The Clinical Study for Cardiovascular Responses and Awareness during Fentanyl - Diazepam - O2 Anesthesia for Open Heart Surgery

Jeon, Yong Joon; Kim, Keon Sik; Kwon, Moo Il

Abstract

Fentanyl-O2 anesthesia has gained wide popularity as an anesthetic technique for patients undergoing cardiac surgery because of its minimal cardiovascular effects and total amnesia for intraoperative events. But, some authors recently reported intraoperative awareness and the excessive cardiovascular response to surgical stimulation during high dose fentanyl-oxygen anesthesia far cardiac operation and suggested the necessity of supplementary anesthetic agent in addition to fentanyl to prevent the intraoperative awareness and maintain hemodynamic stability during the surgical procedure. A variety of supplementary drugs have been used in combination with the opioids in an effort to reduce the incidence of awareness, to control hypertension, and to attenuate the extent of postoperative respiratory depression. One of supplementary drugs, diazepam has little cardiovascular effects by itself, but causes significant depression of arterial blood pressure and cardiac output when given to patients who have received fentanyl or morphine. We measured the heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and rate pressure product (RPP) at induction, tracheal intubation, skin incision, and sternotomy time to evaluate the effects of the diazepam on reduction of the excessive cardiovascular response to anesthetic and surgical stimulation and observed the presence of the intraoperative awareness, under fentantyl-diazepam-O2 anesthesia for open heart surgery on 12 patients with cardiac disease. Anesthesia was induced with fentanyl 20 ug/kg + diazepam 0.1 mg/kg and maintained with continuous infusion of fentanyl (1.5 ug/kg/min. prior to sternotomy and 0.3 ug/kg/min. until the end of cardiopulmonary bypass) and diazepam 0.1 mg/kg was injected just before sternotomy and at the end of cardiopulmonary bypass. The patients required the total dose of fentanyl 76+13.1 ug/kg and diazepam 0.3 mg/kg for the entire operation. These measurements were compared with control data (before induction). The results were as followings: 1)During induction period (infusion of fentanyl 20 ug/kg with diazepam 0.1 mg/kg); HR, SBP, DBP, and MAP slightly decreased compared with control data, but there were not statistically significant. RPP decreased significantly from 15898+/-5099 torr. beatsmin. to 12371+/-2407 torr. beatsmin. and there was statistical significance (p<0.05). 2) During intubation and skin incision; HR, SBP, DBP, MAP and RPP revealed no significant change compared with control data. 3) During sternotomy; HR, SBP, DBP, MAP, and RPP slightly increased, but there were not statistically significant. 4) There was no patient who had the recall or awareness for intraoperative events. 5) Duration of controlled or assisted ventilatory support. postoperatively, was 216+/-36 min. These results suggest that fentanyl-diazepam-O2 anesthesia might be more useful than fentanyl-O2 anesthesia for prevention of intraoperative awareness and attenuation of excessive cardiovascular response during open heart surgery. But, continuous and careful monitoring for hemodynamic changes of patients will be needed necessarily to prevent the significant depression of arterial blood pressure and cardiac output throughout the entire operative procedures.