Assessment of Hepatic Ischemia-reperfusion Injury by Simultaneous Measurement of Tissue PO2, PCO2, and PH

Introduction: The objective of this study was to determine whether the simultaneous measurement of tissue pH, pCO(2), and pO(2) with a multiple-parameter fiberoptic sensor (Paratrend 7) can be used for continuous monitoring of hepatic microperfusion in a pig model of hepatic ischemia given endothelin(A) receptor antagonist (ET(A)-RA) or isotonic saline.

Methods: Fourteen anesthetized swine were subjected to 2 h of hepatic vascular exclusion. The animals were randomized into two groups: control group (n = 7, saline solution iv) and therapy group (n = 7, ET(A)-RA). For evaluation of ischemia-reperfusion injury, the data of the multiple-parameter sensor (pO(2para), pCO(2para), and pH(para)) were compared with partial oxygen pressure in tissue (p(ti)O(2)), laser Doppler flow, and systemic hemodynamic, metabolic data, and time course of transaminases.

Results: In the control group 30 and 60 min after reperfusion, the following values were measured: p(ti)O(2): 34.0 +/- 8.6 / 36.3 +/- 7.0 mm Hg (P < 0.05 vs. preop.: 49.8 +/- 12.1 mm Hg), laser Doppler area: 133.3 +/- 23.2 / 156.4 +/- 15.4 (P < 0.05 vs. preop.: 215.9 +/- 14.8). Animals in the therapy group revealed significantly improved values (p(ti)O(2): 54.0 +/- 8.6 / 58.1 +/- 7.8 mm Hg, laser Doppler: 210.2 +/- 38.5 / 225.2 +/- 21.3; P < 0.05). Using the Paratrend, also an improvement in the therapy group was seen 30 and 60 min after reperfusion. The values showed a strong correlation with p(ti)O(2) (r = 0.895; P < 0.05) and laser Doppler flow (r = 0.807; P < 0.05). In the treatment group, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and glutamate dehydrogenase (GLDH) were reduced 6 and 18 h after reperfusion, respectively, indicating hepatoprotection by the therapy (P < 0.05 vs. control).

Conclusions: The Paratrend sensor offers the opportunity to study postischemic organ hemodynamics through the simultaneous measurement of interstitial pH, pCO(2), and pO(2) in a small tissue region. This method offers a prognostic tool for the study of the effects of experimental vasoactive therapy on liver microcirculation and perspectives for continuous monitoring of human liver microperfusion after liver surgery and trauma.