What is the recommended anesthetic regimen for pediatric anesthesia in infants and children?

Pediatric Anesthetic Regimen for Infants and Children

Induction of Anesthesia

For conventional intravenous induction in children, use of a muscle relaxant is strongly recommended to optimize intubating conditions and minimize adverse respiratory events, particularly in infants. 1

Intravenous Induction Approach

• Administer remifentanil 0.5-1 mcg/kg/min as the opioid component during induction, with an optional bolus of 1 mcg/kg over 30-60 seconds if intubation will occur within 8 minutes 2
• Never use remifentanil as a sole induction agent due to inability to guarantee loss of consciousness and high incidence of apnea, muscle rigidity, and tachycardia 2
• Combine with propofol or sevoflurane for hypnosis, as remifentanil alone cannot ensure unconsciousness 1, 2
• Add a muscle relaxant to achieve optimal intubating conditions, as meta-analyses demonstrate significantly improved conditions when muscle relaxants are used versus high-dose opioid/hypnotic combinations alone 1

Inhalational Induction Alternative

• Sevoflurane inhalational induction without muscle relaxants is very common practice in France (92% of cases) and acceptable when sufficient depth of anesthesia and apnea are achieved 1
• However, muscle relaxants during inhaled induction benefit infants specifically, with prospective randomized studies showing improved intubating conditions and fewer respiratory events 1
• The concentration of sevoflurane, duration of exposure, and associated agents (opioid-propofol) significantly affect both intubating conditions and hemodynamic parameters 1

Rapid Sequence Induction

For rapid sequence induction, suxamethonium remains the first-line muscle relaxant choice in children (doses: <1 month: 1.8 mg/kg; 1-12 months: 2.0 mg/kg; 1-10 years: 1.2 mg/kg; >10 years: 1.0 mg/kg), with rocuronium >0.9 mg/kg as the alternative when suxamethonium is contraindicated 1

Maintenance of Anesthesia

Balanced Anesthetic Technique

The optimal maintenance regimen combines moderate sevoflurane or propofol with remifentanil, allowing patients to remain immobile without muscle relaxants once the intubating dose has worn off. 3

Remifentanil-Based Maintenance (Age-Specific)

For children 1-12 years:

• With halothane (0.3-1.5 MAC): remifentanil 0.25 mcg/kg/min (range 0.05-1.3 mcg/kg/min) 2
• With sevoflurane (0.3-1.5 MAC): remifentanil 0.25 mcg/kg/min (range 0.05-1.3 mcg/kg/min) 2
• With isoflurane (0.4-1.5 MAC): remifentanil 0.25 mcg/kg/min (range 0.05-1.3 mcg/kg/min) 2
• Supplemental boluses of 1 mcg/kg every 2-5 minutes as needed 2

For neonates (birth to 2 months):

• With nitrous oxide (70%): remifentanil 0.4 mcg/kg/min (range 0.4-1.0 mcg/kg/min) 2
• Critical caveat: Neonatal clearance is highly variable and averages 2 times higher than young adults, requiring potentially increased infusion rates and additional boluses 2
• Pretreatment with atropine is essential to blunt bradycardia risk 2
• Reduce bolus doses in neonates receiving potent inhalation agents, neuraxial anesthesia, those with significant comorbidities, or undergoing significant fluid shifts 2

Alternative Maintenance Regimens

For adults and when remifentanil is unavailable:

• With nitrous oxide (66%): remifentanil 0.4 mcg/kg/min (range 0.1-2 mcg/kg/min) 2
• With isoflurane (0.4-1.5 MAC): remifentanil 0.25 mcg/kg/min (range 0.05-2 mcg/kg/min) 2
• With propofol (100-200 mcg/kg/min): remifentanil 0.25 mcg/kg/min (range 0.05-2 mcg/kg/min) 2

Intraoperative Opioid Alternatives

When remifentanil is not used, select age-appropriate opioid dosing:

• Fentanyl: 1-2 mcg/kg 1
• Morphine: 25-100 mcg/kg depending on age (titrated to effect) 1
• Sufentanil: 0.5-1 mcg/kg bolus, or continuous infusion 0.5-1 mcg/kg/h 1
• Alfentanil: 10-20 mcg/kg 1
• Piritramide: 0.05-0.15 mg/kg 1

Titration Principles

• Increase remifentanil by 25-100% increments in adults or up to 50% increments in children every 2-5 minutes for inadequate analgesia 2
• Decrease by 25-50% decrements every 2-5 minutes when excessive effect is observed 2
• At infusion rates >1 mcg/kg/min, consider increasing concomitant anesthetic agents rather than further remifentanil increases 2

Regional Anesthesia Integration

Incorporate regional anesthesia whenever feasible to reduce systemic opioid requirements and improve postoperative analgesia. 1

Local Anesthetic Dosing (Maximum Safe Doses)

Bupivacaine 0.25%:

• Maximum dose: 2.5 mg/kg (1 ml/kg) for wound infiltration and peripheral nerve blocks 1, 4
• Caudal block: 1.0 ml/kg 1
• Epidural (thoracic): 0.2-0.3 ml/kg (max 10 ml) initially 1
• Epidural (lumbar): 0.5 ml/kg (max 15 ml) initially 1
• Peripheral nerve blocks: 0.2-0.5 ml/kg 1

Ropivacaine 0.2%:

