PERITONEAL DIALYSIS

PD is an apparently simple form of dialysis which provides the motivated patient with the ability to perform dialysis at home, at work and at leisure. Travel is much easier and many patients value their independence from hospital.

Continuous ambulatory PD ( CAPD ): involves up to 4 exchanges a day of volumes of 1.5-3 litres (usually 2) of fluid. This fluid comes from two manufacturers, and in multiple formulations as follows:

NOTE: Icodextrin and blood sugar measurements: maltose and perhaps other degradations products of icodextrin cause falsely high readings with some commonly used blood glucose monitoring devices. Hypoglycaemia can therefore be mistakenly excluded in diabetics, or hyperglycaemia diagnosed in any patient, with potentially serious consequences. For diabetic patients receiving icodextrin we are providing a monitoring method that avoides this hazard, the Medisense Optium monitor, but monitoring is still likely to be performed elsewhere. Patients must be made aware of this potential problem, and icodextrin should be prescribed with caution to diabetics.

• Automated PD: uses one of a number of devices that are ideal for overnight administration of large volumes of fluid.
• Home choice (Baxter)
• Sleepsafe (Fresenius)

Quantum a nifty little machine that is able to do a single extra exchange overnight to 'extend' daytime CAPD

PD catheter insertion

Done by the Transplant surgeons laparoscopically under GA.  The patient should be seen by the CDT one week prior to insertion, and the preferred exit site marked with a 5x5 cm box, taking into account belt line and the patient’s line of vision.  Laxatives, Hibiscrub, and appropriate instructions are given.  Antibiotic prophylaxis for this procedure is 1gm IV flucloxacillin in theatre, or 1gm IV vancomycin on the ward, pre-op for those who are penicillin allergic.

PD peritonitis

Signs and symptoms include abdominal pain, pyrexia, cloudy PD effluent, but these may not all be present initially.  The large volumes associated with APD may make cloudiness less apparent.  Patients with any of these features must be reviewed and samples taken from their PD bag. If they do not have their own transport fix a 2-hour emergency ambulance.  A fluid white cell count of ≥100/mm³, or a differential wcc of >50% neutrophils on any total wcc is diagnostic. Initial microscopy is often not helpful but treatment should not be delayed after cultures are sent. Immediate management is:

• vancomycin 30mg/kg dry body weight intraperitoneally, single dose
• oral ciprofloxacin 500 mg bd.

Intraperitoneal antibiotics should remain in-situ for 6 hours; to this end, those patients normally on APD are converted to CAPD.   Most patients are allowed home, but admission is required for pain control, systemic upset etc.

Subsequent antibiotics are adjusted on the basis of culture and sensitivity results, and the patient’s progress.  Failure to improve suggests fungal or secondary peritonitis (see below), or just a bad infection.  Catheter removal is often necessary in such cases and should not be delayed.

Fungal peritonitis

Rare, but serious with high morbidity and mortality.  The priority is usually catheter removal.  Pending surgery, yeasts should be treated with oral fluconazole 200 mg daily, continued for 2 weeks after catheter removal, and other fungi require amphotericin or flucytosine.

Secondary peritonitis

When there is a failure of clinical improvement, particularly with Gram negative or mixed organisms, a surgical cause should be sought. Where necessary seek a surgical opinion, asking for not only catheter removal if appropriate, but either a laparoscopic search for pathology or a mini-laparotomy.

Troubleshooting Peritoneal Dialysis Problems

Exit-site infection

Treat with oral antibiotics, usually flucloxacillin 250-500mg qid for 2 weeks.  Report infection to CDT.  Failure to improve may require admission for IV antibiotics and in some cases surgical repair.  The incidence of Staph. aureus exit site infection is increased by the nasal carriage of that organism, and both impact on peritonitis rate.  An attempt at eradication with nasal mupirocin is of benefit in reducing the infection rate.

