# Peritoneal Dialysis: Membrane, Exchanges, and Daily Safety

Separate clearance from fluid removal, and treat cloudy effluent as an urgent assessment problem.

![Infographic: Peritoneal Dialysis: Membrane, Exchanges, and Daily Safety](https://urinenephrology.org/visual-reference/images/student-peritoneal-dialysis.png?v=20261003c)

## Understand the exchange

Dialysate enters the abdomen, dwells while solutes and water move across the peritoneum, then drains. Diffusion moves small solutes down concentration gradients; an osmotic agent drives ultrafiltration.

## CAPD and APD organize time differently

CAPD uses manual exchanges; APD uses a cycler, usually overnight. Faster transport can dissipate a glucose osmotic gradient during long dwells. Match dwell strategy to transport, residual function, and daily life.

## Daily review is more than clearance

Check weight, blood pressure, edema/breathlessness, drain volumes, constipation, exit site, and missed exchanges. Retained fluid or poor drainage requires a cause search, not automatic repeated use of stronger glucose solution.

## Cloudy effluent: act promptly

Contact the PD team urgently for cloudy fluid or abdominal pain. Obtain effluent cell count/differential and culture using the unit pathway before antibiotics when feasible; do not delay treatment in an unwell patient to await culture.

## Know the peritonitis criteria

ISPD requires at least 2: abdominal pain/cloudy effluent; WBC >100/µL after a dwell ≥2 hours with >50% neutrophils; positive effluent culture. With short APD dwells, >50% neutrophils strongly supports peritonitis even when WBC is <100/µL.

## Prevent avoidable interruptions

Use trained aseptic connection technique and prescribed exit-site care. Report a break in technique, catheter damage, exit-site drainage, leaks, or persistent drainage failure. Retraining and bowel management may correct problems before technique failure.

## Supporting evidence

- [ISPD peritonitis guideline, 2022](https://doi.org/10.1177/08968608221080586)
- [ISPD 2022 peritonitis guideline](https://journals.sagepub.com/doi/10.1177/08968608221080586)

## Source lessons

- [peritoneal dialysis student handout](https://urinenephrology.org/student-resources/dialysis/peritoneal-dialysis-student-handout.html)

Read alongside the full lessons; the findings and decisions shown here require the stated clinical context.