Out-of-Hospital Continuous Positive Airway Pressure Ventilation Versus Usual Care in Acute Respiratory Failure: A Randomized Controlled Trial
Presented at the International Congress of Emergency Medicine, June 2006, Halifax, Nova Scotia, Canada.
Received 6 February 2007; received in revised form 25 June 2007 and 18 October 2007; accepted 9 January 2008. published online 04 April 2008.
Study objective
Continuous positive airway pressure ventilation (CPAP) in appropriately selected patients with acute respiratory failure has been shown to reduce the need for tracheal intubation in hospital. Despite several case series, the effectiveness of out-of-hospital CPAP has not been rigorously studied. We performed a prospective, randomized, nonblinded, controlled trial to determine whether patients in severe respiratory distress treated with CPAP in the out-of-hospital setting have lower overall tracheal intubation rates than those treated with usual care.
Methods
Out-of-hospital patients in severe respiratory distress, with failing respiratory efforts, were eligible for the study. The study was approved under exception to informed consent guidelines. Patients were randomized to receive either usual care, including conventional medications plus oxygen by facemask, bag-valve-mask ventilation, or tracheal intubation, or conventional medications plus out-of-hospital CPAP. The primary outcome was need for tracheal intubation during the out-of-hospital/hospital episode of care. Mortality and length of stay were secondary outcomes of interest.
Results
In total, 71 patients were enrolled into the study, with 1 patient in each group lost to follow-up after refusing full consent. There were no important differences in baseline physiologic parameters, out-of-hospital scene times, or emergency department diagnosis between groups. In the usual care group, 17 of 34 (50%) patients were intubated versus 7 of 35 (20%) in the CPAP group (unadjusted odds ratio [OR] 0.25; 95% confidence interval [CI] 0.09 to 0.73; adjusted OR 0.16; 95% CI 0.04 to 0.7; number needed to treat 3; 95% CI 2 to 12). Mortality was 12 of 34 (35.3%) in the usual care versus 5 of 35 (14.3%) in the CPAP group (unadjusted OR 0.3; 95% CI 0.09 to 0.99).
Conclusion
Paramedics can be trained to use CPAP for patients in severe respiratory failure. There was an absolute reduction in tracheal intubation rate of 30% and an absolute reduction in mortality of 21% in appropriately selected out-of-hospital patients who received CPAP instead of usual care. Larger, multicenter studies are recommended to confirm this observed benefit seen in this relatively small trial.
aDepartment of Emergency Medicine, St. Paul's Hospital, Vancouver, British Columbia, Canada
bDepartment of Emergency Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
cEmergency Health Services, Dartmouth, Nova Scotia, Canada
Address for correspondence: David A. Petrie, MD, FRCPC, Department of Emergency Medicine, Dalhousie University, Halifax, NS, Canada B3H 2Y9; 902-473-8959, fax 902-494-1625
Supervising editor: Theodore R. Delbridge, MD, MPH
Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article, that might create any potential conflict of interest. The authors have stated that no such relationships exist. See the Manuscript Submission Agreement in this issue for examples of specific conflicts covered by this statement. This study protocol was approved by Capital District Health Authority Research Ethics Board. Their file number is CDHA 2000-305, Clinical Trials.gov Identifier NCT00405314.
Author contributions: JT, DAP, SA-S, and DJB conceived and designed the trial. JT, DAP, SA-S, and DJB obtained the funding. JT, DAP, SA-S, and DJB supervised the conduct of the trial and data collection. SA-S supervised management of the data, including quality control. JT, DAP, and DJB supervised the recruitment by paramedics. SA-S provided statistical advice on study design and statistical methodology and conducted descriptive data analyses. JT drafted the first copy of the article, and all authors contributed substantially to its revisions. JT and DAP take responsibility for the paper as a whole.
ABSTRACT
Out-of-Hospital Continuous Positive Airway Pressure Ventilation Versus Usual Care in Acute Respiratory Failure: A Randomized Controlled Trial