Intraoperative evaluation of revascularization effect on ischemic muscle hemodynamics using near-infrared diffuse optical spectroscopies.

Arterial revascularization in patients with peripheral arterial disease (PAD) reestablishes large arterial blood supply to the ischemic muscles in lower extremities via bypass grafts or percutaneous transluminal angioplasty (PTA). Currently no gold standard is available for assessment of revascularization effects in lower extremity muscles. This study tests a novel near-infrared diffuse correlation spectroscopy flow-oximeter for monitoring of blood flow and oxygenation changes in medial gastrocnemius (calf) muscles during arterial revascularization. Twelve limbs with PAD undergoing revascularization were measured using a sterilized fiber-optic probe taped on top of the calf muscle. The optical measurement demonstrated sensitivity to dynamic physiological events, such as arterial clamping/releasing during bypass graft and balloon inflation/deflation during PTA. Significant elevations in calf muscle blood flow were observed after revascularization in patients with bypass graft (+48.1 ± 17.5%) and patients with PTA (+43.2 ± 11.0%), whereas acute post-revascularization effects in muscle oxygenation were not evident. The decoupling of flow and oxygenation after revascularization emphasizes the need for simultaneous measurement of both parameters. The acute elevations/improvements in calf muscle blood flow were associated with significant improvements in symptoms and functions. In total, the investigation corroborates potential of the optical methods for objectively assessing the success of arterial revascularization.