Effect of an increased intraperitoneal pressure on fluid and solute transport during CAPD

Abstract

The effect of an increased intraperitoneal pressure on fluid and solute transport was studied in eight stable CAPD patients. Two permeability tests of two hours each with continuous registration of the intraperitoneal pressure were performed while patients were in supine position. The intra-abdominal pressure was raised by means of a tightening girdle with inflatable cuffs in one of the experiments. Intraperitoneally administered dextran 70 was used as a volume marker in order to determine the peritoneal fluid kinetics. The increment in the intra-abdominal pressure of 10.0 +/- 1.0 mm Hg caused a decline in the net ultrafiltration. This was mainly determined by an increase in the lymphatic absorption: 1.07 +/- 0.18 ml/min (without compression) versus 1.86 +/- 0.25 ml/min (with compression; P < 0.01), whereas the transcapillary ultrafiltration rate tended to decrease: 2.02 +/- 0.23 versus 1.73 +/- 0.27 ml/min (P = 0.08). External compression also diminished solute transport from the circulation to the peritoneal cavity. The decline in the mass transfer area coefficient of urea, creatinine, urate and beta 2-microglobulin was 13%, indicating a smaller effective peritoneal surface area caused by external compression probably due to a decrease in the number of the perfused peritoneal capillaries. The fall in the peritoneal protein clearances was more pronounced the higher the molecular weight of the protein, consistent with a decline in the intrinsic permeability of the peritoneum. Kinetic modeling using computer simulations was used to analyse these effects in terms of the pore theory, using a convection model (large pore radius 184 +/- 14 A) and a diffusion model (large pore radius 1028 +/- 218 A) for the transport of macromolecules.(ABSTRACT TRUNCATED AT 250 WORDS)

Peritoneal Sodium Mass Removal in Continuous Ambulatory Peritoneal Dialysis and Automated Peritoneal Dialysis: Influence on Blood Pressure Control

“…As the 24-hour volume instilled is higher in APD, it is possible that some of our APD patients received a higher intraperitoneal volume per exchange which could induce a higher intraperitoneal pressure. It is now clear that an increase in intraperitoneal pressure is responsible for a significant reduction of the net ultrafiltration volume [16][17][18].…”

Effect of Increased Dialysate Volume on Peritoneal Surface Area among Peritoneal Dialysis Patients

“…The 18% augmentation in PSA-CD after an increase in the volume of the peritoneal solution from 2 to 3 L suggests that the use of large volumes may improve the efficiency of intraperitoneal chemotherapy. The increase in peritoneal hydrostatic pressure associated with the use of largevolume solutions is a limiting factor in peritoneal dialysis, resulting in decreases in net ultrafiltration and solute removal (3,5,(32)(33)(34)(35)(36). This effect would not be a drawback for peritoneal chemotherapy, because such treatment is not aimed at removing fluid and solutes.…”

“…This suggests that an additional increase in dialysate volume might recruit a larger peritoneal surface area, resulting in a higher K BD . However, the associated increase in hydrostatic pressure in the peritoneal space would be expected to increase fluid absorption by peritoneal tissues and lymphatic vessels, thus decreasing net ultrafiltration (3,5,(32)(33)(34)(35)(36) and consequently solute removal. Nevertheless, the fact that the PSA-CD with the 3-L solution was still less than the estimated anatomic peritoneal surface area suggests that methods should be sought to provide an additional increase in PSA-CD without increasing the hydrostatic pressure inside the peritoneal cavity.…”

Fluid absorption in the peritoneum—it is less simple than you thought

“…This has been shown by the application of external compression. This resulted in reduced net ultranltration mainly caused by a higher effective lymphatic absorption rate [12]. It also explains the higher lymphatic absorption present with 3-litre than with 2-litre exchanges [1].…”