“Fever Phobia”Dawn S. Tuell, M.D.

Associate Professor of Pediatrics

Quillen College of Medicine

Disclosure Statement of Financial Interest

• I do not have a financial interest or affiliation with one or more organizations that could be perceived as a real or apparent conflict of interest in the context of the subject of this presentation

What is a fever?

• Depends on who you ask…• Where you take it…• The type of thermometer used…• The time of day…• Age of the child…

FEVER

• An increase in the body’s temperature above normal

What is a normal temperature?

• Range 97.2° (36.2°) – 99.5° (37.5°)• Normal diurnal variation in temperature 0.5°C from the

mean• Vary based on age, gender, physical activity, ambient air

temperature• Vary with anatomic site• Core body temperature is measured most accurately at

the pulmonary artery• There is no single value for normal body temperature

Which of the following children have a fever?

1 2 3 4 5

20% 20% 20%20%20%1. 3 year old with an axillary

temperature of 99°

2. An 18 month old with a pacifier temperature of 99.8°

3. 6 month old who felt hot last night

4. 9 month old with tympanic temperature of 100°

5. None of the above

AAP Definition

• Rectal temp > 100.4°• Oral temp > 100°• Axillary temp > 99°• Tympanic > 100.4°• Forehead/temporal artery > 100.4°

You should add a degree to an axillary temperature to reflect core body temperature

1 2

50%50%

1. True

2. False

Axillary vs. Rectal

• Rectal temperatures are the gold standard for temperature measurement

• Axillary temperatures are not as reliable as rectal and are generally lower

• However “one degree rule” not appropriate due to variability

• Literature shows axillary thermometers did pick up all fevers

• No false positives with axillary temperature

Oral Thermometers

• Safe and comfortable for children older than 5 years• Less lag time• More accurate than axillary thermometers• Affected by temperature of recently consumed fluids or

mouth breathing

Tympanic Thermometer

• Quick, comfortable, cost effective• Infrared ear thermometer does not accurately predict

rectal temperature• Fails to diagnose fever in 3-4 out of every 10 febrile

children• Difficulty in aiming thermometer at TM, especially in

infants younger than 2 months of age• Home use thermometers may be less accurate than

clinical use thermometers

“Tactile” Temperature

• Child “feels warm to the touch”• Subjective, can vary with environmental factors• Sensitivity by parents 71-89%• Specificity and positive predictive value <50%• More useful to exclude rather than confirm presence of a

fever

What is the best way to measure temperature?

• The way that works for you…• Use a consistent form of measurement• Make the measurement at the same site to monitor

changes in body temperature

What is a low grade fever?

1 2 3 4 5

20% 20% 20%20%20%

1. 98.8°-99°

2. 99°-100°

3. 99°-101°

4. 100°-102°

5. 101°-103°

Low grade fever

• 100° (37.8°)- 102° (39°)

What is a high fever?

1 2 3 4

25% 25%25%25%1. <100° (37.8°)

2. 100°-102° (37.9°-38.9°)

3. 102.1°-104° (39°-40°)

4. >104° (40°)

Parental definition of a high fever

Temperature at Which Pediatricians Consider Infants to Have Mild, Moderate and Serious Fever by Infant Age

Why Does My Child Have a Fever?

• Temperature control lies in the thermoregulatory center of the hypothalamus

• Complex set of cytokine-mediated responses and production of acute phase reactants change hypothalamus set point

• Body temperature elevates via heat generation and heat conservation

• Pyrogens are substances that produce fever• Cryogens limit temperature height during fever

The febrile response.

Avner J R Pediatrics in Review 2009;30:5-13

©2009 by American Academy of Pediatrics

How high a fever can go if left untreated.

Crocetti M et al. Pediatrics 2001;107:1241-1246

©2001 by American Academy of Pediatrics

Is Fever a Symptom or a Disease?

1 2

50%50%

1. Symptom

2. Disease

Do we treat as a disease?

• Counsel parents on how to “control” a fever• Order blood tests to evaluate fever• 50% of HCPs report pressure to prescribe antibiotics for a

fever• Parents perceive treatment of fever is antibiotics

The height of the fever predicts a more serious illness

1 2

50%50%

1. True

2. False

Height of Fever

• Pre-pneumococcal conjugate vaccine this was likely a true statement

• Some studies show that hyperpyrexia (T>106/41.1) is associated with a higher incidence of serious illness

• Clinical appearance rather than height of fever is a more powerful predictor of serious illness

• Thorough H&P to guide decision matrix

A response to antipyretic medication lowers likelihood of serious bacterial infection

1 2

50%50%

1. True

2. False

• A response to antipyretic medication does not change the likelihood of a child having serious bacterial infection and should not be used for clinical decision making.

