Yoowannakul Suree, Kotecha Tushar, Fontana Marianna, Davenport Andrew
UCL Centre for Nephrology, University College London, London, UK.
National Amyloid Centre, Royal Free Hospital, Department of Medicine, University College London, London, UK.
Ther Apher Dial. 2019 Aug;23(4):362-368. doi: 10.1111/1744-9987.12779. Epub 2018 Dec 21.
Bioimpedance can be used to measure extracellular water (ECW) and total body water in hemodialysis (HD) patients and estimate ECW excess. However, ECW excess potentially includes both an increase in the plasma volume and also the extravascular volume. Overestimating the amount of fluid to be removed during HD risks intra-dialytic hypotension. We wished to determine the association between estimates of ECW excess comparing several different equations using bioimpedance, brain N-terminal pro-brain natriuretic peptide (NT-proBNP) with cardiac chamber volumes and function as determined by cardiac magnetic resonance imaging pre-HD measurements of ECW and total body water were made using multifrequency bioimpedance and cardiac chamber sizes and function were determined by magnetic resonance imaging. Thirty patients, 20 males (66.7%), mean age 64.4 ± 15.3 years were studied. ECW and ECW/height were positively associated with indexed right ventricular end-systolic (RVESVi) and end-diastolic volume (RVEDVi) (RVESi r = 0.46, r = 0.43; RVEDi r = 0.50, r = 0.44, all P < 0.05), but not with left sided cardiac volumes. Whereas NT-proBNP was associated with indexed left atrial and ventricular size (r = 0.47, r = 0.58, P < 0.05), but not right sided cardiac volumes. Pre-HD NT-proBNP was associated with left sided cardiac chamber sizes, but not with right sided chamber sizes, whereas ECW/height was associated with right sided cardiac chamber sizes. As right-sided cardiac chamber size is more responsive to and reflective of changes in intravascular volume than the left atrium and ventricle, then bioimpedance measured ECW is potentially more reliable in estimating plasma volume expansion.
生物阻抗可用于测量血液透析（HD）患者的细胞外液（ECW）和总体液，并估计ECW过多。然而，ECW过多可能既包括血浆量增加，也包括血管外液量增加。在HD期间高估要清除的液体量有发生透析中低血压的风险。我们希望通过比较使用生物阻抗的几种不同方程所估算的ECW过多与脑N末端脑钠肽前体（NT-proBNP），来确定它们与心脏腔室容积和功能之间的关联，HD前通过多频生物阻抗测量ECW和总体液，通过磁共振成像确定心脏腔室大小和功能。研究了30例患者，其中20例男性（66.7%），平均年龄64.4±15.3岁。ECW和ECW/身高与右心室收缩末期容积指数（RVESVi）和舒张末期容积指数（RVEDVi）呈正相关（RVESi r = 0.46，r = 0.43；RVEDi r = 0.50，r = 0.44，均P < 0.05），但与左心腔容积无关。而NT-proBNP与左心房和心室大小指数相关（r = 0.47，r = 0.58，P < 0.05），但与右心腔容积无关。HD前NT-proBNP与左心腔大小相关，但与右心腔大小无关，而ECW/身高与右心腔大小相关。由于右心腔大小比左心房和心室对血管内容积变化更敏感且更能反映这种变化，因此生物阻抗测量的ECW在估计血浆量扩张方面可能更可靠。