• Maximum dose: 3 mg/kg (1.5 ml/kg) 1, 4
• Same volume ranges as bupivacaine for specific blocks 1

Levobupivacaine 0.25%:

• Maximum dose: 2.5 mg/kg (1 ml/kg) 1
• Same volume ranges as bupivacaine 1

Adjuvants to Prolong Block Duration

• Preservative-free clonidine: 1-2 mcg/kg added to local anesthetic solutions 1
• Preservative-free morphine: 30-50 mcg/kg for caudal blocks only (requires adequate monitoring) 1

Critical Safety Considerations for Local Anesthetics

All local anesthetics are cardiac depressants and may cause CNS excitation or depression. 1

• Calculate maximum allowable dose (mg/kg) before administration to prevent toxicity 1
• Aspirate frequently to minimize intravascular injection risk 1
• Use lower doses in highly vascular tissues 1
• Reduce amide local anesthetic doses by 30% in infants <6 months 1
• Monitor vital signs every 5 minutes initially when high doses or amide local anesthetics are used, then increase intervals to 10-15 minutes once the child awakens 1
• Have 20% lipid emulsion immediately available when long-acting local anesthetics (bupivacaine, ropivacaine) are injected into vascular tissues for treatment of local anesthetic systemic toxicity 1

Special Population Considerations

Neonates and Former Preterm Infants

Neonates require specific management due to immature hepatic and renal function, resulting in prolonged drug metabolism and excretion. 1

• Immaturity of hepatic/renal function alters ability to metabolize and excrete sedating medications, necessitating extended post-sedation monitoring 1
• Former preterm infants have increased risk of postanesthesia apnea, though similar risk with sedation remains unclear 1
• Avoid unnecessary sedation exposure when procedures are unlikely to change medical management (e.g., screening MRI in preterm infants) 1

Geriatric Patients (>65 Years)

Reduce starting dose of remifentanil by 50% in patients over 65 years due to twice the pharmacodynamic sensitivity compared to younger patients 2

• Clearance is reduced approximately 25% in elderly versus young adults 2
• Blood concentrations still fall rapidly after termination despite reduced clearance 2
• Titrate slowly and frequently reassess for CNS and respiratory depression 2

Morbidly Obese Patients

Exercise caution with all potent opioids due to alterations in cardiovascular and respiratory physiology 2

Postoperative Analgesia Transition

When continuing remifentanil as an analgesic into the immediate postoperative period, start at 0.1 mcg/kg/min and adjust by 0.025 mcg/kg/min increments every 5 minutes. 2

• Infusion rates >0.2 mcg/kg/min are associated with respiratory depression (respiratory rate <8 breaths/min) 2
• No residual analgesic activity remains 5-10 minutes after discontinuation due to rapid offset 2
• Administer alternative analgesics before discontinuing remifentanil for procedures where postoperative pain is anticipated 2
• Bolus injections of remifentanil are not recommended for postoperative pain treatment 2
• Remifentanil has not been studied in pediatric patients for postoperative analgesia use 2

Multimodal Postoperative Analgesia

Implement a comprehensive strategy combining NSAIDs, acetaminophen, and regional techniques:

Intravenous NSAIDs:

• Ketorolac: 0.5-1 mg/kg (max 30 mg) single intraoperative dose, then 0.15-0.2 mg/kg (max 10 mg) every 6 hours (maximum 48 hours) 1
• Ketoprofen: 1 mg/kg every 8 hours 1
• Ibuprofen: 10 mg/kg every 8 hours 1

Intravenous Paracetamol:

• Loading dose: 15-20 mg/kg 1
• Maintenance: 10-15 mg/kg every 6-8 hours 1

Breakthrough Pain Management (Age-Specific):

For infants <3 months:

• Morphine: 25-50 mcg/kg IV every 4-6 hours 1
• Nalbuphine: 0.05 mg/kg IV 1

For infants 3-12 months:

• Morphine: 50-100 mcg/kg IV every 4-6 hours 1
• Nalbuphine: 0.1-0.2 mg/kg IV every 3-4 hours 1

For children 1-5 years:

• Morphine: 100-150 mcg/kg IV every 4-6 hours 1
• Tramadol: 1-1.5 mg/kg IV/PO every 4-6 hours 1

For children 5-18 years:

• Morphine: 200-300 mcg/kg single dose adjusted to response 1
• Tramadol: 1-1.5 mg/kg IV/PO every 4-6 hours 1

Monitoring Requirements

Neuromuscular blockade monitoring is warranted in pediatric patients receiving muscle relaxants, as residual blockade occurs in 28% of cases. 1

For sedation and anesthesia, continuous monitoring must include:

• Pulse oximetry with adequate oxygen supply 1
• Vital signs recorded at least every 10 minutes until awakening, then intervals may be increased 1
• Dedicated recovery area with age- and size-appropriate rescue equipment 1
• Dedicated recovery personnel 1

Common Pitfalls to Avoid

Critical errors to prevent:

• Using remifentanil as sole induction agent without hypnotic 2
• Failing to pretreat neonates with atropine before remifentanil administration 2
• Discontinuing remifentanil without establishing alternative analgesia first 2
• Exceeding maximum local anesthetic doses, particularly in infants <6 months 1
• Forgetting to reduce remifentanil doses by 50% in elderly patients 2
• Administering suxamethonium for non-rapid-sequence induction 1
• Ignoring the 2-fold higher remifentanil clearance in neonates 2

1, 4, 2, 3