Hemodynamic and catecholamine response to a rapid increase in isoflurane or sevoflurane concentration during a maintenance phase of anesthesia in humans.
OBJECTIVE
The purpose of this study was to compare hemodynamic and catecholamine changes due to a sudden increase in inhalation anesthetic concentrations (isoflurane and sevoflurane) during surgery.


METHODS
Thirty patients aged 40-70 years scheduled for lower abdominal surgery were anesthetized with either isoflurane or sevoflurane with nitrous oxide and epidural block. During surgery the isoflurane or sevoflurane concentration was kept at 0.5 minimum alveolar concentration (MAC) (end-tidal concentration) for 15 min. Then the isoflurane or sevoflurane concentration (inhalation concentration) was changed to 1.5 MAC and maintained at that level for 10 min. Thereafter, it was decreased to 0.5 MAC for 10 min. Blood pressure, heart rate, and plasma concentrations of epinephrine and norepinephrine were measured.


RESULTS
The blood pressure decreased significantly in both groups after increasing the anesthetic concentration, and it increased after decreasing the concentration. The decrease in systolic blood pressure was significantly larger in the isoflurane group. The heart rate increased significantly after increasing the anesthetic concentration only in the isoflurane group. Plasma concentrations of epinephrine and norepinephrine increased significantly in the isoflurane group, whereas the epinephrine concentration (but not the norepinephrine concentration) decreased in the sevoflurane group.


CONCLUSIONS
During surgery a sudden increase in isoflurane concentration induced larger changes in hemodynamics and sympathetic nerve activity than sevoflurane.
Nishiyama
Tomoki
T
Department of Anesthesiology, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
D000005:Abdomen / Q000601:surgery; D000328:Adult; D000368:Aged; D000769:Anesthesia, Inhalation; D018685:Anesthetics, Inhalation / Q000008:administration & dosage; D001794:Blood Pressure / Q000187:drug effects; D002395:Catecholamines / Q000097:blood*; D004837:Epinephrine / Q000097:blood; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D007432:Intraoperative Period; D007530:Isoflurane / Q000008:administration & dosage; D008297:Male; D008738:Methyl Ethers / Q000008:administration & dosage; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood; D011229:Preanesthetic Medication; D000077149:Sevoflurane
D018685:Anesthetics, Inhalation; D002395:Catecholamines; D008738:Methyl Ethers; D000077149:Sevoflurane; D007530:Isoflurane; D009638:Norepinephrine; D004837:Epinephrine