| Clinical Grading Scale | |
| Process I: Muscle Rigidity Generalized rigidity Masseter rigidity | 15 15 |
| Process II: Myonecrosis Elevated CK >20,000 (after SCh administration) Elevated CK >10,000 (no exposure to SCh) Cola-colored urine Myoglobin in urine (>60 µg/L) Blood or plasma serum potassium >6 mEq/L | 15 15 10 5 3 |
| Process III: Respiratory Acidosis PetCO2 >55 mm Hg with controlled ventilation PaCO2 >60 mm Hg with controlled ventilation PetCO2 >60 mm Hg with spontaneous ventilation Inappropriate hypercarbia Inappropriate tachypnea | 15 15 15 15 10 |
| Process IV: Temperature Increase Rapid increase in temperature Inappropriate temperature (>38.8ºC in perioperative period) | 15 10 |
| Process V: Cardiac Involvement Inappropriate tachycardia Ventricular tachycardia or fibrillation | 3 3 |
| Total Score | >50 (almost certainly MH) 35–49 (very likely MH) |
CK = creatine kinase; MH = malignant hyperthermia; SCh = succinylcholine.