What is the recommended intramuscular (IM) dose of succinylcholine for a pediatric patient?

Intramuscular Succinylcholine Dosing in Pediatric Patients

The recommended IM dose of succinylcholine is 4 mg/kg for most pediatric patients, with a higher dose of 5 mg/kg specifically for infants under 6 months of age, and the total IM dose should not exceed 150 mg regardless of patient weight. 1, 2

Standard Dosing by Age Group

Infants Under 6 Months

• Administer 5 mg/kg IM for infants younger than 6 months of age 1
• This higher dose accounts for the increased volume of distribution and different pharmacokinetics in this age group 3

Infants 6 Months and Older, Children, and Adolescents

• Administer 4 mg/kg IM for all pediatric patients 6 months of age and older 1
• The FDA label confirms IM dosing of 3-4 mg/kg for infants, older pediatric patients, and adults, with a maximum total dose of 150 mg 2

Critical Timing and Onset Considerations

• Expect adequate intubating conditions in 3-5 minutes after IM administration 1
• Onset is significantly slower than IV administration (which produces conditions in 30-45 seconds) 1
• The FDA label indicates onset is usually observed in about 2-3 minutes after IM injection 2
• Duration of neuromuscular blockade is approximately 5-10 minutes 1

Essential Premedication and Monitoring

Atropine Administration

• Administer atropine 0.02 mg/kg (minimum 0.1 mg, maximum 1 mg) before succinylcholine to prevent bradycardia or asystole 1
• This is particularly critical in children aged 28 days to 8 years, especially those with septic shock, hypovolemia, or when using succinylcholine 1
• Research demonstrates that IM succinylcholine 4 mg/kg can be used with or without atropine 0.02 mg/kg in lightly anesthetized young children without producing severe bradycardia 4

Mandatory Airway Management Preparation

• Ventilatory support is absolutely necessary 1
• Personnel skilled in airway management must be present and prepared to respond immediately 1
• Age-appropriate equipment for suctioning, oxygenation, intubation, and ventilation must be immediately available 1

Life-Threatening Contraindications and Warnings

Absolute Contraindications

Do not use succinylcholine in patients with: 1

• Previous history of malignant hyperthermia
• Severe burns or crush injury
• Spinal cord injury
• Neuromuscular disease or myopathy
• Skeletal muscle myopathies 2

Hyperkalemia Risk

• Succinylcholine causes increased serum potassium levels that may be life-threatening in the contraindicated conditions listed above 1
• If cardiac arrest occurs immediately after administration, suspect hyperkalemia, particularly in boys younger than 9 years old 1
• When these contraindications exist, use a nondepolarizing muscle relaxant such as rocuronium instead 1

Clinical Context for IM Route Selection

• IM administration is reserved for situations where a suitable vein is inaccessible 2
• This route is appropriate for emergency tracheal intubation when IV access cannot be rapidly obtained 2
• The IM route provides a reliable alternative with predictable onset, though slower than IV administration 1

Important Clinical Caveats

Sedation and Analgesia

• Succinylcholine provides NO sedation, analgesia, or amnesia 1
• Appropriate sedation must be provided separately for patient comfort and safety 1

Increased Intracranial Pressure

• For patients with increased ICP, consider a defasciculation dose of a nondepolarizing agent (e.g., vecuronium 0.01 mg/kg) before succinylcholine administration 1

Age-Related Pharmacokinetic Differences

• Children generally require more neuromuscular blocking drugs on a mg/kg basis than infants or adults to achieve the same effect 5
• Neonates and infants have immature drug elimination pathways, requiring careful dose consideration 3
• The effective dose in pediatric patients may be higher than predicted by body weight alone 2