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Echocardiographic evaluation of vagolytic effects of atropine sulfate during pediatric halothane anesthesia
H Horigome1, M Tsuji, M Yamashita
1Department of Pediatrics, Ibaraki Children's Hospital, Mito, Japan.
Insights
Atropine sulfate effectively reversed halothane-induced bradycardia and hypotension in children. However, higher doses did not improve left ventricular function, indicating myocardial depression is not fully attenuated by vagolysis.
Area of Science:
- Pediatric Anesthesiology
- Cardiovascular Pharmacology
- Pediatric Cardiology
Background:
- Halothane anesthesia can induce cardiovascular depression in children, characterized by decreased heart rate, blood pressure, and left ventricular function.
- Atropine sulfate is commonly used to counteract these effects, but its optimal dosage for pediatric patients remains debated.
- Understanding the dose-dependent efficacy of atropine is crucial for managing anesthesia-related cardiovascular complications in children.
Purpose of the Study:
- To investigate the antagonistic effects of atropine sulfate on halothane-induced cardiovascular depression in pediatric patients.
- To determine if a higher dose of atropine sulfate is more effective in attenuating halothane-induced myocardial depression.
- To evaluate the impact of different atropine sulfate dosages on cardiac function parameters.
Main Methods:
- A randomized study involving 34 children (1-12 years) undergoing minor surgery.
- M-mode echocardiography assessed left ventricular function (LVSF, LVEDD) at three time points: pre-induction, post-induction, and post-atropine administration.
- Patients received either 0.01 mg/kg or 0.02 mg/kg of atropine sulfate, with comparisons made between groups and time points.
Main Results:
- Halothane induction significantly decreased heart rate (HR), mean blood pressure (MBP), and left ventricular shortening fraction (LVSF), while increasing left ventricular end-diastolic dimension (LVEDD).
- Atropine administration recovered HR and MBP, but LVSF and LVEDD remained unchanged, suggesting persistent myocardial depression.
- No significant differences in cardiovascular parameters were observed between the 0.01 mg/kg and 0.02 mg/kg atropine groups, except for HR and mean velocity of circumferential fiber shortening (mVcf).
Conclusions:
- Atropine sulfate effectively antagonizes halothane-induced bradycardia and hypotension in children.
- The myocardial depression induced by halothane is not necessarily attenuated by vagolysis, irrespective of atropine dosage.
- A lower dose of atropine sulfate (0.01 mg/kg) appears sufficient to counteract the immediate cardiovascular effects of halothane anesthesia in pediatric patients.
Abstract:
The aims of this study were to define the antagonistic effects of atropine sulfate to halothane-induced cardiovascular depression in children, and to clarify whether or not a larger dose of atropine is more effective in attenuating the cardiovascular depression. Thirty-four children aged 1-12 years who had undergone minor surgery, free from cardiac or pulmonary disease, were assigned at random to two groups. M-mode echocardiographic evaluation of left ventricular function in each patient was performed at three points (before induction, point A; after induction, point B; and following administration of atropine, point C). Results were compared between points A and B, B and C and C and A, and between the two study groups with different doses of atropine (0.01 mg/kg vs 0.02 mg/kg). Heart rate (HR), mean blood pressure (MBP) and left ventricular shortening fraction (LVSF) decreased, and left ventricular end-diastolic dimension (LVEDD) were increased significantly by halothane induction. Although HR and MBP recovered following atropine, LVSF and LVEDD remained unchanged. There were no differences found between the values after vagolysis in both study groups, except for HR and mean velocity of circumferential fiber shortening (mVcf). Heart rate increased above that of pre-induction, even following the smaller dose of atropine. The myocardial depression cannot be necessarily attenuated by vagolysis regardless of the dosage of atropine. The smaller dose (i.e. 0.01 mg/kg) seems to be sufficient only to antagonize the bradycardia and hypotension during halothane anesthesia in children.