Comparison of noninvasive positive pressure ventilation with standard medical therapy in hypercapnic acute respiratory failure

Study objective: To compare the efficacy of standard medical therapy (ST) a nd noninvasive mechanical ventilation additional to standard medical therap y in hypercapnic acute respiratory failure (HARF). Design: Single center, prospective, randomized, controlled study. Setting: Pulmonary medicine directed critical care unit in a university hos pital. Patients: Between March 1993 and November 1996, 30 HARF patients were rando mized to receive ST or noninvasive positive pressure ventilation (NPPV) in addition to ST. Interventions: NPPV was given with an air-cushioned face via a mechanical v entilator (Puritan Bennett 7200) with initial setting of 5 cm H2O continuou s positive airway pressure and 15 cm H2O pressure support. Results: At the time of randomization, patients in the ST group had (mean /- SD) Pao(2) of 54 +/- 13 mm Hg, Paco(2) of 67 +/- 11 mm Hg, pH of 7.28 +/ - 0.02, and respiratory rate of 35.0 +/- 5.8 breaths/min. Patients in the N PPV group had Pao(2) of 55 +/- 14, Paco(2) of 69 +/- 15, PH of 7.27 +/- 0.0 7, and respiratory rate of 34.0 +/- 8.1 breaths/min. With ST, there was sig nificant improvement of only respiratory rate (p < 0.05). However, with NPP V, Pao(2) (p < 0.001), Paco(2) (p < 0.001), pH(p < 0.001), and respiratory rate (p < 0.001) improved significantly compared with baseline. Sir; hours after randomization, pH (p < 0.01) and respiratory rate (p < 0.01) in NPPV patients were significantly bet-ter than with ST. Hospital stay for NPPV vs ST patients was, respectively, 11.7 +/- 3.5 and 14.6 +/- 4.7 days (p < 0.0 5). One patient in the NPPV group required invasive mechanical ventilation. The conditions of six patients in the ST group deteriorated and they were switched to NPPV; this was successful in four patients, two failures were i nvasively ventilated. Conclusion: This study suggests that early application of NPPV in HARF pati ents facilitates improvement, decreases need for invasive mechanical ventil ation, and decreases the duration of hospitalization.