Acute hypercapnia increases hepatic surface PO2: an experimental study in the rat
J. E. Modrak, P. J. Papadakos, P. Thorborg & N. Lund

Objective: To assess whether acute hypercapnia affects hepatic tissue oxygen tension as measured at the surface of the rat liver.

Design: Prospective, controlled study.

Setting: University medical school laboratory.

Subjects: Male Sprague-Dawley rats weighing 250-450 grams.

Interventions: An 8-point surface oxygen electrode was used to measure tissue oxygen tension (PtO2) in the rat liver during normocapnia (PaCO2 33-49 mmHg), while breathing 5% CO2 (PaCO2 54-70 mmHg), and while breathing 10% CO2 (PaCO2 74-101 mmHg). Measurements were made at baseline in all 3 groups, following which 5% or 10% carbon dioxide was added to the inhaled gas mixture in the two hypercapnic groups. Measurements were then taken again at 10, 15, 30, 40, and 50 minutes.

Measurements and Main Results: There were no significant differences between the groups at baseline with mean PtO2 being 29.4 ± 2.1 mmHg in the control group, 30.2 ± 5.7 mmHg in the 5% group, and 29.7 ± 5.5 mmHg in the 10% group. At 10 minutes there was an increase in mean PtO2 to 38.7 ± 4.4 mmHg in the 5% group (p < .005), and to 48 ± 3.0 mmHg in the 10% group (p < .001). The mean PtO2 values for both hypercapnic groups remained significantly elevated when compared to the control group for the remaining 50 minutes of the experiment.

Conclusion: We conclude that acute hypercapnia leads to increased hepatic tissue oxygen tension as measured at the surface of the liver.

Keywords: Liver, hypercapnia, tissue oxygenation, oxygenation, microcirculation

Applied Cardiopulmonary Pathophysiology 9: 41-46, 2000

J. E. Modrak, M.D.
Pulmonary and Critical Care Unit
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