Systematic Review of Evidence

Temperature Response

Bacteremic Nonbacteremic• Authors Year Study Design Antipyretic Agent Age of Subjects, y No.∗ T,† °C

(°F) ↓T‡ No.∗ T,† °C (°F) ↓T‡ P§• Torrey et al22 1985 Prospective/observational Acetaminophen/aspirin ≤2 16

40.1 (104.2) 1.3 239 39.9 (103.8) 1.05 .14• Weisse et al23 1987 Prospective/observational Acetaminophen ≤17 11 NG 1.4

16 NG 1.2 .37• Baker et al24 1987 Prospective/observational Acetaminophen ≤6 10 40.1

(104.2)1.5 225 39.6 (103.3) 1.0 NG• Mazur et al25 1989 Retrospective/case control Acetaminophen ≤6 34 39.8

(103.6)1.0 68 39.8 (103.6) 1.5 <.001• Baker et al26 1989 Prospective/observational Acetaminophen ≤2 19 40.1

(104.2)1.7 135 40.0 (104) 1.6 >.05• Yamamoto et al27 1987 Prospective/observational Acetaminophen ≤2 17

40.5 (104.9) 1.6 216 40.4 (104.7) 1.6 .85

Which of the following is not a known complication of fever associated with infection?

1 2 3 4 5

20% 20% 20%20%20%1. Cerebral damage

2. Increased catabolism

3. Seizure

4. Tachycardia

5. Tachypnea

Parental Report of Harmful Effects of Seizures

Type Schmitt (n = 81) Crocetti et al (n= 340)*

Seizure 15% 32%

Brain damage 45% 21%

Death 8% 14%

Dehydration 4% 4%

Really sick 1% 2%

Coma 4% 2%

Delirium 12% 1%

Blindness 3% 1%

No response 6% 9%

Other – 14%

Total 100% 100%

Benefits of a Fever

• Enhance leukocyte mobility and activity• Activates T lymphocytes• Stimulates production of interferon• Inhibit bacterial and viral function• Shortens duration of illness by creating an unfavorable

host environment• Likely beneficial in children with normal host responses

Disadvantages of a fever

• Increased metabolic demand• Increased insensible fluid loss• General discomfort

Hyperthermia vs. Fever

• Fever is a normal physiologic response that results in increase in hypothalamus set point

• Hyperthermia is rare response with failure of normal homeostasis that results in heat production that exceeds capability to dissipate heat

• Characteristics – hot, dry skin, CNS dysfunction, delirium, convulsions, coma

• Should be addressed promptly• Temperature above 41°-42°C can have adverse physiologic

effects• Cannot extract hyperthermia data to apply to fever outcomes

Fever

• Most febrile illnesses last 3-5 days• Treatment of febrile children without a source subject to

great debate• Majority have benign, self-limited illness• Serious bacterial illness can be difficult to diagnose and

has a high morbidity

A 3 week old term newborn presents with a fever of 38°C. What should be done next?

1 2 3 4 5

20% 20% 20%20%20%

1. Draw a blood culture, CBC and start oral antibiotics

2. Risk stratification approach based on WBC count and appearance

3. Reassure and reassess tomorrow

4. Admit for cultures and IV antibiotics

5. None of the above

Fever < 1 month

• Febrile infant < 1 months of age immature immune response

• Up to 10% of febrile infants have serious bacterial illness• Not yet developed many clinical signs to judge clinical

appearance• Most management strategies recommend routine

hospitalization and empiric antibiotics pending results of blood, urine, and CSF cultures

Fever 1-2 months

• Risk stratification using WBC, UA and often CSF to determine need for hospitalization and empiric antibiotics

A 10 month old girl has a temperature of 102° (38.9 °) for 2 days. Her parents deny any other symptoms except increase in fussiness. Immunizations are UTD. Findings on PE are normal. Which test is most helpful in establishing a diagnosis in this child?

