The laser Doppler assessment of sternal wound microcirculation in patients undergoing cardiac surgery
Creators: name: Bhaskaran, Premjithlal
Publisher: name: Imperial College London
Year: 2017

description: Background: Cardiac surgical procedures such as a coronary artery bypass graft (CABG) and aortic valve replacement (AVR) surgeries with a cardiopulmonary bypass (CPB) which can lead to a spectrum of post-operative complications mainly as a result of delayed sternal wound healing and activation of systemic inflammatory responses. Delayed wound healing is secondary to a reduced regional blood flow, systemic diseases, poor surgical techniques and many other reasons can lead to sternal wound dehiscence and infection. Diabetic mellitus (DM) is a major metabolic disease, involving most of the systems of the body. One of the long-term consequences of DM is pathological changes of macro and microcirculation that causes narrowing of vasculature and reduced response to hormonal and neurological stimulation to control the rate of regional perfusion. Aim: This study is to establish the role and significance of the laser Doppler scanner in the sternal wound healing in patients undergoing cardiac surgery such as CABG and AVR. Reduced sternal perfusion follows cardiac surgery secondary to progression of DM uses of left internal mammary artery as a bypass graft. The laser Doppler can be used as a diagnostic and prognostic tool to forecast and predict the disease process of delayed wound healing and sequalae of consequences. Method: 60 patients of CABG and AVR were selected fulfilling the inclusion and exclusion criteria equally divided into diabetic and non-diabetic. The sternal area of interest was scanned using the laser Doppler scanner at 5 time point readings such as preoperatively, 24 hours postoperatively, 48 hours postoperatively and 72 hours postoperatively.Results: Patients undergoing CABG with use of left internal mammary artery, the perfusion on the left lateral aspect of sternal incision mirroring the left internal mammary artery harvests sites in diabetic and non-diabetic patients. There was a statistically significant difference (P &lt;0.05) in skin perfusion in mean area studied on both sides and in both diabetic and non-diabetic patients. Importantly both groups showed lower perfusion on the left side. Diabetic patients had a more pronounced drop in perfusion on the left side compared to the right side, however by 72 hours skin perfusion was near normal in both diabetic and non-diabetic patients. The difference in skin perfusion between diabetic and non-diabetic patients was present throughout all the time points studied and pre-operative measurements returned to near normal at last time point studied. (T1 – pre-operative, T5 – 72 hours post-operative and P = 0.30). One of the non-diabetic patients showed delayed perfusion and treated with surgical debridement, VAC pump and antibiotics. Patients undergoing aortic valve replacement surgery showed similar perfusion bilaterally due to absence of left internal mammary artery harvest sites in diabetic and non-diabetic patients. There was a statistically significant difference (P &lt;0.05) in skin perfusion in mean area studied on both sides and in both diabetic and non-diabetic patients and this difference was present throughout all the time points studied. There was no difference as expected between left and right side in diabetic and non-diabetic patients undergoing valvular heart surgery due to absence of left internal mammary artery harvest. The difference in skin perfusion between diabetic and non-diabetic patients was present throughout all the time points studied and pre-operative measurements returned to near normal at last time point studied. (T1 – pre-operative, T5 – 72 hours post-operative and P = 1.0). There was a delayed sternal perfusion on the left side of the sternum in one of the diabetic patient. He suffered from wound infection and treated responded to antibiotics. Conclusion: LDF of sternal wound can be used as a diagnostic and prognostic tool in patients undergoing open cardiac surgery to predict the outcome and management.