During the Attack
MH is diagnosed on clinical grounds. A patient's heart rate is constantly monitored during an operation. Surgeons will be quick to notice an the start of an MH attack as a patient's heart rate is likely to dramatically increase as well as breathing. Patients will also tend to break out in a sweat and become rigid as muscle contraction occurs.
This may seem a very frightening thought, but fast treatment can stop an attack just as quickly as one begins.
Image taken from Flicr: www.flickr.com/photos/interplast/314471193/