Instantaneous Rigor Causing Trismus During Cardiac Arrest Requiring Emergency Surgical Airway: A Case Report.

Instantaneous rigor, which is also known as cadaveric spasm, is a rare condition characterized by muscle rigidity occurring immediately at the moment of death, cardiac arrest, or peri-cardiac arrest. When it involves the temporomandibular joint, it can result in sudden trismus and create an unanticipated airway emergency during resuscitation. An elderly female in her late 60s was brought to the emergency department with altered sensorium and shortness of breath following a massive episode of hematemesis, along with progressive abdominal distension. She had underlying hepatitis C-related chronic liver disease. On arrival, she was critically ill with a Glasgow Coma Scale score of E1V1M2, unrecordable blood pressure, bradycardia, and signs of shock. During initial resuscitation, the patient developed cardiac arrest with asystole as the initial rhythm. Cardiopulmonary resuscitation was initiated; however, immediately following arrest, severe trismus developed, rendering bag-mask ventilation or orotracheal intubation impossible. An emergency front-of-neck access was promptly performed using surgical cricothyrotomy, and the airway was successfully secured within five minutes. Despite 30 minutes of advanced life support, return of spontaneous circulation was not achieved. Laboratory findings revealed severe anemia, coagulopathy, metabolic acidosis, hyperkalemia, and acute kidney injury. Instantaneous rigor is a rare but critical cause of sudden airway failure during cardiac arrest. Early recognition and prompt transition to a surgical airway are essential to avoid delays in ventilation. Emergency physicians should remain proficient in emergency surgical airway techniques to manage such unpredictable scenarios effectively.