Tachyphylaxis Associated with Continuous Cisatracurium versus Pancuronium Therapy

Study Objectives. To compare dosing requirements over time among patients receiving continuous cisatracurium versus pancuronium therapy, and to identify factors that may account for changes in pancuronium versus cisatracurium infusion requirements over time. Design. Retrospective, comparative cohort analysis. Setting. A tertiary level 1 trauma center. Patients. Forty‐five consecutive adult patients who were admitted to intensive care units at our institution from January 1998–August 2000 and received continuous cisatracurium or pancuronium therapy for at least 48 hours. Measurements and Main Results. Dosing requirements of patients treated with pancuronium or cisatracurium were recorded over time throughout the treatment period. Factors that could affect dosing requirements of a neuromuscular blocking agent (NMBA) were stratified as time invariant (admitting service, acute physiology and chronic health evaluation II score, duration of mechanical ventilation, pressure control ventilation, baseline hepatic or renal insufficiency, thermal injury, train‐of‐four assessment, and concurrent drug administration or disorders affecting neuromuscular transmission) or time variant (concurrent sedation and narcotic analgesia therapy; serum magnesium, potassium, and creatinine concentrations; arterial pH level; temperature; peak airway pressure; and partial pressure of oxygen:fraction of inspired oxygen ratio). Hierarchical linear modeling was used to compare the dosing requirements and to identify confounders affecting the relationship. The infusion rate escalation for the cisatracurium group was greater (0.39 μg/kg/min; 95% confidence interval [CI] 0.22–0.56; 23 patients) than for the pancuronium group (−0.06 μg/kg/min; 95% CI −0.24‐0.12; 22 patients; p