Basics about fever in children and an overview of management guidelines.

1. Approach to the Febrile Child
General Pediatrics Block
Fatima Farid - Pediatric Resident Year 2

2. Contents
◦ Introduction
◦ Case presentation
◦ History
◦ Physical examination
◦ Further management
◦ Conclusion

3. Physiological body temperature

4. Normal body temperature
◦ The upper normal body temperature is approximately 37.7 C overall.
◦ There is physiological variation with age, time of day, level of activity and phase of menstrual cycle.
◦ Infants and young children have higher temperature than older children/ adults: higher surface area to body weight
ratio and metabolic rates.

5. Normal body temperature
◦ Temperature nadir is in the morning time and peaks in late afternoon/ early evening. Mean amplitude of variation is
0.5C.
◦ During a febrile illness, daily low and high temperature readings are maintained but at higher than normal
levels.
◦ Daily variations can be as high as 1C in those recovering from a febrile illness.

6. Temperature homeostasis
◦ The thermoregulatory center of the hypothalamus balances heat production and dissipation to maintain a steady
body temperature.
◦ At environmental temperatures higher than 35C, the body’s ability to dissipate heat is overwhelmed and the core
temperature rises.

7. Elevated body temperature

8. Elevated body temperature
◦ Fever is defined as, “abnormal elevation of body temperature that occurs as part of a specific biologic response that
is mediated and controlled by the central nervous system”- UpToDate.
◦ Elevated body temperature is divided into two types:
◦ Fever: increased body temperature with an elevated hypothalamic set- point
◦ Hyperthermia: increased body temperature with a normal hypothalamic set- point
◦ It is important to distinguish between the two as they have different implications and management
strategies
◦ Hyperthermia does not respond to anti- pyretic agents and can be rapidly fatal.

9. Copyrights apply

10. Pathogenesis of fever
◦ Inflammation triggers peripheral synthesis of interleukins (IL-1 and IL-6), TNF, INF- alpha, and other cytokines
from phagocytic cells in blood/ tissues.
◦ These cytokines enter blood and are carried to the anterior hypothalamus where they induce an abrupt increase
in prostaglandin synthesis (especially PGE2).
◦ The induction of PGE2 in the brain raises the hypothalamic set- point for body temperature.
◦ After the set- point is raised, the thermoregulatory center recognizes the current body temperature to be too low and
initiates a series of events to raise body temperature to the new set- point.

11. Pathogenesis of fever
◦ Reaching new temperature set- point involves augmentation of heat production by increased metabolic rate, muscle
tone and activity, and decreased heat loss through diminished perfusion of skin.
◦ Pyrogenic cytokines also:
◦ Increase synthesis of acute phase reactants in the liver
◦ Decrease serum iron and zinc levels
◦ Provoke leukocytosis
◦ Accelerate skeletal muscle proteolysis
◦ The upper limit of temperature due to fever is 42C- but it is unusual for temperature to exceed 41C without
some element of concomitant hyperthermia.

12. Practical aspects of fever

13. Measurement of temperature
◦ Rectal thermometry:
◦ Reference standard for measurement of core body temperature
◦ Digital rectal thermometer used.
◦ Glass thermometer not advisable: difficult to read, may cause injury if breaks and can spread infections.
◦ Lag between core and rectal vault temperature
◦ Contraindicated in patients with neutropenia, bleeding diathesis (i.e thrombocytopenia) and necrotizing
enterocolitis

14. Measurement of temperature
◦ Oral thermometry:
◦ Preferred modality in cooperative children
◦ 0.6C lower than rectal temperature due to mouth breathing (especially in tachypneic patients)
◦ Affected by recent ingestion of hot/ cold liquids

15. Measurement of temperature
◦ Axillary thermometry:
◦ Consistently lower than rectal temperature but with wide variations- hence a standard conversion cannot be used
◦ May be used in neutropenic children who cannot use oral thermometer
◦ Infrared thermometry:
◦ Measure amount of heat produced by tympanic membrane- close to core temperature depending on quality of
device
◦ Contact/ non- contact forehead thermometers measure heat released by temporal arteries. Affected by sweating
and vascular changes. Variable results/ correlation to rectal temperature.
◦ Smart- phone apps using external sensor- adequate studies absent.

