When should Nimbex (cisatracurium) be used for tracheal intubation and skeletal muscle relaxation?

When to Use Nimbex (Cisatracurium)

Nimbex (cisatracurium) should be used as an adjunct to general anesthesia to facilitate tracheal intubation and provide skeletal muscle relaxation during surgery or mechanical ventilation in the ICU. 1

Primary Indications for Tracheal Intubation

Use cisatracurium to facilitate tracheal intubation, as muscle relaxants reduce poor intubating conditions from 24.6% to 4.1% and are strongly recommended. 2 The evidence demonstrates that muscle relaxant-free intubation is an independent risk factor for difficult intubation, with a large cohort of 103,784 patients showing poor intubating conditions in 6.7% without muscle relaxants versus 4.5% with them. 2

Dosing for Intubation

• For standard intubation: Use 0.15 mg/kg (3 x ED95) to achieve good-to-excellent intubation conditions in 2 minutes 1, 3
• For faster intubation: Use 0.2 mg/kg (4 x ED95) to achieve intubation conditions in 1.5 minutes 1, 3
• The clinically effective duration is 55 minutes for 0.15 mg/kg and 61 minutes for 0.2 mg/kg during propofol anesthesia 1

Important caveat: In elderly patients and those with renal dysfunction, extend the interval between cisatracurium administration and intubation attempt due to slower onset times. 1

Injury Prevention

Cisatracurium is recommended to reduce pharyngeal and laryngeal injury during intubation. 2 Without muscle relaxants, pharyngeal/laryngeal injury rates are 18.7-22.6%, which decrease to 9.7% with muscle relaxant use. 2 This reduction in airway trauma directly impacts patient quality of life by decreasing postoperative complications including vocal cord damage, hoarseness, and sore throat. 2

Intraoperative Muscle Relaxation

For maintenance of neuromuscular block during prolonged surgery, administer 0.03 mg/kg cisatracurium every 20 minutes. 1 Maintenance dosing is typically required 40-50 minutes after an initial 0.15 mg/kg dose and 50-60 minutes after a 0.2 mg/kg dose. 1

Critical consideration: When using volatile anesthetics (isoflurane or enflurane at 1.25 MAC), the duration of action is prolonged, but no initial dose adjustment is necessary if cisatracurium is given shortly after volatile agent initiation. 1

ICU Mechanical Ventilation

Severe ARDS

In early severe ARDS (PaO₂/FiO₂ < 150), use cisatracurium as a 48-hour continuous infusion: 15 mg bolus followed by 37.5 mg/hr. 4 This approach reduces adjusted 90-day mortality (hazard ratio 0.68, P = 0.04) and 28-day mortality (absolute difference -9.6%, P = 0.05). 4 The mortality benefit is most pronounced in patients with PaO₂/FiO₂ < 120. 4

Additional benefits in ARDS include:

• Increased ventilator-free days 4
• Increased ICU-free days 4
• Decreased barotrauma (pneumothorax develops more often without NMBAs) 4
• No increased risk of ICU-acquired weakness (MRC score < 48 rates were similar between groups) 4

General ICU Paralysis

For ICU patients requiring paralysis, significantly higher doses than standard surgical doses are required. 5 ICU patients needed 10 ± 4.7 ED95 (mean 38 ± 14 mg total) versus 3 ± 0.3 ED95 (mean 11 ± 2 mg) in elective surgery patients to achieve complete paralysis. 5 After standard 0.15 mg/kg dosing, 0/17 ICU patients were completely paralyzed versus 15/17 surgical patients. 5

Mandatory monitoring: Train-of-four (TOF) monitoring is essential in ICU patients due to altered pharmacodynamics and pharmacokinetics. 5 Target TOF of 1-2 out of 4 stimuli for optimal neuromuscular blockade. 6

Special Populations

Renal or Hepatic Dysfunction

No dose adjustment is necessary in renal or hepatic failure because cisatracurium undergoes organ-independent Hofmann elimination. 6, 7 However, onset time may be slightly prolonged (3.6 vs 3.1 minutes), and recovery shows wider inter-individual variability in renal failure patients. 7 Despite this, TOF monitoring remains essential to guide dosing. 7

Obese Patients

Calculate cisatracurium dose based on ideal body weight, not actual body weight. 6

Recovery and Reversal

Recovery to TOF ratio > 0.7 occurs within 34-85 minutes (mean 55 minutes) after discontinuation, regardless of organ function. 6 Recovery occurs approximately 7 minutes after neostigmine administration across all dose groups. 3

Critical pitfall: Never rely solely on clinical assessment for recovery; always use objective TOF monitoring, as recovery time can range from 20 to 270 minutes. 6

Common Pitfalls to Avoid

• Do not use peripheral nerve stimulation monitoring during the initial 48-hour infusion in ARDS (this was specifically not permitted in the landmark mortality trial) 4
• Be aware of tachyphylaxis with prolonged use, requiring higher doses to maintain effect 6
• Extend intubation timing in elderly and renal dysfunction patients to account for slower onset 1
• In ICU settings, standard surgical doses are inadequate—expect to use 3-4 times higher cumulative doses 5