• Martin Andreas, Markus Zeitlinger, Martina Hoeferl, Walter Jaeger, Daniel Zimpfer, Joerg-Michael Hiesmayr, Guenther Laufer, and Doris Hutschala.
• Department of Cardiac Surgery, Medical University of Vienna, Vienna, Austria.
• Ann. Thorac. Surg. 2013 Apr 1; 95 (4): 1323-9; discussion 1329-30.

BackgroundInternal mammary artery (IMA) harvesting for coronary artery bypass grafting (CABG) influences tissue perfusion and represents a risk factor for deep sternal wound infection (DSWI). Cephalosporins are routinely administered for prophylaxis during cardiac operations to decrease perioperative wound infections. We hypothesized that mammary artery preparation impairs antibiotic penetration into presternal tissue during CABG.MethodsEight patients undergoing skeletonized left mammary artery harvesting for CABG were included. Standard antibiotic prophylaxis was administered: 4 g of cefazolin before skin incision and an additional 2 g during skin closure. Concentrations of cefazolin were measured in subcutaneous tissue on the presternal right and left sides (surgically affected) after sternotomy and additionally in subcutaneous tissue on the thigh (surgically unaffected) by microdialysis over a 10-hour period.ResultsMean peak tissue concentration and the area under the curve (AUC) on the left sternal side were significantly reduced compared with the right side and compared with the thigh (mean peak concentration, 13.1±5.8 versus 24.1±4.7 and 27.8±9.7 μg/mL; p=0.005 and p=0.013; AUC 74.2±31.0 versus 110.4±25.0 and 140.3±46.3 μg×hours per milliliter; p=0.004 and p=0.002). Mean subcutaneous concentrations of cefazolin on the left sternal side exceeded the minimal inhibitory concentration (MIC90) of Staphylococcus epidermidis of 4 μg/mL in only 5 of 8 (37.5%) patients after 5 hours.ConclusionsIMA harvesting significantly impairs local antibiotic penetration during CABG. Common antibiotic dosing schemas should be reevaluated in this cardiac surgical setting.Copyright © 2013 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

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