Prolonged Intermittent Kidney Replacement Therapy

Abstract

Kidney replacement therapy (KRT) is a vital, supportive treatment for patients with critical illness and severe AKI. The optimal timing, dose, and modality of KRT have been studied extensively, but gaps in knowledge remain. With respect to modalities, continuous KRT and intermittent hemodialysis are well-established options, but prolonged intermittent KRT is becoming more prevalent worldwide, particularly in emerging countries. Compared with continuous KRT, prolonged intermittent KRT offers similar hemodynamic stability and overall cost savings, and its intermittent nature allows patients time off therapy for mobilization and procedures. When compared with intermittent hemodialysis, prolonged intermittent KRT offers more hemodynamic stability, particularly in patients who remain highly vulnerable to hypotension from aggressive ultrafiltration over a shorter duration of treatment. The prescription of prolonged intermittent KRT can be tailored to patients' progression in their recovery from critical illness, and the frequency, flow rates, and duration of treatment can be modified to avert hemodynamic instability during de-escalation of care. Dosing of prolonged intermittent KRT can be extrapolated from urea kinetics used to calculate clearance for continuous KRT and intermittent hemodialysis. Practice variations across institutions with respect to terminology, prescription, and dosing of prolonged intermittent KRT create significant challenges, especially in creating specific drug dosing recommendations during prolonged intermittent KRT. During the coronavirus disease 2019 pandemic, prolonged intermittent KRT was rapidly implemented to meet the KRT demands during patient surges in some of the medical centers overwhelmed by sheer volume of patients with AKI. Ideally, implementation of prolonged intermittent KRT at any institution should be conducted in a timely manner, with judicious planning and collaboration among nephrology, critical care, dialysis and intensive care nursing, and pharmacy leadership. Future analyses and clinical trials with respect to prescription and delivery of prolonged intermittent KRT and clinical outcomes will help to guide standardization of practice.

Figure 1

Treatment parameters during continuous KRT (CKRT), prolonged intermittent KRT (PIKRT), and intermittent hemodialysis (HD). The blood flow rates, dialysate flow rates, and ultrafiltration rates may vary across centers. Kidney Disease Improving Global Outcomes (KDIGO) recommends effluent flow rate of 20–25 ml/kg per hour for CKRT, and intermittent HD to be provided three times a week. *For CKRT and PIKRT, this number may represent dialysate flow rate, replacement fluid flow rate, or a combination, on the basis of institutional practices.

Figure 2

Models of nursing support for PIKRT in the intensive care unit (ICU). This figure shows the different nursing models used at various institutions to provide prolonged KRT in the ICU.

Figure 3

Use of PIKRT in the ICU. PIKRT can be used as a substitute for CKRT or intermittent HD, or as a transition between CKRT and intermittent HD during de-escalation of care in the ICU. The Cardiovascular Sequential Organ Failure Assessment (CV-SOFA) score is one of the many tools used to determine hemodynamic stability of the patient. CV-intermittent HD SOFA SCORE: mean arterial pressure (MAP) >70=0, MAP <70 mm Hg =1, dopamine ≤5 or dobutamine (any dose) =2, dopamine >5, epinephrine ≤0.1, or norepinephrine ≤0.1=3, dopamine >15, epinephrine >0.1, or norepinephrine >0.1=4.

Figure 4

Urea kinetics during different modalities of KRT. Urea kinetics are a suboptimal marker for assessing adequacy of KRT. However, current guidelines for adequacy of hemodialysis and CKRT utilize urea kinetics and Kt/V_urea. Standard Kt/V_urea (StdKt/V_urea) may be utilized to compare weekly clearances among different modalities. CKRT with an effluent flow rate of 20 ml/kg per hour provides StdKt/V_urea of 6 (assuming no interruptions of therapy), and intermittent HD, three times per week, with a single pool Kt/V_urea of 1.3 per treatment provides a weekly clearance of 2.0. PIKRT protocol at our institution usually provides a single pool Kt/V_urea of approximately 0.9 per session and, if given 6 days a week, will provide a weekly StdKt/V_urea of 3.5. Adapted from ref. , with permission.