Objective: To describe the prehospital use of a continuous positive airway pressure (CPAP) system for the treatment of presumed acute severe pulmonary edema (ASPE).
Methods: The efficacy of prehospital CPAP treatment was analyzed in terms of changes in oxygen saturation, need for intubation or ventilatory support, and possible morbidity associated with the CPAP therapy. This was a retrospective cohort study conducted in the mobile intensive care unit of a university hospital. Participants included all consecutive patients with a clinical picture of ASPE treated by a mobile intensive care unit between January 1, 1998, and December 31, 1999.
Results: 121 patients were included in this study. 116 patients received prehospital CPAP therapy. Two patients (1.7%) from the CPAP-treated patients were intubated in the field. A total of six patients required endotracheal intubation before hospital, and six other patients after that. After the beginning of CPAP treatment, there was statistically significant elevation in blood oxygen saturation (mean and standard deviation [SD] before CPAP 77% +/- 11% and after CPAP 90% +/- 7%) (p < 0.0001) as well as reductions in the respiratory rate (mean and SD before CPAP 34 +/- 8 breaths/min and after CPAP 28 +/- 8 breaths/min) (p < 0.0001), systolic blood pressure (mean and SD before CPAP 173 +/- 39 mm Hg and after CPAP 166 +/- 37 mm Hg) (p = 0.0002), and heart rate (mean and SD before CPAP 108 +/- 25 beats/min and after CPAP 100 +/- 20 beats/min) (p = 0.0017). The main reason for in-hospital death (8%) was myocardial infarction. No technical problems or complications occurred during CPAP treatment.
Conclusions: Prehospital CPAP treatment in patients with ASPE improved oxygenation significantly and lowered respiratory rate, heart rate, and systolic blood pressure. Because of the retrospective nature of this study, the hemodynamic effects of nitroglycerine and morphine cannot be excluded. The mortality rate was low, which needs to be confirmed in a controlled, prospective study.