Effects of combining midazolam and barbiturate on the response to tracheal intubation: changes in autonomic nervous system.
OBJECTIVE
To investigate the effects on the autonomic nervous system of anesthesia induction with a combination of midazolam and barbiturate using plasma catecholamine concentration and heart rate (HR) variability in comparison with the induction with barbiturate alone.


METHODS
Prospective study.


METHODS
Operating room of a university hospital.


METHODS
40 ASA physical status I and II patients aged 30 to 70 years, who were scheduled for general anesthesia.


METHODS
Anesthesia was induced with 0.1 mg/kg midazolam followed by 3 mg/kg thiopental sodium (Midazolam-Barbiturate group) or thiopental 5 mg/kg (Barbiturate group) with 6 L/min oxygen.


METHODS
Arterial blood pressure (BP), HR, HR variability, and plasma concentrations of epinephrine and norepinephrine were measured.


RESULTS
Blood pressure and HR increased in response to tracheal intubation in both groups, but the increase was significantly larger in the Barbiturate group. In the Barbiturate group, the high-frequency component (HF) in HR variability increased significantly during intubation, whereas in the Midazolam-Barbiturate group, HF decreased continuously. The low-frequency component (LF)/HF ratio increased in both groups, with significantly higher values noted in the Barbiturate group. Plasma epinephrine concentrations decreased before intubation and increased in response to tracheal intubation in the Barbiturate group. Finally, plasma norepinephrine concentrations increased in response to tracheal intubation only in the Barbiturate group.


CONCLUSIONS
Anesthesia induction with a combination of midazolam-thiopental was effective in reducing hemodynamic and cardiac autonomic nervous system responses to tracheal intubation in comparison with the conventional induction with thiopental alone.
Surgical Center, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan. nishiyam@ims.u-tokyo.ac.jp.
Tomoki
T
Nishiyama
Kazuhide
K
Misawa
Takeshi
T
Yokoyama
Kazuo
K
Hanaoka
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D019162:Anesthetics, Combined / Q000008:administration & dosage*; D018686:Anesthetics, Intravenous / Q000008:administration & dosage*; D001341:Autonomic Nervous System / Q000187:drug effects* / Q000378:metabolism; D001463:Barbiturates / Q000008:administration & dosage*; D001794:Blood Pressure / Q000187:drug effects; D004837:Epinephrine / Q000097:blood; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007442:Intubation, Intratracheal; D008297:Male; D008874:Midazolam / Q000627:therapeutic use*; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood; D011446:Prospective Studies; D013997:Time Factors
D019162:Anesthetics, Combined; D018686:Anesthetics, Intravenous; D001463:Barbiturates; D008874:Midazolam; D009638:Norepinephrine; D004837:Epinephrine