Edrophonium requirements for reversal of deep neuromuscular block following infusion of mivacurium

Reversal of mivacurium-induced neuromuscular blockade with a cholinesterase inhibitor: A systematic review

BACKGROUND

Mivacurium is a short-acting non-depolarizing muscle relaxant, which is hydrolyzed by butyrylcholinesterase. The neuromuscular block (NMB) can be antagonized with cholinesterase inhibitors (CHEI), but the short duration of action of mivacurium questions the need. This systematic review evaluated if the use of CHEIs (neostigmine, pyridostigmine or edrophonium) facilitates reversal of mivacurium-induced NMB.

METHOD

Randomized controlled trials and crossover-studies comparing spontaneous recovery with CHEI reversal in patients with mivacurium-induced NMB, assessed with quantitative neuromuscular monitoring, were included. Mean time from injection of the CHEI or allowing of spontaneous recovery to an endpoint representing full recovery was used as outcome. First response to train-of-four nerve stimulation (T₁ ) described the level of NMB for administration of the CHEI. Moderate NMB refers to T₁  ≥ 5% and deeper NMB refers to T₁  < 5%. Systematic critical appraisal was performed using the Scottish Intercollegiate Guidelines Network guidelines. Overall quality assessment was done using the Grading of Recommendations Assessment, Development and Evaluation approach.

RESULTS

Sixteen studies with data from 546 patients were included. Low quality of evidence was found that neostigmine and edrophonium administered at moderate NMB accelerated recovery with up to approximately 5.5-6.5 and 6.5-9.0 minutes, respectively. At deeper NMB only edrophonium accelerated recovery. The effect of neostigmine was not clarified at deeper mivacurium-induced NMB. No studies with reversal by pyridostigmine were identified.

CONCLUSION

Low quality of evidence supports that neostigmine and edrophonium accelerate the recovery of mivacurium-induced NMB with 5-6.5 and 6-9.0 minutes respectively, when administered at moderate NMB. At deeper NMB only edrophonium accelerated the recovery.

The quantitative distinction between train-of-four "counts of 2" and posttetanic "counts of 2" evidenced by a stable paralysis/stable infusion rate method in anesthetized patients receiving mivacurium

In this study we quantitatively evaluated, by a stable paralysis/stable infusion rate method, the difference between two standardized paralysis levels--train-of-four (TOF) count of 2 responses and posttetanic count (PTC) of 2. Ten ASA physical status I-II consenting adult patients scheduled for elective surgery were anesthetized (sufentanil/propofol), tracheally intubated, mechanically normoventilated with a fixed O(2)/air mixture, and normothermic; oropharynx and thenar temperatures were maintained above 36 degrees and 32.5 degrees C, respectively. After partial recovery from 200 microg/kg mivacurium (MIV), stable tactile TOF and PTC counts of 2 paralysis levels were induced on the adductor pollicis muscle by manual adjustments of an infusion pump containing MIV. The paralysis levels and the infusion rates were considered as stable once they remained constant at 4 consecutive time points separated by 5 min each. Infusion rates observed were: TOF count 2-6 (2-11) and PTC 2-17 (3-18) microg . kg(-1) . min(-1) (P < 0.001; Wilcoxon's paired comparison test). Under the present conditions, obtaining and maintaining a PTC of 2 requires MIV infusion rates far in excess of the "standard" recommendations mentioned in the literature for MIV infusion management.

Prolonged paralysis following mivacurium administration

Mivacurium is a benzylisoquinolone, choline-like, non-depolarizing muscle relaxant. Its onset of action is similar to that of atracurium but its duration of action is shorter (approximately 10-15 minutes). Mivacurium is metabolized by plasma cholinesterases at approximately 70% of the rate of metabolism of suxamethonium. Deficiency or abnormality of plasma cholinesterase may cause the duration of action of both suxamethonium and mivacurium to be greatly prolonged. We describe a case of prolonged mivacurium paralysis after day surgery. Laboratory investigations showed a genetic tendency toward abnormal cholinesterase levels, but markedly depressed cholinesterase activity was suggestive of additional acquired causes. This patient had a history of liver disease, malnutrition and anticholinesterase use, which we believe were the most significant factors involved.

Neostigmine requirements for reversal of neuromuscular blockade following an infusion of mivacurium

PURPOSE

To study the efficacy of neostigmine compared with placebo for the antagonism of neuromuscular blockade at the end of a mivacurium infusion, and to determine its optimal dose.

METHODS

One hundred adult patients undergoing an elective surgical procedure received a standardized anaesthetic with 20-30 micrograms.kg-1 alfentanil, a propofol infusion and nitrous oxide. Muscle relaxation was maintained at 90-95% T1 depression with 0.2 mg.kg-1 mivacurium followed by an infusion. Neuromuscular blockade was measured with an integrated evoked electromyogram in response to train-of-four (TOF) stimuli at the ulnar nerve every 20 sec. Patients were randomized into four groups. At the end of surgery, the mivacurium infusion was stopped and patients received, immediately, in a double-blind manner, neostigmine (10, 20, or 40 micrograms.kg-1) or placebo according to a random number table. The T1 and TOF ratio were recorded until adequate recovery of neuromuscular function (TOF ratio > 0.70). During the reversal period, non-invasive blood pressure and heart rate were recorded every minute. The incidence of postoperative nausea and vomiting (PONV) was recorded in the recovery room.

RESULTS

Data from 94 patients who completed the protocol were analysed. Compared with placebo, neostigmine 10 micrograms.kg-1 did not reduce the time to TOF > 0.70 (17.0 +/- 5.1 vs 14.6 +/- 4.2 min respectively). However the time was decreased with neostigmine 20 micrograms.kg-1 and 40 micrograms.kg-1 (P < 0.001), but with no difference between these last two groups (11.4 +/- 3.0 and 11.4 +/- 3.5 min respectively). Changes in systolic blood pressure and heart rate were not different between the four groups. Very few PONV events were observed in all groups (global incidence 7.4%).

CONCLUSION

Recovery of neuromuscular blockade following a mivacurium infusion is accelerated by neostigmine. A dose of neostigmine 20 micrograms.kg-1 appears optimal with no further reduction in recovery time obtained from a larger dose.