# Temporal changes in toe-brachial index results in haemodialysis patients

## TL;DR

This study shows that toe-brachial index measurements in dialysis patients change during treatment, suggesting they should be done before dialysis starts or in between sessions.

## Contribution

The study is the first to systematically evaluate how hemodialysis affects toe-brachial index values over time.

## Key findings

- TBI values decreased during dialysis but returned to baseline post-dialysis.
- TBI results were lower in patients with a history of lower limb ulcers and in females.
- TBI classifications shifted during dialysis, with some moving from normal to abnormal.

## Abstract

Toe brachial index (TBI), the ratio of toe pressure to systolic blood pressure (SBP), helps predict peripheral arterial disease. In patients with kidney failure this may be performed during haemodialysis for convenience. Until recently there has been little evaluation of the impact of haemodialysis in limb and systemic perfusion on these values. We aimed to determine if the values of TBI would change during and after dialysis compared to pre-dialysis assessments.

Using a repeated measures study, TBIs and toe pressures were measured using the Hadeco Smartop Vascular Ultrasound Doppler in 31 patients undergoing haemodialysis. TBI assessments were completed pre-dialysis and compared to values obtained at 1 hour, 2 hours, 3 hours, and post-dialysis to monitor change in TBI results. Comparison of values for each patient were tested for differences using paired t-tests. Linear mixed-effects models were used to test for the effect of patient and clinical factors on change in outcome measures.

Mean TBI decreased from pre-dialysis at 1 hour (0.72 to 0.63, p = 0.01) and remained lower at 2 hours and 3 hours, before returning to pre-dialysis levels at post-dialysis. Mean systolic blood pressure also declined during dialysis. Mean TBI results were lower in those with a history of lower limb ulceration and in females.

Sixteen patients (51.6%) had a normal TBI at baseline, 14 (45.2%) had a mildly low TBI, and one (3.2%) had a severely low TBI. Between baseline and 1 h, five patient’s results moved from normal to mildly abnormal and one from mildly abnormal to severely abnormal. As haemodialysis concluded (post-dialysis) there were 17 (56.7%) ‘normal’ TBIs, with no severely abnormal TBIs (p = 0.73). 0.30)

TBI and toe pressures are impacted significantly by dialysis. TBI and toe pressure assessments should be conducted before haemodialysis begins, or between dialysis sessions to avoid variability.