Adverse events during rotary-wing transport of mechanically ventilated patients: a retrospective cohort study

INTRODUCTION: Patients triaged to tertiary care centers frequently undergo rotary-wing transport and may be exposed to additional risk for adverse events. The incidence of physiologic adverse events and their predisposing factors in mechanically ventilated patients undergoing aeromedical transport are unknown. METHODS: We performed a retrospective review of flight records of all interfacility, rotary-wing transports to a tertiary care, university hospital during 2001 to 2003. All patients receiving mechanical ventilation via endotracheal tube or tracheostomy were included; trauma, scene flights, and fixed transports were excluded. Data were abstracted from patient flight and hospital records. Adverse events were classified as either major (death, arrest, pneumothorax, or seizure) or minor (physiologic decompensation, new arrhythmia, or requirement for new sedation/paralysis). Bivariate associations between hospital and flight characteristics and the presence of adverse events were examined. RESULTS: Six hundred eighty-two interfacility flights occurred during the period of review, with 191 patients receiving mechanical ventilation. Fifty-eight different hospitals transferred patients, with diagnoses that were primarily cardiopulmonary (45%) and neurologic (37%). Median flight distance and time were 42 (31 to 83) km and 13 (8 to 22) minutes, respectively. No major adverse events occurred during flight. Forty patients (22%) experienced a minor physiologic adverse event. Vasopressor requirement prior to flight and flight distance were associated with the presence of adverse events in-flight (P < 0.05). Patient demographics, time of day, season, transferring hospital characteristics, and ventilator settings before and during flight were not associated with adverse events. CONCLUSION: Major adverse events are rare during interfacility, rotary-wing transfer of critically ill, mechanically ventilated patients. Patients transferred over a longer distance or transferred on vasopressors may be at greater risk for minor adverse events during flight.