Q: Out of the followings which is the most reliable early sign of malignant hyperthermia (MH)?
B) Sinus tachycardia
C) Masseter muscle rigidity
D) Generalized muscle rigidity
Malignant hyperthermia (MH) is a hypermetabolic crisis when a MH-susceptible (MHS) patient is exposed to a volatile anesthetic or succinylcholine. Interestingly, the most reliable initial clinical sign 'heralding' the development of MH is hypercarbia. This hypercarbia is usually resistant to increasing the minute ventilation on a ventilator. It is not uncommon to see PaCO2 >65 mmHg.
Larach MG, Gronert GA, Allen GC, et al. Clinical presentation, treatment, and complications of malignant hyperthermia in North America from 1987 to 2006. Anesth Analg 2010; 110:498.