HYPERCAPNIA - IS THERE A CAUSE FOR CONCERN

Concern that barotrauma may lead to further deterioration in pulmonary function in patients with ARDS has stimulated interest in developing methods of reducing it. These new modalities have had limited acceptan ce. The reasons for this include technical difficulties, associated co mplications, and the hypercapnia produced by the reduction in minute v entilation associated with diminished peak inspiratory pressure (PIP). Recent reports have shown that hypercapnia does not produce many of t he adverse effects previously attributed to it. We studied the effects of moderate levels of hypercapnia produced by inverse ratio ventilati on with low tidal volumes in patients with severe pulmonary dysfunctio n (Lung Injury Score greater-than-or-equal-to 2.5). The mean peak PaCO 2 and PIP of the group were 63.3 +/- 15.7 mm Hg and 44.0 +/-12.4 cm H2 O, respectively. We found no adverse effects on cardiac function, oxyg en utilization, or long-term neurologic function in patients after hyp ercapnia. We conclude that moderate levels of hypercapnia are safe, an d may be permitted in the care of patients with severe pulmonary dysfu nction.