A novel approach to monitor tissue perfusion: Bladder mucosal Pco₂, Po₂, and pHi during ischemia and reperfusion

Purpose: The purpose of this study is to determine if monitoring urinary bladder Pco₂, Po₂ and calculated intramucosal pH would be a reliable index of tissue perfusion. Materials and Methods: This nonrandomized controlled study was conducted in a laboratory at a university medical center. Eight immature female Yorkshire pigs were studied with T-9 aortic cross-clamping for 30 minutes followed by a 60-minute period of reperfusion. Cystotomy was performed for placement of a Foley catheter and Paratrend 7 o₂/co₂ sensor. Results: Baseline hemodynamic and metabolic measurements were obtained along with measurements of bladder mucosal Po₂ and Pco₂ (mean ± SEM). Blood flow measured with microspheres confirmed absence of blood flow during occlusion and hyperemia during reperfusion. Bladder mucosal Po₂, decreased from 42 ± 14.0 mmHg (5.6 kPa) to 1.3 ± 1.3 mmHg (1.4 kPa) during the 30-minute interval of ischemia. This was followed by an increase of bladder Po₂ to greater than baseline values at the end of the reperfusion period. Bladder mucosal Pco₂ increased from 57 ± 4.7 mmHg (7.6 kPa) to 117 ± 7.1 mmHg (15.6 kPa) (P < .05) during ischemia. During reperfusion the Pco₂ returned to baseline levels (55 ± 4.0 mmHg [7.3 kPa]). Calculated bladder mucosal pHi declined from 7.31 ± 0.04 to 7.08 ± 0.05 (P < .05) during the ischemic period and after reperfusion pHi was 7.17 ± 0.03. Conclusions: Monitoring urinary bladder Po₂, Pco₂, or calculating pHi may provide a simple and reliable means of monitoring tissue perfusion.