Impact of rapid ultrafiltration rate on changes in the echocardiographic left atrial volume index in patients undergoing haemodialysis: A longitudinal observational study

Abstract

Objective: Optimal fluid management is essential when caring for a patient on haemodialysis (HD). However, if the fluid removal is too rapid, the resultant higher ultrafiltration rate (UFR) disadvantageously promotes haemodynamic instability and cardiac injury. We evaluated the effects of a rapid UFR on changes in the echocardiographic left atrial volume index (LAVI) over a period of time. Design: Longitudinal observational study. Setting and participants: A total of 124 new patients on HD. Interventions: Echocardiography was performed at baseline and repeated after 19.7 months (range 11.3- 23.1 months). Changes in LAVI (δLAVI/year, mL/m2/ year) were calculated. The UFR was expressed in mL/ hour/kg, and we used the mean UFR over 30 days (∼12-13 treatments). Main outcome measures: The 75th centile of the δLAVI/year distribution was regarded as a 'pathological' increment. Results: The mean interdialytic weight gain was 1.73 ±0.94 kg, and the UFR was 8.01±3.87 mL/hour/kg. The significant pathological increment point in δLAVI/year was 4.89 mL/m2/year. Correlation analysis showed that δLAVI/year was closely related to the baseline blood pressure, haemoglobin level, residual renal function and UFR. According to the receiver operating characteristics curve, the 'best' cut-off value of UFR for predicting the pathological increment was 10 mL/hour/kg, with an area under the curve of 0.712. In multivariate analysis, systolic blood pressure, a history of coronary artery disease, haemoglobin <10 g/dL and high UFR were significant predictors. An increase of 1 mL/hour/kg in the UFR was associated with a 22% higher risk of a worsening LAVI (OR 1.22, 95% CI 1.05 to 1.41). Conclusions: An increased haemodynamic load could affect left atrial remodelling in incident patients on HD. Thus, close monitoring and optimal control of UFR are needed.