Introduction
Severe dyspnea is a common presenting complaint to emergency medical services (EMS) providers. Dyspnea can result from a variety of conditions, including acute cardiogenic pulmonary edema, acute exacerbation of chronic obstructive pulmonary disease, acute asthma exacerbation, and pneumonia. Out-of-hospital treatment of patients in severe respiratory distress presents unique challenges. These patients often require positive-pressure ventilation, but may have factors that make invasive ventilation by intubation or insertion of a supraglottic airway device difficult. Examples of such factors include intact airway reflexes, environmental challenges, and intubation's being a low-frequency skill for most paramedics.1, 2, 3 Additionally, “standard” out-of-hospital therapy for severe dyspnea is diverse, depending on the region of the world, ranging from simple supplemental oxygen therapy to diuretic and ionotropic infusions. The approaches currently used are varied and lack evidence to support any particular practice patterns.Editor's Capsule Summary
What is already known on this topic
Out-of-hospital providers have few options for treating severe respiratory distress.
What question this study addressed
Does out-of-hospital noninvasive positive-pressure ventilation (NIPPV) reduce mortality?
What this study adds to our knowledge
In this meta-analysis of 7 randomized controlled trials including 632 adults, NIPPV was associated with reduced mortality and a reduced need for intubation.
How this is relevant to clinical practice
This meta-analysis supports the expanded use of out-of-hospital NIPPV for severe respiratory distress in adults.
Inhospital treatment of acute cardiogenic pulmonary edema and acute exacerbation of chronic obstructive pulmonary disease with noninvasive positive-pressure ventilation (NIPPV), which includes continuous and bilevel pressure modalities, has been studied extensively.4, 5, 6, 7, 8, 9 A recent Cochrane review of 21 studies involving 1,071 adult patients with acute cardiogenic pulmonary edema reported significantly reduced inhospital mortality (risk ratio [RR] 0.6; 95% confidence interval [CI] 0.45 to 0.84) and intubation (RR 0.53; 95% CI 0.34 to 0.83) when NIPPV was compared with standard medical care.4 A second Cochrane review of 14 studies involving 758 patients with acute exacerbation of chronic obstructive pulmonary disease on the use of NIPPV showed similarly impressive results, with reductions in hospital mortality (RR 0.52; 95% CI 0.35 to 0.76) and need for intubation (RR 0.41; 95% CI 0.33 to 0.53).7
A number of commercial systems are available that allow NIPPV to be administered out-of-hospital relatively easily without large ventilators.10, 11, 12, 13 NIPPV is increasingly being used by EMS providers for the treatment of severe respiratory distress in the out-of-hospital setting.14, 15, 16, 17, 18, 19, 20, 21, 22, 23 The primary objective of our systematic review was to determine whether out-of-hospital–administered NIPPV for the treatment of adults (aged ≥16 years) with severe respiratory distress reduces inhospital mortality compared with standard therapy. Our secondary objectives included hospital length of stay, ICU length of stay, need for invasive ventilation, and complications arising from the use of NIPPV.