RELATIONSHIP BETWEEN SYSTEMIC OXYGEN-SUPPLY DEPENDENCY AND GASTRIC INTRAMUCOSAL PCO2 DURING PROGRESSIVE HEMORRHAGE

Background: As systemic oxygen delivery (DO2) is reduced, oxygen consu mption (VO2) is maintained until a critical level is reached (DO(2)cri t) below which VO2 becomes supply-dependent and anaerobic metabolism e nsues, We examined the relationship between gastric intramucosal PCO2 (PiCO(2)) and, the onset of systemic supply dependency, We also compar ed PiCO(2) to mixed venous and portal venous blood PCO2 (PmvCO(2) and PpvCO(2)) to assess their utility as premonitory indicators of supply dependency. Methods: Six dogs were subjected to stepwise hemorrhage to effect a progressive decrease in DO2. Inflection points for changes i n VO2, PiCO(2), PmvCO(2), and PpvCO(2) versus DO2 were determined, Res ults: Mean DO(2)crit was 6.0 +/- 0.7 mL.kg(-1).min(-1) whereas the DO2 at which inflection points occurred for PiCO(2) and PpvCO(2) were 13. 2 +/- 1.4 and 11.2 +/- 1.5 mL.kg(-1).min(-1), respectively (p < 0.05 f or both). Conclusion: Continuous monitoring of PiCO(2) using capnometr ic recirculating gas tonometry can serve as an early indicator of syst emic hypoperfusion before the onset of systemic supply dependency.