Accelerated recovery from pipecuronium in patients treated with chronic anticonvulsant therapy

Abstract

Study Objective: To determine whether chronic anticonvulsant therapy affects recovery time from pipecuronium. Design: Open-labeled, controlled study. Setting: Inpatient neurosurgical service at a university medical center. Patients: ASA physical status II and III patients within 30% of their ideal body weight and without significant history of ethanol abuse or renal or hepatic disease. Nineteen patients were admitted into the study and were divided into three groups based on the number of anticonvulsant medications (MED) they were taking: MED = 0, control group (6 patients); MED = 1, one anticonvulsant (6 patients); MED = 2, two or more anticonvulsants (7 patients). Interventions: Intravenous (IV) administration of pipecuronium 80 μg/kg with general anesthesia after thiopental sodium 4 to 6 mg/kg IV, maintained with 70% nitrous oxide in oxygen, 0.2% to 0.3% end-tidal isoflurane, and fentanyl. Measurements and Main Results: The evoked compound electromyogram (ECEMG) of the adductor pollicis brevis muscle was measured after stimulation of the ulnar nerve by train-of-four (TOF) supramaximal impulses at 2 Hz repeated every 20 seconds. Measurements include T-1 % (ECEMG signal at 25%, 50%, and 75% of baseline), TR% (TOF ratio), and recovery index (RI). Patients administered chronic anticonvulsant therapy recovered more rapidly from pipecuronium than untreated patients. For instance, time to 25% recovery of baseline (T-1 25%) was 123 ± 13 minutes for MED = 0, 91 ± 7 minutes for MED = 1, and 58 ± 5 minutes for MED = 2 (p < 0.05). TOF recovery to 20% (TR 20%) and RI were similarly affected. Conclusions: Patients treated with chronic anticonvulsant therapy recovered from pipecuronium more rapidly than unmedicated patients. Furthermore, there seemed to be a dose-effect relationship between the number of anticonvulsants received and a decreased time to recovery from pipecuronium neuromuscular blockade.