Hyperpyrexia
It is often said that fever never goes unnoticed by parents. I think most of us would agree with that and that there seems to be a direct correlation between the level of parental concern and the level of elevation of the mercury. The question, though, is whether the temperature of 106 degrees F should make us, as health care providers, more concerned.
Hyperpyrexia History
- In 1976 (that was a good year), McCarthy and Dolan used the term “hyperpyrexia” in relationship to a temperature of 41.1 C (106 F).
- They found it to be associated with an increased occurrence of serious bacterial infections, particularly meningitis.
- This, obviously, was prior to the widespread use of vaccinations against HiB and S. pneumoniae.
Hyperpyrexia: What it boils down to…
- The overall literature is inconclusive.
- In 1990, Alpert and Fleisher found no correlation between increased risk for serious bacterial infection and hyperpyrexia.
- State that kids with hyperpyrexia “need to be evaluated as thoroughly and carefully as any other febrile child but do not merit special consideration.”
- More recently, in 2006, Trautner et al found the following:
- Out of 130,828 patient visits, 103 had hyperpyrexia.
- Ages = 3months – 16.9 years.
- 58% had no identifiable cause!
- 22 / 103 had laboratory proven viral illness
- 20 / 103 had serious bacterial infection
- Bacteremia in 11 of the 20.
- UTI in 8 of the 20.
- 17% had an abnormal CXR.
- Those with underlying medical problems had more risk of serious bacterial infections.
- Neither age, nor the WBC (once again, it is the last bastion of the intellectually destitute), nor absolute neutrophil count were helpful in risk stratifying patients.
- Significant limitation: study population was prior to the widespread use of Prevnar vaccine; however, there were only 4 cases of S. pneumoniae.
- Would seem to indicate that kids with hyperpyrexia are at equal risk of having a Serious Bacterial Infection as they are of having a viral illness… although, again, 58% had no identifiable source.
- My humble assertion:
- First of all, nature doesn’t really draw lines in the sand… is there really a difference between 105.8 F and 106 F?
- The appearance of the child matters more than the number on the thermometer.
- 106 F does tend to grab providers’ attention and often results in more testing… which is understandable.
- If the child appears toxic, test everything and start empiric antibiotics! Then think of other stuff to cover (ie, HSV).
- If the child is not toxic, but has a temperature of 106, it is reasonable to check a blood culture based on the study above. I would also have a lower threshold for checking U/A, Urine culture and CXR.
- If you believe the child appears well enough to be treated as an outpatient, I don’t see any utility in checking a WBC, as it will not help you define a source nor will it help you risk stratify your patients with regards to serious bacterial infection.
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