Transcutaneous Monitoring of Blood Gas Tensions in Patients on Intermittent Peritoneal Dialysis

Abstract: A relative contraindication to intermittent peritoneal dialysis (IPD) is chronic lung disease. To evaluate whether the instillation of 2 L of fluid into the peritoneal cavity affects respiratory function, five IPD patients were studied in the supine position during the first 4 h of a routine IPD session. Blood gas tensions were monitored transcutaneously throughout the study period. At the onset of dialysis, mean transcutaneous blood oxygen tension (P_tco₂) was 70.6 ± 9.1 mm rig. It decreased to 55 ± 9.9 mm Hg (22% change from basal values) during the instillation of dialysate. Upon drainage, P_tco₂ returned to baseline. This sequence of events repeated itself on subsequent exchanges, although with decreasing decrements of P_tco₂ with each consecutive exchange (decrease to 58.6 ± 7.05, 61 ± 6.5, 63.8 ± 5.2 mm Hg corresponding to 16%, 12.7%, and 9.6%, respectively, during the second to fourth exchanges). Transcutaneous blood carbon dioxide tension, P_tcco₂, showed a very mild increase during the study (33 ± 7.1 to 38 ± 6.0 mm Hg). In two patients, the same study protocol was performed during the last 4 h of an IPD session. In these two patients, there was only a 5% variation of P_tco₂ from baseline values. These results suggest that an adaptive response to the hypoxemia induced by dialysate instillation rapidly occurs in IPD patients.