Tandem Therapeutic Plasma Exchange Reduces Continuous Renal Replacement Therapy Downtime

Introduction: Continuous renal replacement therapy (CRRT) has become a primary treatment of severe acute kidney injury in children admitted to the intensive care unit. CRRT "downtime" (when the circuit is not active) can represent a significant portion of the prescribed treatment time and adversely affects clearance. The objective of this study was to evaluate factors associated with CRRT "downtime" and to determine whether instituting a tandem therapeutic plasma exchange (TPE) protocol could significantly and robustly decrease circuit downtime in patients receiving both therapies. Methods: This is a retrospective cohort study of 116 patients undergoing CRRT in the pediatric, neonatal, or cardiac ICU at UPMC Children's Hospital of Pittsburgh from January 2014 to July 2020. We performed multivariable logistic regression to determine factors associated with CRRT downtime. We instituted a tandem TPE protocol whereby TPE and CRRT could run in parallel without pausing CRRT in April 2018. We analyzed the effect of the protocol change by plotting downtime for patients undergoing CRRT and TPE on a run chart. The effect of initiating tandem TPE on downtime was assessed by special cause variation. Results: For 108/139 (77.7%) sessions with downtime data available, the median (IQR) percentage of downtime was 6.2% (1.7-12.7%). Multivariable logistic regression showed that TPE was significantly associated with CRRT downtime (p = 0.003), and that age, sex, race, catheter size, and anticoagulation were not. For patients undergoing TPE, the median (IQR) percentage of downtime was 14.7% (10.5-26%) and 3.4% (1.3-4.9%) before and after initiation of tandem TPE, respectively (p < 0.001). The difference in downtime percentage met criteria for special cause variation. Conclusions: Interruptions for TPE increase CRRT downtime. Tandem TPE significantly reduces CRRT downtime in patients undergoing both procedures concomitantly.