Capillary refill time and tissue oxygen saturation as factors influencing lower limb ischemia in VA-ECMO: a case-control study.

BACKGROUND AND OBJECTIVES

Venous-Arterial Extracorporeal Membrane Oxygenation (VA-ECMO) is a pivotal means for rapid cardiopulmonary support, yet it may result in lower limb ischemia. This study aims to explore the high-risk factors for lower limb ischemia following VA-ECMO.

METHODS

117 patients who received VA-ECMO treatment at Guangxi Zhuang Autonomous Region People's Hospital from June 2022 to December 2023 were divided into lower limb ischemia group and non ischemia group for case-control analysis.

RESULTS

In this case-control study of 117 VA-ECMO patients, 22 (18.80%) experienced lower limb ischemia. Patients with ischemia had significantly lower body surface area (BSA) and lower tissue oxygen saturation (StO) levels, but higher capillary refill time (CRT) levels compared to those without ischemia (P < 0.05). Spearman correlation analysis showed that StO and CRT had strong correlations with ischemia. Binary logistic stepwise regression analysis identified CRT and StO as independent risk factors for lower limb ischemia. Specifically, lower StO levels were associated with an increased risk of ischemia (OR = 0.615, P < 0.05), while higher CRT levels were also associated with an increased risk (OR = 27.571, P < 0.05). The Receiver Operating Characteristic (ROC) curve shows that the areas of CRT and StO are 0.924 (P < 0.001, 95% CI 0.866-0.983) and 0.951 (P = 0.023, 95% CI 0.906-0.997), respectively.

CONCLUSIONS

StO reflects real-time tissue perfusion adequacy, whereas CRT serves as a marker of microvascular dysfunction. Lower StO levels (indicating impaired oxygenation) and higher CRT levels (suggesting delayed capillary refilling) were independently associated with an increased risk of lower limb ischemia, suggesting that monitoring these parameters may be useful in identifying patients at higher risk for this complication. These findings provide valuable insights for risk stratification and potential intervention strategies in the management of VA-ECMO patients.