16. Should we adjust non- rectal temperature measurements?
Source: Febrile infant (younger than 90 days): Definition of fever- UpToDate

17. Abnormally high temperature
◦ In an otherwise healthy neonate (0- 30 days) and young infants (1- 3 months), fever of concern is defined by rectal
temperature >= 38.0 C.
◦ In children 3- 36 months, fever is defined as rectal temperature ranging from 38- 39C, and fever of concern if rectal
temperature >= 39.0C.
◦ In older children and adults, fever is defined as oral temperature 37.8- 39.4C, and fever of concern by oral
temperature >= 39.5 C.
◦ Lower threshold of temperature for high risk children: sickle cell disease, neutropenia.

18. Is caregiver report of measured fever valid?
◦ Rectally measured temperatures greater than 38C should be taken seriously due to significant risk of
serious bacterial infections (bacteremia, UTI, pneumonia and meningitis).
◦ Non- rectal temperatures should be investigated based on clinical condition of child.
Source: Febrile infant (younger than 90 days): Definition of fever- UpToDate

19. Is tactile fever significant?
Source: Febrile infant (younger than 90 days): Definition of fever- UpToDate

20. Can bundling cause fever?
◦ When ambient temperature and humidity permit normal heat loss (ie, humidity <75 percent, ambient temperature
<35°C), an elevated rectal temperature >38°C should not be attributed to bundling in infants 7 to 90 days of age.
◦ In addition, a fever >38.5°C should not be attributed to bundling regardless of the manner taken.
◦ When evaluating an infant who is afebrile by rectal temperature at presentation but had a fever at home, bundling is
an important factor to consider if the fever is based upon temperature measurements other than a rectal
temperature.

21. Can bundling cause fever?
Source: Febrile infant (younger than 90 days of age): Definition of fever- UpToDate

22. Case presentation

23. Ali is a one-month-old boy, who
is brought to the ED today with
complaint of crying and fever.
What would you like to ask his
mother?

24. Ali is a one-month-old boy, born at term and previously healthy.
Since last night, child has been irritable, uninterested in feeding and having
fever.
Rectal temperature measured between 38- 38.5 C. No associated shivering/
rigors or abnormal movements. Responded to Adol every four hours.
In systemic review:
1. Child has been crying excessively and inconsolably since last night
2. Loss of interest in feeding with poor suck whenever feeds
3. Vomited twice (milk only, non- projectile, non- bloody/ non- bilious)
4. Urine output has decreased also, with dark colour but no foul smell/ blood
5. Runny nose and mild cough for the past three days
6. No history of skin rash, abnormal movements, excessive sleepiness,
unresponsiveness, ear pain/ discharge, cyanosis/ apnea, change in bowel
habits.

25. Ali’s older sister has been sick with URTI for the last week. He has no recent travel
abroad or visitors from abroad.
Birth History: Born at 38 weeks by NVD. Birth weight 3.5 kg. Uneventful antenatal
and post- natal period (maternal serology/ HVS/ MSU normal as per her).
Medical/ Surgical History: Nil, no previous hospitalizations.
Drug History: Vitamin D drops only
Immunizations: Received BCG and Hepatitis B vaccines at birth.
Allergies: None
Nutritional History: Exclusively breast- fed
Developmental History: Appropriate for age
Family History: Non- consanguineous parents. One older sister aged 6 years. No
medical illnesses of significance.
Social History: Father employed, mother housewife. No smokers/ pets at home.

