NIRS was feasible when tolerated, but acceptability and interpretability limited its use in advanced CKD, with moderate correlations with popliteal VTI supporting its potential utility in this population.
Key Findings
Results
NIRS test acceptability was lower in CKD participants compared to controls, with 79% of CKD tests deemed acceptable versus 100% of controls.
38 CKD participants (Stage 5, dialysis and non-dialysis) and 20 controls were included
Acceptability was one of four feasibility dimensions assessed, alongside technical limitations, interpretability, and safety
Lower acceptability in CKD was linked to higher ankle systolic blood pressure and BMI
These findings are consistent with a calcified, poorly compressible vasculature in advanced CKD
Results
Interpretability of NIRS results was reduced in 39% of CKD tests.
Reduced interpretability affected 39% of CKD participant tests
Reduced interpretability was unrelated to ankle systolic blood pressure or BMI
This contrasts with acceptability limitations, which were associated with markers of vascular severity
The cause of reduced interpretability was distinct from the calcified, poorly compressible vasculature mechanism affecting acceptability
Results
Popliteal hyperemic velocity-time integral (VTI) showed moderate correlations with NIRS reperfusion indices, while brachial VTI did not correlate.
Popliteal VTI correlated moderately with NIRS reperfusion time from nadir to baseline (r = -0.64)
These moderate correlations support the potential utility of NIRS as a microvascular assessment tool in this population
Results
Higher ankle systolic blood pressure and BMI were associated with reduced NIRS test acceptability in CKD participants.
A priori analyses examined associations between participant characteristics and feasibility within CKD participants
Ankle systolic blood pressure and BMI were identified as participant characteristics linked to acceptability limitations
These characteristics are consistent with medial calcification and poorly compressible vasculature typical of advanced CKD
Interpretability was not associated with these same characteristics, suggesting a different underlying mechanism
Methods
NIRS using an ischemic challenge assessed lower limb reperfusion kinetics of the tibialis anterior as a candidate tool for early PAD detection in CKD.
Near-infrared spectroscopy (NIRS) was applied to the tibialis anterior muscle during an ischemic challenge
The study targeted CKD Stage 5 participants, including both dialysis and non-dialysis patients
People with advanced CKD have a high burden of PAD but early detection is limited by disease-related changes such as medial calcification
Feasibility was defined across four dimensions: acceptability, technical limitations, interpretability, and safety
What This Means
This research investigated whether a non-invasive light-based technology called near-infrared spectroscopy (NIRS) could be used to detect early blood vessel problems in people with advanced chronic kidney disease (CKD). People with advanced CKD frequently develop peripheral artery disease (PAD), a condition where blood flow to the limbs is reduced, but existing detection tools often fail in this population because kidney disease causes calcium deposits to harden the blood vessel walls. The study tested NIRS on 38 people with advanced CKD and 20 healthy controls by briefly restricting blood flow to the lower leg and then measuring how quickly blood flow returned.
The researchers found that while NIRS worked well when patients could tolerate the test, there were notable limitations in the CKD group. Only 79% of CKD tests were considered acceptable (compared to 100% in controls), largely because patients with higher blood pressure at the ankle and higher body weight — both signs of more severe vascular disease — had difficulty completing the procedure. Additionally, about 39% of CKD tests produced results that were difficult to interpret clearly, though this problem appeared to have a different cause than the acceptability issues. On the positive side, NIRS measurements showed moderate agreement with ultrasound measurements of blood flow behind the knee, suggesting the technology is capturing meaningful information about local blood vessel function.
This research suggests that NIRS has potential as a tool for assessing blood vessel health in people with advanced kidney disease, but that important practical barriers exist — particularly for patients with the most severe vascular disease. Future work would be needed to refine the technique to improve both the proportion of patients who can tolerate the test and the clarity of results before it could be widely used for early PAD detection in CKD patients.
Bok E, Wiebe N, Nelson M, Stickland M, Bello A, Braam B, et al.. (2026). Microvascular dysfunction in chronic kidney disease: A feasibility study.. Clinical physiology and functional imaging. https://doi.org/10.1111/cpf.70092