Canis ISSN: 2398-2942

Anesthesia: reversal of neuromuscular blocking agents

Contributor(s): Elizabeth Leece, Alexander Valverde

Introduction

  • Whenever using neuromuscular blocking agents it is essential to understand what governs the duration of blockade with each of the different agents and how different disease states can alter recovery.
  • Reversal of blockade can be performed if required and the agents used and the problems associated with this technique should be understood.
  • Since clinically relevant doses of the neuromuscular blocking agents cause paralysis of the musculature involved in respiration it is vital to be able to monitor respiratory function and allow the patient to recover from anesthesia only when ventilatory function has returned to normal.
  • Monitoring the degree of neuromuscular blockade Anesthesia: monitoring of neuromuscular blockade is also extremely helpful in determining the recovery following administration of these drugs.
  • It is recommended that reversal is not attempted in the presence of complete blockade.
  • Reversal of neuromuscular blockade may not be necessary in a patient that has a full return of train-of-four (TOF) and double burst suppression (DBS) on nerve stimulation and has normal ventilatory function.

Uses

  • To restore normal neuromuscular transmission following non-depolarizing block by raising Ach concentration in the synaptic cleft by using anticholinesterases.

Disadvantages

  • Effects of anticholinesterases at muscarinic receptors are potentially undesirable, eg bradycardia, bradyarrhythmias, bronchoconstriction, bronchosecretion, gastrointestinal hypermotility and hypersecretion. Prevented by the concurrent administration of antimuscarinic drugs, eg atropine Atropine and glycopyrrolate Glycopyrronium.
  • The ability of different anticholinesterases to antagonize neuromuscular block depends on:
    • The muscle relaxant present.
    • The method by which the block was maintained (repeat dose or infusion).
    • The dose of anticholinesterase injected.
    • The degree of block present when antagonism is attempted (the greater degree of spontaneous recovery present, the greater the chance of successful antagonism).
  • Anticholinesterases augment neuromuscular block when phase I block is present.

Preparation

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Procedure

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Aftercare

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Outcomes

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Further Reading

Publications

Refereed papers

Other sources of information

  • BSAVA Manual of Small Animal Anaesthesia and Analgesia. (1999) Seymour C & Gleed R D (eds).


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