The hypnotic and analgesic effects of oral clonidine during sevoflurane anesthesia in children: a dose-response study.
Although clonidine has both hypnotic and analgesic actions, the dose relationship for each actions is still unknown in a clinical setting when clonidine is used as a premedication in children. We studied 80 ASA physical status I children (age range, 3-8 yr). Subjects were randomly divided into two groups (minimum alveolar anesthetic concentration [MAC]-Awake group, n = 40; MAC-Tetanus group, n = 40). Each patient received one dose of clonidine from 1 to 5 microg/kg orally, 100 min before arrival at the operating room. Anesthesia was induced and maintained with sevoflurane in oxygen and air. Before tracheal intubation, end-tidal sevoflurane was decreased stepwise by 0.2% at the start of 1.2%, a verbal command was given to the patients, and MAC-awake was determined in each patient. We also investigated MAC-tetanus, determined with transcutaneous electric tetanic stimulations, after tracheal intubation in each patient by observing the motor response to a transcutaneous electric tetanic stimulus to the ulnar nerve at a sevoflurane concentration decreased stepwise by 0.25% at the start of 2.75%. The initial reduction in MAC-tetanus was not as steep as that in MAC-awake. Clonidine reduced MAC-tetanus by 40% at the maximal dose of 5 microg/kg, whereas MAC-awake was already reduced by 50% at 2 microg/kg. We conclude that separate dose-response relationships for oral clonidine are present regarding the hypnotic and analgesic effects in children undergoing sevoflurane anesthesia.


CONCLUSIONS
Separate dose-response relationships for oral clonidine were found regarding the hypnotic and analgesic effects in children undergoing sevoflurane anesthesia.
Inomata
Shinichi
S
Department of Anesthesiology, the University of Tsukuba, Tsukuba City, Ibaraki 305-8575, Japan. inomatas@md.tsukuba.ac.jp
Kihara
Shin-Ichi
S
Miyabe
Masayuki
M
Sumiya
Kenji
K
Baba
Yasuyuki
Y
Kohda
Yukinao
Y
Toyooka
Hidenori
H
D000316:Adrenergic alpha-Agonists / Q000009:adverse effects; D000700:Analgesics / Q000009:adverse effects; D000768:Anesthesia, General; D018685:Anesthetics, Inhalation / Q000009:adverse effects; D002648:Child; D002675:Child, Preschool; D003000:Clonidine / Q000009:adverse effects; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000009:adverse effects; D008297:Male; D008738:Methyl Ethers / Q000009:adverse effects; D011650:Pulmonary Alveoli / Q000378:metabolism; D000077149:Sevoflurane
D000316:Adrenergic alpha-Agonists; D000700:Analgesics; D018685:Anesthetics, Inhalation; D006993:Hypnotics and Sedatives; D008738:Methyl Ethers; D000077149:Sevoflurane; D003000:Clonidine