Fever in Kids:Fever in Kids:
Lou Romig MD, FAAP, FACEP
Miami Children’s Hospital
Hot TopicsHot Topics
What is fever?
Facts and fallacies about fever
Febrile seizures
How and why to treat kids with fever
What is fever?What is fever?
Fever is a neurochemical response common to many animals
Controlled in the human hypothalamus and mediated by numerous endogenous and exogenous chemicals
What is fever?What is fever?
Nerves in the hypothalamus maintain a normal “set point” temperature, usually in a range around 37C (98.6F)
Set point varies in a circadian rhythm with lowest at around 4am and highest between 4-8pm
What is fever?What is fever?
Endogenous pyrogens can cause:
body temp
sleepiness
appetite
Increased immune response
What
about
the
numbers?
What’s “normal”?What’s “normal”?
Most common definitions are based on a study by Wunderlich in 1868
“Normal” 37C (98.6F)
“Upper limit of normal” 38C (100.4F)
Weaknesses: thermometry used, use of axillary temps
What’s “normal”?What’s “normal”?
Mackowiak and Wasserman 1992: 700 oral temps in 148 healthy young
adult subjects
Individual variation precludes the assignment of any single temperature as the normal.
Range 35.6(96.0) – 38.2(100.8)
What’s “normal”?What’s “normal”?
There is no substantiation to the belief that the elderly have lower body temps normally
A higher normal range of temp in children has not been documented in the research
What’s “fever”?What’s “fever”?
Mackowiak and Wasserman:
Any oral temp >37.2C (98.9F) in the early morning
Any oral temp >37.8C (100F) at any time
ThermometryThermometry
Gold standards are rectal for children and oral for older children and adults
Axillary temps are not reliable and may vary as much as 1°C from rectal
There is no reliable conversion factor for axillary vs rectal temps
ThermometryThermometry
Tympanic thermometry is not accurate and may be technique-dependent
Infrared temporal artery (TA) thermometry is only slightly better than tympanic thermometry
TA temps are consistently lower than rectal temps but there is no reliable conversion factor
How hot is
“high”?
How hot is “high”?How hot is “high”?
Dubois, 1949
Human upper limit of fever 41 – 42C (105.8-107.6F)
Almost never exceeds 42C unless there’s a failure in thermoregulation
How hot is “high”?How hot is “high”?
McCarty and Dolan, 1976
40C (104F) may be the upper limit of fever in infants <12 weeks old
Remember that young infants can have infections with normal or lowered body temps
Fever can cause
damage…
Why the concern?Why the concern?
Seizures and complications
Brain damage because of the infection causing the fever (meningitis or encephalitis)
Fact or fiction?Fact or fiction?
No human studies published
Animal studies suggest that a body temp of >42C (107.6F) in humans may trigger enough adverse effects on a cellular level to cause death
Fact or fiction?Fact or fiction?
Animal studies:
T> 105 may cause respiratory alkalosis and occasional electrolyte imbalances
T > 105.8 may cause cellular swelling and damage in the brain, kidneys and liver
An infection is more dangerous if it gives a high fever or if the fever doesn’t come down with
treatment…
Hi temp = “bad” infection?Hi temp = “bad” infection?
No studies have conclusively proven any
correlation between height of temperature and
outcome of an infection or disease outcome.
Hi temp = “bad” infection?Hi temp = “bad” infection?
Several studies suggest that children with temperatures greater than 41°C (105.8°F)
have a greater chance of having a serious bacterial illness.
Hi temp = “bad” infection?Hi temp = “bad” infection?
Several studies suggest that fever of ≥ 40°C (104 °F) signals
increased risk of serious bacterial illness for infants from
birth to three months of age.
Poor response to tx = bad?Poor response to tx = bad?
Failure of antipyretics to control fever has not been proven to correspond with severity of illness.
Improved general appearance after antipyretics may indicate a less severe illness.
Cover up if you have chills!Cover up if you have chills!
What’s cookin’ with chills?What’s cookin’ with chills?
Chills are evidence of the hypothalamus causing the body to generate heat to reach the altered set-point.
Covering up will only keep in the heat.
Don’t give milk to babies Don’t give milk to babies with fever!with fever!
Oh, Puhleeez!
““Doin’ the fever flop”Doin’ the fever flop”
Characteristics of F.S.Characteristics of F.S.
Incidence of 2-5% in US
6 mo – 3 yrs, median 18-22 mo
Boys more often than girls
Often occurs with the first fever of an illness
Characteristics of F.S.Characteristics of F.S.
