Quantificazione degli adattamenti muscolari metabolici attraverso spettroscopia a raggi infrarossi e risposta emodinamica a seguito di un programma riabilitativo di cammino alla massima velocità libera dal dolore nell’arteriopatia periferica

Background: exercise training reduces walking disability in peripheral arterial disease (PAD). Metabolic adaptations induced by rehabilitation programs have been documented by invasive methods. Near infrared spectroscopy (NIRS), potentially useful for the study of non-invasive static and dynamic muscle metabolism, has not yet been used to assess the effects of exercise in PAD. The aim of the present study is to document hemodynamic and metabolic adaptations, by NIRS technique, associated with variations in performance recorded at the end of a program of exercise therapy in PAD prescribed at hospital and carried out at home (Ti.To). Method: 55 PAD patients with claudicatio intermittens (group E) and 15 healthy subject (group C) were enrolled. Evaluation were carried out upon entry (T0) and at 7±2 month (T9). Ankle-brachial index (ABI) and muscle VO2 consumption (mVO2 ) in the gastrocnemius by NIRS, were determined at rest. Participants than performed an incremental treadmill test for determination of pain threshold speed (PTS). Cardiovascular response (dFc), and rate of muscle oxygenation, were determined in a predetermined speed range (1,7-3 km/h) by NIRS, through quantification of variation in oxygenated (O2Hb), deoxygenated (HHb), total (tHb) and differential (dHb) haemoglobin. Group E performed a rehabilitation program (Ti-To) based on 2 daily 10-min home walking session at maximal asymptomatic speed and the patients attending monthly check-ups at hospital. Group C continued to carry out normal daily activities. Results: 42 patients and 15 healthy subjects were studied. All subject in group E completed the Ti- To program. Group C showed no significant changes in hemodynamic and metabolic parameters at the end of the study. At the end of the rehabilitation program group E, while continuing to show different values of outcome parameters than the group C, showed a trend to normalization with a) significantly changes in PTS (p<0.0001) compared with significantly higher values of ABI (p<0.0001) and mVO2 (p=0.0011), b) lower muscle perfusion deficit in dynamic phase for increase of O2HbAUC (p=0.0010) and c) concomitant reduction of cardiovascular response (p=0.0293). At the end of rehabilitation program, compared to the group with significant ABI increase, patient without favorable hemodynamic changes in worse limb showed a dramatic increase in mVO2 and similar functional changes. Conclusion: Ti-To program in PAD leads to functional improvements by means of peripheral adaptations, hemodynamic or muscles, otherwise combined together, with reduction of compensatory cardiovascular response. NIRS measurement, allows to non-invasive study of muscle metabolic useful to evaluate the effects of different rehabilitative training program in PAD.