26. Vitals:
BP 80/ 40 mmHg
HR 150 beats/min
Temperature 39 C
Respiratory Rate 61 breaths/min
SpO2 95% on room air
General: Crying inconsolably. Tachypneic and tachycardic. Capillary refill
4 seconds. Mottled skin, but no rash present.
ENT: Clear nasal discharge present. Throat congested with normally sized
tonsils. Bilaterally congested tympanic membranes with intact light reflex.
Chest/ CVS: Bilateral equal air entry, no added sounds. Normal heart
sounds, no murmur. Peripheral pulses well- felt bilaterally.
Abdomen: Mildly distended but soft, no palpable organomegaly. Normal
uncircumcised male genitalia, hernial orifices intact.
CNS: Irritable, bulging anterior fontanelle. Pupils bilaterally equal and
reactive. Tone and power difficult to assess. Reflexes normal. Cranial
nerves grossly normal.

27. Investigations:
CBG: pH 7.47, PCO2 30, PO2 80, HCO3 24, Na 135, K 3.8, Glucose 55,
Lactic Acid 4
FBC: Hb 10.0; WBC 17,000; Neutrophils 80%; Platelets 200,000.
CRP: 70
Urea/ Electrolytes: Na 136, K 3.8
Creatinine/ LFT: Normal
Urine Routine: Dark yellow sample, RBC 0- 2, WBC 3- 5
Blood and Urine Cultures: Pending
CXR: Minimal peri- hilar haziness

28. Source: LH Guidelines- Evaluation and management of a febrile infant less than 2 months.

29. CSF analysis: Turbid sample. Glucose 2, protein 100. 50 WBC, 90%
neutrophils, 5 RBC.
CSF microscopy: Gram negative rods
Child was started on IV Ampicillin + Gentamycin + Cefotaxime
Final blood and CSF cultures were positive for E coli.
Antibiotic course was completed and repeat CSF culture sterile.
Ali was discharged home in good condition.
Evoked audiometry response 5 weeks after discharge showed bilaterally
normal hearing.

30. Management of fever

31. Effects of fever
◦ Fever is an integral part of the inflammatory response to fight infection.
◦ Benefits:
◦ Retardation of pathogen growth/ reproduction due to decreased serum iron
◦ Enhanced immunological function till temperature of 40C (beyond which effect is reversed)
◦ Harm:
◦ Discomfort to child (myalgias and arthralgias due to raised PGE-2)
◦ Increased somnolence due to raised IL-1
◦ Increased metabolic rate, demands on pulmonary and cardiovascular systems: detrimental only in children with
underlying chronic disease.

32. Guiding points
1. Fever is an important clinical sign
2. It is not an illness but a physiological response
3. The first step in management of fever is to determine its cause
4. Once the cause is known, the main reason to treat fever is to improve the child’s comfort
5. In otherwise healthy children, most fevers are self- limited and benign provided that the cause is known, and fluid
loss replaced
6. Fever does not cause brain damage
7. There is no evidence that fever makes illness worse

33. Should fever be treated?
◦ Routine treatment of fever in an otherwise normal child is not warranted.
◦ There is no evidence that reducing fever reduces morbidity or mortality from a febrile illness (with possible exception
in children with limited reserves for increased metabolic demands).
◦ Benefits: improve discomfort, reduce insensible water loss, analgesia.
◦ Harms: delayed identification of underlying illness and drug toxicity.

34. Indications for short term treatment
Source: Fever in infants and children: Pathophysiology and management- UpToDate

35. Antipyretic agents
◦ The choice of antipyretic agent may be influenced by underlying medical conditions (i.e liver failure should avoid
acetaminophen), or possible interactions with chronically used drugs (i.e SSRI enhance anti- platelet effect of Ibuprofen).
◦ Acetaminophen is the first line recommended drug because of its long track record of safety at therapeutic doses.
◦ Should not be used independently by parents in children younger than 3 months (fever may be the only sign of
infection in this age).
◦ Dose: 10- 15 mg/kg/ dose every 4- 6 hours. Maximum 1g/dose and 75 mg/kg/day.
◦ Works in 30- 60 minutes, peak effect in 3- 4 hours and total duration of 4- 6 hours.
◦ Rare side effects: SJ syndrome, TEN, acute generalized exanthematous pustulosis- children who develop skin lesions
while using acetaminophen should discontinue the same and seek prompt medical treatment.

