Increased anesthetic risk has been observed in patients with myotonic dystrophy. In the perioperative period, evaluating the risk to myotonic dystrophy patients and selecting appropriate anesthetic drugs, opioids, and doses of neuromuscular blockade during surgery is important.
Mathieu et al. reported a perioperative complication rate of 8.2% and showed that the majority of them were found in the respiratory systems [3]. Using multivariate analysis, they also revealed that the risk of perioperative pulmonary complications was significantly higher after an upper abdominal surgery (odds ratio (OR) 24.4, 95% CI 4.0 to 149.3) and for patients with proximal limb weakness (OR 14.1, 95% CI 1.5 to 134.4).
The patients was predicted to be at high risk. In fact, the patient was constantly in a poor respiratory condition and symptoms were classified as grade 4 in the muscular impairment rating scale (grade 4, “mild to moderate proximal weakness”) [4], an elevated risk of postoperative respiratory complications was suggested from the preoperative stage. Moreover, if in non-surgical cases, we experienced a case with undiagnosed myotonic dystrophy who developed a sudden onset of dyspnea and required long-term respiratory management [5], and we need to be aware of patients with myotonic dystrophy type 1, including the possibility of sudden clinical changes.
In our clinical case, we used remimazolam followed by its antagonist flumazenil to prevent postoperative respiratory complications. Moreover, this case report is the first to present the use of remimazolam for general anesthesia in an ERCP patient with myotonic dystrophy type 1.
Remimazolam is a benzodiazepine drug, similar to midazolam, and has a mild muscle relaxant effect. This negative effect may exert adverse events such as respiratory depression and paralysis especially in patients with myotonic dystrophy. On the other hand, the advantages of remimazolam include less circulatory depression [6], fewer injection-site reactions during administration, and the availability of flumazenil to reverse the sedative effects. Remimazolam is also an ultra-short-acting intravenous anesthetic that is rapidly metabolized, primarily by hepatic tissue esterases, and its metabolites lack any activity, representing another benefit [2, 7]. These characteristics of remimazolam make the agent effective and safe for a wide range of patients undergoing general anesthesia, including the elderly, patients with unstable circulation and patients with respiratory failure. Doi et al. also reported that the safety and efficacy of remimazolam for inducing and maintaining general anesthesia, even in high-risk surgical patients (ASA-PS ≥ 3) [8]. Half of the participants showed comorbidities such as cardiovascular, metabolic, and respiratory failures. We speculated that no patients in that study were suffering from neuromuscular disease, and the use of remimazolam for such patients remains unverified.
Several studies on remimazolam as a sedative have been published and the efficacy of remimazolam has been introduced. Chen et al. demonstrated that remimazolam could provide safe, effective sedation for patients undergoing upper gastrointestinal endoscopy [9]. The present study suggests that remimazolam allows rapid recovery from sedation and has lower potential to cause cardiovascular and respiratory depression compared with propofol. In another study, Chen et al. also demonstrated that hypotension and respiratory depression as adverse events were decreased in a remimazolam group compared to a propofol group for colonoscopy [10]. As noted in these reports about remimazolam use, during the induction and maintenance of anesthesia, blood pressure was stable with no problems. Intraoperatively, we maintained BIS stability at around 60. After remimazolam administration was ended, the patient immediately emerged from anesthesia and the use of flumazenil improved the quality of awakening. Sinclair et al. demonstrated that a muscle relaxant without reversal was an independent risk factor in children with myotonic dystrophy [11]. This study was limited to pediatric cases; the conclusions might be different compared to adult ones. Remimazolam is not a muscle relaxant but does have a mild muscle relaxant effect; we judged to use flumazenil to antagonize remimazolam effect fully. Postoperative respiratory complications thus did not appear to arise in this case.
Verification of the effects of remimazolam and of those cases requiring flumazenil antagonism is necessary, along with an investigation of appropriate cases for remimazolam use in the future. However, at least in this clinical case, stable anesthesia management was possible, and postoperative respiratory complications were not encountered using remimazolam.
