The effects of intrathecal Bupivacaine plus general anesthesia on stress hormones in Coronary Artery Bypass Grafting

Activation of stress response during cardiac surgeries such as cardiopulmonary bypass (CPB) can increase myocardial oxygen demand and consumption through induced tachycardia and augmented peripheral vascular resistance. These physiologic consequences may lead to increased morbidity and mortality by putting too great a strain on the already compromised organ systems. Materials and Methods: This controlled trial study was conducted to evaluate the effect of intrathecal bupivacaine plus general anesthesia on stress response in patients undergoing open heart surgery. Methods In this case, thirty patients undergoing open heart surgery were randomly assigned to receive either intravenous opioid [control group (n=15)] or intravenous opioid plus intrathecal bupivacaine [ITB group (n=15)]. Arterial blood samples were obtained from each patient at five predetermined times to measure plasma levels of norepinephrine and epinephrine and cortisol including: Immediately prior to spinal anesthesia; 5 min after sternotomy; 30 min after initiation of cardiopulmonary bypass (CPB); 30 min after separation from CPB; and 4 hours after separation from CPB. Results: Administration of intrathecal bupivacaine plus general anesthesia significantly decreased plasma levels of cortisol, adrenalin and noradrenaline in treatment group as compared with control group at 5 min after sternotomy and 30 min after CPB starting and 4 hour after CPB ending, respectively. Conclusion: the findings showed the application of intrathecal bupivacaine to patients undergoing open heart surgery significantly decreases plasma levels of stress hormones.