Simulated epidural test doses using adrenaline and adrenaline/clonidine in sevoflurane-anaesthetized children.
A pilot study was conducted using a simulated epidural test dose to ascertain the effects adrenaline, adrenaline/clonidine mixture, and clonidine alone on the accepted criteria for determining the occurrence of an epidural intravascular injection. Seventy-five ASA 1 or 2 children aged from six months to twelve years were sequentially allocated to one of three groups: group A: adrenaline 0.5 microgram/kg, group AC: adrenaline 0.5 microgram/kg and clonidine 0.3 microgram/kg, and group C: clonidine 0.3 microgram/kg. Effects on heart rate, T-wave amplitude and systolic blood pressure were determined after induction of anaesthesia and stabilization using sevoflurane in nitrous oxide and oxygen. Heart rate varied from baseline in a biphasic manner. The maximal increase in mean heart rate for all groups was < 10 beats per minute (bpm). A heart rate rise of > 10 bpm was not seen at any time in 54% of groups A and AC and 92% of group C (Chi-square 11.4, P = 0.003). T-wave changes were also biphasic. 50% of groups A and AC had no increase in T-wave size of > 25% at any sample point, compared with 96% in group C (Chi square = 49.4, P < 0.0001). 34% of groups A and AC did not have a change in systolic blood pressure of > 15 mmHg during the study compared with 100% of group C (Chi-square = 30.2, P < 0.0001). There were no significant differences between groups A and AC for any parameter. Negative predictive value estimates for the current criteria for intravascular injection were low. Clonidine 0.3 microgram/kg produced no effects on the study variables.
Burstal
R
R
Department of Anaesthesia, Intensive Care and Pain Management, John Hunter Hospital, Newcastle, New South Wales.
Hollard
J
J
McFadyen
B
B
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000767:Anesthesia, Epidural; D018685:Anesthetics, Inhalation; D001794:Blood Pressure / Q000187:drug effects; D002648:Child; D002675:Child, Preschool; D003000:Clonidine / Q000494:pharmacology*; D004338:Drug Combinations; D004837:Epinephrine / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007223:Infant; D008738:Methyl Ethers; D000077149:Sevoflurane; D013564:Sympathetic Nervous System / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
D000316:Adrenergic alpha-Agonists; D018685:Anesthetics, Inhalation; D004338:Drug Combinations; D008738:Methyl Ethers; D014662:Vasoconstrictor Agents; D000077149:Sevoflurane; D003000:Clonidine; D004837:Epinephrine