Prolonged Recovery of Neuromuscular Transmission during General Anaesthesia after Mivacurium Administration - Case Report

Introduction: Mivacurium is the shortest-acting nondepolarizing relaxant, used for brief procedures, such as those performed in the ambulatory setting. The recommended intubating dose of 0.2 mg/kg usually provides a clinically effective neuromuscular block for approximately 15 to 20 minutes and spontaneous recovery is 95% complete within about 25 to 30 minutes. Case presentation: 71-years-old woman was admitted for an elective laparotomy surgery with an intraoperative examination. Standard monitoring and TOF Scan (both the adductor pollicis muscle and the orbicularis oculi) were used. 8 mg dexamethasone, 0.1 mg fentanyl, 150 mg propofol, and 18 mg mivacurium were administered for induction. At the end of the procedure, there was no response from TOF. The return of neuromuscular transmission was achieved only after 75 minutes from the induction. Discussion: Mivacurium as a short-acting non-depolarizing muscle relaxant is well suited for short-term operations and operations of unpredictable duration. However, previous studies have shown that an extended neuromuscular block is likely in patients with significantly reduced plasma cholinesterase activity (especially in patients who are homozygous for the atypical plasma cholinesterase gene) as well as when administering some drugs and during other clinical situations. Conclusions: Extensively prolonged apnoea during general anaesthesia is a dangerous incident. Therefore, we still need systematic reviews to determine the prevalence of incidents of extended neuromuscular block after mivacurium. In case of prolonged muscle relaxation, we should think about possible reversible causes of this phenomenon since it is not always related to genetic causes. Furthermore, mechanical ventilation and close clinical monitoring are required during administering mivacurium. All of this to achieve the best possible patient outcomes.