Transcript Kid Fevers : A Hot Topic

Fever in Kids:
Lou Romig MD, FAAP, FACEP
Miami Children’s Hospital
Hot Topics
 What is fever?
 Facts and fallacies about
fever
 Febrile seizures
 How and why to treat kids
with 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?
 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?
 Endogenous pyrogens can
cause:

body temp

sleepiness

appetite

Increased immune response
What
about
the
numbers?
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
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”?


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”?
 Mackowiak and Wasserman:


Any oral temp >37.2C (98.9F)
in the early morning
Any oral temp >37.8C (100F)
at any time
Thermometry
 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
Thermometry

Tympanic thermometry is not
accurate and may be techniquedependent

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”?
 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”?
 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?
Seizures and complications
Brain damage because of
the infection causing the
fever (meningitis or
encephalitis)
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?
 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?
No studies have
conclusively proven any
correlation between
height of temperature
and outcome of an
infection or disease
outcome.
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?
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?
 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!
What’s cookin’ with chills?
 Chills are evidence of the
hypothalamus causing the
body to generate heat to
reach the altered setpoint.
 Covering up will only keep
in the heat.
Don’t give milk to babies
with fever!
Oh,
Puhleeez!
“Doin’ the fever flop”
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.
 85% of all F.S. last for <15 min
and don’t recur within 24 hrs
 50% have temp between 3940C
 25% have temp > 40C
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.
 Simple F.S. are generalized
tonic-clonic with brief postictal period
 Complex or atypical F.S. can be
focal, atonic, or prolonged
It’s in the genes
Multiple studies have
shown several genetic
loci that code for
susceptibility to febrile
seizures
Fever + Sz  Febrile Seizure
 Meningitis/Sepsis
 Seizure disorder
 Medication/Poison-induced
“Febrile seizure” is NOT an
EMS diagnosis
Febrile Seizures:
Fact or Fiction
F.S. are caused by the
rate of 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 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”
 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
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
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.
 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
Antipyretics
 There is no evidence to
support one antipyretic
over another when
considering effectiveness
 No delivery route (po/pr) is
more effective than
another
Antipyretics
 Several studies have
shown that many parents:


Don’t even attempt to
treat fever before seeking
medical evaluation
Don’t give correct
antipyretic doses
Antipyretics
 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 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 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?
 Animal studies suggest
that the fever mechanism
is a positive adaptive
response

Triggers host immune
responses

May stabilize cell
membranes
(Why) should
we treat
fever?
Reasons 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 fever
 Patient comfort
 Parent comfort
Should EMS
providers
be treating
fever?
Pro’s
 Providing an additional
service to our
customers
 Comfort measure
Con’s
 Treat and release?
 Documentation of fever
 Dosing of meds
 Reinforcement of fears
Summary
 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.