Near-infrared spectroscopy for noninvasive evaluation of chest wall ischemia immediately after left internal thoracic artery harvesting

Objective. The conclusions remain controversial about whether the sternal blood flow is preserved or diminished after internal thoracic artery (ITA) harvesting for coronary artery bypass grafting (CABG), especially in diabetic patients. We investigated the blood supply of the chest wall noninvasively using near-infrared spectroscopy (NIRS) immediately after CABG. Methods. The study group comprised 30 patients who underwent CABG using a skeletonized left ITA through median sternotomy. As a control group, three nondiabetic patients undergoing valve surgery through median sternotomy were also included. On arrival of the patient in the intensive care unit immediately after surgery, two reflectance sensors were placed on the bilateral parasternal regions at the fourth intercostal space to record regional oxygen saturation (rSO₂) and hemoglobin index (HbI) continuously approximately for 17 h. Results. The differences in right and left values (R-L rSO₂ and R-L HbI) were significantly greater in the diabetic patients than in the nondiabetic patients (3.74% ± 2.47% vs. 1.98% ± 1.67 %, p = 0.036; and 0.28 ± 0.19 vs. 0.13 ± 0.13, p = 0.020). The R-L HbI was significantly greater in the on-pump patients than in the off-pump patients, although there was no significant difference in R-L rSO₂. Both R-L rSO₂ and R-L HbI were similar among the control, nondiabetic, and off-pump patients. Conclusion. The technique of NIRS enables noninvasive, continuous monitoring of chest wall perfusion immediately after ITA harvesting. Our study using NIRS showed a decrease in blood flow and oxygen metabolism of the hemisternum after LITA harvest in diabetic CABG patients.