The risks associated with urgent land-based transport of critically ill patients are not well known and have important implications for patient safety, care delivery, and policy development. We seek to determine the incidence of in-transit critical events and associated patient- and transport-level factors.

We conducted a retrospective cohort study using clinical and administrative data. We included adults undergoing urgent land-based critical care transport by a dedicated transport provider between January 1, 2005, and December 31, 2010. The primary outcome was in-transit critical event, defined by adverse events or resuscitative procedures.

In-transit critical events were observed in 333 (6.5%) of 5,144 urgent land transports. New hypotension (4.4%) or new vasopressors (1.6%) were the most common critical events, with fewer respiratory events (1.3%). Advanced care paramedics had a higher rate compared with critical care paramedics (odds ratio [OR] 1.6; 95% confidence interval [CI] 1.1 to 2.2), especially for patients with baseline hemodynamic instability. In multivariate analysis, mechanical ventilation (adjusted OR 1.7; 95% CI 1.3 to 2.2), baseline hemodynamic instability (adjusted OR 3.7; 95% CI 2.8 to 4.9), out-of-hospital duration (adjusted OR 3.6; 95% CI 2.9 to 4.5 per log-fold increase in time), and neurologic diagnosis (adjusted OR 0.5; 95% CI 0.3 to 0.7 compared with that of medical patients) were associated with critical events.

Critical events occurred in approximately 1 in 15 transports and were associated with mechanical ventilation, hemodynamic instability, and transport duration, and were less frequent in neurologic patients. The finding that hypotension is common and predicted by pretransport hemodynamic instability has implications for the preparation and management of this patient group.