The Influence of Hypothermia on Transfusion Requirement in Patients Who Received Clopidogrel in Proximity to Off-Pump Coronary Bypass Surgery

PURPOSE: Hypothermia adversely affects the coagulation that could be of clinical significance in patients receiving clopidogrel. We evaluated the influence of hypothermia on transfusion requirements in patients undergoing isolated off-pump coronary artery bypass surgery (OPCAB) who continued clopidogrel use within 5 days of surgery. MATERIALS AND METHODS: Protocol-based, prospectively entered data of 369 patients were retrospectively reviewed. The time-weighted average of intraoperative temperatures and the temperature upon ICU admission (TWA-temp) was assessed. Patients were divided into normothermia (> or =36degrees C, n=224) and hypothermia (<36degrees C, n=145) group. The transfusion requirement for perioperative blood loss was assessed and compared. RESULTS: Patients with hypothermia were older and had lower body surface area (BSA) than patients with normothermia. Age and BSA adjusted transfusion requirement was significantly larger in the hypothermia group [patients requiring transfusion: 64% versus 48%, p=0.003; number of units: 0 (0-2) units versus 2 (0-3) units, p=0.002]. In multivariate analysis of predictors of perioperative multiple transfusion requirements, hypothermia was identified as an independent risk factor along with age, female gender, BSA, chronic kidney disease, and congestive heart failure. CONCLUSION: Hypothermia was associated with increased transfusion requirement in patients undergoing OPCAB who received clopidogrel in proximity to surgery. Considering the high prevalence and the possibility of hypothermia being a modifiable risk factor, aggressive measures should be undertaken to maintain normothermia in those patients.

The Impact of the Preoperative Severity of Target-Vessel Stenosis on the Short-Term Patency of Radial Artery Grafts

The fate of a grafted radial artery remains unknown. The purpose of this study was to determine whether the preoperative severity of stenosis of the target vessel influence short-term patency of radial artery (RA) grafts used as coronary artery bypass conduits. In 54 patients who had coronary artery bypass grafting (CABG) with RA grafts, RA patency was determined with multi-slice computed tomography (MSCT) 1 year after CABG. These patients were divided into three groups on the basis of the percentage of the target vessel stenosis: mild ( or = 80%, n=18). MSCT was also performed 1 week later to exclude early occlusion of RA grafts. In 3 patients, the MSCT failed to adequately discriminate the status of the RA graft due to poor image resolution. The overall incidence of RA occlusion was 23.5% (12 of 51) at 1 year in the entire population. The mild stenosis, moderate stenosis and severe stenosis group showed an occlusion rate of 50% (8 of 16), 23.5% (4 of 17) and 0% (0 of 18), respectively. The severe stenosis group had significantly lower rate of RA graft occlusion compared to the mild stenosis group (p< 0.001) and moderate stenosis group (p< 0.05). No difference in occlusion between grafts used for the different coronary artery branches could be demonstrated. Preoperative severity of the target coronary artery significantly affected the short-term RA grafts patency. Correct indication is the key factor for short-term RA patency.