Masseter Muscle Rigidity After Initiating Monitored Anaesthesia Care of Propofol and Remifentanil

Abstract

Masseter muscle rigidity can be seen following administration of opioids, succinylcholine, and nondepolarizing muscle relaxants. We report a case of a 56-year-old male patient in a “Cannot Intubate Cannot Ventilate Situation” due to masseter muscle rigidity after initiating monitored anaesthesia care (MAC) with remifentanil and propofol using target-controlled infusion in procedural cardiology. For rapid effect and equilibrium between plasma-concentration and effect site-concentration using target-controlled infusion, remifentanil overdose is possible during the induction period of MAC. Moreover, the presence of propofol could result in a significantly greater remifentanil concentration. To manage masseter muscle rigidity, muscle relaxants and emergent ventilation systems should be prepared to secure airway maintenance. In addition, alternative airway management devices and techniques should be on hand even if no airway difficulties are expected.