Near-Infrared Spectroscopy-Guided Selective Distal Perfusion in Femoral Venoarterial Extracorporeal Membrane Oxygenation: A Feasibility Study

Background/Objectives: We evaluated the feasibility of a near-infrared spectroscopy (NIRS)-guided selective strategy based on a single absolute regional tissue oxygen saturation (rSO2) threshold and described clinically overt limb ischemia. Methods: This single-center retrospective study included 110 adults receiving femoral venoarterial extracorporeal membrane oxygenation between April 2020 and December 2024. All underwent bilateral lower-extremity NIRS monitoring. In 83 patients, distal perfusion catheter (DPC) placement was triggered by rSO2 < 40% in the cannulated limb or clinically evident limb ischemia; 27 received routine prophylactic DPC placement at cannulation. Primary endpoints were DPC avoidance and clinically overt limb ischemia. Results: Extracorporeal cardiopulmonary resuscitation (ECPR) accounted for 64.5% of patients. Under the selective strategy, 45/83 patients (54.2%; exact 95% CI, 42.9–65.2%) avoided DPC placement, with no clinically overt limb ischemia (0/45; exact 95% CI, 0–7.9%). Limb ischemia occurred in 2/83 versus 2/27 patients (2.4% versus 7.4%; risk difference, −5.0 percentage points; 95% CI, −21.1 to +3.0; p = 0.252). Because threshold crossing triggered DPC placement, the reported threshold characteristics reflect the operation of the management protocol rather than independent diagnostic accuracy. Conclusions: A single-threshold NIRS-guided selective strategy was feasible in this ECPR-dominant population, allowing just over half of patients to avoid prophylactic DPC placement. No clinically overt limb ischemia was observed in this subgroup, but the upper 95% confidence limit of 7.9% precludes a definitive safety conclusion. Prospective studies are needed to assess limb ischemia risk and refine selection criteria.