Optimal end-tidal concentration of sevoflurane to test an ankle clonus in children.
METHODS
A prospective randomized study on the end-tidal concentrations of sevoflurane at which ankle clonus existed.


BACKGROUND
The ankle clonus reflex is a transient neurologic abnormality, which normally occurs in patients during emergence from general anesthesia.


OBJECTIVE
To determine the optimal end-tidal concentration of sevoflurane to test an ankle clonus in children during emergence from general anesthesia.


METHODS
We studied 30 children (aged 5-15 years). General anesthesia was induced with thiopental sodium. Anesthesia was maintained with sevoflurane, oxygen, and air. At completion of surgery, 3% volume of the end-tidal sevoflurane concentration was maintained for at least 10 minutes. Ankle clonus was checked at 1.0% to 0.1% volume of the end-tidal sevoflurane concentration with an interval of 0.05% volume.


RESULTS
Of children, 80% had bilateral ankle clonus, which was found most frequently when patients responded poorly to verbal commands. The median of the end-tidal sevoflurane concentration for a reactive ankle clonus was 0.45% volume (interquartile range 0.5% to 0.4% volume).


CONCLUSIONS
The ankle clonus should be tested at 0.45% volume of end-tidal sevoflurane concentration in children undergoing scoliosis surgery during emergence from the general anesthesia.
Chang
Chul Ho
CH
Department of Anesthesiology and Pain Medicine, and Anesthesia and Pain Research Institute, Yonsei University College of Medicine, CPO Box 1217, Seoul 120-752, Republic of Korea.
Choi
Seung Ho
SH
Shim
Yon Hee
YH
Lee
Ki-Young
KY
Lee
Hwan-Mo
HM
Shin
Yang-Sik
YS
D000293:Adolescent; D000762:Anesthesia Recovery Period; D000768:Anesthesia, General / Q000009:adverse effects; D000842:Ankle / Q000502:physiology; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007320:Inspiratory Capacity / Q000187:drug effects / Q000502:physiology; D008297:Male; D008738:Methyl Ethers / Q000008:administration & dosage*; D011446:Prospective Studies; D012021:Reflex, Abnormal / Q000187:drug effects* / Q000502:physiology*; D000077149:Sevoflurane
D008738:Methyl Ethers; D000077149:Sevoflurane