reliable early sign of malignant hyperthermia

Q: Out of the followings which is the most reliable early sign of malignant hyperthermia (MH)?

A) Hypercarbia 
B) Sinus tachycardia 
C) Masseter muscle rigidity
D) Generalized muscle rigidity
E) Hyperthermia


Answer: A

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.


Reference:

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.