Malignant hyperthermia (MH) is suspected or confirmed when an anesthesiologist is unable to bring down the levels of ETCO2 even if minute ventilation is increased to compensate that. If the muscle rigidity is seen this can further give a confirmatory diagnosis of malignant hyperthermia.
How Do You Treat Malignant Hyperthermia?
If the above mentioned signs are present and there is no other alternative clinical diagnosis suspected the treatment of malignant hyperthermia must be started on an urgent basis. Following protocol can be started if the treatment of malignant hyperthermia has to be started.
Hypercarbia (increased CO2) Management– An abnormal and sudden as well as an unexpected rise in the ETCO2 levels is one of the important and earliest signs of malignant hyperthermia.1 However, many other clinical or technical conditions can cause an increase in ETCO2.
Minute Ventilation Can Be Increased– if the hypercarbia comes down to the normal levels after increasing the minute ventilation, then such a hypercarbia is mostly unlikely to be caused by malignant hyperthermia. During anesthesia, the hypercarbia is mostly due to the hypoventilation. This can be treated by spontaneous ventilation or increasing the tidal volume.2
Obstructive Ventilation Should Be Corrected– If there are technical problems, then these might hamper the ventilation process and thus the CO2 levels will be increased. Malignant hyperthermia patient is assessed for any type of bronchial obstruction or any other condition like pneumothorax. The breathing circuits are closely monitored for any leaking or malfunctioning. Anesthesia machine needs to be thoroughly checked to see for any defects like lowering of the fresh gas flow or CO2 absorbent being exhausted or the tidal volume being undelivered even.
Oxygen And Ventilation Should Be Optimized– oxygen inspiration should be raised to a 100%. Ventilation rate and/or the tidal volume should be increased so that ventilation can be maximized and ETCO2 is reduced for malignant hyperthermia patients.
Triggering Drugs or Agents Should Be Immediately Discontinued– the volatile anesthetic agents should be discontinued immediately; and the operating surgeon should be informed about the diagnosis of malignant hyperthermia. The surgery usually needs to be terminated as immediately as possible. If the surgery cannot be terminated and needs to be completed, then the anesthesia is administered in an intravenous manner and non-triggering drugs should be used for the same. In such cases, propofol is the most often used drug.
Dantrolene Is Administered– the only known antidote for malignant hyperthermia till date is dantrolene. It should be administered intravenously in a bolus dose of 2.5mg/kg of body weight and then the dose should be subsequently lowered to a bolus dose of 1mg/kg of body weight till the signs of malignant hyperthermia are seen to be controlled. Dantrolene should be administered very rapidly if possible. The dantrolene brings the etco2 back to normal limits very quickly, usually within a few minutes and in most of the cases dantrolene is seen to reverse the acute hypermetabolic process. Generally, higher doses of dantrolene are not required, except for in some rarest of the rare cases where the patient is quite a muscular male. In fact, the diagnosis of malignant hyperthermia must be questioned by the clinician if a quick response to dantrolene is not visible.
Dantrolene should be adequately stocked in all the facilities where general anesthesia is administered for surgeries and procedures. Also, there should be a dedicated malignant hyperthermia treatment cart which must be ready and stocked at all times. Malignant hyperthermia association of the United States strongly recommends this as well.
Hyperkalemia Management– based on the abnormal ECG findings, hyperkalemia must be managed in order to prevent dangerous arrhythmias and cardiac arrest. Those who have a greater muscle-mass are more at a risk of hyperkalemia and precautions and treatment must be considered accordingly.
- Electrolytes, blood gases etc. are checked
- Acidosis, cardiac arrhythmias, hyperthermia etc. must be managed according to the signs and symptoms.
Malignant hyperthermia is a dangerous condition and requires a prompt diagnosis and an emergent treatment. In the absence of these, malignant hyperthermia can prove to be fatal.
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