The evaluation of prevalence of poor distal leg perfusion in totally endoscopic cardiac surgeries: a cohort study

Introduction To ensure patient safety during Totally Endoscopic Cardiac Surgeries (TECS), patients are peripherally cannulated for coupling to the Cardiopulmonary Bypass (CPB) (1). Despite its necessity, the cannulated leg might experience clinically relevant ischemia (CRI), defined as a minimum of 15% Tissue Oxygenation Index (TOI) drop, lasting at least 4 minutes, possibly leading to poor peri- and postoperative clinical outcomes (2). TOI-values were assessed using non-invasive, Near-Infrared Spectroscopy (NIRS; 200NX-NIRO, Hamamatsu®, Japan) measurements of the skin covering the ipsilateral calf muscles. NIRS enables the quantification of the TOI, based on the difference in light absorption between oxygenated en deoxygenated haemoglobin molecules. The 200NX-NIRO has shown great sensitivity and specificity in the clinical setting (3-5). The objective was to evaluate the prevalence of poor distal leg perfusion related to short-term, peri-operative, CPB-time, since these data remain largerly unknown. Methods All consecutive patients 18 years or older, and scheduled for a TECS-based valve surgery (YIL AVR and/or MVATS), coronary surgery (ENDO ACAB or ENDO CABG), or a combination were included. Perioperative TOI-values were assessed at: baseline (B) = 5 minutes before insertion of the femoral arterial cannula (FAC); Event 1 (E1) = insertion of the FAC; Event 2 (E2) = onset of CPB; Event 3 (E3) = offset of CPB; Event 4 (E4) = removal of the FAC. Results 116 patients were included for statistical analysis. Differences between TOI-values were analysed using Wilcoxon signed rank tests. CRI in the cannulated leg was demonstrated in 18,80% (n = 22) of all cases, and showed significantly lower TOI-values for all events (E1, E2, E3 and E4) compared to the baseline TOI-value (Figure 1): p Discussion Although not all patients showed CRI in the cannulated leg, some degree of hypoperfusion was demonstrated over all cannulated legs. However, these are interim results and thus, further research regarding postoperative follow-up is necessary and might offer insights on how to prevent or prematurely treat ischemia and/or ischemia-related complications in the subclinical stage.