Study addresses ‘ongoing problem’ of assessing fluid status in peritoneal dialysis
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In a recently published study, researchers examined the challenges of assessing hydration status for patients on peritoneal dialysis, deeming the search for the optimal technique “an ongoing clinical problem.”
“Fluid overload is a common complication in [chronic kidney disease (CKD)], particularly in CKD stage 5 before and after the initiation of renal replacement therapy,” Maria-Eleni Alexandrou, MD, MSc, PhD, of Hippokration Hospital, Aristotle University of Thessaloniki, in Greece, and colleagues wrote. “Fluid overload increases blood pressure (BP) and cardiac preload and has been associated with heart failure, left ventricular hypertrophy, and mortality both in hemodialysis and peritoneal dialysis (PD) populations. Thus, one of the main goals of adequate renal replacement therapy in patients with [end-stage renal disease (ESRD)] is to avoid fluid overload and maintain euvolemia.”
In addition to the fact that symptoms and physical signs do not always convey hydration status accurately, the researchers contended that other currently used methods for determining fluid overload — including ultrasound assessment of inferior vena cava diameter, bioelectrical impedance analysis techniques and lung ultrasound — all have associated limitations and potential risks.
According to Alexandrou and colleagues, bioimpedance analysis estimates fluid distribution in body compartments in a simple and non-invasive way; it is also the most well-studied of hydration assessment tools. While the researchers suggested all the bioimpedance techniques are “highly reproducible and validated in healthy populations,” they can lead to errors in volume prediction due to different devices and lack of standardization.
Further, the researchers noted that certain studies have found technique failure and increased mortality when volume overload was assessed with BIA techniques.
“Results of randomized trials on the value of BIA-based strategies to improve volume-related outcomes are largely contradictory,” they wrote.
Although, Alexandrou and colleagues argued, few studies have looked at using inferior vena cava diameter measurements for patients on PD, the method has been associated with adverse echocardiography indexes. Further, experienced operators are required, which leads to high costs. Therefore, the researchers argued it would be difficult to broadly implement its use in clinical practice.
Lastly, the researchers examined the most recently developed technique for fluid assessment: lung ultrasound. Able to identify volume excess in the critical lung area, preliminary evidence of patients on PD showed that B-lines from the ultrasound correlate with echocardiographic parameters but not with BIA measurements.
“As lung echocardiography and biomarkers detect intravascular and pulmonary volume excess, while BIA methods estimate overall hydration status, the methods can be complementary,” they elaborated.
Alexandrou and colleagues concluded that none of the techniques has “proved its value” for assessing hydration status on patients undergoing PD.
“As these techniques estimate fluid overload in different compartments of the body, the information provided by combining them could be complementary and more effective in the assessment of volume status,” they suggested, recommending further research be done in this area to improve volume-related outcomes for patients.
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