A novel approach to monitor tissue perfusion: Bladder mucosal P co2, P o2, and pHi during ischemia and reperfusion

Abstract

Purpose: The purpose of this study is to determine if monitoring urinary bladder P co 2, P o 2, 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 o 2 co 2 sensor. Results: Baseline hemodynamic and metabolic measurements were obtained along with measurements of bladder mucosal Pot and P o 2 (mean ± SEM). Blood flow measured with microspheres confirmed absence of blood flow during occlusion and hyperemia during reperfusion. Bladder mucosal P o 2 decreased from 42 ± 14.0 mm Hg (5.6 kPa)to 1.3 ± 1.3 mm Hg(1.4 kPa) during the 30-minute interval of ischemia. This was followed by an increase of bladder P o 2 to greater than baseline values at the end of the reperfusion period. Bladder mucosal P co 2 increased from 57 ± 4.7 mm Hg (7.6 kPa) to 117 ± 7.1 mm Hg (15.6 kPa) ( P < .05) during ischemia. During reperfusion the P co 2 returned to baseline levels (55 ± 4.0 mm Hg [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 P o 2, P co 2, or calculating pHi may provide a simple and reliable means of monitoring tissue perfusion.