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 spla nchnic ischemia.Measurements were made during surgery and for approxim ately 18 hours postoperatively on 19 non-selected adult patients under going 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) remai ned unchanged for the first 2 hours in both groups. After 4 hours a si gnificant (P<0.05) decrease in pH(i) was noted in the dopexamine group which remained significantly below the placebo group during the monit oring period. The dopexamine treated patients had a significantly long er period of low pH(i) but the pH-gap i.e, the difference between arte rial pH and pH(i) did not differ between the two groups. Patients with postoperative complications, defined as infections (2), myocardial in farction (1), single- (2) or multiple organ failure and death (1), did not have longer periods with pH(i) below 7.30. In these patients, how ever, a pH-gap > 0.12 occurred more often than in those without compli cations, indicating that an increased incidence of complications was r elated to a pH-gap > 0.12. It is our opinion that true mucosal ischemi a is best detected by estimating the difference in carbon dioxide tens ion between arterial blood and mucosa. This can be expressed either di rectly as PCO2-gap (PtonCO2-PaCO2) or indirectly as pH-gap.