Military experience of human factors in airway complications

We were pleased to read the article by Flin and colleagues 1 based around the landmark NAP4 work 2 and applaud the review of human factors in airway complications. Within Defence Anaesthesia we have been very aware of the importance of human factors when dealing with time-critical complex trauma 3. Recognising that certain adverse factors are inevitable in the deployed military environment (e.g. heat, noise, fatigue), we aim for excellence in all other areas (including situation awareness, work preparation and teamwork). We rehearse these skills during pre-deployment training for Afghanistan on the Military Operational Surgical Training Course (MOST) 4 and the Hospital Exercise (HospEx) 5. On the MOST course, candidates develop mental models around the management of complex trauma and practise with the team with which they are deploying in a high-fidelity simulator. During a 48-h period on HospEx, the whole hospital unit rehearses all the systems and processes involved in running the field hospital. Blast and ballistic injuries to the neck and face can present particular airway management issues. A recent analysis of the UK-Joint Theatre Trauma Register 6 revealed 375 cases of face and neck injuries during 2003–08 7 and of these, there were 28 penetrating vascular injuries and 13 penetrating laryngotracheal injuries (total battle injury figures (n = 869) were only available for 2006–08). For casualties with time-critical complex blast and ballistic trauma, the option to ‘wake up’ as originally described in the Difficult Airway Society Guidelines 8 is not appropriate. Our default position for securing the airway in the majority of our trauma patients involves rapid sequence induction using a Macintosh size-4 laryngoscopic blade, with a gum-elastic bougie and two suction devices close to hand; no more than three attempts at intubation (with re-oxygenation between each) is permitted before clear communication of failed intubation with immediate procession to a surgical airway. Successful airway control is communicated after confirmation of a capnography trace. This is based on a review of our collective experience and the literature 9. The decision on who will perform the surgical airway is made by the trauma team leader and lead anaesthetist during preparation to receive the patient. Human factors are particularly important if a patient's airway is secured on a moving Chinook CH47 helicopter as part of the Medical Emergency Response Team (MERT) 10 as conditions are noisy and often hot and dusty, and clinical care may have been delivered in poor light. If a patient is admitted from the pre-hospital phase and the trachea has already been intubated, there has to be clear communication to the team leader as to whether there is a capnography trace and the position of the tube at the patient's lips. The trauma team anaesthetist performs direct laryngoscopy to recheck the tube. A consultant radiologist then reports a digital chest X-ray and comments on the tube's position in relation to the carina. We hope that our pre-deployment training, particularly on MOST, will raise the importance of human factors in a trauma setting. We believe that the authors have identified a powerful tool that could be used to examine human factors concerning airway management in a pre-hospital setting.