Limitations of difficult airway prediction in patients intubated in the emergency department

Physiognomic assessment of difficult laryngoscopy before rapid sequence intubation has been advocated for all emergency department (ED) intubations. The study objectives were to evaluate whether Mallampati scores, thyromental distance, and neck mobility could have been assessed in non-cardiac arrest ED-intubated patients and determine whether such tests would have been feasible in our rapid sequence intubation-associated laryngoscopy failures.

We retrospectively reviewed 37 months of ED intubations using prospectively collected data from electronic medical records, critical care flow sheets, and a trauma registry. All non-cardiac arrest ED-intubated patients were included for analysis. Mallampati scoring was deemed unobtainable if patients could not follow simple commands. Neck mobility and thyromental measurement were deemed unobtainable with cervical spine precautions.

Eight hundred fifty intubations met the inclusion criteria, and 838 patients underwent rapid sequence intubation. Laryngoscopy failed in 3 patients who underwent rapid sequence intubation. Eight patients had awake nasal intubation, and 4 oral intubations were done without rapid sequence intubation. Four hundred fifty-two (53%) patients could not follow simple commands, and cervical spine immobilization was present in 370 (44%) patients. Only 32% of patients could follow simple commands and were not cervical spine immobilized. Among the 3 rapid sequence intubation laryngoscopy failures, no patients were following commands.

Mallampati scoring, neck mobility testing, and measurement of thyromental distance could have been done in only one third of our non-cardiac arrest ED intubations and in none of the rapid sequence intubation failures. The inability to widely obtain these assessment tools, coupled with the low incidence of failed rapid sequence intubation, indicates limitations to using these screening tests in the ED setting.