What muscle relaxer has the least hemodynamic response?

Cisatracurium Has the Least Hemodynamic Response Among Muscle Relaxants

Cisatracurium is the muscle relaxant with the most stable hemodynamic profile, producing no dose-related effects on mean arterial blood pressure or heart rate even at high doses (2-8 x ED95), and unlike atracurium, it does not cause histamine release at therapeutic doses. 1

Hemodynamic Comparison of Common Muscle Relaxants

Cisatracurium (Most Hemodynamically Stable)

• No dose-related effects on MAP or heart rate following doses ranging from 2 to 8 x ED95 (0.1 to 0.4 mg/kg) administered over 5-10 seconds in healthy adults or patients with serious cardiovascular disease 1
• Specifically studied in 141 patients undergoing coronary artery bypass grafting (CABG) with comparable hemodynamic profiles to controls across the dose range 1
• Does not cause dose-related elevations in plasma histamine concentration at therapeutic doses (2-8 x ED95), unlike atracurium 1
• No clinically significant changes in MAP or heart rate in pediatric patients (ages 1 month to 12 years) receiving doses up to 0.15 mg/kg 1

Rocuronium (Mild Hemodynamic Effects)

• No dose-related effects on MAP over the dose range of 0.12 to 1.2 mg/kg (4 x ED95) within 5 minutes after administration 2
• MAP changes (≥30%) occurred in only 2-5% of geriatric and adult patients 2
• Mild vagal blocking activity can cause tachycardia (≥30% increase) in approximately one-third of adult patients under opioid/nitrous oxide/oxygen anesthesia 2
• Tachycardia occurred in 12 of 127 pediatric patients, particularly those anesthetized with halothane without atropine 2
• Does not release histamine even at large doses 3
• No significant changes in heart rate or mean arterial pressure in comparative studies 4

Atracurium (Significant Hemodynamic Effects)

• Produces significant reduction in mean arterial blood pressure and increased heart rate at all measurement times 5
• Results in significant increase in plasma histamine concentrations: 232% at one minute and 149% at three minutes from baseline 5
• 62% of patients receiving atracurium had clinical signs of histamine release (flushing, rash, or bronchospasm) 5
• The histamine release significantly correlated with decreased MAP and increased heart rate 5

Clinical Recommendations by Patient Population

Patients with Cardiovascular Disease

• Cisatracurium is the preferred choice for patients with serious cardiovascular disease, including those undergoing CABG surgery 1
• The hemodynamic stability has been specifically validated in this high-risk population 1

Patients with Renal or Hepatic Failure

• Benzylisoquinoline muscle relaxants (atracurium/cisatracurium) are recommended in cases of renal/hepatic failure due to organ-independent elimination 6
• Cisatracurium is preferred over atracurium because it is more potent, requiring lower doses and generating significantly less laudanosine metabolite 6
• Approximately 77% of cisatracurium is cleared by organ-independent Hofmann elimination 3

Pediatric Patients

• Cisatracurium shows no clinically significant hemodynamic changes across all pediatric age groups (1 month to 12 years) 1
• Rocuronium may cause tachycardia in pediatric patients, especially under halothane anesthesia without atropine 2

Important Caveats

Onset Time Trade-off

• While cisatracurium has superior hemodynamic stability, its onset time is significantly slower than rocuronium 3, 7
• Rocuronium achieves good intubating conditions within 60-90 seconds after 0.6 mg/kg, while cisatracurium requires 120 seconds at 0.15 mg/kg 1, 2
• For rapid sequence intubation where hemodynamic stability is critical, consider using a higher dose of cisatracurium (0.15-0.2 mg/kg) with appropriate timing 3

Histamine Release Considerations

• The key advantage of cisatracurium over atracurium is the absence of histamine release, which is the primary mechanism of atracurium's hemodynamic effects 1, 5
• Even small amounts of histamine release can cause clinically significant hypotension and tachycardia 5

Monitoring Requirements

• Regardless of which muscle relaxant is chosen, quantitative neuromuscular monitoring is essential to guide dosing and reversal 8
• Continue monitoring after reversal agent administration to detect potential recurarization 8