Wednesday, November 5, 2014

Preventing PD Peritonitis: What's the Evidence?

Peritoneal dialysis associated peritonitis is the second commonest cause of death among PD patients (35/1000 years) and the most common cause of treatment failure. It confers a CV risk of 7 times normal for 6 months following the bacteremia, so we need to remain ever vigilant when dealing with PD patient, and its worth refreshing our knowledge on how to prevent this feared complication. There is a paucity of high quality evidence for many of the most fundamental questions in PD. Such is the lack of evidence, the International Society for Peritoneal Dialysis (ISPD) have issued a consensus document where they state they are unable to issue formal guidelines.

The best resources I have found on the topic are a Kidney International supplement from 2006, and the ISPD document already mentioned. In the first instance, which patients are at risk of developing peritonitis? The best described risk factors are hypoalbuminemia (similar to the association in haemodialysis patients), Staph aureus  carriage at inception of dialysis (HR 1.53), initiation of PD early after catheter insertion (HR 0.98/day), PD after transplant failure (HR 2.18), lower hemoglobin (HR 0.88/gram/l), faster PD transport rates (HR 2.92) and previous peritonitis. A special risk group to consider are those PD patients undergoing invasive procedures such as endoscopy or IUD insertion. There is evidence that antibiotic prophylaxis using cephalosporins may help reduce peritonitis rates.

The cornerstone of peritonitis prevention is minimizing contamination risk with effective hand washing and immaculate exchange technique. Specialized nurse-led training is key. If peritonitis occurs, retraining and re-education are the most important interventions. Home visits by PD nurses can cut recurrence rates in half, and should be performed where possible. A Cochrane review could find no RCT data to support any particular insertion technique, catheter type, number of cuffs or positioning. It demonstrated that of all catheter-related interventions designed to prevent peritonitis in PD, only disconnect (twin-bag and Y-set) systems have been proved to be effective. Topical antibiotic prophylaxis is a standard of care and there are multiple RCTs demonstrating the efficacy of mupirocin cream application at the exit site. Ointment is to be avoided as it can erode the catheter polymer.  In contrast, nasal mupirocin is more difficult to justify. Cochrane point out that while there is trial data that nasal mupirocin reduces exit-site/tunnel infection, it has no effect on peritonitis rates. Preoperative intravenous prophylaxis reduces early peritonitis but not exit-site/tunnel infection. 

Recent published trials in the area of antimicrobial prophylaxis have been disappointing. They include the Honeypot study, discussed previously on RFN, which demonstrated the application of honey to exit sites approximately doubled the risk of developing peritonitis in diabetic patients. The MP3 study published in JASN in 2012 found polysporin to increase rates of fungal exit site infections without any improvement in primary outcomes of exit site infection or peritonitis. Finally, a special mention goes to cats, who are responsible for at least 25 case reports of pastuerella peritonitis, as well as an assortment of other bugs. Not to be outdone, rodents feature  in the case reports also, coining the term “hamster bite peritonitis” caused by pastuerella aerogenes.
In summary, technique and continuing re-education are of fundamental importance, as are topical antibiotics to prevent exit site infection.  Beyond this, trial data are severely lacking and local opinion and consensus must guide practice.

Authored by Eoin O'Sullivan

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