100% oxygen was resumed and a “Failed Airway Algorithm” was applied to the patients by performing a cricothyrotomy with the “Quick-Trach Emergency Cricothyrotomy Device.”
After airway management, anaesthesia was maintained with Midazolam (0.1 mg/kg/h) and Fentanyl(1 μg/kg/h). The patients underwent positive pressure ventilation in a pressure-controlled mode; the limit was set at 30 cm H2O airway pressure; the targeted tidal volume was 7 mL/kg; inspired oxygen concentration (FIO2) at 1; respiratory rate was set to achieve an End-Tidal CO2 (ETCO2) concentration of 35–45 mmHg. The patients were continuously monitored by standard non-invasive measures including electrocardiogram, cutaneous pulse oximetry, non-invasive blood pressure measurement (every 5 min) and capnography.
Subsequently, the patients were rapidly admitted to intensive care unit (ICU). The Ezt was replaced by an ETT in ICU, with an airway exchange catheter as soon as possible.
The emergency physicians filled the study forms immediately after each airway management. The study form included patient's age and sex, Glasgow coma scale (GCS) score, approximate height (less or more than 130 cm), clinical status and indication for intubation (cardio-respiratory arrest, severe neurological distress, severe respiratory distress or other). The forms were anonymous. Predictive signs of DI (short neck, restricted mouth opening <3 cm, estimated thyromental distance <6 cm, morbid obesity and cervico-facialtrauma) and number of intubation attempts were also noted. Incidents and complications of intubation were reported by means of open-ended questions. All the data were then managed in a computer database.
During the study period, 239 patients needed prehospital airway management and no patient was excluded.
These 239 patients were divided into 2 groups: 225 (94%) patients in “easy airway management” and 14 (6%) patients in “difficult airway management”. The characteristics for both groups are illustrated in Table 1.
| Easy airway management | Difficult airway management | |
|---|---|---|
| Patients per group | 225 (94%) | 14 (6%) |
| Sex: female/male ratio | 78/147 | 6/8 |
| Mean age [range age] | 54 years [16 days to 96 years] | 64 years [45–93 years] |
| Mean initial GCS score | 5 | 4 |
| Mean intervention time of MICU [range time] | 72 min [20–145 min] | 65 min [25–150 min] |
| Predictive DI signs | 51 (23%) | 10 (71%) |
| Use stylet | 39 (17%) | 14 (100%) |
| Scene intervention | ||
| At home | 108 (48%) | 8 (57%) |
| Outside | 45 (20%) | 2 (14%) |
| Hospital or care place | 72 (32%) | 4 (29%) |
| Intubations indications | ||
| CRA | 84 (38%) | 8 (57%) |
| Respiratory distress | 36 (16%) | 4 (29%) |
| Neurologic distress | 81 (36%) | 2 (14%) |
| Others: voluntary drug poisoning | 24 (10%) | 0 |
| Intubations complications | ||
| Dental trauma | 1 (0.4%) | 0 |
| Macroscopic inhalationa | 7 (3%) | 2 (14%) |
| Oesophageal intubationa | 13 (6%) | 3 (21%) |
| Selective intubation | 12 (5%) | 0 |
| Collapse post-intubation | 33 (15%) | 0 |
| ACR | 0 | 0 |
| Mean intubations attempts | 1.25 | 3 |
| [range attempts] | [1–2] | [2–5] |
GCS: Glasgow coma scale; MICU: mobile intensive care unit; DI: difficult intubation; CRA: cardio-respiratory arrest.
a Only during ETI attempts.All the patients had successful airway management, and no patient required a surgical airway management. We did not encounter a “cannot ventilate–cannot intubate” situation in our study.
Among the 239 cases of airway management in a prehospital setting, the Ezt was used 14 times. It was used in eight men and six women; the male-to-female ratio was 1.33. The age range was 45–93 years; mean age was 64 years.
The Ezt was used for ventilation for a maximum of 150 min, intervention time by MICUs in prehospital situations was 25–150 min, and the mean time was 65 min.
Only Ezt size 41 Fr was used during the study because no patient in the height range 90–130 (Ezt of size 28 Fr) presented difficult airway management.
