The introduction of a lightweight mini vaporizer and malignant hyperthermia

To the Editor, The introduction of a lightweight mini vaporizer (AnaConDa; Sedana Medical, Sweden) that can be used with an intensive care unit (ICU) ventilator has led to a resurgence of interest in the use of potent volatile agents as an alternative to intravenous agents for longterm sedation or for treatment of status asthmaticus in patients requiring tracheal intubation. In an editorial comment concerning the use of sevoflurane for treatment of status asthmaticus, Wasowicz and Jerath review the benefits of using volatile anesthetics for these reasons and mention several of the potential dangers of administration of potent volatile anesthetic agents outside the operating room environment. Unfortunately, what is omitted from their discussion is the mention of the risk of malignant hyperthermia (MH), although the danger of MH is stated clearly in the report by Ruszkai et al. To underline this possibility, at the European Malignant Hyperthermia Group meeting in May 2014, Johannsen et al. reported on the development of MH in an ICU patient sedated with sevoflurane. In their case, the AnaConDa device was used for management of pneumonia in a 59-yr-old man and MH developed after five hours of sevoflurane anesthetic sedation. The signs included acute hemodynamic deterioration, metabolic and respiratory acidosis, increase of body temperature from 39.6-40.7 C over 30 min, and elevation of creatine kinase to 3,450 U L. Fortunately, the clinicians recognized the signs of MH and treated with dantrolene, and the patient survived. A subsequent in vitro contracture test substantiated the clinical diagnosis of MH. Although only low concentrations of potent volatile agents are used to achieve sedation in the ICU, the risk of developing MH still exists, and appropriate therapy with dantrolene and supportive care must be immediately available. Because early symptoms of developing MH crisis are rather non-specific and can be misleading to other more frequent diagnoses, e.g., sepsis, the awareness of MH is crucial for ICU physicians of any medical specialty wherever volatile anesthetics are applied. It is recommended that, when MH occurs as a result of sedation with volatile anesthetics, the details should be reported to the appropriate MH registry or similar database. Certainly, the Malignant Hyperthermia Association of the United States (www.mhaus.org) as well as the European Malignant Hyperthermia Group (www.emhg.org) would be interested in learning of such cases.