Canadian journal of anaesthesia = Journal canadien d'anesthésie
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Comparative Study Clinical Trial Controlled Clinical Trial
Atropine-induced heart rate changes: a comparison between midazolam-fentanyl-propofol-N2O and midazolam-fentanyl-thiopentone-enflurane-N2O anaesthesia.
Atropine-induced heart rate (HR) changes were studied in 19 patients (ASA physical status I) during anaesthesia-maintained predominantly with propofol-N2O or thiopentone-enflurane-N2O. Ten patients (Group A) received midazolam (0.07 mg.kg-1), fentanyl (1 microgram.kg-1), propofol (2 mg.kg-1) and succinylcholine (1 mg.kg-1). Following tracheal intubation, anaesthesia was maintained with propofol (6 mg.kg-1.hr-1), N2O (67 per cent) and O2 (33 per cent). ⋯ Ten minutes after tracheal intubation, incremental doses of atropine (equivalent cumulative doses: 1.8, 3.6, 7.2, 14.4, 28.8 micrograms.kg-1) were administered at two-minute intervals and HR responses calculated during the last 45 sec of each intervening period. No differences were observed between the groups following 1.8 and 3.6 micrograms.kg-1 atropine, but propofol-N2O anaesthesia was associated with reduced responses (P less than 0.01) following 7.2, 14.4 and 28.8 micrograms.kg-1 atropine. These results suggest that there is a predominance of parasympathetic influences during propofol-N2O anaesthesia compared with thiopentone-enflurane-N2O anaesthesia.
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Comparative Study
Intraoperative cardiac output monitoring by transtracheal Doppler tube.