Of 203 patients attending a US Level 1 trauma centre who had pre-hospital airway management, 25 (12%) had unrecognised oesophageal intubations.

Patients were treated in the field by fire rescue personnel of various municipalities and with different experience levels. Patients transported by air were significantly more likely to be successfully intubated than those transported by ground, perhaps due to both increased experience and the use by air crews of succinylcholine. The authors in their discussion contrast these results with those of European studies which report higher success rates with pre-hospital systems that employ emergency physicians and anaesthetists.

Prehospital intubations and mortality: a level 1 trauma center perspective
Anesth Analg. 2009 Aug;109(2):489-93