Dopexamine and dopamine in the prevention of low gastric mucosal pH following cardiopulmonary by‐pass

Abstract

The effect of low-dose dopexamine and dopamine on gastric intramucosal pH (pHi) during cardiac surgery and 16 hours postoperatively was studied in 35 adults patients (coronary artery bypass grafting and/or valve replacement). The patients were assigned randomly to treatment groups with either dopexamine (1 microgram.kg-1.min-1 (n = 12), dopamine 2.5 micrograms.kg-1.min-1 (n = 11) or to a control group (n = 12). The infusions were started after induction of anaesthesia and were continued until 16 hours after CPB. pHi and arterial pH (pHa) did not differ between groups and remained unchanged during cardiopulmonary by-pass and for the first four postoperative hours. Both the carbon dioxide tension of arterial blood (PaCO2) and of the saline in the tonometer (PtonCO2) changed in parallel with a decrease during CPB and an increase after CPB and surgery with maximal values 12 hours after termination of CPB. A significant correlation was noted between pHi and pHa and between arterial and tonometric PCO2. It is concluded that low dose dopexamine and dopamine have no influence on pHi during and after cardiac surgery. The observed changes in pHi and PtonCO2 were due to changes in pHa and in PaCO2 and not a sign of gastric mucosal ischemia.

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“…They observed significant increases in splanchnic blood flow in the order of 27–36%. Two level II studies [27,28] failed to demonstrate any effect of dopamine on gastric intramucosal pH (pHi). A significant worsening in pHi associated with low CPB flow rate and dopamine was observed by Schneider and coworkers [29] in a randomized, double-blind, placebo-controlled trial ( n = 100) conducted in 1998.…”

“…There was no difference in hepatic venous oxygenation, and pHi decreased during and after CPB in all patients. A further three randomized controlled trials [28,53,54] concluded that dopexamine had no influence on pHi compared with dopamine or placebo. Dopexamine has also been shown to increase jejunal perfusion (as measured by laser Doppler flowmetry) and ICG dye clearance [55].…”

Effects of Dopexamine in a Rat Model of Supracoeliac Aortic Cross-Clamping and Declamping

“…Whether intestinal CO 2 tonometry represents a precise tool to evaluate regional splanchnic ischaemia is widely debated [21] , but nevertheless, it is applied in numerous clinical and experimental studies. Increased accuracy of measurements may be achieved using a phosphate-buffered solution [22] as well as calculating the PCO 2 gap which better refl ects splanchnic ischaemia [23][24][25] , instead of intramural pH which may vary, depending on systemic arterial PCO 2 . Alternatively, mesenteric ischaemia can be estimated using polarographic electrodes to measure surface oxygen tension.…”

Comparison of the effects of fentanyl and remifentanil on splanchnic tissue perfusion during cardiac surgery

“…Nevertheless, the pHi value cannot be interpreted without considering the systemic acid-base status in the arterial blood [7]. For this reason, the PCO 2 gap, defined as the difference between gastric intramucosal CO 2 pressure (Pg CO 2 ), measured by gastric tonometry, and arterial CO 2 pressure (Pa CO 2 ), appears to be a meaningful marker of splanchnic perfusion [5,7]. The purpose of this study was therefore to compare the effects of two opioid agents-fentanyl and remifentanil-on splanchnic perfusion, using gastric tonometry.…”

“…The monitoring of gastric intramucosal pH (pHi) by gastric tonometry has been proposed as a sensitive method to assess the adequacy of splanchnic perfusion [5,6]. Nevertheless, the pHi value cannot be interpreted without considering the systemic acid-base status in the arterial blood [7]. For this reason, the PCO 2 gap, defined as the difference between gastric intramucosal CO 2 pressure (Pg CO 2 ), measured by gastric tonometry, and arterial CO 2 pressure (Pa CO 2 ), appears to be a meaningful marker of splanchnic perfusion [5,7].…”