The difficult airway in the emergency department

Evelyn Wong Yih-Yng Ng Background The patient with difficult airways is a common challenge for emergency physicians. Aims Our goal was to study the reasons for difficult airways in the emergency department. Methods We performed a prospective observational study of patients requiring advanced airway management from 1 January 2000 to 31 December 2006. Results There were 2,343 patients who received advanced airway management of which 93 (4.0%) were deemed difficult. The main diagnoses were cardiac arrest (28), trauma (27) and congestive heart failure (10). The main reasons for the difficult airways were attributed to an anterior larynx (38, 40.9%), neck immobility (22, 23.7%) as well as the presence of secretions and blood (14, 15.1%). The mean number of attempts at intubation was 3.6 versus 1.2 for all cases. The mortality rate of 40.5% among patients with difficult airways was not different from that of all patients who had airway management (41%). There were seven (0.3%) failed airways. Anaesthetists performed 21 (22.6%) of the rescue airways while surgeons performed 5 (5.4%). Of the rescue strategies performed, 24 were through the use of the bougie, 3 by cricothyroidotomy, 4 by tracheostomy, 6 with the GlideScope and 3 with the laryngeal mask airway. The rest the airways were secured by tracheal intubation using the laryngoscope. Disclaimer: The views expressed in this paper are those of the author(s) and not those of the editors, editorial board or publisher. - The difficult airway is a challenge to emergency physicians. In the anaesthesia literature, is frequency ranges from 0.4 to 8.5% [13] of elective intubations. In the emergency medicine literature, is more commonfrom 2 to 14.8% [49]but it includes prehospital intubation and may be performed by paramedics or doctors. The definition of the difficult airway varies in different literature sources. The American Society of Anesthesiologists Task Force on Management of the Difficult Airway defines it as the clinical situation in which a conventionally trained anaesthesiologist experiences difficulty with face mask ventilation of the upper airway, difficulty with tracheal intubation or both [10]. Suggested descriptions of the difficult airway include but are not limited to difficult face mask ventilation, difficult laryngoscopy, difficult tracheal intubation and failed intubation. The emergency medicine literature generally considers the difficult airway in three dimensions: difficult mask ventilation, difficult intubation and difficult cricothyroidotomy, by experienced personnel [11]. There is no consistent or single definition of the difficult and the failed airway. Table 1 Primary diagnoses CVA cerebrovascular accident This paper aims to identify the reasons for difficult airways in emergency medicine practice as well as to study the rescue methods used in a tertiary hospital in South-East Asia. The study site emergency department has an ongoing airway registry that prospectively captures patient demographics, diagnosis, indications for intubation, persons and discipline of intubating physicians, number of attempts, method of intubation including rescue methods, reasons for difficult intubation, success rates and complications. Data are collected using a study form, which is completed by the intubating physician immediately after the procedure. Where the data were incomplete, the research assistant would approach the intubating physician to fill the gaps. This project was approved by the hospitals Ethics Committee. The data used for this study were from 1 January 2000 to 31 December 2006. The data were analysed using the Statistical Package for the Social Sciences (SPSS) software for Windows (version 10.1; SPSS Inc). Table 2 Reasons for difficult intubation Reasons for difficulty Table 3 Personnel performing the first intubation and rescue attempts For the purpose of this study, we adopted the following definitions: 1. A difficult airway is one where there was difficulty administering adequate mask ventilation or if there were at least three attempts at orotracheal intubation or a failed intubation or if cricothyroidotomy was difficult. A failed airway is one where tracheal intubation cannot be achieved, after multiple attempts, by the orotracheal or nasal-tracheal or transtracheal (cricothyroidotomy or tracheostomy) route or attempts at intubation are abandoned. From 2000 to 2006, there were a total of 808,721 emergency department (ED) visits; 2,343 of them required advanced airway intervention, giving a rate of 2.9 per 1,000 emergency department visits. Ninety-three (4.0%) of these were deemed difficult intubations, seven (0.3%) of which were failed airways. The mean age of the patients was 57 years for patients with difficult intubations compared to 63 years for all patients in the registry. The gender ratio was 75.5% men in the difficult airway group compared to 66.5% men among all patients. The most common indications for intubation were cardiac arrest (39.1%), acute pulmonary oedema (18.0%) and trauma (13.2%). However, the most common diagnoses resulting in difficult intubations were seizure (16.7%), burns (14.7%) and pneumonia (12.3%) (Table 1). Table 4 Methods of intubation for the first and final attempts OTI orotracheal intubation, RSI rapid sequence intubation Table 5 Rescue devices LMA laryngeal mask airway The three most common reasons cited for difficult intubations were the presence of an anterior larynx (40.9%), neck immobility (23.7%) and profuse oral secretions and bleeding (15.1%) (Table 2). The Mallampati score was seldom used. The mean number of attempts at intubation was 3.6 for the difficult airway group and 1.2 for all patients in the registry. Emergency physicians were most likely to attempt difficult intubations first (91.3%) and were most likely to also perform the rescue attempt (68.8%). Anaesthetists performed 22.6% of rescue airways (Table 3). Of the 46 patients who underwent orotracheal intubation with no drugs, 3 were converted to surgical airways (2 cricothyroidotomies and 1 tracheostomy). Of the 11 patients who underwent orotracheal intubation with induction agents only 2 had to receive neuromuscular blocking agents subsequently through rapid sequence intubation (RSI). Three of the patients who initially had RSI subsequently had tracheostomies performed by the surgeons (Table 4). The most common rescue device used in our department was the Macintosh-type laryngoscope with the curved blade alone (54.8%), followed by the laryngoscope with the bougie (25.8%) and the GlideScope (6.5%) (Table 5). Most of the bougie attempts were made by anaesthetists (83.3%). There were seven failed airways but no deaths attributed to the failures (Table 6). The mortality rate of 40.5% among Table 6 Failed emergency department airways EM emergency medicine, AN anaesthesia, GS general surgery, OT operating theatre Cardiac arrest Cardiac arrest Cardiac arrest patients with difficult airw (...truncated)