Recovery Time after Hemodialysis Is Inversely Associated with the Ultrafiltration Rate

INTRODUCTION: The present study aimed to determine the variables that are associated with a longer dialysis recovery time (DRT) and to define the relationship that exists between DRT and the ultrafiltration rate (UFR) in prevalent chronic hemodialysis (CHD) patients. METHODS: We studied 210 prevalent CHD of 5 hemodialysis units in Central Italy. Patients were invited to answer to the question: "How long does it take you to recover from a dialysis session?" Answers to this question were subsequently converted into minutes. Demographic, clinical and laboratory parameters were recorded for each patient as well as the UFR (mL/kg/h), the dialysate sodium concentration and temperature. RESULTS: Median DRT was 180 min (60-420). Ninety five (45%) patients had a DRT ≥ the median value. Mean UFR was 9.2 ± 3.0 mL/kg/h. Patients with a lower DRT had a less prevalent disability in the instrumental activities daily living, had a higher UFR, and a lower dialysate temperature, as compared with subjects with higher DRT. According to the logistic regression model, UFR was associated with a DRT below the median (i.e., 180) in the unadjusted model (OR 1.12; 95% CI 1.02-1.23; p = 0.019), after adjusting for age and sex (OR 1.11; 95% CI 1.01-1.22; p = 0.025), and in the fully adjusted model (OR 1.11; 95% CI 1.04-1.22; p = 0.040). UFR increase was associated with increasing probability of DRT below the median (p for trend = 0.035). The highest tertile of DRT was associated with UFR below the mean value (i.e., 9.2 mL/kg/h) in multinomial logistic regression having the lowest DRT tertile as reference. DRT was significantly lower in patients with UFR > 13 mL/kg/h than in patients with UFR 10-13 or < 10 mL/kg/h. CONCLUSION: DRT is inversely associated with UFR in CHD patients. Whether a high UFR should be recommended to reduce the DRT needs to be elucidated through an adequate prospective randomized study.