EFFECT OF DOPEXAMINE ON CALCULATED LOW GASTRIC INTRAMUCOSAL PH FOLLOWING VALVE-REPLACEMENT

Gastric tonometry was used to study the possible effect of dopexamine infusion on a low calculated intramucosal pH (pH(i)) as a sign of splanchnic ischemia. Measurements were made during surgery and for approximately 18 hours postoperatively on 19 non-selected adult patients undergoing valve replacement. Patients developing a postoperative pH(i) > 7.30 were randomized to receive dopexamine (2 mu g . kg(-1) min(-1)) or placebo in a double blind fashion. Eighteen patients were randomized, 10 to receive dopexamine and 8 to placebo. The calculated pH(i) remained unchanged for the first 2 hours in both groups. After 4 hours a significant (P<0.05) decrease in pH(i) was noted in the dopexamine group which remained significantly below the placebo group during the monitoring period. The dopexamine treated patients had a significantly longer period of low pH(i) but the pH-gap i.e, the difference between arterial pH and pH(i) did not differ between the two groups. Patients with postoperative complications, defined as infections (2), myocardial infarction (1), single- (2) or multiple organ failure and death (1), did not have longer periods with pH(i) below 7.30. In these patients, however, a pH-gap > 0.12 occurred more often than in those without complications, indicating that an increased incidence of complications was related to a pH-gap > 0.12. It is our opinion that true mucosal ischemia is best detected by estimating the difference in carbon dioxide tension between arterial blood and mucosa. This can be expressed either directly as PCO2-gap (PtonCO2-PaCO2) or indirectly as pH-gap.