The Role of Peritoneal Dialysis in the Management of Patients Undergoing Cardiac Surgery

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Patients with kidney failure treated with maintenance dialysis are at high risk for cardiovascular morbidity and mortality (1). As such, they frequently undergo invasive cardiac procedures such as coronary artery bypass grafting (CABG) and valvular surgery. There is conflicting evidence as to whether there are differences in outcomes between patients with kidney failure treated with hemodialysis (HD) versus peritoneal dialysis (PD) after such procedures, and surgeons will commonly request a modality change from PD to HD (2, 3). Although there are valid clinical reasons to convert patients from PD to HD after cardiac surgery, many cases are driven by a lack of understanding of the advantages and disadvantages of the modality in the postoperative setting (Figure).

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Potential advantages and disadvantages of PD compared with HD postcardiac surgery

Citation: Kidney News 16, 7

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Bassil et al. (4) recently published the largest retrospective study to date examining mortality and a variety of important secondary outcomes in 590 patients with kidney failure who underwent CABG and/or valvular surgery at the Cleveland Clinic from October 2009 to October 2019 using an intent-to-treat study design. The cohort included 62 patients on PD and 528 on HD with some notable differences in baseline and perioperative characteristics. Patients on PD predictably had lower baseline mean serum albumin given the dialytic albumin losses that occur with PD, higher rates of dyslipidemia, and lower rates of heart failure and prior CABG compared with patients on HD. The HD group had a higher number of days from admittance to surgery, had more cardiopulmonary bypass time, and were more likely to undergo valvular surgery alone versus the PD group.

Over one quarter of patients (16 out of 62) converted from PD to HD postoperatively; among these conversions, 25% (n = 4) were driven by clinician preference. The remaining PD to HD conversions were due to hemodynamic instability (n = 7), catheter malfunction (n = 3), cardiac tamponade (n = 1), and gadolinium exposure (n = 1). Some of these patients might reasonably have remained on PD, highlighting the need for nephrology teams skilled in managing the modality.

There was no difference between PD and HD in the primary outcomes of in-hospital mortality (2% versus 5%; p = 0.51) or 30-day survival (98.2% versus 95.7%; p = 0.30). Patients treated with HD were more likely to experience a composite outcome of death, cardiac arrest, pericardial effusion, or sternal wound infection (odds ratio, 9.5; 95% confidence interval, 1.3–70.1). There was no difference in the number of intraoperative packed red blood cell transfusions between groups. This is a reassuring finding, as patients on PD often have higher blood urea nitrogen concentrations compared with those on HD, raising concerns about an increased risk of bleeding from uremic platelet dysfunction. However, these concerns have not been observed in the outpatient setting (5).

There was no difference between groups in time spent in the intensive care unit, an important clinical and operational finding. Hospital-acquired PD-associated peritonitis is often raised as a concern in discussions surrounding dialysis modalities, but there was no observed difference in rates of postoperative sepsis between patients on PD (4.9%) and HD (2.7%) (p = 0.32). It should be noted that PD-associated peritonitis uncommonly leads to bacteremia in contrast to HD catheter-related bloodstream infections and the possible serious complications of subsequent metastatic infection (6).

Important limitations include residual confounding (given the retrospective study design) and generalizability (given the single-center nature of the data). An ideal study might prospectively randomize patients on PD postoperatively, who could reasonably use either modality, to PD versus HD. As we await higher quality evidence, the study from Bassil and colleagues (4) provides us reassurance that, absent strong clinical contraindications to PD, it is reasonable to continue the modality after cardiac surgery.