The Association of an Early Net Ultrafiltration Rate and 28-Day Mortality in Patients Receiving Continuous Kidney Replacement Therapy.

Buyun Wu,Yudie Peng,Changying Xing,Huijuan Mao,Yining Shen

doi:10.3389/fmed.2021.766557

Abstract

Background: An early net ultrafiltration (NUF) rate may be associated with prognosis in patients receiving continuous kidney replacement therapy (CKRT). In this study, we tested whether high or low early NUF rates in patients treated with CKRT were associated with increased mortality.Methods: We conducted a retrospective, observational study among all patients in the Medical Information Mart for Intensive Care IV database who received CKRT for more than 24 h within 14 days after intensive care unit admission. We defined the early (initial 48 h) NUF rate as the amount of fluid removal per hour adjusted by the patients' weight and took it as a classified variable (low rate: <1.6, moderate rate: 1.6–3.1 and high rate: > 3.1 ml/kg/h). The association between 28-day mortality and the NUF rate was analyzed by logistic regression and mediation analyses.Results: A total of 911 patients were included in our study. The median NUF rate was 2.71 (interquartile range 1.90–3.86) ml/kg/h and the 28-day mortality was 40.1%. Compared with the moderate NUF rate, the low NUF rate (adjusted odds ratio 1.56, 95% CI 1.04–2.35, p = 0.032) and high NUF rate (adjusted odds ratio 1.43, 95% CI 1.02–2.01, p = 0.040) were associated with higher 28-day mortality. The putative effect of high or low NUF rates on 28 day mortality was not direct [adjusted average direct effects (ADE) for a low NUF rate = 0.92, p = 0.064; adjusted ADE for a high NUF rate = 1.03, p = 0.096], but mediated by effects of the NUF rate on fluid balance during the same period [adjusted average causal mediation effects (ACME) 0.96, p = 0.010 for a low NUF rate; adjusted ACME 0.99, p = 0.042 for a high NUF rate]. Moreover, we found an increase trend in the NUF rate corresponding to the lowest mortality when fluid input increased.Conclusion: Compared with NUF rates between 1.6–3.1 ml/kg/h in the first 48 h of CKRT, NUF rates > 3.1 and <1.6 ml/kg/h were associated with higher mortality.

Highlights

Fluid overload (FO), defined as an absolute increase in total body volume or a relative increase in the percentage of extracellular volume over the isovolumic status of the patient, is a common complication of all emergencies
Compared with the moderate net ultrafiltration (NUF) rate, the low NUF rate and high NUF rate were associated with higher 28-day mortality
Compared with NUF rates between 1.6–3.1 ml/kg/h in the first 48 h of continuous kidney replacement therapy (CKRT), NUF rates > 3.1 and < 1.6 ml/kg/h were associated with higher mortality

Summary

Introduction

Fluid overload (FO), defined as an absolute increase in total body volume or a relative increase in the percentage of extracellular volume over the isovolumic status of the patient, is a common complication of all emergencies It occurs in more than 1/3 of critically ill patients and about 2/3 of patients with acute kidney injury (AKI) who need kidney replacement therapy [1, 2], and is associated with adverse outcomes [3, 4]. A high NUF rate (>1.75 ml/kg/h) was related to increased mortality [7, 11,12,13] Based on these studies, Murugan et al recently proposed that the relationship between the NUF rate and mortality in critically ill patients receiving continuous kidney replacement therapy (CKRT) might be “J” type and that a NUF rate of 1.01– 1.75 ml/kg/h might be the optimal range [7]. We tested whether high or low early NUF rates in patients treated with CKRT were associated with increased mortality

Methods

Results

Discussion

Conclusion