Effects of Anesthetic Induction Methods in Open Heart Surgery on Unconsciousness and Cardiovascular Response

Lee, Bong Jae; Kim, Keon Sik; Choi, Young Kyoo; Kwon, Moo Il

Abstract

Rapid induction,complete loss of conciousness,and stability of cardiovascular system are the variables that should be considered in choosing anesthetics and method of induction for patients with cardiovascular diseases. The great attention should be given because elevation of blood pressure and tachycardia during induction of anesthesia can deteriorate patients cardiovascular system. High-dose of fentanyl was used for the induction of open heart surgery since 1978 and showed effectiveness in stabilizing cardiovascular changes. Many authors argued that fentanyl may not induce unconciousness. As endeavor to shorten the oneset time of unconsciousness, commonly used intravenous anesthetics with fentanyl were tried. Among patients scheduled for open heart surgery, 30 patients with ejection fraction higher than 0.5 were randomly selected and divided into three groups. For the induction of anesthesia, group 1 was given fentanyl alone; group 2 fentanyl with diazepam(0.1mg/kg); and group 3 fentanyl with thiopental sodium (0.2mg/kg). Loss of conciousness (oneset time of unconciousness and dosage of fentanyl) and cardiovascular responses(systolic blood pressure, diastolic blood pressure, mean arterial pressure, heart rate, and rate pressure product) just before induction,before intubation, and immediately after intubation were compared and results were as followes. l. It took 322 seconds to induce unconciousness in group 1, 213 seconds in group 2,and 87 seconds in group 3. It was shortened significantly in group 2 and group 3 as compared to group 1 and in group 3 as compared to group 2(p<0.05). 2. Dosage of fentanyl was 30 mcg/kg in group 1, 20 mcg/kg in group 2, and 8 mcg/kg in group 3. As compared to group 1 and group 2, it was significantly decreased in group 3 (p<0.05). 3. Systolic blood pressures before tracheal intubation in gmup 2 and group 3 significantly decreased as compared to the level of preinduction(p<0.05), 4. Diastolic blood pressure before tracheal intubation in group 3 significantly decreased as compared to the level of preinduction(p<0.05). 5. Mean arterial blood pressure before tracheal intubation in group 2 and group 3 significantly decreased as compared to the level of preinduction(p<0.05). 6. There was no significant change in heart rate. 7. Rate pressure product before tracheal intubation in group 3 significantly decreased as compared to the level of preinduction and rate pressure product after tracheal intubation in group 1 significantly increased as compared to the level of preinduction(p<0.05). Considering above results, it is difficult to choose specific anesthetics and methods for the induction of open heart surgery. It depend on the patients cardiovascular function and physicians experience and their preference. Meticulous observation and continuous monitoring of cardiovascular response are very important when intravenous anesthetics are used with fentanyl.