Effect of posture on intraperitoneal pressure and peritoneal permeability in children

Abstract.

The posture of the patient influences both the intraperitoneal pressure (IPP) and the peritoneal permeability. We have studied the effects of the supine and the upright position in six children. Two peritoneal equilibration tests (PET) of 90-min dwell time each were performed consecutively, firstly in the supine position and then in the upright position. The same amount of dialysate was instilled (1,000 ml/m²; isotonic 1.36% dextrose) for each PET. Using the same filling volume, the IPP was significantly higher in the upright position (18.4±4.8 cm H₂O) than in the supine position (8±2.4 cm H₂O). The mean percentage IPP increase was 130%±35%. The decline in glucose resorption rate from the dialysate during the PET was significantly lower in the upright position. Despite this greater relative loss of osmotic gradient in the upright than the supine position, no significant difference in net ultrafiltration was noted after 90 min of dwell. The peritoneal equilibration ratio during the PET was lower in the upright than the supine position for urea, creatinine, and phosphate. These results favor performing peritoneal dialysis in a supine position, both to increase dialysis efficiency and to reduce patient discomfort.