Gastric intramucosal PCO2 as a quantitative indicator of the degree of acute hemorrhage

Gastric intramucosal PCO2 (PiCO2) is a marker of splanchnic dysoxia and hypoperfusion that is increasingly used in intensive care medicine. We assessed two methods, saline-balloon tonometry versus continuous capnometric recirculating gas tonometry (CRGT), for detecting changes in PiCO2 in animals subjected to various degrees of hemorrhage and examined whether changes in PiCO2 would correlate with the degree of hemorrhage as assessed by blood loss volume.

Following a baseline equilibration period, 20 anesthetized dogs were subjected to bleeding of 0, 23, 35, 41, or 47 mL/kg. After 30 minutes, the shed blood was reinfused and the experiments continued for an additional 120 minutes.

Aggregate baseline PiCO2 was 43 mm Hg by both methods. PiCO2 did not change significantly over time in the control animals by either method. PiCO2 by CRGT rose significantly in each of the other groups at the end of the hemorrhage period and after resuscitation. Similar trends were observed in PiCO2 measured by saline tonometry but were significant only with the most severe hemorrhage. Strong correlation was observed between the degree of hemorrhage and change in PiCO2 by both methods.

PiCO2 serves as a quantitative indicator of the severity of hypovolemic perfusion failure associated with hemorrhage. Compared with standard saline tonometry, CRGT may be a more sensitive method of monitoring the severity of hemorrhage.