Acute effects of haemodialysis on central venous and arterial pressure characteristics.

Haemodynamic stability of patients during haemodialysis (HD) sessions is of pivotal importance and accurate determination of dry weight remains a challenge. Little information is available about central venous and aortic pressure during dialysis. In this pilot study we used a non-invasive technique to describe the changes in central venous pressure (CVP) during dialysis. An ultrasound-assisted pressure-manometer was used at the cephalic vein during haemodialysis to quantify CVP. Central aortic pressure changes were assessed as aortic augmentation index and subendocardial viability ratio. Bioimpedance was applied to measure total body water, as well as extracellular and intracellular water before and after HD. Measurements were performed prior during and after 1 and 2 h on HD. Ten patients were included with a median age of 72 years (23-82). Haemodialysis reduced the weight by 2.0 kg, corresponding to a measured decrease in total body water of 1.9 L. The mean CVP showed a significant decrease (9.0-0.8 cmH₂O; P = 0.0005) during dialysis. The significant drop in CVP was found during the first hour (9-2.8 cmH₂O). Starting and stopping dialysis was reflected by a reduction of 2.6 cmH₂O and a rise of 2.8 cmH₂O (n.s.). Aortic augmentation index decreased from 26.1% to 21.0% (n.s.). Subendocardial viability ratio increased from 126% to 156% (P < 0.05) during HD, and decreased to 139% direct after HD (n.s.). This is the first study that illustrates a prominent reduction of CVP during the first hour of haemodialysis. Non-invasive CVP measurement is feasible during haemodialysis and adds another piece in the puzzle of factors involved in haemodynamic stability.