MEDizzy - A patient with a medical history significant for Graves

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Infections due to Neisseria and others

A patient with a medical history significant for Graves disease develops a temperature of 106° F (41.1° C), tachycardia, and altered mental status 7 hours after undergoing elective cholecystectomy for symptomatic cholelithiasis. The differential diagnosis for this change of status includes infections, thyroid storm, and malignant hyperthermia of anesthesia. Which of the following statements is true regarding this clinical scenario?

ExplanationIn fever, the hypothalamic set point rises secondary to various inflammatory mediators. Intact thermal control mechanisms are brought into play to bring body temperature to the new set point. In hyperthermia, on the other hand, thermal control mechanisms fail, with the result that heat production exceeds dissipation. In the presence of infec- tion, pyrexia results from an altered hypothalamic set point, producing fever. Pyrexia associated with thyroid storm or malignant hyperthermia of anesthesia results from excess heat generation in conjunction with ineffective thermal control mechanisms. External cooling methods are appropriate in the initial treatment of hyperthermia but not necessarily fever. In fever, antipyretics should be administered first if possible. If this is not done, the body will continually try to reach the abnormally high set point of the hypothalamus, potentially resulting in the development of rigors during the cooling process. Rigors could develop during treatment of hyperthermia if the patient's temperature is lowered below the normal level. However, one would not expect rigors after the temperature had been lowered just 2° unless the set point had been elevated. The onset of significant pyrexia shortly after surgery makes the diagnosis of malignant hyperthermia of anesthesia very likely. Malignant hyperthermia of anesthesia usually develops during the initial stages of surgery, but it can develop several hours later. Although external cooling plays a role, the cornerstone of therapy is I.V. dantrolene sodium. Dantrolene is a muscle relaxant; it decreases the heat generated by involuntary muscle contractions. In thyroid storm, the set point should be normal, so antipyretics would not play a role.