Poor drainage

Most poor drainage is temporary and is due to the catheter being caught in amongst loops of bowel. Administration of half a sachet of Picolax whilst stopping PD for a short period is usually curative. Poor drainage due to fibrin deposition sometimes occurs, particularly in relation to peritonitis and may be eased by the use of IP heparin. A minority of cases are caused by adhesions, kinking, malposition or omental plugging and may require surgery. PD catheters are highly mobile, so that the finding of a 'displaced' catheter on X-ray therefore means little in relation to poor drainage. So don't do them unless there's a really strong reason. There is absolutely no need for lateral pelvis films, which give a very high radiation dose.

Blocked PD catheter

The absolutely blocked PD catheter may be salvaged by a urokinase infusion. This can however be painful.

Bloody bag

Bloody PD effluent can be frightening but is usually benign. In women it can occur during menstruation or at ovulation. In most cases the patient can be reassured and sent home. Rarely it may be seen in a leaking aortic aneurysm or other intra-abdominal crisis.

PD leak

A leak of PD fluid from the peritoneum to the abdominal wall may be suspected by increasing flank oedema in the absence of other fluid accumulation, and in association with poor fluid drainage. Proving this can be difficult. Ultrasound may detect a defect in the anterior peritoneum, usually in relation to the catheter. The most sensitive test however is CT scanning of the abdomen using a contrast-filled bag that has been in place for at least one hour prior to the scan (100mls contrast is diluted into one bag; PD nursing team do this on the ward). Treatment is usually by rest and a period of nocturnal APD with no daytime exchanges (to minimize intra-abdominal pressure) may avoide that. Haemodialysis is sometimes necessary.

Contaminated line

Patients who may have (if there is any possibility) inadvertently disconnected their system and contaminated their line should receive prophylactic antibiotics in the form of a single dose of vancomycin 30 mg/l PD fluid given intraperitoneally and left in-situ for six hours.

Dialysis adequacy

Measurement of PD adequacy requires collection of PD effluent, urine (for residual function) and blood.  Adequacy should be checked regularly and after any problems, and the regimen adjusted in response. Measurement should not be performed for the first 8 weeks of treatment, but then every 4-12 months.  Residual renal function is significant in most people who are doing well on PD. 

There is continuing controversy about acceptable targets for PD, but it seems likely that too little dialysis is bad.  Weekly creatinine clearance and Kt/V are the accepted measurements.  The latter is more dependent upon PD, the former on residual renal function, and there may be marked discrepancies between the two.  Currently accepted minimum targets are:  (DOQI and our own):

CREATININE CLEARANCE at least 60 litres per week/1.73m² (50 l/week in low transporters) (normal creat clearance is around 1000 litres per week)

TOTAL Kt/V at least 2.0 per week (1.7 in low transporters)

For a description of how to measure Kt/V and creatinine clearance on PD, contact the CDT, or read UpToDate. 

Peritoneal Equilibration Testing (PET)

The PET test describes how rapidly solutes are absorbed from the peritoneum in a standardised manner.  Basically, higher rates of solute transfer are good for biochemical clearance of small molecules, but bad for ultrafiltration.  Low transporters may receive poor dialysis; they should benefit from long dwell times (eg CAPD).  Fast transporters achieve inadequate ultrafiltration, and may benefit from rapid-cycling PD (e.g., APD).  The PET test is performed using a standard 2 litre 2.27% or no. 4 bag, which is left in-situ for 4 hours. Blood and PD fluid samples are taken for creatinine and glucose at 0, 2 and 4 hours and are used to assess D/P ratios.  See the CDT for the full protocol, and for tables to interpret the results, or the very good section in UpToDate.

Paddy Gibson was the main author for this page, last amended Thursday, November 30, 2006.

NOTE that the accuracy of any statements in this information CANNOT be guaranteed. It is published in the belief that it is correct, and we endeavour to keep it so - but we do make mistakes. Furthermore, over some subjects there are differing opinions, or differing degrees of certainty. We have usually not attempted to discuss these here because the aim has been to provide an immediate and brief guide. In all areas, prior medical knowledge is assumed. The EdRenHANDBOOK is not suitable for use by those without such a background. Contact us by email or at the address given at the foot of the contents page with any comments or corrections.