Conditions Requiring Higher Doses of Nimbex (Cisatracurium)
Several clinical conditions may require higher doses of cisatracurium (Nimbex) than usual, with obesity being a notable exception where dosing should be based on ideal body weight rather than actual body weight.
Physiological Conditions Requiring Higher Doses
Burns: Patients with burns develop resistance to non-depolarizing neuromuscular blocking agents and may require individualization of dosing with potentially higher doses 1
Up-regulation of nicotinic acetylcholine receptors: Occurs in conditions with chronic damage to motoneurons, extensive deep burns, or prolonged critical illness, requiring higher doses of non-depolarizing muscle relaxants due to reduced sensitivity 2
Hypothermia: Unlike rocuronium, cisatracurium's duration of action is affected by body temperature, with each degree Celsius decrease in core temperature extending the duration of action by approximately 9.8 minutes 3
Prolonged administration: The duration of neuromuscular blockade with cisatracurium may increase with longer administration times, requiring careful monitoring and potential dose adjustments 3
Disease States Affecting Cisatracurium Requirements
ARDS requiring neuromuscular blockade: Patients with moderate to severe ARDS who cannot achieve lung-protective ventilation with deep sedation alone may require continuous cisatracurium infusion, typically starting with a 15 mg bolus followed by 37.5 mg/h for up to 48 hours 2
Patients with dyssynchronous ventilation: Those who are persistently hypoxemic, ventilated in prone position, or at risk for injurious ventilation may require higher doses of cisatracurium to achieve adequate neuromuscular blockade 2
Anesthetic Considerations
Inhalation anesthetics: When cisatracurium is administered during stable isoflurane or enflurane anesthesia, the infusion rate should be reduced by 30-40%, suggesting that in their absence, higher doses may be needed 1
Prolonged surgical procedures: During long surgical procedures with enflurane or isoflurane anesthesia, less frequent maintenance dosing or lower maintenance doses of cisatracurium may be necessary, indicating that higher doses might be needed in other anesthetic contexts 1
Important Exceptions - When to Use Lower Doses
Obesity: Despite requiring higher doses of many medications, obese patients should receive cisatracurium based on ideal body weight rather than actual body weight 2, 4
Neuromuscular diseases: Patients with myasthenia or primary muscle damage (myopathies) show increased sensitivity to non-depolarizing muscle relaxants and require 50-75% reduction in cisatracurium dosing 2
Renal/hepatic failure: Benzylisoquinoline muscle relaxants like cisatracurium are recommended in these conditions, but dosing should be carefully monitored 2
Monitoring Recommendations
Train-of-four (TOF) monitoring: Essential for individualizing cisatracurium dosing in all patients, especially those with conditions that might alter drug response 2
Titration to clinical effect: When higher doses are needed, cisatracurium should be titrated to the desired level of neuromuscular blockade using peripheral nerve stimulation to guide dosing 1
Continuous assessment: For patients receiving cisatracurium infusions, regular assessment of neuromuscular function is crucial to avoid overdosing while maintaining adequate blockade 2
Remember that cisatracurium dosing should always be individualized based on neuromuscular monitoring, and higher doses should only be administered with appropriate monitoring capabilities in place 1.