RCT: High-Intensity NPPV Reduced Criteria for Intubation in Acute COPD Exacerbations
16 Sep, 2024 | 16:50h | UTCBackground: Acute exacerbations of chronic obstructive pulmonary disease (COPD) often lead to hypercapnic respiratory failure requiring ventilatory support. Noninvasive positive pressure ventilation (NPPV) is standard care, commonly delivered at low intensity with lower inspiratory pressures. However, approximately 15% of patients still require endotracheal intubation despite low-intensity NPPV. High-intensity NPPV, using higher inspiratory pressures to achieve greater reductions in PaCO₂, has shown benefits in stable hypercapnic COPD patients, but its effect during acute exacerbations is unclear.
Objective: To determine whether high-intensity NPPV reduces the need for endotracheal intubation in patients with acute COPD exacerbations and persistent hypercapnia compared to low-intensity NPPV.
Methods: In a multicenter, randomized clinical trial conducted at 30 respiratory wards in China from January 2019 to January 2022, 300 patients with acute COPD exacerbations and PaCO₂ greater than 45 mm Hg after 6 hours of low-intensity NPPV were enrolled. Participants were randomized 1:1 to receive either high-intensity NPPV (inspiratory positive airway pressure [IPAP] adjusted to achieve tidal volumes of 10–15 mL/kg predicted body weight, typically IPAP 20–30 cm H₂O) or to continue low-intensity NPPV (IPAP adjusted for tidal volumes of 6–10 mL/kg, maximum IPAP 20 cm H₂O). Patients in the low-intensity group meeting prespecified criteria for intubation were allowed to crossover to high-intensity NPPV. The primary outcome was the need for endotracheal intubation during hospitalization, defined by prespecified clinical and gas exchange criteria. Secondary outcomes included actual endotracheal intubation rates, mortality, length of hospital stay, and adverse events.
Results: Of the 300 patients (mean age 73 years; 68% male), the primary outcome occurred in 4.8% of the high-intensity group versus 13.7% of the low-intensity group (absolute difference –9.0%; 95% CI, –15.4% to –2.5%; one-sided P = .004; adjusted risk ratio [RR], 0.35; 95% CI, 0.14–0.76). However, actual endotracheal intubation rates did not differ significantly between groups (3.4% vs 3.9%; absolute difference –0.5%; 95% CI, –4.8% to 3.7%; P = .81). The high-intensity group had greater reductions in PaCO₂ levels over 72 hours (mean PaCO₂ at 72 hours: 53 mm Hg vs 64 mm Hg; P < .001) and higher rates of achieving normocapnia (21.8% vs 4.6%; P < .001). Abdominal distension occurred more frequently in the high-intensity group (37.4% vs 25.5%; absolute difference 11.9%; 95% CI, 1.5%–22.4%; P = .03), but other adverse events and serious adverse events were similar between groups.
Conclusions: High-intensity NPPV reduced the proportion of patients meeting criteria for endotracheal intubation compared to low-intensity NPPV in patients with acute COPD exacerbations and persistent hypercapnia. However, actual intubation rates did not differ, possibly due to crossover from low- to high-intensity NPPV in patients meeting intubation criteria.
Implications for Practice: High-intensity NPPV may be considered for patients with acute COPD exacerbations who remain hypercapnic after initial low-intensity NPPV, as it may reduce progression to severe respiratory failure requiring intubation criteria. Clinicians should monitor for abdominal distension and potential alkalosis, although these did not significantly affect overall tolerance or safety.
Study Strengths and Limitations: Strengths include the multicenter randomized design, clear enrollment criteria, and standardized protocols. Limitations include early trial termination, unblinded interventions, potential bias due to allowed crossover, and lack of power to detect differences in mortality or actual intubation rates.
Future Research: Further large-scale trials are needed to confirm these findings, assess the impact on actual intubation rates and mortality, and explore the efficacy of high-intensity NPPV in different clinical settings and patient populations, including those without prior NPPV exposure or with more severe respiratory distress.