The effectiveness of NIRS technology to the early diagnosis of lower limb ischemia in patients on peripheral VA ECMO: a systematic review and meta-analysis

Background: Acute lower limb ischemia is a major complication of peripheral venoarterial ECMO, significantly impacting patient outcomes and survival rates. Traditional methods for assessing limb perfusion, such as physical exams and Doppler ultrasound, are often unreliable and do not provide continuous monitoring. Near-infrared spectroscopy (NIRS), a non-invasive technique, shows promise for perfusion monitoring in venoarterial ECMO patients, but its effectiveness in the early detection of limb hypoperfusion remains unreviewed. Aim: Evaluate the effectiveness of NIRS technology in the early diagnosis of lower limb ischemia in patients undergoing peripheral VA ECMO. Methods: The search strategy covered five databases. Inclusion criteria included studies in Portuguese, English, Spanish, or German involving participants aged 18 or older dependent on peripheral VA ECMO. The intervention assessed was limb perfusion monitoring using NIRS in VA ECMO patients. The primary outcome was the effectiveness of NIRS in the early diagnosis of limb ischemia. Exclusion criteria included review articles, book chapters, books, editorials, conference papers, and studies on pediatric patients, central VA ECMO, or venovenous ECMO. Study quality was evaluated using the ROBINS-I tool. Meta-analysis was performed using R package meta. Narrative synthesis was applied when meta-analysis was unfeasible. Results: Of 180 studies, 164 were excluded after initial screening. Of the remaining 16 studies, eight were removed for irrelevance, high bias risk, or pediatric focus, leaving eight studies. The results revealed a pooled sensitivity of the diagnostic method of 0.71 (95% CI: [0.67, 0.74]) and a pooled specificity of 0.68 (95% CI: [0.61, 0.74]). Conclusions: NIRS technology is an effective diagnostic tool for reliably detecting true positive cases of limb ischemia. Implications for Clinical Practice: The decrease in NIRS values and the difference between limbs may indicate hypoperfusion, requiring further investigation. NIRS also helps assess distal perfusion catheter functionality, enhancing our ability to provide safe, high-quality care.