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Simulated epidural test doses using adrenaline and adrenaline/clonidine in sevoflurane-anaesthetized children
R Burstal1, J Hollard, B McFadyen
1Department of Anaesthesia, Intensive Care and Pain Management, John Hunter Hospital, Newcastle, New South Wales.
Insights
Clonidine alone did not alter heart rate, T-wave amplitude, or blood pressure in children, unlike adrenaline. Adrenaline and adrenaline/clonidine mixtures showed similar effects, indicating low predictive value for current intravascular injection criteria.
Area of Science:
- Anesthesiology
- Pediatric Anesthesia
- Pharmacology
Background:
- Detecting accidental epidural intravascular injection is crucial in pediatric anesthesia.
- Current diagnostic criteria may have limitations in identifying such events.
Purpose of the Study:
- To evaluate the effects of adrenaline, clonidine, and their combination as simulated epidural test doses.
- To assess their impact on established criteria for identifying epidural intravascular injection in children.
Main Methods:
- A pilot study involved 75 children (6 months-12 years) randomly assigned to receive adrenaline, adrenaline/clonidine, or clonidine.
- Hemodynamic parameters (heart rate, systolic blood pressure) and T-wave amplitude were monitored.
- Sevoflurane-based anesthesia was used for stabilization before test dose administration.
Main Results:
- Clonidine (0.3 microgram/kg) alone had no significant effect on heart rate, T-wave, or blood pressure.
- Adrenaline (0.5 microgram/kg) and the adrenaline/clonidine mixture showed comparable effects on the monitored variables.
- A significant proportion of children in the clonidine group met the criteria for no adverse effects (92% for heart rate, 96% for T-wave, 100% for blood pressure).
- Negative predictive values for current intravascular injection criteria were found to be low.
Conclusions:
- Clonidine 0.3 microgram/kg is ineffective as a test dose for epidural intravascular injection in children.
- Adrenaline and adrenaline/clonidine mixtures exhibit similar effects, suggesting limitations in current diagnostic criteria.
- Further research is needed to refine methods for detecting epidural intravascular injection in pediatric patients.
Abstract:
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.
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