Hemodialysis: CVP, ultrasound and adverse events
Two questions regarding hemodialysis patients: 1) What is the correlation of central venous pressure (CVP) with ultrasonographic measurement of central veins? And 2), how are these variables associated with intradialytic adverse events? Researchers at the Mayo Clinic in Rochester (US) conducted a prospective observational study to provide answers, and these are:
IVC diameter and collapsibility (as measured by ultrasound) have the highest accuracy in predicting low and high CVP.
Pre-dialytic CVP or ultrasonographic measurements are not able to predict adverse events.
The authors enrolled 59 patients requiring hemodialysis via dialysis catheter, and recorded CVP measurements through catheter, internal jugular vein aspect ratio, subclavian vein collapsibility, inferior vena cava (IVC) maximal diameter, and IVC collapsibility both before and after hemodialysis.
Median pre- and post-dialysis CVPs were 8 mm Hg and 6 mm Hg, respectively (P < 0.01). In pre-dialysis, IVC collapsibility was shown to have the highest AUC to predict CVP > 8 mm Hg (0.79; P < 0.01). In post-dialysis, IVC maximal diameter had the highest AUC to predict CVP ≤ 4 mm Hg (0.86, P < 0.01). 15 patients (25 %) had adverse events, and neither pre-dialytic CVP nor ultrasonographic variables were associated with the occurrence of these events.
The authors conclude that i) pre-dialytic CVP value is not associated with intradialytic adverse events, ii) ultrasonographic measurements of central veins cannot predict adverse events, and iii) IVC measurements can discriminate high vs. low CVP in dialysis population.