# Chapter 25: Dialysis & Renal Replacement Therapy

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Explore these related Lecture Series modules and Clinical Mastery reviews:

[Dialysis Module](https://urinenephrology.org/2025_UDPA_Lectures_Live/dialysis/index.html) [🏆 Mastery: Dialysis Advanced (KRT, HVHDF)](https://urinenephrology.org/mastery/dialysis-advanced/index.html)

## Chapter 25: Dialysis & Renal Replacement Therapy

### Indications for Dialysis

#### Urgent Indications for RRT (AEIOU)

- **A**cidosis: Severe metabolic acidosis (pH \< 7.1) refractory to bicarbonate therapy.
- **E**lectrolytes: Severe, refractory hyperkalemia with ECG changes.
- **I**ngestions: Certain dialyzable toxins (e.g., salicylates, lithium, ethylene glycol, methanol).
- **O**verload: Refractory fluid overload causing pulmonary edema.
- **U**remia: Symptomatic uremia, such as pericarditis, encephalopathy, or severe bleeding.

### Hemodialysis (HD)

#### Principles

In HD, blood is pumped from the patient, through an external filter called a dialyzer (the "artificial kidney"), and then returned to the patient. The dialyzer contains thousands of hollow fibers made of a semipermeable membrane. Blood flows through the fibers while dialysate flows around them in the opposite direction (counter-current flow). Waste products and excess electrolytes are removed by diffusion down a concentration gradient, while excess fluid is removed by ultrafiltration using a pressure gradient.

#### The Hemodialysis Prescription

A typical HD prescription includes the dialyzer type, blood flow rate (Qb), dialysate flow rate (Qd), dialysate composition (e.g., sodium, potassium, bicarbonate, calcium), treatment time, and anticoagulation. A standard in-center prescription is 3-4 hours, three times per week.

#### Acute Complications During HD

- **Hypotension:** The most common complication, caused by rapid fluid removal exceeding vascular refilling. Managed by reducing the ultrafiltration rate and administering saline.
- **Muscle Cramps:** Related to rapid fluid and electrolyte shifts.
- **Dialysis Disequilibrium Syndrome:** Neurologic symptoms caused by cerebral edema from too-rapid solute removal. More common in the first few treatments.

### Peritoneal Dialysis (PD)

#### Principles

PD uses the patient's own peritoneal membrane as the dialyzer. Dialysate, containing dextrose as an osmotic agent, is instilled into the peritoneal cavity via a PD catheter. Waste products diffuse from the peritoneal capillaries into the dialysate, and excess fluid is removed via osmosis. The used dialysate is then drained out.

#### Modalities

- **Continuous Ambulatory Peritoneal Dialysis (CAPD):** Manual exchanges performed by the patient 4-5 times throughout the day.
- **Automated Peritoneal Dialysis (APD):** A machine (cycler) performs multiple exchanges automatically overnight while the patient sleeps.

#### Complications

The most significant complication of PD is **peritonitis**, an infection of the peritoneal cavity, which presents with cloudy dialysate, abdominal pain, and fever. Prompt treatment with intraperitoneal antibiotics is crucial.

### Kidney Transplantation

Kidney transplantation is the treatment of choice for most patients with ESRD, offering the best long-term survival and quality of life. Patients can receive a kidney from a living or deceased donor. The procedure requires lifelong immunosuppressive medication to prevent rejection of the transplanted organ.

[← Table of Contents](https://urinenephrology.org/nephrology-textbook/index.html) [← Previous: Chapter 24](https://urinenephrology.org/nephrology-textbook/chapters/chapter-21-procedures.html) [Next: Chapter 26 →](https://urinenephrology.org/nephrology-textbook/chapters/chapter-23-emergency.html)

## 📚 Sources

1.  **Cooper BA, et al; IDEAL.** Early vs late dialysis initiation. *N Engl J Med.* 2010;363(7):609-619. [PMID: 20581422](https://pubmed.ncbi.nlm.nih.gov/20581422/).
2.  **STARRT-AKI Investigators.** Timing of KRT initiation. *N Engl J Med.* 2020;383(3):240-251. [PMID: 32668114](https://pubmed.ncbi.nlm.nih.gov/32668114/).
3.  **Maduell F, et al; ESHOL.** Online HDF mortality benefit. *J Am Soc Nephrol.* 2013;24(3):487-497. [PMID: 23411788](https://pubmed.ncbi.nlm.nih.gov/23411788/).
4.  **Grooteman MP, et al; CONTRAST.** HDF vs HD outcomes. *J Am Soc Nephrol.* 2012;23(6):1087-1096. [PMID: 22539829](https://pubmed.ncbi.nlm.nih.gov/22539829/).
5.  **National Kidney Foundation.** KDOQI 2015 Hemodialysis Adequacy Update. *Am J Kidney Dis.* 2015;66(5):884-930. [PMID: 26498416](https://pubmed.ncbi.nlm.nih.gov/26498416/).
6.  **Li PK, et al.** ISPD Peritonitis Recommendations 2022. *Perit Dial Int.* 2022;42(2):110-153. [PMID: 35264029](https://pubmed.ncbi.nlm.nih.gov/35264029/).

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### Also on this topic

The same subject at other levels of depth.

- **Lecture:** [🩺 Renal Replacement Therapy in AKI](https://urinenephrology.org/2025_UDPA_Lectures_Live/aki/rrt.html)


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