What are the recommended inducing doses of atracurium and rocuronium for anesthesia?

Inducing Doses of Atracurium and Rocuronium

For standard intubation, administer rocuronium 0.6 mg/kg or atracurium 0.4-0.5 mg/kg as initial bolus doses, with rocuronium providing faster onset (approximately 2 minutes) compared to atracurium (2-2.5 minutes). 1, 2

Standard Intubation Dosing

Rocuronium

• Initial dose: 0.6 mg/kg IV bolus for most adult patients under opioid/nitrous oxide/oxygen anesthesia 1
• This dose provides good to excellent intubating conditions within 60-90 seconds in the majority of patients 3
• Maximum neuromuscular block is achieved approximately 3-5 minutes after injection 1
• Clinical duration typically lasts 20-35 minutes under balanced anesthesia 1

Atracurium

• Initial dose: 0.4-0.5 mg/kg IV bolus (1.7-2.2 times the ED95) for most adult patients 2
• Good or excellent intubating conditions can be expected in 2-2.5 minutes 2
• Maximum neuromuscular block occurs approximately 3-5 minutes after injection 2
• Clinically required block generally lasts 20-35 minutes under balanced anesthesia 2

Rapid Sequence Intubation Considerations

Rocuronium for RSI

• Doses ≥1 mg/kg are suitable for rapid-sequence induction under relatively light anesthesia 3
• Higher doses permit intubation within 60-180 seconds but result in prolonged duration of action 3
• The trade-off between rapid onset and extended duration must be carefully considered, particularly if difficult intubation is encountered 3

Atracurium for RSI

• Dose of 1 mg/kg without priming can be used as an alternative for rapid sequence induction 4
• This dose provided 51.4% success rate for intubation without coughing or bucking within one minute 4
• Excellent or good intubating conditions were achieved in 86.5% of patients receiving 1 mg/kg 4
• Lower doses (0.75 mg/kg and 0.6 mg/kg) provided 43.6% and 26.3% success rates respectively 4

Dosing Adjustments for Inhalational Anesthetics

With Isoflurane or Enflurane

• Reduce rocuronium initial dose by approximately one-third (to 0.25-0.35 mg/kg) if administered under steady-state concentrations of these agents 1
• Reduce atracurium initial dose by approximately one-third when using enflurane or isoflurane 2
• These volatile anesthetics significantly potentiate neuromuscular blockade 1, 2

With Halothane

• Halothane has only marginal (approximately 20%) potentiating effect on atracurium 2
• Smaller dosage reductions may be considered with halothane compared to isoflurane/enflurane 2

Pediatric Dosing

Rocuronium in Pediatrics

• Initial dose: 0.6 mg/kg for children ≥2 years of age; no adjustment required from adult dosing 1
• Lower dose of 0.45 mg/kg may be used depending on anesthetic technique and patient age 1
• For sevoflurane induction, doses of 0.45-0.6 mg/kg produce excellent to good intubating conditions within 75 seconds 1
• Time to maximum block is shortest in infants (28 days to 3 months) and longest in neonates 1

Atracurium in Pediatrics

• No dosage adjustments required for children ≥2 years of age 2
• Initial dose: 0.3-0.4 mg/kg for infants (1 month to 2 years) under halothane anesthesia 2
• Maintenance doses may be required with slightly greater frequency in infants and children than adults 2

Special Population Considerations

Cardiovascular Disease or Histamine Concerns

• Atracurium: 0.3-0.4 mg/kg given slowly or in divided doses over one minute for patients with significant cardiovascular disease or history suggesting greater risk of histamine release 2
• Rocuronium has mild vagolytic effects and does not release histamine, even in large doses 3

Renal/Hepatic Failure

• Do not modify the initial dose in renal/hepatic failure patients, irrespective of the muscle relaxant type used (GRADE 1+ recommendation) 5
• Atracurium is particularly advantageous in renal/hepatic failure as approximately half is eliminated by organ-independent Hofmann reaction and ester hydrolysis 5
• Benzylisoquinoline muscle relaxants (atracurium/cisatracurium) are probably recommended in cases of renal/hepatic failure (GRADE 2+ recommendation) 5
• While rocuronium's duration of action is extended in renal failure, the time to onset remains unchanged, justifying the usual intubating dose 5

Following Succinylcholine Use

• Atracurium: 0.3-0.4 mg/kg is recommended following succinylcholine for intubation under balanced anesthesia 2
• Further reductions may be desirable with potent inhalation anesthetics 2
• Patient should be permitted to recover from succinylcholine effects prior to atracurium administration 2

Geriatric Patients

• Geriatric patients (≥65 years) exhibited slightly prolonged clinical duration with rocuronium 1
• No specific dose reduction is mandated, but be prepared for extended duration of action 1

Critical Pitfalls to Avoid

• Never administer atracurium or rocuronium intramuscularly - both must be given intravenously only 2
• Do not mix atracurium with alkaline solutions (e.g., barbiturate solutions) as this may cause drug inactivation 2
• Avoid underdosing in rapid sequence scenarios where adequate intubating conditions are critical 4
• Remember that higher doses of rocuronium (>1 mg/kg) for RSI result in significantly prolonged duration, which may be problematic if intubation fails 3
• Use peripheral nerve stimulator monitoring to guide dosing and assess recovery, particularly when using maintenance doses 1, 2