What are the symptoms and treatment for an atracurium (muscle relaxant) overdose?

Atracurium Overdose: Symptoms and Treatment

The treatment for atracurium overdose requires immediate airway management, ventilatory support, cardiovascular monitoring, and administration of anticholinesterase agents with anticholinergics for reversal. 1

Symptoms of Atracurium Overdose

• Enhanced pharmacological effects including prolonged neuromuscular blockade, which manifests as complete muscle paralysis and inability to breathe 1
• Cardiovascular effects primarily due to histamine release, which may cause:
  • Hypotension 1
  • Increased heart rate (up to 27% increase has been documented) 1
  • Mean arterial pressure changes (13% increase has been reported) 1
• Respiratory paralysis is the primary cause of death in overdose cases if not managed promptly 1

Diagnostic Approach

• Train-of-four (TOF) monitoring is the most reliable method for evaluating the degree of neuromuscular blockade and should be used to assess overdose severity 2, 3
• Clinical assessment of complete muscle paralysis, including absence of respiratory effort 1
• Cardiovascular monitoring to detect hemodynamic changes related to histamine release 1

Treatment Protocol

Immediate Management

• Secure the airway and provide mechanical ventilation to prevent death from respiratory paralysis 1
• Proper patient positioning to optimize ventilation and circulation 1
• Fluid administration to support blood pressure if hypotension occurs 1
• Vasopressor agents may be necessary if hypotension persists despite fluid resuscitation 1

Pharmacological Reversal

• Anticholinesterase agents should be administered to facilitate recovery:
  • Neostigmine 1
  • Edrophonium 1
  • Pyridostigmine 1
• Always administer with an anticholinergic agent to prevent muscarinic side effects:
  • Atropine 1
  • Glycopyrrolate 1

Monitoring During Recovery

• Continuous peripheral nerve stimulation to monitor recovery from neuromuscular blockade 2, 3
• Target TOF ratio >0.7 which typically indicates adequate recovery of neuromuscular function 4
• Extended monitoring period as overdose can significantly prolong duration of action:
  • In pediatric patients, recovery time after 5-6 times the normal dose was 50-55 minutes 1
  • In adults, recovery time after overdose can be approximately twice normal (83 minutes vs. 35-45 minutes) 1

Special Considerations

• Laudanosine accumulation - a breakdown product of atracurium that may accumulate with prolonged high-dose infusions or overdose 4, 5

  • Can theoretically cause central nervous system excitation at extremely high doses 5
  • However, even with prolonged infusions, laudanosine levels typically remain below seizure-inducing thresholds 6, 7

• Patients with renal impairment may have higher laudanosine concentrations due to decreased elimination 7

• Cross-resistance can occur in rare cases where patients develop resistance to both atracurium and other neuromuscular blocking agents, making management more challenging 8

Prognosis

• With proper supportive care and monitoring, complete recovery is expected 1
• Recovery time is dose-dependent but typically occurs within 45-96 minutes after discontinuation of the drug, even in overdose situations 7
• Mortality is primarily associated with failure to secure the airway and provide adequate ventilatory support 1