NEAR-INFRARED SPECTROSCOPY FOR MONITORING DISTAL LIMB PERFUSION DURING PEDIATRIC MINIMAL INVASIVE CARDIAC SURGERY FOR CONGENITAL HEART DEFECTS

Abstract

Introduction Acute femoral artery occlusion due to remote access bypass (femoral arterial cannulation), is a routine for pediatric minimal invasive cardiac surgery and prevention of leg ischemia is necessary. This technique requires peripheral vessel cross clamping, which may lead to transient perfusion deficit of the lower extremities.Strategies to prevent muscle necrosis or development of compartment syndrome include invasive or non-invasive monitoring of tissue oxygen saturation of involved extremity. A variety of means are utilized, to assess lower extremity (LE) perfusion – including pulse palpation, pulse oximetry, subjective assessment of LE by colour, temperature etc. Regional oxygen saturation measured by near-infrared spectroscopy (NIRS), used as a potential surrogate of cerebral and somatic mixed venous oxygen saturation-is a noninvasive tool to continuously monitor LE perfusion. We sought to evaluate the safety of peripheral arterial cannulation by using NIRS in such subset of patients. Methods We evaluated 50 pediatric patients, weight 10-30kg, age 3-12years, divided in: Group A (N=25), - underwent peripheral femoral artery cannulation for remote access perfusion for MICS, group B (N=25), receive conventional sternotomy incision. All patients were monitored by transcutaneous NIRS (placed on calves of both legs) for quality control of distal leg perfusion during cardiopulmonary bypass. Baseline NIRS value, followed by continuous NIRS values were recorded. Total creatinine kinase (CK) and serum myoglobin levels, mid-thigh and mid -calf circumference (to rule out compartment syndrome), were measured at preoperatively, 6hour and 24hour after surgery. Intra-operatively, all hemodynamic parameters along with blood gas parameters like PH, PO2, PCO2, SCVO2, lactate etc. were recorded at baseline, on bypass, clamp on, clamp off and off bypass period. Total CPB time, ventilation duration, hospital and ICU stay were also recorded. Results The baseline NIRS comparable in group A (72.6±6.86) over cannulated versus (71.76±4.05), contralateral leg, while, in group B, it was (69.96±5.75 vs.69.84±5.50). During clamping of femoral artery in Group A, NIRS dropped to 39.12±5.60 (vs. baseline), while it remained stable in the contralateral leg and group B patients. After successful implantation of the distal leg perfusion, the NIRS normalized to baseline within 5 to 7 minutes. Myoglobin and CK levels increased in both the groups, more so in Group A. There were no clinical side effects from increased CK or myoglobin. None of our patients had residual vascular complications. ±±±± Discussion We speculate that remote CPB with direct femoral artery cannulation can be safely used in pediatric patients- with a body weight 10-30 kg and CPB time less than 60 minutes- without increasing operative morbidity and complications. When prolonged CPB time is expected probably one should change the MICS policy by adding selective distal leg perfusion to minimize the complications