A Dynamic Objective Evaluation of Peripheral Arterial Disease by Near-Infrared Spectroscopy

Objectives: Near-Infrared Spectroscopy (NIRS), suitable for dynamic measurements, is not routinely used for peripheral arterial disease (PAD). We propose a dynamic NIRS-based measurement to quantify variations in muscle metabolism in PAD. Method: Sixty-seven consecutive PAD patients (males = 56, age 71.6 +/- 8.7 years) and 28 healthy subjects (males = 12, age 30.4 +/- 11.9 years) were studied. An echo-colour Doppler (ECD) was performed and the ankle-brachial index (ABI) was calculated. Participants performed an incremental treadmill test with NIRS probes on the gastrocnemius. Variations in oxygenated (HbO(2)), deoxygenated (HHb), total (tHb = HbO(2) + HHb), and differential (dHb = HbO(2) - HHb) haemoglobin were recorded and quantified as area-under-curve (AUC) within the range 1.7-3.0 km h(-1). Heart rate was recorded, and the number of beats in the same interval was calculated (dHr). Results: O(2)Hb(AUC), HHb(AUC) and dHb(AUC) differed between diseased and non-diseased legs (P < 0.0001) and exhibited different patterns related to PAD severity according to the ABI value. A compensatory heart rate increase was observed in PAD patients. Compared with the ECD positivity for occlusions/stenoses or multiple plaques, only the receiver-operating characteristic (ROC) analysis of dHb(AUC) (area = 0.932, P < 0.0001) showed a sensitivity/specificity of 87.6/93.4 for values <=-197 (LR + LR-: 13.36/0.13). Conclusion: The dynamic NIRS-based test, quantifying muscle metabolic response according to presence and degree of PAD, allows the evaluation of patients with walking disabilities. (c) 2009 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.