Abstract
Background and Aims
There is a clear relationship between volume overload and morbidity and mortality in hemodialysis patients, which makes it essential to accurately adjust the ...normohydrated weight. For this, bioimpedance has become an indispensable tool in dialysis units. In recent years there has been a rapid development of lung ultrasound for the evaluation of pulmonary congestion through the quantification of B lines. Several studies have shown a correlation between the number of B lines and the volume overload estimated by bioimpedance in patients on dialysis. However, all these studies perform a 28-zone lung ultrasound protocol, which may be a limitation in clinical practice. Several studies have recently been published showing a correlation between 28-zone lung ultrasound protocol and simplified 4, 6, and 8-zone ultrasound protocols, which have been widely studied in patients treated in intensive care or emergency units. We set out to evaluate the relationship between bioimpedance and simplified 8-zone lung ultrasound protocol in hemodialysis patients.
Method
Pilot cross-sectional observation study that included 29 patients on hemodialysis at Infanta Sofía University Hospital during March 2022. Bioimpedance predialysis and postdialysis, 8-zone lung ultrasound protocol (delimited by the parasternal, anterior axillary, posterior axillary, and 4th intercostal space) and inferior vena cava ultrasound. Predialysis proBNP and Ca-125 were measured.
Results
There is a significant reduction in overhydration estimated by bioimpedance and in the number of B lines after the hemodialysis session (p<0.05). No correlation has been established between the two parameters, neither pre-dialysis nor post-dialysis. Nor with the pre-dialysis levels of proBNP or Ca125. There is a correlation of r = 0.45 (p<0.05) in the subgroup of patients from the afternoon shift (n = 9) between the number of B lines and extracellular water.
Conclusion
Lung ultrasound allows the evaluation of the degree of lung congestion, and therefore of extracellular water, becoming a useful tool for adjusting the dry weight of hemodialysis patients. In our study we found no association between the number of B lines in the simplified 8-zone lung ultrasound protocol. It is possible that this type of lung ultrasound is not sensitive enough in outpatients on hemodialysis, but it is sensitive enough in critically ill patients in whom lung overload is greater. Further studies with a larger number of patients are needed for evaluation.
