Influence of Vasoactive Infusions on Body Temperature During Off Pump Coronary Artery Bypass Grafting

Introduction Unintentional hypothermia in patients undergoing off pump coronary artery bypass grafting (OPCABG) under general anesthesia (GA) is a known complication. The wide sternotomy wound as well as low ambient operating room temperature further promotes heat loss. The changes in temperature could further be affected by the use of various vasoactive drugs by affecting the thermoregulatory response. This study is aimed to detect the temperature changes and the influence of vasoactive infusions on the temperature in the patients undergoing OPCABG under GA. Aims The main purpose of this article is to assess the core and skin temperature changes during OPCABG surgery and to assess the effect of vasoactive infusion used intraoperatively on the core temperature Settings and Design Single center, nonrandomized, open label, observational study. Methods and material After informed consent and ethical clearance from institutional review board, 151 adult patients undergoing elective OPCABG surgeries under GA were included in the study. A common anesthetic protocol and warming strategy was used in all patients. The core temperature measured with a nasopharyngeal probe and the skin temperature measured at the palmar surface of the right index finger were recorded at induction, at 30 minutes intervals thereafter, and at end surgery. The demographic variables and the duration of surgery were also recorded. The type and dose of vasoactive agents used intraoperatively were also recorded. The study population was divided post hoc into groups and subgroups for further analysis. Results All the patients showed a decrease in core temperature at end surgery. The temperature changes showed an initial exponential decrease in the first hour followed by a gradual decrease subsequently. The peripheral temperature showed a gradual increase from induction to end surgery. The temperature gradients showed a linear decrease with the core temperature and peripheral skin temperature reaching equilibrium at end surgery. The study population was divided into four groups depending on the type of vasoactive drugs received intraoperatively: vasoconstrictor (V), vasodilator (D), mixed vasoconstrictor and vasodilator (M), and no vasoactive drugs (N) group. The patients in the vasoconstrictor group had a higher core temperature at end surgery when compared with vasodilator group. Conclusions OPCABG under GA results in decrease in core temperature. The decrease in temperature is exponential in the initial 1 hour followed by a more gradual decrease. The temperature changes are possibly affected by the vasoactive drugs used intraoperatively. The effect of vasoactive drugs on core temperature is higher when used during the initial exponential decrease in temperature. However, further adequately powered randomized controlled trials may be required to establish these findings.