Low–Fractional Oxygen Concentration Continuous Positive Airway Pressure is Effective in the Prehospital Setting

Abstract

Objective. The objective of this study was to determine the effects of low–fractional concentration of inspired oxygen (FiO₂) continuous positive airway pressure (CPAP) in prehospital noninvasive ventilation (NIV). With increasing concerns about the detrimental effects of hyperoxia, we sought to determine whether CPAP using a low FiO₂ (28%–30%) was effective in the prehospital setting. Methods. The study was a six-month prospective, nonblinded observational study conducted in a large, busy urban emergency medical services (EMS) system (Las Vegas, NV). Results. A total of 340 patients participated in the study. Most patients presented with symptoms consistent with a diagnosis of congestive heart failure/acute pulmonary edema (47.4%), followed by chronic obstructive pulmonary disease (COPD) (40.9%), asthma (22.7%), and pneumonia (15.9%). Improvements were seen in respiratory rate (p = 0.00) and oxygen saturation (p = 0.00). The overall CPAP discontinuation rate was 16.5%. The most common reason for CPAP discontinuation was anxiety/claustrophobia. The total number of patients requiring prehospital intubation was 5.6%. Subjective paramedic assessment of patient status at hospital delivery found that 71.5% of patients’ conditions were improved, 15.1% remained unchanged, and 13.4% were worse. Conclusions. CPAP using a low FiO₂ (28%–30%) was highly effective in the treatment of commonly encountered prehospital respiratory emergencies.

Key words: :

• prehospital CPAP
• noninvasive ventilation
• EMS
• continuous positive airway pressure