85% of all F.S. last for <15 min and don’t recur within 24 hrs
50% have temp between 39-40C
25% have temp > 40C
Characteristics of F.S.Characteristics of F.S.
1/3 will have recurrence of F.S.
The younger the age at 1st F.S., the higher the incidence of recurrence
El-Radhi, 1998
Presenting temp <39 for 1st F.S. have 2.5x risk for recurrence within the same illness and 3x risk for recurrence with other illnesses
Characteristics of F.S.Characteristics of F.S.
Simple F.S. are generalized tonic-clonic with brief post-ictal period
Complex or atypical F.S. can be focal, atonic, or prolonged
It’s in the genesIt’s in the genes
Multiple studies have shown several genetic loci that code for susceptibility to febrile seizures
Fever + Sz Fever + Sz Febrile Seizure Febrile Seizure
Meningitis/Sepsis
Seizure disorder
Medication/Poison-induced
“Febrile seizure” is NOT an EMS diagnosis
Febrile Seizures:Febrile Seizures:Fact or FictionFact or Fiction
F.S. are caused by the rate F.S. are caused by the rate of rise of tempof rise of temp
Berg, 1993 – failed to prove the rate of rise theory
Bottom line – we don’t know what causes F.S.!
F.S. cause brain damageF.S. cause brain damage
No studies have demonstrated that febrile seizures without complicating hypoxia cause brain damage
One study suggests that recurrent F.S. may result in decreased IQ
F.S. can cause “epilepsy”F.S. can cause “epilepsy”
Risk factors for afebrile sz: Complex 1st F.S.
Abnormal neuro state before 1st F.S.
Afebrile sz history in parents or siblings
If >2 risk factors, 10% chance of developing “epilepsy”
Treating the fever can Treating the fever can prevent F.S.prevent F.S.
Canfield, 1980; Knudson, 1991; van Stuijvenberg, 1998
Antipyretics are not protective
Rectal/oral diazepam at time of fever is protective
Daily oral phenobarbital is protective but has undesirable side effects
Treating the fever can Treating the fever can prevent F.S.prevent F.S.
There is no evidence that
bringing the fever down by any
means will stop or prevent a febrile
seizure.
The Bottom Line for F.S.The Bottom Line for F.S.
They’re more scary than dangerous
Most resolve without anticonvulsant treatment
Antipyretic treatment does not prevent or treat F.S.
Not all seizures with fever are febrile seizures
AntipyreticsAntipyretics
There is no evidence to support one antipyretic over another when considering effectiveness
No delivery route (po/pr) is more effective than another
AntipyreticsAntipyretics
Several studies have shown that many parents:
Don’t even attempt to treat fever before seeking medical evaluation
Don’t give correct antipyretic doses
AntipyreticsAntipyretics
Acetaminophen (APAP) 10-15 mg/kg po/pr q4h
There is no difference in effectiveness based on po or pr routes
There is no increased effectiveness when pr dose of APAP is increased to 45mg/kg
Ibuprofen 10mg/kg po q6-8h
APAP vs IbuprofenAPAP vs Ibuprofen
There is no significant benefit to using either antipyretic preferentially
There is no benefit in alternating the two meds but there is a significantly increased chance of dosing error and possible overdose
Cooling methodsCooling methods
Never use ice, cold water or alcohol
Use tepid water or cool compresses over head and pulse points
Beware of chills if
using external cooling
Should we even treat fever? Should we even treat fever?
Animal studies suggest that the fever mechanism is a positive adaptive response
Triggers host immune responses
May stabilize cell membranes
(Why) should(Why) should we treat we treat fever? fever?
Reasons to treat feverReasons to treat fever
Increased metabolic stress and oxygen demand:
Patients with poor cardiac reserve
Patients with poor pulmonary reserve
Lowering the “seizure threshold”
Reasons to treat feverReasons to treat fever
Patient comfort
Parent comfort
Should EMS Should EMS providersproviders
be treating be treating fever?fever?
Pro’sPro’s
Providing an additional service to our customers
Comfort measure
Con’sCon’s
Treat and release?
Documentation of fever
Dosing of meds
Reinforcement of fears
SummarySummary Fever is not the clearly defined
concept many believe it to be.
Both the lay public and the medical community need more education about fever.
“Fever Phobia” is unfounded.
Fever treatment by EMS personnel is controversial.
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