Clinical Professor and Program Director Stanford University Medical Center Palo Alto , California
Objectives: Chronic limb-threatening ischemia (CLTI) is a severe form of peripheral artery disease associated with high risks of impaired wound healing and limb amputation. Current methods like ABI and TcPO2 are limited in guiding intraoperative revascularization and are limited in patients with calcified arteries or extensive tissue loss. Speckle plethysmography (SPG), used in the Flowmet-D device, offers real-time blood flow measurement by analyzing light scatter from red blood cells. This study evaluates the utility of the Flowmet-D device to predict wound healing and optimize care in CLTI patients undergoing endovascular intervention.
Methods: A prospective pilot study at Stanford Hospital and Advanced Wound Care Center enrolled 50 CLTI patients with non-healing wounds scheduled for revascularization from April 2022 to February 2024. Data on patient demographics, wound dimensions, and hemodynamic parameters were collected. The primary outcome was wound improvement, defined as wound area reduction or epithelialization, with secondary outcomes including re-intervention and major adverse limb events (MALE). The Flowmet-D measured blood flow indices and waveforms before, during, and after revascularization. Data analysis, including ROC curves, Cox proportional hazards, and Kaplan-Meier methods, assessed associations between Flowmet Index changes and outcomes.
Results: Among 50 patients (76% male, 96% with hypertension, 78% with diabetes), 62% showed wound improvement during a mean follow-up of 105 days, and 42% achieved complete healing. Patients with wound improvement had higher post-procedure Flowmet Index values (22.7 vs. 9.22, p < 0.01) and greater changes in Flowmet Index (12.02 vs. 0.52, p < 0.01). A Flowmet Index >9.55 optimally predicted wound improvement (AUC 0.87, HR 6.62, p = 0.01), (Figure 1). A change in Flowmet Index >2.45 predicted reduced risk of re-intervention or amputation (AUC 0.89, HR 0.19, p = 0.02).
Conclusions: TThe Flowmet-D device shows promise in predicting wound healing and reducing adverse outcomes in CLTI patients. A post-procedure Flowmet Index >9.55 and a change ≥2.45 are associated with wound improvement and a reduction in MALE, respectively, offering valuable intraoperative and postoperative guidance for revascularization. Larger multicenter studies are needed to validate its utility and define its role in optimizing CLTI care.
