Combined effect of isoflurane and esmolol on sympathetic responses to tracheal intubation

Abstract

BACKGROUND: Influences of isoflurane and esmolol on endotracheal intubation induced sympathetic changes could be different. The effect of isoflurane and its combination with esmolol on catecholamine, blood pressure and pulse during endotracheal intubation were investigated. METHODS: Thirty patients were anesthetized with 3.0% isoflurane and tracheal intubation was carried out at the 5th min following the exposure to isoflurane. Half of them received intravenous saline and the other half received esmolol 2 mg/kg at the 4th min. Cardiovascular parameters were recorded and venous blood samples were taken for measurement of catecholamines every min. RESULTS: One min after administration of isoflurane, there was increase of heart rate (P < 0.05), while at the same time the epinephrine level fell (P < 0.05) and norepinephrine level remained unaltered. Both catecholamines raised after intubation (P < 0.05). The sympathetic responses to and the beta-antagonistic effect of esmolol on intubation were not significantly changed in the presence of isoflurane. CONCLUSIONS: Isoflurane increased heart rate while paradoxically decreased epinephrine. Norepinephrine was more specifically related to endotracheal intubation, for its serum level had little change before the event. Based on catecholamine findings, the mechanism of isoflurane effect on the sympathetic system is probably different from that of endotracheal intubation.

背景：此實驗測量isoflurane對由氣管插管引起交感神經變化的影響，以及isoflurane與esmolol同時給與時的效果。方法：三十位病人，在用3%isoflurane換氣四分鍾後，注射esmolol或監水，每分鍾測量一次血液兒茶酚胺含量(catecholamine)及血壓與脈搏。結果：在給予isoflurane一分鍾後，脈博升高(P＜0.05)，在此同時，血液腎上腺素減低(P＜0.05)，去甲腎上腺素則無變化。插管後兩種激素皆升高。Isoflurane對由插管引起交感神經變化與esmolol之β效果皆無影響。結論：由isoflurane引起心博過快時，腎上腺素反而減低。去甲腎上腺素只在插管後有升高。表示與它有特別關系，因在此前沒有變化。Isoflurane效果與由插管引起的交感神經變化可能不經同一機轉。