This topic has come up a couple of times in the CICM past papers, notably in Question 9 from the second paper of 2009 and in Question 1 from the second paper of 2002. Each time the college examiner failed to distinguish between hyperthermia and fever, which are distinct entities. To borrow a turn of phrase from Still (1979), fever is a regulated increase in body temperature associated with an increased hypothalamic temperature setpoint and thermopreferendum (the behavioural preference for an environmental temperature), whereas in hyperthermia the body temperature is elevated above this preferred homeostatic set point. As such causes of elevated body temperature shoud be classified in terms of whether the temperature is elevated because of the body's thermoregulatory mechanisms, or in spite of them.
However, for the purpose of answering questions on this topic, the trainees were not expected to discriminate between hypothermia and fever. As such Paul Marik's excellent article on fever remains a definitive resource for the person trying to generate a broad range of differentials. The need to generate such a range has come up several times in the CICM written papers. Given the broad range of things that can get infected (or non-infectiously inflamed) one can hardly call any list a "definitive" list. However, somewhere in one's cognitive arsenal one ought to have a table which looks like this, covering the major categories.
Infectious causes (i.e. sources) |
Noninfectious causes |
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Bota, Daliana Peres, et al. "Body temperature alterations in the critically ill."Intensive care medicine 30.5 (2004): 811-816.
Marik, Paul E. "Fever in the ICU." Chest Journal 117.3 (2000): 855-869.
Efstathiou, Stamatis P., et al. "Fever of unknown origin: discrimination between infectious and non-infectious causes." European journal of internal medicine21.2 (2010): 137-143.
Stitt, John T. "Fever versus hyperthermia." Federation proceedings. Vol. 38. No. 1. 1979.