The Science Journal of the American Association for Respiratory Care

1997 OPEN FORUM Abstracts

AN INNOVATIVE APPROACH TO REFLECT SPLANCHNIC PERFUSION USING AN INDWELLING CONTINUOUS ARTERIAL BLOOD GAS MONITORING SENSOR.

Steve Hays RRT, RCP; Keith R. Momii, MMSc, RRT, RCP; Jaclyn Jones, RRT, RCP; Dennis Hastings, RRT, RCP. Department of Pulmonary Care Services, The University of Texas Medical Branch, Galveston, Texas.

Background: Splanchnic hypoperfusion has been shown to predict multiple organ failure secondary to severe circulatory shock. The resulting tissue ischemia provides an index of mortality and morbidity in critically ill trauma patients and several other populations, including those that undergo cardiopulmonary bypass (CBP) CBP has been associated with splanchnic ischemia and subsequent multiple organ failure. Inconsistent reproducibility of calculated intramucosal pH via gastric balloon tonometry limits its reliability in the clinical setting. This study offers a novel approach to reflect splanchnic perfusion by using a continuous arterial blood gas monitoring sensor as an alternative to gastric balloon tonometry. It was hypothesized that the bladder functions as a tonometer, thereby allowing PCO_{2} to be monitored in the urine. Methods: A group of four anesthetized pigs were studied. Total hemoglobin and arterial PCO_{2} was maintained in normal range. Two separate calibrated Paratrend 7 (Diametrics Medical, Inc.) sensors were placed via bladder cystotomy side by side with one sensor abutting the bladder mucosa, the other placed inside a 30 Fr. Foley catheter. The tip of the sensor was positioned proximal to the urine inlet port such that no part of the sensor was in direct contact with bladder mucosa. Baseline measurements were established. The aorta was cross-clamped and PCO_{2} measurements were obtained at time intervals of 0, 5, 15, and 30 minutes. The cross-clamp was then released and PCO_{2} measurements were made again at time intervals of 0, 5, 15, 30, 45, and 60 minutes. Results: The data suggests that bladder mucosal PCO_{2} is a responsive indicator of hypoperfusion during interruptions in blood flow induced by aortic cross-clamping The sensor positioned inside the Foley catheter was less responsive and displayed a delayed response once the cross-clamp was released.

(See original for figure)

Conclusion: Bladder mucosal PCO_{2} appears to be a responsive indicator of splanchnic hypoperfusion. The bladder mucosal PCO_{2} sensor displayed a sensitive response to fluctuations in PCO_{2} as compared to Foley PCO_{2}. Irrespective of the small sample size, the delayed response rise in Foley PCO_{2} after release of the cross-clamp indicates a need for further study. A Foley catheter design permitting direct monitoring of bladder mucosal PCO_{2} could provide a simple and continuous means to trend splanchnic hypoperfusion.

OF-97-063

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