Noninvasive ventilation (NIV) may be used as a first-line intervention in conjunction with usual care to reduce the likelihood of mortality and endotracheal intubation in patients admitted with acute hypercapnic respiratory failure (AHRF) secondary to an acute exacerbation of chronic obstructive pulmonary disease (COPD), a review found.
Researchers reviewed the literature up to January 2017, considering all randomized controlled trials that compared usual care plus NIV bi-level positive airway pressure (BiPAP) versus usual care alone in an acute hospital setting for patients with acute exacerbation of COPD due to AHRF. AHRF was defined by a mean admission pH below 7.35 and a mean partial pressure of carbon dioxide (PaCO2) above 45 mm Hg. Primary review outcomes were mortality during hospital admission and need for endotracheal intubation. Secondary outcomes included hospital length of stay, treatment intolerance, complications, changes in symptoms, and changes in arterial blood gases.
Seventeen good-quality randomized controlled trials involving 1,264 patients were included in the analysis. Data were analyzed as both one overall pooled sample and according to two predefined subgroups related to exacerbation severity (admission pH between 7.35 and 7.30 vs. below 7.30) and treatment setting (intensive care unit-based vs. ward-based). Results were published July 13 by the Cochrane Database of Systematic Reviews.
Use of NIV decreased the risk of mortality by 46% (risk ratio [RR], 0.54 [95% CI, 0.38 to 0.76]; n=12 studies; number needed to treat for an additional beneficial outcome [NNTB], 12 [95% CI, 9 to 23]) and decreased the risk of needing endotracheal intubation by 65% (RR, 0.36 [95% CI, 0.28 to 0.46]; n=17 studies; NNTB, 5 [95% CI, 5 to 6]). Researchers graded both outcomes as moderate quality owing to uncertainty regarding risk of bias for several studies.
NIV use was also associated with reduced length of hospital stay (mean difference, −3.39 days; 95% CI, −5.93 to −0.85 days; n=10 studies), reduced incidence of complications unrelated to NIV (RR, 0.26; 95% CI, 0.13 to 0.53; n=2 studies), and improvement in pH (mean difference, 0.05; 95% CI, 0.02 to 0.07; n=8 studies) and partial pressure of oxygen (PaO2) at one hour (mean difference, 7.47 mm Hg; 95% CI, 0.78 to 14.16 mm Hg; n=8 studies).
The magnitude of benefit for these outcomes appears similar for patients with mild acidosis (pH 7.30 to 7.35) or more severe acidosis (pH <7.30) and when NIV was applied within the intensive care unit or ward setting.
The authors noted that the review provides convincing evidence to support the use of NIV as an effective treatment strategy for patients admitted to the hospital for acute exacerbations of COPD and respiratory failure. However, they cautioned that certain factors may affect patient safety, including degree of illness, availability of trained staff for implementation and monitoring, adequate staff-to-patient ratios, and understanding of different NIV interfaces and equipment.