The effects of sodium nitroprusside-induced hypotension on splanchnic perfusion and hepatocellular integrity

The purpose of our study was to investigate the effects of sodium nitroprusside-induced hypotension on splanchnic perfusion and hepatocellular integrity. Thirty patients undergoing radical prostatectomy were allocated randomly to a sodium nitroprusside (SNP) or control group (control). Regional pCO(2) was measured using gastric tonometry, and the regional to arterial difference in partial pressure of CO3 and intramucosal pH were calculated. The cytosolic liver enzyme ol-glutathione S-transferase and standard liver enzyme markers (alanine aminotransferase, aspartate aminotransferase, and gamma-glutamyltransferase) were also measured. Mean arterial pressure in the SNP group was 50 mm Hg for 97 min during surgery. A significant increase from baseline in regional pCO(2) (from 40.0 +/- 4.2 mm Hg to 45.3 +/- 1.3 mm Hg) and regional to arterial difference in partial pressure of CO2 (from 4.1 +/- 1.1 mm Hg to 9.7 +/- 1.4 mm Hg) was seen at 90 min after skin incision only in the SNP group. Intramucosal pH decreased significantly from 7.40 +/- 0.02 to 7.35 +/- 0.03 during the same period in this group. Tonometric variables returned to baseline values within 2 h postoperatively. alpha-Glutathione S-transferase concentrations increased significantly in the SNP group from baseline to peak concentrations at the end of surgery (SNP: 9.93 +/- 4.94 mu g/L; control: 5.85 +/- 1.86 mu g/L). A return to baseline values was seen 24 h postoperatively. No significant changes in standard liver enzyme markers were seen throughout the study period. It is concluded, that splanchnic perfusion was transiently impaired during controlled hypotension. This is supported by significant changes in tonometric data. Increased serum levels of alpha-glutathione S-transferase may indicate a disturbance in hepatocellular integrity. Implications: We studied gastric mucosal tonometry and the cytosolic liver enzyme alpha-glutathione S-transferase to evaluate the effects of controlled hypotension induced by sodium nitroprusside on splanchnic perfusion and hepatocellular integrity. Splanchnic perfusion decreased and alpha-glutathione S-transferase increased during and after a hypotensive period, but returned to baseline values within the first postoperative day, indicating a transient impairment of splanchnic perfusion and hepatocellular integrity.