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 Mythology

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.