Treatment of acute hypoxemic nonhypercapnic respiratory insufficiency withcontinuous positive airway pressure delivered by a face mask - A randomized controlled trial

Context Continuous positive airway pressure (CPAP) is widely used in the be lief that it may reduce the need for intubation and mechanical ventilation in patients with acute hypoxemic respiratory insufficiency. Objective To compare the physiologic effects and the clinical efficacy of C PAP vs standard oxygen therapy in patients with acute hypoxemic, nonhyperca pnic respiratory insufficiency. Design, Setting, and Patients Randomized, concealed, and unblinded trial of 123 consecutive adult patients who were admitted to 6 intensive care units between September 1997 and January 1999 with a PaO2/FIO2 ratio of 300 mm H g or less due to bilateral pulmonary edema (n=102 with acute lung injury an d n=21 with cardiac disease). Interventions Patients were randomly assigned to receive oxygen therapy alo ne (n=61) or oxygen therapy plus CPAP (n=62). Main Outcome Measures Improvement in PaO2/FIO2 ratio, rate of endotracheal intubation at any time during the study, adverse events, length of hospital stay, mortality, and duration of ventilatory assistance, compared between the CPAP and standard treatment groups. Results Among the CPAP vs standard therapy groups, respectively, causes of respiratory failure (pneumonia, 54% and 55%), presence of cardiac disease ( 33% and 35%), severity at admission, and hypoxemia (median [5th-95th percen tile] PaO2/FIO2 ratio, 140 [59-288] mm Hg vs 148 [62-283] mm Hg; P=.43) wer e similarly distributed. After 1 hour of treatment, subjective responses to treatment (P<.001) and median (5th-95th percentile) PaO2/FIO2 ratios were greater with CPAP (203 [45-431] mm Hg vs 151 [73-482] mm Hg; P=.02), No fur ther difference in respiratory indices was observed between the groups. Tre atment with CPAP failed to reduce the endotracheal intubation rate (21 [34% ] vs 24 [39%] in the standard therapy group; P=.53), hospital mortality (19 [31%] vs 18 [30%]; P=.89), or median (5th-95th percentile) intensive care unit length of stay (6.5 [1-57] days vs 6.0 [1-36] days; P=.43), A higher n umber of adverse events occurred with CPAP treatment (18 vs 6; P=.01), Conclusion In this study, despite early physiologic improvement, CPAP neith er reduced the need for intubation nor improved outcomes in patients with a cute hypoxemic, nonhypercapnic respiratory insufficiency primarily due to a cute lung injury.