Observational study on patterns of neuromuscular blockade reversal

Abstract

BackgroundUsing electronic health record data, we hypothesized that larger reversal doses are used for patients with deeper levels of neuromuscular blockade (NMB) as evidenced by the last recorded TOF measurement. We also examined if dosing regimens reflect current practice guidelines of using ideal body weight (IBW) for NMB agents and total body weight (TBW) for neostigmine.MethodsThis is a retrospective observational study of adult, ASA 1–4 patients who underwent general anaesthesia and received non-depolarizing NMB agents between 01/01/2004 and 12/31/2013. For the primary outcome, percentages of cases receiving neostigmine and median doses administered for each subjective train-of-four (TOF) category were calculated. Secondary analyses evaluated associations between NMB dosing and neostigmine administration based on Body Mass Index (BMI) categories.ResultsA total of 135,633 cases met inclusion criteria for the study. There was no clinically significant difference in median neostigmine dosing based on last TOF count prior to reversal administration: 37.5 mcg/kg for TOF of 4/4 vs. 37.9 mcg/kg for TOF of 0/4 for the total neostigmine dose. Significantly higher number of patients with lower TOF counts received additional neostigmine administration: 5.7 % for 0/4 vs. 1.5 % for 4/4 TOF counts. The median times to extubation following neostigmine administration were clinically similar across TOF count categories. The median doses for neostigmine based on TBW decreased with higher BMI categories and were significantly different between the lowest and highest categories: 42.8 mcg/kg vs 30.8 mcg/kg for total doses (p < .0001) respectively. The percentages of cases requiring reversal in addition to the initial dose increased with increasing BMI categories and were 2.1 % for BMI < 18 vs. 3.3 % for BMI ≥ 40. The total median dose of NMB agents in ED95 equivalents per IBW increased from 2.9 in the Underweight category to 4.2 in the Class III Obese category. The majority of patients in the pancuronium subgroup received very low ED95 equivalent dose of 0.1 and did not require reversal. Patients receiving cisatracurium were given significantly higher median ED95 equivalent dose of 5.6 vs 2.8–3.9 compared to other intermediate acting NMB agents, while receiving clinically similar doses of neostigmine.ConclusionsNeither neostigmine dosing nor times to extubation were affected by the depth of the neuromuscular blockade prior to reversal. The need for additional reversal, or rescue, correlated strongly with the depth of NMB. There was significant variability in neostigmine dosing across the BMI categories. Underweight patients received relatively lower NMB doses while simultaneously receiving relatively higher reversal doses, and the opposite was true for patients with BMI >40.

A retrospective observational study of neuromuscular monitoring practice in 30,430 cases from six Danish hospitals

“…Neostigmine was administered to half of all patients where a non‐depolarising NMB drug was given, at a mean dose of 32 µg.kg −1 , but predominantly in doses of a full or half vial, regardless of patient weight. The proportion of patients that received a reversal drug was considerably lower than in an American study where 86% received neostigmine, where only subjective neuromuscular monitoring was available . The use of objective neuromuscular monitoring in our study enabled anaesthetists to omit reversal in cases with spontaneous recovery to a TOF ratio > 0.9.…”

“…This probably explains the widespread use of a rather small standard dose of one or a half vial of neostigmine. This is in contrast to when only subjective neuromuscular monitoring is available, where it is reasonable to use a weight‐based dosing standard, as was also the case in the American study . In 6% of cases with neostigmine, reversal was administered at a TOF ratio > 0.9.…”

Reevaluation and update on efficacy and safety of neostigmine for reversal of neuromuscular blockade

“…It is recommended to initiate neostigmine under neuromuscular monitoring as well. However, a recent retrospective study indicated that neither the doses of neostigmine nor the duration to extubation were affected by the depth of the neuromuscular blockade prior to reversal, exposing discrepancies between existing guidelines and the actual clinical practice 63. More evidence are needed if the current concepts of timing of neostigmine administration are to be updated.…”