Objective: To determine the viability of prehospital noninvasive ventilation (NIV) as a prelude to a definitive clinical trial.
Methods: This was a retrospective observational study of patients (aged > 55 years, severe shortness of breath) transported to a tertiary emergency department (10/5/03-12/28/04). Data were extracted from paramedic and hospital medical records. The primary outcome measure was the number of patients who could potentially benefit from prehospital NIV. They were defined as "conscious upon paramedic arrival and who required ventilatory support (bag/valve/mask ventilation [BVM], NIV or endotracheal intubation) during transport or within 30 minutes of arrival at the emergency department (ED)." The secondary outcome measures were the effectiveness of existing paramedic treatment regimens and paramedic management times.
Results: Two hundred sixty-four patients were enrolled (mean age 75.5 +/- 8.7 years, 59.1% male). Sixty-seven patients (25.4%, 95% CI: 20.3-31.2) met the primary outcome measure: 31 (11.7%, 95% CI: 8.2-16.4) received prehospital BVM, an additional 35 (13.3%, 95% CI: 9.5-18.1) received NIV in the ED and one (0.4%, 95% CI: 0.0-2.4) was intubated in the ED. Prehospital treatment resulted in significant (p < 0.001) improvements in systolic blood pressure (151.2 dropping to 144.2 mmHg), respiratory rate (29.4 dropping to 26.3 breaths/minute), and oxygen saturation (92.3% rising to 96.2%). Median paramedic management time was 33 minutes (IQR 29-40).
Conclusion: Prehospital treatment significantly improved patient vital signs. However, a considerable proportion of patients still required ventilatory support either prehospital or early in their ED course. Further research is indicated to determine if these patients would benefit from prehospital NIV.