Bladder Mucosal CO₂Compared with Gastric Mucosal CO₂as a Marker for Low Perfusion States in Septic Shock

Abstract

Recent reports indicate the possible role of bladder CO2 as a marker of low perfusion states. To test this hypothesis, shock was induced in six beagle dogs with 1 mg/kg of E. coli lipopolysaccharide, gastric CO2 (CO2-G) was measured with a continuous monitor, and a pulmonary catheter was inserted in the bladder to measure CO2 (CO2-B). Levels of CO2-B were found to be lower than those of CO2-G, with a mean difference of 36.8 mmHg (P < 0.001), and correlation between both measurements was poor (r 2 = 0.16). Even when the correlation between CO2-G and ΔCO2-G was narrow (r 2 = 0.86), this was not the case for the relationship between CO2-B and ΔCO2-B (r 2 = 0.29). Finally, the correlation between CO2-G and base deficit was good (r 2 = 0.45), which was not the case with the CO2-B correlation (r 2 = 0.03). In our experience, bladder CO2 does not correlate to hemodynamic parameters and does not substitute gastric CO2 for detection of low perfusion states.

Evaluation of gastric and bladder tonometry as indicators of tissue perfusion in induced hypotension in dogs

“…Few studies have assessed the CO 2 of the bladder mucosa for monitoring tissue perfusion. In a septic model, bladder tonometry, when compared with gastric tonometry, could not detect hypoperfusion . However, other studies have shown an increase of PbCO 2 in hypoperfusion such as hemorrhagic shock or following aortic occlusion .…”

“…However, in other studies, the recovery of lactate values took several hours after initiation of the treatment . Some authors have observed that use of vasopressors, such as dopamine or epinephrine, temporarily increases plasma lactate concentrations . Considering these findings, a possible explanation for the study result that the plasma lactate concentration at the end of the study was not the same as the baseline value was that dopamine increased the plasma lactate concentration or that several hours would have been necessary to normalize it.…”

Regional capnometry to evaluate the adequacy of tissue perfusion

“…The PbCO 2 value is well correlated with DO 2 and PgCO 2 (55,56). However, these results were not confirmed by another group of researchers (57). Clinical studies of the accuracy of this device are required.…”

“…The results of several animal studies have suggested that monitoring the intramucosal PCO 2 in the bladder (PbCO 2 ) may be a minimally invasive technique for monitoring perfusion (55)(56)(57). This technique measures PbCO 2 via the gas analysis of saline samples collected from the balloon of a Foley catheter inserted into the bladder.…”

Urinary pCO2 Monitoring System with a Planar Severinghaus Type Sensor

“…While blood pCO 2 is frequently measured in critically ill patients, it does not reflect microcirculatory changes that accompany sepsis. Urinary pCO 2 (U-pCO 2 ) on the other hand may provide useful information on changes in microcirculatory perfusion [9][10][11][12][13]. Sepsis is the most frequent diagnosis in medical intensive care units (ICU) and one of the most common causes of death in hospitals worldwide.…”