Thiopental Pediatric Dosing
Intravenous Induction Dosing
For IV induction of anesthesia in pediatric patients, thiopental should be dosed at 5–8.5 mg/kg, with neonates requiring significantly lower doses (3.4 mg/kg) compared to infants 1–6 months (6.3 mg/kg) and older children (5–10.5 mg/kg depending on premedication status). 1, 2, 3
Age-Specific IV Dosing
Neonates (0–14 days): The ED50 for satisfactory induction is 3.4 mg/kg IV, which is significantly lower than older infants due to developmental pharmacokinetic differences. 2
Infants (1–6 months): The ED50 increases to 6.3 mg/kg IV for satisfactory induction without gross movements or coughing. 2
Children (unpremedicated): The ED90 is 10.5 mg/kg IV, which is substantially higher than in premedicated children. 3
Children (premedicated): The ED90 drops to 4.2–5.2 mg/kg IV depending on the premedication regimen used (trimeprazine-droperidol-physeptone combinations are most effective). 3
Emergency rapid-sequence induction: A dose of 5 mg/kg IV has been validated in pediatric emergency surgery when combined with neuromuscular blockade. 4
IV Administration Technique
Administer as a 1% solution (10 mg/mL) at a rate of approximately 1 mL every 5 seconds; higher concentrations markedly increase muscular movements and cardiorespiratory irregularities. 1
The induction dose typically provides 5–7 minutes of anesthesia. 1
Maintenance can be achieved with intermittent boluses of 20–40 mg (2–4 mL of 1% solution) every 4–7 minutes or continuous infusion of 0.2% solution at ~3 mL/minute. 1
Rectal Administration Dosing
For rectal induction, use age-adjusted dosing: 50 mg/kg for infants <6 months, 35 mg/kg for infants 6–12 months, and 25 mg/kg for children >12 months (maximum 700 mg total), administered as a 1% solution. 5, 1
Rectal Dosing Details
Infants <6 months: 50 mg/kg rectally as a 1% solution. 5
Infants 6–12 months: 35 mg/kg rectally as a 1% solution. 5
Children >12 months: 25 mg/kg rectally as a 1% solution, with a maximum total dose of 700 mg. 5
Mean induction time is rapid, and duration of deep sedation averages 60.79 ± 27 minutes, making rectal thiopental the drug of choice for pediatric sedation in neuroimaging due to rapid onset and offset. 5
Rectal thiopental has a significantly shorter discharge time compared to intramuscular cocktail regimens. 5
Intramuscular Administration Dosing
For IM induction, administer 6.6–10 mg/kg as a 5% solution (50 mg/mL). 1
The usual IM dose range is 6.6–10 mg/kg using a 5% concentration. 1
IM administration is less commonly used than IV or rectal routes in pediatric practice. 1
Critical Safety Considerations
Cardiovascular Depression
Thiopental causes significant reduction in cardiac output, stroke volume, and blood pressure through direct myocardial depression, even at standard induction doses of 7.5–8.5 mg/kg. 6
Premedication with atropine may ameliorate cardiac output reduction by permitting compensatory tachycardia during induction. 6
Intubation after thiopental induction causes hypertension and tachycardia that are not prevented by diazepam premedication. 6
Mandatory Monitoring and Rescue Capability
Age- and size-appropriate resuscitative equipment (intubation equipment, cardioversion, oxygen, suction, secure IV access) and qualified personnel must be immediately available before any thiopental administration. 1
Facilities for assisting ventilation and administering oxygen are necessary adjuncts for all routes of thiopental administration. 1
Cardiorespiratory arrest may occur; patients require careful observation during and after use. 1
Solution Preparation
Use only bacteriostatic-free diluent; Lactated Ringer's Injection is incompatible. 1
Preferred diluent for IV/rectal is Sterile Water for Injection; 5% Dextrose or 0.9% NaCl are acceptable alternatives. 1
Do not mix with acidic solutions (atropine sulfate, succinylcholine, metocurine) in the same syringe, as pH alteration precipitates free barbituric acid. 1
Freshly prepare solutions and use promptly; reconstituted solutions are chemically stable at room temperature for 24 hours. 1
Common Pitfalls to Avoid
Avoid underdosing neonates based on older pediatric dosing: Neonates require approximately half the dose of older infants (3.4 vs 6.3 mg/kg). 2
Do not use unpremedicated dosing in premedicated children: This results in excessive dosing and prolonged recovery; premedication reduces requirements by 50–60%. 3
Never administer concentrations >1% intravenously: Higher concentrations markedly increase adverse respiratory and hemodynamic effects. 1
Recognize that rectal midazolam is ineffective for procedural sedation: It has minimal effect compared to rectal thiopental for neuroimaging. 5