When do we treat fever?

[pspressman]

This misconception is actually more common, I think, among nurses, who frequently page that a patient is febrile, asking for tylenol (though that may be my recently-post-night-float bias).  Depending on the situation, decreasing the fever may actually harm the patient.

Here we have a metabolically expensive process preserved through 4 million years of evolution, and all too often we treat it as an annoyance.  We have known for years that fever is a physiologic response-- that endogenous pyrogens IL-1 and TNF-alpha are released by our own white blood cells for the express purpose of acting on our CNS to increase our preset body temperature.  Fever has been shown to enhance neutrophil and macrophage function, increase T cell proliferation, and inhibit microbial growth. Heat shock proteins are released during fever which promote cell survival during stress.  Several studies have shown the benefits of fever: some are listed below.

Several justifications have been offered for treating fever.  Some of these are reasonable, some are not.  Prevention of febrile seizures, for example, has NOT been demonstrated with use of antipyretics in double blind, placebo controlled trials.  Patient comfort may be considered with fever-- however, if you are prolonging or worsening their other symptoms by treating fever, as has been demonstrated in rhinovirus, chickenpox, malaria, and possibly influenzae, are you really helping the patient feel more comfortable?  Arguments have been made for decreasing oxygen consumption, reducing cardiovascular stress, and preventing fever associated mental status-- these are all somewhat controversial, so I could go either way on patients with these disorders.

In short, I would maintain that the only clinical scenario in which treating fever has been clearly justified by research is in acute brain injury, in which elevated temperatures have been associated with worse neurologic outcome. 

References:

Greisman, Lisa A. and Philip A Mackowiak. "Fever: beneficial and detrimental effects of antipyretics." Current Opinion in Infectious Diseases (2002) 15:241-245.

Mackowiak, Philip A. "Diagnostic Implications and Clinical Consequences of Antipyretic Therapy."  Clinical Infectious Diseases (2000) 31 Supplement: S230-233.

Ryan, Michael and MItchell M. Levy. "Clinical review: Fever in intensive care unit patients." Critical Care (2003) 7:221-225.

Shulman, Carl et al.  "The effect of antipyretic therapy upon outcomes in critically ill patients: a randomized, prospective study." Surgical Infections (2005) 6:369-375. 

[David Weingarten]

This is a great post, and I definitely think it's good information to have in your intellectual armamentarium, but I think that Fever Hysteria, especially in the ICU, centers more around finding the source of the fever than treating the fever itself.

Trying to decide when a fever is worth working up and when it's more likely just post-operative cytokine release or some post-operative aspiration pneumonitis is the big challenge.  Is this patient sick?  Do I need to have a nurse poke him 2 times (or more, depending on RN skill and pt body habitus) for blood cultures and labs?  Do I need to remove or replace his central line/A-line/PIV's?  Do I need to start broad-spectrum antibiotics?  In my mind, those are the much more important thoughts that should run through your mind when the RN calls you to report a "fever."

Still, this is nice data to have in the back of your mind for when an RN, patient or family member asks you why you're not giving the patient anything to bring his fever down.

-- David