From the Research
Managing trismus in intubated patients after muscle relaxant use requires prompt recognition and appropriate intervention, with the most recent and highest quality study suggesting that the use of neuromuscular blocking agents is associated with a decreased prevalence of procedure-related complications 1. To manage trismus, first ensure adequate sedation and analgesia with medications like propofol (50-200 mcg/kg/min), midazolam (1-2 mg IV), or fentanyl (25-100 mcg IV) to reduce muscle tension. If trismus persists, consider administering a non-depolarizing neuromuscular blocking agent such as rocuronium (0.6-1.2 mg/kg IV) or vecuronium (0.08-0.1 mg/kg IV) to achieve complete muscle relaxation, as supported by a study that found improved intubating conditions with the use of a muscle relaxant 2. Some key points to consider when managing trismus include:
- Maintaining the airway with the existing endotracheal tube and ensuring it is properly secured
- Monitoring ventilation parameters closely and adjusting as needed
- Investigating the underlying cause of trismus, which may result from inadequate reversal of neuromuscular blockade, masseter muscle spasm, or underlying conditions like malignant hyperthermia
- Temperature monitoring, especially if malignant hyperthermia is suspected
- Planning for a gradual weaning of muscle relaxants while maintaining adequate sedation, as trismus typically resolves as the effects of muscle relaxants completely wear off, but persistent cases may require further evaluation for other causes such as temporomandibular joint disorders or central nervous system pathology. It is also worth noting that the use of a muscle relaxant for tracheal intubation diminishes the incidence of adverse postoperative upper airway symptoms, results in better tracheal intubation conditions, and reduces the rate of adverse haemodynamic events, as found in a study comparing two induction regimens with and without muscle relaxant 2. Additionally, a study on the comparison of intubation conditions with and without the use of a muscle relaxant found that excellent conditions occurred more frequently in the relaxant group, and that a more flexible approach to the issue of the need for neuromuscular blockade prior to intubation is proposed 3. However, the most recent and highest quality study should be prioritized, which in this case is the study that found the use of neuromuscular blocking agents to be associated with a decreased prevalence of procedure-related complications 1.