feverofunknownorigin.pptVIP

Fever of Unknown Origin Bryan Youree Vanderbilt University Medical Center Objectives Definition and pathophysiology of fever FUO: classifications and etiology Diagnostic workup of FUO Prognosis Fever versus Hyperthermia Fever: resetting of the thermostatic set-point in the anterior hypothalamus and the resultant initiation of heat-conserving mechanisms until the internal temperature reaches the new level. Hyperthermia: an elevation in body temperature that occurs in the absence of resetting of the hypothalamic thermoregulatory center Mechanisms of Hyperthermia and Associated Conditions 1. Excessive heat production: exertional hyperthermia, thyrotoxicosis, pheochromocytoma, cocaine, delerium tremens, malignant hyperthermia 2. Disorders of heat dissipation: heat stroke, autonomic dysfunction 3. Disorders of hypothalamic function: neuroleptic malignant syndrome, CVA, trauma What is the normal human body temperature? A. 37.5° C B. 98.6° F C. 340.15 K D. Each human being is a unique individual, and therefore, normal temperature cannot be defined. What is the normal human body temperature? A. 37.6° C B. 98.6° F C. 340.15 K D. Each human being is a unique individual, and therefore, normal temperature cannot be defined. Wunderlich’s Maxim After analyzing 1 million axillary temperatures from ~25,000 patients, Wunderlich identified 37.0° C (36.2-37.5) as the mean temperature in healthy adults. Temperature readings 38.0° C were deemed as “suspicious/probably febrile.” Normal Body Temperature For healthy individuals 18 to 40 years of age, the mean oral temperature is 36.8° ± 0.4°C (98.2° ± 0.7°F) Low levels occur at 6 A.M. and higher levels at 4 to 6 P.M. The maximum normal oral temperature is 37.2°C (98.9°F) at 6 A.M. and 37.7°C (99.9°F) at 4 P.M. These values define the 99th percentile for healthy individuals. Normal Body Temperature Caveats Rectal temperatures are generally 0.4°C (0.7°F) higher than oral readings. Tympanic membrane (TM) values are 0.8°C (1.6°F) lower th