What is the recommended dosing and administration protocol for a continuous intravenous infusion of atracurium (non‑depolarizing neuromuscular blocker)?

Atracurium Continuous Infusion Protocol

For continuous IV infusion of atracurium, initiate with a bolus dose of 0.4-0.5 mg/kg, then start infusion at 5-9 mcg/kg/min in the operating room or 11-13 mcg/kg/min in the ICU, titrating to train-of-four monitoring with a target of 1-2 twitches. 1

Initial Bolus Dosing

• Standard dose: 0.4-0.5 mg/kg for intubation 1
• High-risk patients (cardiovascular disease, asthma, history of anaphylaxis): 0.3-0.4 mg/kg given slowly over 1 minute to minimize histamine release 1
• With potent inhalation anesthetics: Reduce initial dose by one-third (0.25-0.35 mg/kg) if isoflurane or enflurane already established; smaller reductions with halothane 1
• Post-succinylcholine: 0.3-0.4 mg/kg after patient recovers from succinylcholine effects 1

Continuous Infusion Rates

Operating Room Setting

• Initial rate: 9-10 mcg/kg/min to rapidly counteract spontaneous recovery after bolus 1
• Maintenance rate: 5-9 mcg/kg/min maintains 89-99% neuromuscular block under balanced anesthesia 1
• Range: Individual patients may require 2-15 mcg/kg/min 1
• With inhalation anesthetics: Reduce infusion rate by one-third with enflurane/isoflurane; smaller reductions with halothane 1
• During hypothermia: Reduce rate by approximately 50% during cardiopulmonary bypass at 25-28°C 1

ICU Setting

• Standard rate: 11-13 mcg/kg/min (range 4.5-29.5 mcg/kg/min) 1
• Pediatric patients: May require higher rates than adults 1
• Important caveat: Wide interpatient variability exists; requirements may increase or decrease over time 1

Preparation and Administration

Dilution concentrations 1:

• 0.2 mg/mL (20 mg in 100 mL)
• 0.5 mg/mL (50 mg in 100 mL)

Critical administration points:

• Use precision infusion device for accurate dosing 1
• Initiate infusion only after early evidence of spontaneous recovery from bolus dose 1
• Adjust rate based on peripheral nerve stimulation response 1

Monitoring Requirements

Train-of-four (TOF) monitoring is mandatory 2:

• Target: 1-2 twitches present for adequate surgical relaxation
• TOF ratio < 0.9 indicates residual blockade
• Monitor every 15-30 minutes during infusion
• Assess response before each rate adjustment

Special Populations

Pediatric Dosing

• ≥2 years: No dose adjustment needed 1
• Infants (1 month-2 years): 0.3-0.4 mg/kg initial bolus under halothane 1
• Neonates (<1 month): Require 25% less infusion (approximately 0.40 mg/kg/hr vs 0.53 mg/kg/hr for older children) 3
• Maintenance doses required more frequently than adults 1

Renal/Hepatic Failure

• No dose adjustment required 4, 1
• Atracurium undergoes organ-independent elimination (Hofmann degradation and ester hydrolysis) 4
• Laudanosine (active metabolite) accumulates in renal failure but does not reach toxic concentrations even after 72 hours 4
• This represents a significant advantage over other neuromuscular blockers 4

Duration and Recovery

• Onset: Maximum block within 3-5 minutes of bolus 1
• Duration: Recovery begins 20-35 minutes after bolus 1
• Recovery time: 25% recovery at 35-45 minutes; 95% recovery at 60-70 minutes under balanced anesthesia 1
• No cumulative effect: Repeat doses do not prolong recovery time 1

Reversal Protocol

• Timing: Attempt reversal when spontaneous recovery begins (approximately 20-35 minutes after 0.4-0.5 mg/kg bolus) 1
• Agents: Neostigmine, edrophonium, or pyridostigmine with anticholinergic (atropine or glycopyrrolate) 1
• Complete reversal: Usually within 8-10 minutes 1
• Critical warning: Do not attempt reversal at deep levels of block; ensure at least 2 twitches present to avoid residual blockade 2

Key Safety Considerations

Histamine Release

• Atracurium causes more histamine release than cisatracurium but less than d-tubocurarine 2
• Minimize risk by slow injection over 1-3 minutes for high-risk patients 2
• Consider H1/H2 receptor antagonist pretreatment in patients with severe asthma or anaphylaxis history 2

Hemodynamic Effects

• Hypotension occurs in approximately 60-64% of ICU patients receiving continuous infusion 5
• No significant difference in hypotension incidence compared to cisatracurium 5
• Monitor blood pressure closely, especially during initial infusion

Drug Interactions

• Potentiation: Aminoglycosides, magnesium, diuretics, antiarrhythmics, hypothermia, acidosis increase blockade duration 2
• Resistance: Burn patients require higher doses due to receptor upregulation 2
• Myasthenia gravis: Extreme sensitivity; use with caution and reduced doses 2

Practical Algorithm

1. Assess patient risk factors (cardiovascular disease, asthma, renal/hepatic failure)
2. Administer appropriate bolus (0.3-0.5 mg/kg based on risk)
3. Wait for early spontaneous recovery (first twitch returns)
4. Start infusion at 9-10 mcg/kg/min (OR) or 11-13 mcg/kg/min (ICU)
5. Titrate to TOF target of 1-2 twitches
6. Adjust for anesthetics (reduce by one-third with isoflurane/enflurane)
7. Monitor continuously with peripheral nerve stimulator
8. Reverse when appropriate (≥2 twitches present, spontaneous recovery begun)

The evidence strongly supports atracurium as an excellent choice for continuous infusion, particularly in patients with renal or hepatic dysfunction where its organ-independent elimination provides significant safety advantages 4, 1.