Rocuronium resistance associated with rivastigmine transdermal therapy

Dear Editor, Cholinesterase inhibitors are widely used in patients with Parkinson’s disease dementia (PDD), and anesthesiologists are increasingly encountering these medications in the perioperative setting.[1] Because these drugs increase acetylcholine levels at the neuromuscular junction, they may interfere with the action of neuromuscular blocking agents (NMBAs). We describe a case of incomplete neuromuscular blockade with rocuronium in a patient using a rivastigmine transdermal patch. Institutional review determined that this to be exempt from consent requirements. A 73-year-old man with body mass index (BMI) 19.2) with PDD and chronic obstructive pulmonary disease on home oxygen presented for emergent sacral ulcer debridement. His medical history also included hypothyroidism and chronic hypotension. His home medications included rivastigmine 4.6 mg/24-hour patch, carbidopa-levodopa, ropinirole, and others. The rivastigmine patch was removed prior to surgery. General anesthesia was induced with fentanyl and propofol, followed by rocuronium 50 mg intravenously. Despite allowing adequate time for onset, the patient demonstrated a mild gag reflex during laryngoscopy. After being positioned prone, curare clefts were noted on capnography, and train-of-four monitoring showed four twitches with fade. Although the patient remained largely immobile, the findings suggested incomplete neuromuscular blockade. Because the procedure was brief (18 minutes) and the surgical exposure was acceptable, no additional NMBA was administered. Anesthesia was maintained with sevoflurane, and ventilation was adjusted to synchronize with spontaneous respiratory efforts. At the end of the case, sugammadex 200 mg was administered, and the patient was extubated without complication. His postoperative course was uneventful. Resistance to nondepolarizing NMBAs has been described in patients receiving acetylcholinesterase inhibitors, most commonly donepezil. Rivastigmine differs in that it inhibits both acetylcholinesterase and butyrylcholinesterase, which may further increase acetylcholine availability at the neuromuscular junction. This increased acetylcholine can competitively oppose steroidal NMBAs such as rocuronium, reducing their effectiveness. In our patient, other recognized causes of NMBA resistance, including chronic anticonvulsant therapy, upper motor neuron lesions, neuromuscular disorders, or prolonged critical illness, were not present. The interaction with rivastigmine, therefore, appeared to be the most likely explanation.[2] Managing such situations can be challenging. Administering additional rocuronium risks prolonged blockade in elderly patients. Using a benzylisoquinolinium agent such as atracurium or cisatracurium may introduce unpredictable effects due to potential synergism.[3] Reversal with neostigmine may be unreliable in patients already taking cholinesterase inhibitors, making sugammadex the more dependable option when steroidal NMBAs are used.[4] Whether cholinesterase inhibitors should be held prior to surgery remains controversial. Short-acting agents may be stopped the day before elective procedures; however, this is not feasible in urgent cases, and prolonged discontinuation may worsen cognitive symptoms. As the population ages and the use of dementia medications increases, anesthesiologists should remain aware of this interaction. Careful neuromuscular monitoring and close intraoperative communication are essential to ensure patient safety.[5] Further studies are needed to better guide perioperative management in patients receiving cholinesterase inhibitors. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.