Management of severe respiratory insufficiency due to Pneumocystis carinii pneumonitis in immunosuppressed hosts. The role of continuous negative-pressure ventilation

Continuous negative-pressure therapy was used to assist ventilation in 19 spontaneously breathing patients, 6 mth to 17 yr of age, who developed progressive respiratory insufficiency (arterial PO ₂<70 mm Hg despite a fraction of inspired O ₂≥50%) due to Pneumocystis carinii pneumonitis. Within 1 hr of therapy, arterial PO ₂ increased from a mean ±SE of 61.9±3.7 to 75.4±7.0 mm Hg (P<0.05) and, by 6 hr, to 79.9±4.7 mm Hg (P<0.005). In the 14 survivors, these improvements were sustained and, within 24 hr, permitted a decrease in inspired O ₂ concentration from a mean ±SE of 50.4±1.2% to 40.1±1.6% (P<0.005). By contrast, in nonsurvivors, O ₂ requirements could not be decreased significantly despite increases in negative pressure. Improvements in arterial oxygenation were associated with decreases in alveolar-arterial PO ₂ differences in all patients; however, significant decreases occurred only with pressures of -8 to -12 cm H ₂O. Higher negative pressures were ineffective and usually produced pulmonary air leak. Since the introduction of continuous negative-pressure therapy as a means of assisting ventilation in management of progressive respiratory insufficiency, the over-all survival rate among patients with Pneumocystis carinii pneumonitis at this institution has increased from 69 to 89%.