Background: Previous studies have demonstrated decreased rates of intubation and mortality with prehospital use of continuous positive airway pressure (CPAP). We sought to validate these findings in a larger observational study.
Methods: We conducted a before and after observational study of consecutive patients transported by emergency medical services (EMS) during the 12 months before and the 12 months following implementation of a prehospital CPAP protocol for acute respiratory distress. Included were all patients transported by EMS meeting preestablished criteria indicative of acute respiratory distress and CPAP use (patient's problem specified as cardiac, respiratory distress, respiratory disease, or congestive heart failure [CHF]; age ≥ 12 years; chest sounds documented as wheezes or rales; Glascow Coma Scale [GCS] ≥ 11; respiratory rate ≥ 24 breaths per minute; systolic blood pressure ≥ 90 mmHg; and oxygen saturation < 90%). Data were abstracted from ambulance call reports (ACRs) and hospital records. All cases in which "do not resuscitate" (DNR) was documented on the patient chart or ACR or whose in-hospital outcome (death or discharge) was unknown were excluded.
Results: In all, 442 patients met the above criteria. The mean (SD) age was 73.0 (13.9) years, and 51.5% were women. In-hospital mortality rates did not differ for these patients: 17/228 (7.5%) in the before group and 17/214 (7.9%) in the after group (p = 0.85). In-hospital intubation rates were similar for both groups (12.7 vs. 14.5%, p = 0.59). An analysis of the subgroup that had a hospital diagnosis of chronic obstructive pulmonary disease (COPD), CHF, or pulmonary edema (n = 273) showed mortality was somewhat lower in the before group (3/138, 2.2%) than in the after group (8/135, 5.9%) (p = 0.13). In-hospital intubation rates were also similar for both groups in this subgroup analysis (11.6 vs. 9.6%, p = 0.61).
Conclusion: In contrast to previous studies, we were unable to demonstrate a decrease in intubation or mortality related to the use of prehospital CPAP. Our findings may be specific to our EMS system but suggest that further large-scale, randomized, controlled trials may be warranted to firmly establish the benefit of prehospital CPAP.