1.Pathogenesis
Malignant hyperthermia (MH) is the only known genetic disorder that can cause perioperative death from conventional anesthetic medications. It is a subclinical muscle disease in which the skeletal muscle cell membranes of susceptible patients with malignant hyperthermia are congenitally defective and have a familial tendency. Under the action of triggering drugs (such as halogen-containing volatile anesthetics and succinylcholine, etc.), the concentration of calcium ions in myocytes accumulates rapidly and increases sharply, resulting in muscle contracture due to strong contraction of myocytes, a sharp increase in heat production, and a rapid rise in body temperature. Due to the elevated metabolism, a large amount of lactic acid and carbon dioxide are produced at the same time, and a series of changes such as acidosis, hypoxemia, hyperkalemia and cardiac arrhythmia occur, which can lead to death in serious cases.
2.Typical clinical manifestations
(1) Sudden onset of hypercapnia in patients with general anesthesia, progressive increase in end-expiratory CO2, which cannot be improved by increasing ventilation.
(2) The patient’s body temperature rises sharply, rapidly reaching 39 to 40 ℃, up to 45 ℃ ~ 46 ℃, sweating profusely.
(3) Skeletal muscle stiffness and even coracoacromial dystonia;
3.Clinical diagnosis
(1)According to the typical clinical manifestations
(2)Combine with relevant laboratory tests (mainly phosphocreatine kinase and myoglobin) myoglobinuria, if it can be quantified, it has more clinical diagnostic significance.
(3) Exclude possible causes of hypermetabolic state: e.g. hyperthyroidism, pheochromocytoma, severe systemic infections, idiopathic transfusion reactions and certain non-specific reactions.
(3) Exclude possible causes of hypermetabolic state, such as hyperthyroidism, pheochromocytoma, severe systemic infection, idiopathic transfusion reaction and some non-specific triggering drug reactions such as neuroleptic syndrome. Combining the above three aspects, it is possible to
The clinical diagnosis of “malignant hyperthermia” can be made. It is important to note that a caffeine-flurane isolated skeletal muscle contraction provocation test is also required to confirm the diagnosis of malignant hyperthermia.
Caffeine-flurane isolated skeletal muscle contraction excitation test is currently the gold standard for screening and confirming the diagnosis of malignant hyperthermia.
4.Treatment countermeasures
(1) Once MH is highly suspected, the use of inhaled anesthetics and other suspected drugs should be terminated immediately; replace the anesthesia machine or ventilator that is not exposed to volatile anesthetics.
Hyperventilate with high-flow pure oxygen; terminate the operation as soon as possible; and seek help from higher-level doctors at the same time.
(2) Dantrolene is an effective drug for malignant hyperthermia and should be administered intravenously as soon as possible if available;
(3) Immediately start systemic cooling (including physical cooling, intravenous cold saline infusion, intra-gastric ice saline irrigation, intracorporeal ice bath, extracorporeal circulation cooling, etc.). Effective
Effective cooling (especially central cooling) is the key to successful treatment of MH patients!
(4) Establish invasive arterial pressure and central venous pressure monitoring as early as possible, and perform continuous monitoring of urine output.
(5) Repeatedly review and monitor arterial blood gas, actively correct acidosis and rescue hyperkalemia;
(6) Prevent and actively treat cardiac arrhythmias;
(7) Infuse fluids according to the fluid balance and apply appropriate antihypertensive drugs and diuretics to stabilize hemodynamics and protect renal function;
(8) Application of adrenal corticosteroids;
(9) Postoperative patients are routinely transferred to the ICU, and monitoring and treatment should be strengthened to ensure that the patient safely passes the dangerous period;
(10) If the resuscitation is successful and the condition is stable, muscle specimens of the patient should be taken for skeletal muscle contraction test to clarify the diagnosis and further genetic testing should be performed. The patient’s immediate
The patient’s immediate family should also be advised to undergo relevant tests to screen for “susceptibles”. For those identified as susceptible to malignant hyperthermia, a preanesthetic evaluation should be performed to develop a
A reasonable anesthetic plan should be developed during the preanesthetic evaluation to avoid the use of sensitive drugs that may cause malignant hyperthermia and to avoid the recurrence of malignant hyperthermia.