Lowest core body temperature and adverse outcomes associated with coronary artery bypass surgery

Abstract

To examine the effect of lowest core body temperature on adverse outcomes associated with coronary artery bypass graft (CABG) surgery, data were collected on 7134 isolated CABG procedures carried out in New England from 1997 to 2000. Excluded from the analysis were patients with pump times <60 and >120 min and those operated upon using continuous warm cardioplegia. Data for lowest core temperature were divided into quartiles for analysis (≤31.4°C, 31.5-33.1°C, 33.2-34.3°C, and ≥34.4°C).

Patients with lower core body temperature on cardio-pulmonary bypass (CPB) had higher in-hospital mortality rates. Crude mortality rates were 2.9% in the ≤31.4°C group, 2.1% in the 31.5 - 33.1°C group, 1.3% in the 33.2 - 34.3°C group and 1.2% in the ≥34.4°C group. The trend toward higher mortality as core temperature decreased was statistically significant (p_trend<0.001). Adjustment for differences in patient and disease characteristics did not significantly change the results and the test of trend remained significant (p<0.001).

Rates of perioperative stroke were somewhat lower in the colder groups. Rates in the two colder groups were0.9% compared with 1.6% and 1.4% in the warmer groups (p_trend = 0.082). This remained a marginal but significant trend after adjustment for possible confounding factors (p=0.044).

Low core body temperatures on CPB are associated with higher rates of in-hospital mortality among isolated CABG patients. Rates of intra- or postoperative use of an intra-aortic balloon pump are also higher with lower core temperatures. We concluded that temperature management strategy during CABG surgery has an important effect on patient outcomes.