Objective: It is well-known that vasodilatator function is affected in patients with renal failure. We hypothesized impaired venous forearm distensibility in haemodialysis patients. The purpose of this study was to investigate which provocation method generated 'maximal' venous distensibility in the forearm of haemodialysis patients compared to healthy volunteers by using duplex ultrasound.
Design: The study group consisted of haemodialysis patients (n=30) and healthy volunteers (n=30). In each participant ultrasound measurements of the venous diameter were performed by using 3 different provocation methods.
Methods: The applied provocation methods were: 1) hydrostatic pressure, 2) venous congestion and 3) hydrostatic pressure and warmth. Significance of differences in mean diameter changes within the groups was assessed with the paired t-test. Significance of differences in mean diameter changes between the groups was compared by using multivariate regression analysis.
Results: In haemodialysis patients, the increase in mean diameter after the different methods was: 29% after methods 2 versus 1, 23% after methods 3 versus 2 and 59% after methods 3 versus 1. In healthy volunteers, the mean diameter increase was: 27% after methods 2 versus 1, 29% after methods 3 versus 2 and 64% after methods 3 versus 1. The greatest increase in the mean internal venous diameter among the haemodialysis patients and the healthy volunteers was after the provocation method which combined hydrostatic pressure with warmth (mean difference: 1mm, 95% CI: .57, 1.36; P<.001 and mean difference: 1.4mm, 95% CI: .88, 1.78; P<.001, respectively). After adjustment for the baseline variables, both groups demonstrated a non-significant mean diameter difference for each of the provocation methods.
Conclusion: Hydrostatic pressure combined with warmth generates the greatest venous distensibility in the lower arm in haemodialysis patients in a sitting position and is not significantly different compared to healthy volunteers. Without the superior provocation method, venous diameters of haemodialysis patients can be assessed as false-negatives yielding that a primary radio cephalic arteriovenous fistula (RCAVF) at wrist level (the first choice) in these patients will be withheld.