| ST-Segment Displacement during Isoflurane and Enflurane Anesthesia. |
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Soo Il Lee |
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Department of Anesthesiology, College of Medicine, Dong-A University, Pusan, Korea. |
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| Abstract |
BACKGROUND
Isoflurane and enflurane have different activity on the cytoplasmic calcium movements of a cardiac muscle cell and a vascular smooth muscle cell. Isoflurane is less depressive in cardiac contraction, and more potent in vasodilation than enflurane. This study is to elucidate the effects of these anesthetics on the ST-segment displacement.
METHODS
The anesthesia was induced by the intravenous injection of thiopental (6 mg.kg 1) and pipecuronium (0.1 mg.kg 1). The patients (n=80) undergoing tympanoplasty were randomly allocated to two groups for the maintenance METHODS: Group I was inhaled with isoflurane (1~2%), O2 (2 L.min 1), and N2O (2 L.min 1), Group II, enflurane (1.5~2.5%), O2 and N2O. Continuous electrocardiographic recordings with Holter monitor were made during anesthesia.
The recordings were scanned on an Avionics Electrocardioscanner with particular emphasis on ST-segment changes. The criteria describe an episode as ST-segment displacement greater than or equal to 0.1 mV measured 80 ms from J-point lasting for more than 1 minutes. Mean heart rate was calculated. Results were categorized as induction, maintenance, and emergence, and inferred from unpaired t-test, x2-test, and Mann-Whitney U test with p<0.05 considered significant.
RESULTS
Enflurane had higher incidence of ST-segment depression during induction, more maximally depressed ST-segment during maintenance and slower heart rate during induction and maintenance than isoflurane.
CONCLUSION
It could be suggested that enflurane make stronger influence on the ST-segment depression than isoflurane. However, the clinical significance remains to be studied. |
| Key Words:
Anesthetics, volatile: enflurane; isoflurane; Heart, EKG: heart rate; ST-segment depression |
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