1 2 3 4 5

20% 20% 20%20%20%1. Blood culture

2. Chest radiograph

3. Complete blood count

4. C-reactive protein

5. Urine culture

Fever 3-36 months

• Usually benign viral origin• CBC, blood culture, urine culture – utility is diminshing• With S. pneumo and Hib vaccines occult bacteremia

decreased from 3% to <0.7% in this vaccinated age group• Occult UTI much more likely with a prevalence of 2.1-

8.7% - highest in girls younger than 1 year

A previously healthy 12 month old has a fever of 101.2° You would recommend

1 2 3 4 5

20% 20% 20%20%20%

1. Alternate Ibuprofen and Acetaminophen every 4 hours

2. Ibuprofen every 6-8 hours

3. Acetaminophen every 4-6 hours

4. Use antipyretic based on the appearance of the child

5. Sponging or bathing with tepid water

Sponging

• Bathing with cold water should not be used as it leads to vasoconstriction

• Rubbing alcohol can cause vasoconstriction and absorption through the skin leading to toxicity

• Tepid bathing provides only marginal temperature reduction but increases discomfort and shivering

Antipyretics

• Ibuprofen and Acetaminophen inhibit cyclo-oxygenase which converts arachidonic acid to prostaglandin

• Interleukin mediated steps continue to increase the hypothalamus set point

• Decreased prostaglandins work to override the interleukins

• Lower hypothalamus set point only in the febrile state

Caregiver's use of antipyretics.

Crocetti M et al. Pediatrics 2001;107:1241-1246

©2001 by American Academy of Pediatrics

Parental Antipyretic Practices

• A child must maintain a “normal” temperature at all times

• ½ of parents consider a temperature of <38 (100.4) to be a fever

• 25% of caregivers give antipyretics for temperature of <37.8 (100.4)

• 85% parents report awakening their child from sleep to give antipyretics

• Up to ½ administer incorrect doses of antipyretics

Acetaminophen

• Dose 10-15 mg/kg per dose q 4-6 hours• Onset of antipyretic effect within 30-60 minutes• Approximately 80% of children will experience a

decreased temperature• Hepatotoxicity most commonly seen with acute overdose• Concern with supra-therapeutic doses and frequent

administration

Acetaminophen use has been associated with the following:

1 2 3 4 5

20% 20% 20%20%20%1. May suppress immune response

to rhinovirus

2. May be important risk factor for development and/or maintenance of asthma

3. Associated with rhinoconjunctivitis symptoms

4. Associated with eczema symptoms

5. All of the above

Ibuprofen

• Dose 5-10 mg/kg dose q 6-8 hours• Recommended for infants > 6 months• More effective antipyretic• Longer duration of anti-pyresis• Potential for gastritis• Concern for nephrotoxicity, especially in dehydration or

medically complex children• Possible association between ibuprofen and varicella-

related invasive group A streptococcal disease

Combination Antipyretics

• NOT recommended by AAP in 2011 Clinical Report• 67% parents alternate antipyretics• 50% pediatricians advocated this practice• No conclusive proof alternating is safe• May be more efficacious in reducing temperature in short

term, no long term difference• Can be confusing to parents• Potential for incorrect dosing and increased risk of toxicity• Primary endpoint, reduce discomfort, not normalize

temperature

“Dump” the combo antipyretic practice

A 18 month old had his first febrile seizure last month, you would advise parents

1 2 3 4 5

20% 20% 20%20%20%1. Antipyretic therapy will reduce recurrence of febrile seizures

2. Febrile seizures have excellent long-term outcomes

3. The higher the fever, the more likely a seizure will occur

4. Give antipyretics for 24 hours after immunizations to prevent a seizure

5. Go to the ER anytime a seizure occurs

Febrile Seizures

• AAP Clinical Practice Guideline, 2008 & 2011• High rate of recurrence• No greater risk for developmental delays, learning

disabilities, or seizures without fever• Antipyretics ineffective in preventing recurrent febrile

seizures• Regular vs. sporadic treatment does not influence

outcome of febrile seizures

A 12 month old has an appointment for WCC and immunizations. You routinely advise

1 2 3

33% 33%33%1. Pretreatment with acetaminophen

or ibuprofen prior to immunizations to minimize discomfort and febrile response

2. Treatment with acetaminophen or ibuprofen after immunizations to minimize febrile response

3. Antipyretics are not routinely needed for immunizations

• Recent study suggests possibility of decreased immune response to vaccines in patients treated early with antipyretics

• Goal in treating a fever: child’s comfort not normalization of temperature

Fever Management

• Restore nutrients and water lost• Proper hydration• Comfortable environment

Parental Education

• Fever is a normal response to infection• Fever is a symptom, not a disease• Fever determination doesn’t always need to be exact• Treat the child’s comfort rather than a specific

temperature• Fever will persist until disease process resolves• Clinical appearance is important• Use the term “fever therapy” instead of “fever control”• Safe storage of antipyretics