Peritoneal Dialysis for Acute Kidney Injury during the COVID-19 Pandemic

Patient Selection for Peritoneal Dialysis for AKI

Candidates for treatment with PD for AKI require KRT for the usual clinical indications, including refractory volume overload, metabolic acidosis, or hyperkalemia. Those with active abdominal pathology such as peritonitis or small bowel obstruction, recent abdominal surgery, severe hyperkalemia, or increased intra-abdominal pressure are not ideal candidates (2). Obesity (body mass index >30 kg/m²) is a relative contraindication, and catheter placement is at the discretion of the operator. Patients who experience CRRT circuit clotting should be evaluated for conversion to PD.

Peritoneal Dialysis Catheter Insertion

During the COVID-19 pandemic, limitations on personal protective equipment and conversion of operating rooms to ICU beds can limit the availability of laparoscopic or interventional PD catheter insertion. Surgeons performing bedside PD catheter insertions provide the most flexibility for obtaining PD access. Additionally, limiting the number of operators and assistants in the room at the time of catheter insertion minimizes unnecessary exposure to COVID-19. During insertion, a purse-string suture to secure the deep cuff may reduce the risk of PD fluid leak and allow for immediate use (3). An initially well-placed PD catheter also may function as a permanent dialysis access if there is no recovery from the AKI episode.

Initial Peritoneal Dialysis Prescription

Automated peritoneal dialysis (APD) is preferred over continuous ambulatory peritoneal dialysis (CAPD); however, resource limitations may necessitate the use of both modalities. The initial prescription is of much debate, but the most important benefit of APD is the ability to adjust the dwell volume and exchange frequency as the clinical situation dictates. APD can begin with dwell volumes up to 2000 ml without significant risk of early leak in the supine intubated patient (2,4). Using every 2-hour cycles for 12 hours, a total volume of 10,000–12,000 ml is a practical starting point because PD fluid is commercially available as 5000- or 6000-ml bags. However, the total treatment volume should be determined by the clinical circumstances. After the first treatment, the net ultrafiltration can be reviewed, and prescription can be adjusted. If the patient’s dialysis needs are met, 12-hour dry time can be prescribed before the next treatment in order to allow for catheter healing if needed. For euvolemic patients, it is recommended to start with 2.5% dextrose solution with the addition of heparin 500 U/L to prevent PD catheter clotting. The dextrose concentration of PD fluid can be adjusted higher for more ultrafiltration or lower for hypotension or volume depletion.

The PD prescription should be re-evaluated daily for volume and metabolic control. APD can be prescribed as a true continuous therapy utilizing one long 24-hour cycler treatment or two complete 12-hour cycler treatments consecutively for patients who require more dialysis. Lastly, cycles can be prescribed as frequently as hourly in the most hypercatabolic patients. Of note, previously published experiences report effective use of high-volume PD for AKI in patients in the ICU using 2000-ml dwells and hourly cycles resulting in total treatment volumes as high as 36–44 L in 24 hours (4).

Prone Positioning

In a recent report on critically ill patients with COVID-19 hospitalized in two New York City hospitals, 31% required KRT, and 17% were placed in prone position during their ICU stay (7). Although prone positioning is a feared limitation, it is not an absolute contraindication. There is a published patient report of successful use of APD in a prone acute respiratory distress syndrome patient (8). In addition, prone positioning is usually intermittent, occurring in 8- to 16-hour intervals. APD can be prescribed as noted earlier, with high frequency of exchanges while patients are supine.

Increased Intra-Abdominal Pressure in Mechanically Ventilated Patients

Presence of PD fluid increases intra-abdominal pressure and is thought to limit diaphragmatic excursion and compromise ventilation. However, the respiratory effect is minimal, and the incidence of early leakage was <10% even at dwell volumes of 2000 ml (4,9). Despite this, intensivists may request lower initial dwell volumes. A strategy utilizing a lower initial dwell volume and titrating up in 500-ml increments every 24 hours for a target of 2000-ml dwell can be used if no evidence of leak or change in ventilator parameters is observed. Additionally, a simple noninvasive measure of intra-abdominal pressure with the PD catheter has been described and should target <18 cm H₂O (2). As a practical matter, ventilator parameters such as plateau pressure and fraction of inspired oxygen are typically continuously monitored. Dwell volumes can be reduced or patients can be temporarily drained empty to assess the effect of PD on ventilator mechanics as needed.

Excessive Continuous Kidney Replacement Therapy Circuit Clotting

Although poorly understood, patients with COVID-19 appear to be hypercoagulable, and there are many anecdotal reports of CRRT circuit clotting in critically ill patients with COVID-19 (10). This can occur despite the use of in-filter fixed heparin or systemic heparin, leading to increased use of alternative anticoagulants such as argatroban or bivalirudin if regional citrate anticoagulation is unavailable. Repeated circuit clotting results in lost blood, lost treatment time, and wasted CRRT filters while supplies are limited. PD is an acceptable alternative KRT choice in these patients because it obviates the need for systemic anticoagulants and preserves scarce CRRT supplies for other patients.

Coronavirus Disease 2019 Modifications to Maximize Staff Safety

Minimizing exposure to COVID-19 is of paramount concern in order to protect staff and preserve personal protective equipment. Both major equipment manufacturers have long tubing sets available ranging from 10 to 20 feet in length. Using the long tubing set allows the bedside staff to perform APD at a distance and minimize high-risk contact with the patient with COVID-19. If CAPD is utilized, exchanges can be synchronized with other existing nursing activities in order to limit unnecessary entries into the patient room and minimize the number of high-risk close contacts.

Need for a Multidisciplinary Team

Nephrologists, intensivists, surgeons, nurses, and hospital administrators must work together in order to provide this resource with the goal that one patient treated with PD can liberate a hemodialysis or CRRT machine for use by another patient. Nursing educators from equipment manufacturers can be leveraged to train PD-naïve staff to perform CAPD or APD. Staff can be trained using telehealth combined with hands-on experience using mannequins or aprons. Additionally, video resources demonstrating proper APD or CAPD techniques are widely available. One strategy to rapidly train staff would be to provide intense training to a small group of “PD champions” who can then be used as a local resource to train other staff. It is also necessary to have redundant plans for PD access involving surgeons and interventional radiologists or nephrologists. A centralized PD team composed of a nephrologist, operator, and nurses can streamline patient selection and promote professional communication to create a seamless KRT option for this vulnerable population.

PD for AKI is a viable option for critically ill patients with COVID-19 and can augment traditional dialysis capabilities during a time of crisis and beyond.