Preserved gastric tonometric variables in cardiac surgical patients administered intravenous perflubron emulsion

Low gastric intramucosal pH (pHi) and an increased gastric-arterial Pco₂ difference (CO₂ gap) are markers of tissue hypoperfusion. Perfluorocarbons (PFCs) have a large oxygen-carrying capacity and release oxygen when encountering low tissue oxygen tension. Nine cardiac surgical patients instrumented for gastric tonometry were enrolled as part of a multicenter, randomized, single-blinded study of a PFC emulsion (perflubron emulsion [Oxygent^TM]). Patients were randomized to receive PFC (n = 4) or placebo (n = 5) after intraoperative autologous blood harvesting by acute normovolemic hemodilution. At baseline there were no intergroup differences in tonometric-, hemodynamic-, or oxygen delivery-derived variables, e.g., Control group (pHi, 7.37 ± 0.06; CO₂ gap, 6.4 ± 1.3 mm Hg) versus PFC group (pHi, 7.38 ± 0.06; CO₂ gap, 6.7 ± 1.5 mm Hg). After acute normovolemic hemodilution, pHi was significantly lower (P < 0.01) in the Control group (7.22 ± 0.25) than in the PFC group (7.44 ± 0.25), and CO₂ gap was significantly higher (P < 0.001) in the Control group (23.4 ± 5.1 mm Hg) than in the PFC group (1.8 ± 0.8 mm Hg). These differences in tonometric variables persisted during surgery. The PFC group showed a significantly (P < 0.007) shorter time to first bowel movement postoperatively (2.0 ± 0.8 vs 5.4 ± 1.6 days). Time to consumption of solid food was also shorter in the PFC group and almost achieved statistical significance (P = 0.056).