Detecting Mitochondrial Oxygen Tension as a Measure of Local Tissue Oxygenation in Patients With Peripheral Arterial Disease Before and After Endovascular Therapy

INTRODUCTION: Assessment of mitochondrial oxygen tension (mitoPO 2) is a novel technique for measuring skin perfusion. It is based on the oxygen-dependent quenching of delayed fluorescence of 5-aminolevulinic acid (5-ALA), known as the protoporphyrin IX-triple state lifetime technique. This study aimed to determine the tolerability and feasibility of measuring mitoPO 2 in the lower limbs of patients with peripheral arterial disease (PAD) undergoing endovascular therapy. In addition, the study investigated the changes in mitoPO 2 pre- and postoperatively.

MATERIALS AND METHODS: This prospective single-center study included patients with Rutherford stage 4 to 6 scheduled for endovascular therapy. Plasters containing 5-ALA were placed over the tibia and at the lower lateral leg 12 hours before the operation. 5-ALA tolerability was assessed by noting the occurrence of related side effects during application, measurements, and in the 48 hours after removal of the plaster. MitoPO 2 was measured immediately before and after the operation over the tibia at the anterior tibialis muscle and the lateral side of the lower leg, and was followed by transcutaneous oxygen pressure and ankle-brachial index measurements.

RESULTS: Ten patients were included in this study. No side effects or adverse events related to 5-ALA were observed. One patient reported weak itching within 48 hours after removing the 5-ALA plaster. MitoPO 2 measurements were feasible in all patients at the tibia and lower leg, but were not feasible on the dorsum of the foot. Postoperatively, a significant drop in mitoPO 2 was detected at the tibia. No significant difference was found in mitoPO 2 levels pre- and postoperative at the lower lateral leg. For transcutaneous oxygen pressure, no significant differences were detected postoperatively.

CONCLUSIONS: 5-ALA is tolerable and safe in patients with PAD. MitPO 2 measurements at the tibia and lower lateral leg are feasible and capable of detecting changes in perfusion following endovascular therapy. Further research is needed with larger cohorts and longer follow-up to investigate the relationship between mitoPO 2, oxygen supply, and tissue regeneration.Clinical ImpactThis study demonstrated the feasibility and safety of mitochondrial oxygen tension (mitoPO 2) measurement using 5-aminolevulinic acid (5-ALA) for assessing local skin perfusion in patients with peripheral arterial disease (PAD) undergoing endovascular therapy. Changes in mitoPO 2 post-intervention suggest sensitivity to real-time microvascular and physiological alterations. This technique could potenitally improve overall patient outcomes and wound healing by enhancing patient stratification, treatment planning, perioperative monitoring, and postoperative follow-up.