36. Antipyretic agents
◦ Acetaminophen continued:
◦ Unproven associated between acetaminophen and asthma
◦ Overdose of acetaminophen may be lethal.
◦ Overdose may occur if acetaminophen is administered simultaneously with combination cough/ cold
remedies that contain acetaminophen; unsupervised ingestion; unclear instructions about
administration.

37. Antipyretic agents
◦ Ibuprofen:
◦ Should not be used independently by parents in children younger than 3 months (fever may be the only sign of
infection in this age).
◦ Recommended in children older than 6 months when antipyretic and anti- inflammatory actions are desired (i.e JIA) in a
well- hydrated child.
◦ Infants younger than 6 months are at increased risk for renal toxicity because of immature renal function.
◦ Dose is 10 mg/kg/dose every 6 hours. Maximum 600 mg/dose and 40 mg/kg/day.
◦ Action begins within 60 minutes, peaks in 3- 4 hours and total duration is 6- 8 hours.
◦ Adverse effects: gastritis, GI bleeding, acute kidney injury (even with appropriate doses).
◦ Overdose is less fatal than that of acetaminophen and can occur in similar circumstances.

38. Antipyretic agents
◦ Combined or alternating therapy is not recommended:
◦ Although it may be more effective in reducing temperature, it is unclear whether this is of clinical
significance.
◦ May lead to confusion and inaccurate dosing
◦ Enhance fever phobia in care- taker
◦ The two should not be administered simultaneously
◦ Current recommendation is to start with acetaminophen and change to ibuprofen if response not
achieved, and vice versa.
◦ Persistent fever or development of red flags should prompt re- assessment.

39. External cooling
◦ Not routinely recommended for temperature reduction in previously well infants/ children with fever.
◦ Studies have shown only short- lived benefit when combined with medications, and an increase in child’s discomfort.
◦ May be used as an adjunct to antipyretic therapy in times where more rapid and greater reduction of body
temperature is necessary.
◦ Antipyretic agents are necessary to reset the thermoregulatory set- point, without which external cooling
will result in an increase in heat production.
◦ Antipyretic should be administered at least 30 minutes before start of tepid sponging.

40. External cooling
Source: Fever in infants and children: Pathophysiology and management- UpToDate

41. External cooling
◦ Sponging should be done with warm water (30C) and is superior to immersion in water:- evaporation from skin
augments heat loss.
◦ Alcohol should not be used as fumes are absorbed across alveolar membranes and possible skin resulting in CNS
toxicity.
◦ Cooling blankets are useful in hospitalized/ critically ill children or those with problems of temperature control (i.e.
acute head injury).

42. Duration of treatment
◦ Duration of therapy depends on the child’s response- end point is comfort.
◦ Prolonged use is generally unnecessary because most febrile illnesses are of viral origin.
◦ Re- evaluation for secondary bacterial infection may be warranted in children whose fever and discomfort persist
beyond 4- 5 days; marked increase in maximum temperature height; development of new localizing signs.

43. Conclusion
◦ Fever is an abnormal increase in body temperature that results from elevation of the hypothalamic set-point.
◦ The cause of fever should be evaluated, particularly in infants younger than three months of age and infants and
children with underlying medical conditions that increase the risk of serious infection.
◦ Decisions regarding the treatment of fever in children should be made on a case-by-case basis.

44. References
◦ Fever in infants and children: Pathophysiology and management- UpToDate
◦ Febrile infant (younger than 90 days of age): Definition of fever- UpToDate
◦ Febrile infant (younger than 90 days of age): Management- UpToDate
◦ LH Guidelines- Evaluation and management of a febrile infant less than 2 months.

45. Thank You