The Ezt was positioned successfully at first attempt, except for two patients: one needed an adjustment because of air leaks, and for the other patient, the Ezt was replaced due to a complete obstruction of the Ezt during bronchial suction after aspiration of gastric contents.
Predictive signs of DI were found in 61 patients of the 239 airway management cases; this represents 25% of patients with airway management in prehospital situations. The predictive signs of DI are shown in Table 2. The study shows the presence of predictive signs of DI in 71% of cases of the “difficult airway management” group.
| Predictive signs of difficult intubation | Numbers (%) |
|---|---|
| Morbid obesity | 26 (42%) |
| Cervico-facial trauma | 16 (26%) |
| Short neck | 11(18%) |
| Restricted mouth opening <3 cm | 7 (12%) |
| Thyromental distance <6 cm | 1 (2%) |
| Total | 61 |
A number of previous studies show that the EzT is comparable to the ETT with respect to oxygenation and ventilation, and might even have minor advantages, as the EzT can be inserted slightly more quickly and easily than the ETT [4] and [7].
Our results are in agreement with other studies showing that a short learning period may be sufficient to train emergency physicians since the success rate is high [4] and [7].
In our study, the insertion of the Ezt was successful at the first attempt in all cases. These results are in agreement with other studies carried out which show a very low insertion failure rate [5].
During this study, we noted one specific complication associated with Ezt, to our knowledge never described. This was complete obstruction of the Ezt during bronchial suction after aspiration of gastric contents. The aspiration occurred after 2 failed ETI attempts. The first Ezt was removed and a second Ezt was used without complication.
The main advantages of the Ezt are: shorter insertion time for Ezt than for ETI, better protection against aspiration than a laryngeal mask and the possibility of blind insertion of the Ezt in patients trapped in a sitting position (car crash) [5], [6] and [7].
Unfortunately, in our study, we were unable to assess the time needed to establish an airway for ethical reasons as we were acting in severe emergency cases.
Our difficult intubation rate was 6%, compared with 2.7–12.3% cited in the emergency medicine literature [8],[9], [10], [11], [12] and [13].
Our study showed that prehospital airway difficulties can be predicted in 71% of cases, with easily identifiable predictive signs of DI (morbid obesity, cervico-facial trauma, short neck, restricted mouth opening <3 cm, thyromental distance <6 cm), and we found only 29% unanticipated airway difficulties in prehospital settings.
Our findings suggest that in prehospital emergencies, except for cervico-facial trauma injuries (26% of patients), the most frequent causes of DI are similar to those encountered in clinical practice: morbid obesityand short neck [14].
Rapid evaluation of predictive signs of DI could make airway difficulties possible to anticipate before performing laryngoscopy, to plan alternatives to direct laryngoscopy and to preclude multiple attempts.
However, our study highlights that the stylet is not used enough in French practice, even when there were predictive signs of DI, despite our protocol's recommendations and international guidelines (only 17% of overall ETI and 76% in cases of anticipated airway difficulties).
Nevertheless this prospective observational study had several limitations. No study details optimal training in Ezt use or that Ezt training on manikins is transferable to real patients, thus training in the use of Ezt was not based on evidence-based medicine. Incomplete forms were the most common problem, requiring a supplementary search of the medical files to complete the forms. Selective intubation (no lung expansion visible and absence of sounds during auscultation, reversible situation after moving ETT) was investigated only if it was identified on-site and thus the incidence may have been underestimated in this study. Another limitation of our study is that the data were self-reported by the persons who performed the intubations and hence the number of attempts or complications may have been underestimated.
It is essential that emergency physicians receive rigorous training in difficult airway management as well as how to investigate predictive signs of DI in order to plan alternatives to ETI and to avoid potential complications that may arise with several attempts.
Despite the wide range of available techniques for the management of DI, not all are suitable for use in prehospital emergency airway management. The Ezt may be recommended because of the very high success rate of ventilation and the possibility of blind intubation. The low failure rate after a short training period demonstrates that it is easy to use and has a steep learning curve.
Clinical evaluations of the Ezt in prehospital situations are scarce, but these results show that emergency physicians with minimal training, in cases of difficult airway management and in prehospital emergency medicine, can use the EzT safely and effectively. It could be proposed as the first-line alternative technique in difficult airway management in prehospital.
| Tags : airway
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