Atracurium during halothane anesthesia in humans

Area of Science:

• Anesthesiology
• Pharmacology
• Neuromuscular Physiology

Background:

• Neuromuscular blocking agents are essential in anesthesia for facilitating endotracheal intubation and surgical procedures.
• Understanding the dose-response relationship and duration of action of atracurium is crucial for safe clinical application.
• Atracurium offers a potentially favorable profile due to its predictable, non-enzymatic degradation.

Purpose of the Study:

• To evaluate the neuromuscular effects of varying doses of atracurium.
• To determine the dose-response relationship and duration of neuromuscular blockade induced by atracurium.
• To assess the impact of atracurium on cardiovascular parameters and its antagonization.

Main Methods:

• Twenty patients undergoing anesthesia with 0.8% end-tidal halothane were studied.
• Neuromuscular blockade was quantified using electromyography of the adductor pollicis muscle following ulnar nerve stimulation.
• Patients received single atracurium doses of 0.1, 0.15, 0.2, or 0.4 mg/kg, divided into four groups of five.

Main Results:

• Atracurium doses of 0.1 and 0.15 mg/kg produced dose-dependent blockade (25-93%) with durations of 6-32 minutes.
• Doses of 0.2 and 0.4 mg/kg resulted in profound blockade (≥95%) lasting 42-104 minutes.
• Intubation was easily achieved with higher doses, and neuromuscular blockade was readily reversed by neostigmine and atropine, with minimal (<5%) cardiovascular changes.

Conclusions:

• Atracurium demonstrates a predictable dose-response relationship for neuromuscular blockade in patients anesthetized with halothane.
• Higher doses of atracurium provide prolonged blockade suitable for facilitating intubation.
• Atracurium exhibits a favorable safety profile with minimal hemodynamic impact and effective antagonization.