<p><b>Objective</b>: Studies of adult hospital patients have identified medical errors as a significant cause of morbidity and mortality. Little is known about the frequency and nature of pediatric patient safety events in the out-of-hospital setting. We sought to quantify pediatric patient safety events in EMS and identify patient, call, and care characteristics associated with potentially severe events. <b>Methods</b>: As part of the Children's Safety Initiative -EMS, expert panels independently reviewed charts of pediatric critical ambulance transports in a metropolitan area over a three-year period. Regression models were used to identify factors associated with increased risk of potentially severe safety events. Patient safety events were categorized as: Unintended injury; Near miss; Suboptimal action; Error; or Management complication (“UNSEMs”) and their severity and potential preventability were assessed. <b>Results</b>: Overall, 265 of 378 (70.1%) unique charts contained at least one UNSEM, including 146 (32.8%) errors and 199 (44.7%) suboptimal actions. Sixty-one UNSEMs were categorized as potentially severe (23.3% of UNSEMs) and nearly half (45.3%) were rated entirely preventable. Two factors were associated with heightened risk for a severe UNSEM: (1) age 29 days to 11 months (OR 3.3, 95% CI 1.25-8.68); (2) cases requiring resuscitation (OR 3.1, 95% CI 1.16-8.28). Severe UNSEMs were disproportionately higher among cardiopulmonary arrests (8.5% of cases, 34.4% of severe UNSEMs). <b>Conclusions</b>: During high-risk out-of-hospital care of pediatric patients, safety events are common, potentially severe, and largely preventable. Infants and those requiring resuscitation are important areas of focus to reduce out-of-hospital pediatric patient safety events.</p
