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Effect of an acute increase in PCO2 on splanchnic perfusion and metabolism
1Department of Anesthesiology, University Clinic Ulm, Prittwitzstrasse 43, 89075 Ulm, Germany. peter.kiefer@medizin.uni-ulm.de
Objectives:
To evaluate the acute effects of an increase in PCO2 on splanchnic tissue perfusion and metabolism.
Design:
Clinical prospective study in the intensive care unit in a university clinic.
Patients:
Six patients with severe acute lung injury requiring mechanical ventilation. All patients had bilateral infiltrates on chest radiography, a PaO2/FIO2 ratio less than 200 mmHg, and stable hemodynamics without vasoactive drugs.
Interventions:
PCO2 was increased 5-20% by an added dead space from baseline, followed by a return to baseline.
Measurements And Results:
Splanchnic blood flow was measured using primed continuous infusion of indocyanine green dye with hepatic venous sampling and systemic hemodynamics by routine monitoring; we also determined the gastric mucosal-arterial PCO2 difference and splanchnic lactate/pyruvate exchange. PCO2 was increased by an added dead space; after 60 min all measurements were repeated; after return to baseline a third measurement followed. The increase in PCO2 had no significant effect on splanchnic blood flow or indices of perfusion and metabolism.
Conclusion:
Our results suggest that acute moderate changes in PCO2 have no major effect on splanchnic perfusion and metabolism.