Continuous positive airway pressure (CPAP) is commonly used in the treatment of acute cardiogenic pulmonary edema (ACPE) and acute exacerbations of chronic obstructive pulmonary disease (AECOPD). In-hospital evidence is robust: CPAP has been shown to improve respiratory status and to reduce intubation rates. There is less evidence on prehospital CPAP, although the emergency medical services (EMS) adoption of this modality is increasing. The objectives of this study were to 1) measure the effectiveness of prehospital CPAP on morbidity, mortality, and transport times; and 2) audit the selection of patients by medics for appropriateness and safety.

We conducted a before-and-after study from August 1 to October 31 in 2010 and 2011, before and after the implementation of prehospital CPAP in a city of one million people with large rural areas. Medics were trained to apply CPAP to patients with respiratory distress and a presumed diagnosis of ACPE or AECOPD. Charts were selected using the search criteria of the chief complaint of shortness of breath, emergent transport to hospital, and any patients receiving CPAP in the field. Data extracted from ambulance call reports and hospital records were analysed with appropriate univariate statistics.

A total of 373 patients enrolled (186 pre-non-invasive ventilation [NIV] and 187 post-NIV), mean age 71.5 years, female 51.4%, and final diagnoses of ACPE 18.9%, AECOPD 21.9%. In the post group of 84 patients meeting NIV criteria, 41.6% received NIV; and of 102 patients not meeting the criteria, 5.2% received NIV. There were 12 minor adverse events in 36 applications (33.3%) as per protocol. Comparing post versus pre, there were higher rates of emergency department (ED) NIV (20.0% v. 13.4%, p<0.0001) and higher overall mortality (18.8% v. 14.9%, p<0.0001). There were no differences in ED intubation (2.1% v. 2.3%, p<0.001) and length of stay (6.8 v. 8.7 days, p=0.24).

Despite the robust in-hospital data supporting its use, we could not find benefit from CPAP in our prehospital setting with respect to morbidity, mortality, and length of stay. EMS must exercise caution in making the decision to invest in the equipment and training required to implement prehospital CPAP.

The impact of the use of mask continuous positive airway pressure (CPAP) on patients with acute respiratory distress in the prehospital, rural setting has not been defined. The goal was to test the use of CPAP using the Respironics® WhisperFlow® CPAP in patients presenting with acute respiratory distress. This was a collaborative evaluation of CPAP involving a rural EMS agency and the regional medical center. Patient outcomes including the overall rate of intubation-both in the field and in the emergency department (ED), and length of stay in the hospital and Intensive Care Unit (ICU) were tracked.

The study was an eight-month, crossover, observational, non-blinded study.

During the four months of baseline data collection, 7.9% of patients presenting with respiratory distress were intubated within the first 48 hours of care. Their average ICU length of stay was 8.0 days. During the four months of data collection when CPAP was available in the prehospital setting, intubation was not required for any patients in the field or in the ED. Admissions to the ICU decreased. Those patients admitted to the ICU, the average ICU length of stay deceased to 4.3 days.

The use of the CPAP in the prehospital setting is beneficial for patients in acute respiratory distress.