FC 114LUNG ULTRASOUND-GUIDED ULTRAFILTRATION IN HAEMODIALYSIS PATIENTS REDUCES THE RISK OF DIALYSIS HYPOTENSION
Authors: Torino Claudia , Tripepi Rocco , Tripepi Giovanni Luigi , Mallamaci Francesca , Zoccali Carmine , behalf of the LUST Working Group on 
Published: May 2021

Abstract

Background and Aims
Lung ultrasound (US) is a reliable method for the identification of patients with lung congestion in the hemodialysis population (JACC Cardiovascular Imaging 2010;3:586-94) and a high number of US-B lines (an equivalent of B lines in the chest X-ray) is a powerful predictor of death and cardiovascular events in this population (JASN 24:639–646, 2013.) .US-B lines are strongly related with the Left Ventricular filling pressure (capillary wedge pressure) and may also be potentially useful for the identification of patients with low blood volume at risk for dialysis hypotension. With this background in mind, in the frame of the “LUng water by Ultra-Sound Guided Treatment (LUST) to Prevent Death and Cardiovascular Complications in High Risk ESRD Patients with Cardiomyopathy Trial” (NCT02310061) we investigated, as a secondary study end-point, whether the systematic use of lung US may mitigate the risk of dialysis hypotension.

Method
We included in this analysis 377 HD patients. In patients in the active arm of the trial (n=197) dialysis ultrafiltration prescription was guided by lung US while in the control arm (n=180) ultrafiltration was prescribed on the basis of standard clinical criteria. The duration of the trial was 2 years. Hypotensive episodes during dialysis were pre-defined as a reduction in mean arterial pressure of &gt;20%, associated with typical symptoms (light-headedness, sweating, nausea and/or vomiting). Incident rate was expressed as number of hypotensive episodes/patient/year. Negative binomial regression (Biometrics. 2014;70:920-31) was applied to analyse the association between US-B lines and the incidence rate of dialysis hypotension. Since a high degree of lung congestion and/or a high variability in lung congestion over time may predispose to dialysis hypotension, in the active arm we also tested the relationship between the average number of US-B lines and the standard deviation (SD) of the same parameter across the trial (2733 pre-dialysis lung US recordings) and the risk of dialysis hypotension.

Results
During the trial, 890 hypotensive episodes occurred in the active arm and 1292 in the control arm. The corresponding incidence rates were 3.15/patient/yr and 4.73/patient/yr, respectively, with an Incident Risk Ratio of 0.66 (95% CI: 0.61-0.72, P&lt;0.001) underlying a 34% reduction in the risk of this outcome. In the active arm, the degree of lung congestion across the trial (average number of US-B lines) was positively associated with a higher risk of dialysis hypotension because for each US-B line there was a 6% excess (95%CI: 1%-12%, P=0.02) risk of the same outcome. The variability of US-B lines (SD) did not significantly associate with the risk of dialysis hypotension (P=0.09).

Conclusion
Findings in this study show that lung US is a safe method to guide the prescription of dialysis ultrafiltration. Indeed, the systematic application of this technique reduced the risk of dialysis hypotension by the 34%. The finding in the active arm of the trial that a higher number of US-B lines underlies an excess risk of dialysis hypotension suggests that special care should be applied to tailor ultrafiltration in patients with lung congestion to minimize the risk of this outcome.