heat illness in children

1. Dr.Anitha
2nd year post graduate

2.  Heat stroke is a common medical catastrophe
during the summer months.
 Failure of thermoregulatory mechanism
coupled with an exaggerated acute phase
response occurs during heat stroke.
 Heat stroke demands urgent attention
because
 of high mortality
 and can cause permanent neurological
damage

3.  The human body temperautre is regulated by
means of complex anatomic and physiologic
mechanisms.
 Thermosensors are located centrally in
preoptic area of anterior hypothalamus and
peripherally in skin.
 The central integrative area in the
hypothalamus receives information from
thermosensors and instructs thermo-
regulator

5. • Body temperature is maintained within a narrow
range by balancing heat gain with heat dissipation.

• The body's heat gain results from both metabolic
processes and absorption of heat from the
environment.
• Evaporation is the principal mechanism of heat
loss in a hot environment, but this becomes
ineffective above a relative humidity of 75 percent.

6.  Radiation (emission of infrared electromagnetic
energy), is the major mode of heat loss in cool
environments)
 The other major methods of heat dissipation
 conduction (direct transfer of heat to an adjacent,
cooler object),
 convection (direct transfer of heat to convective
air currents)
 These cannot efficiently transfer heat when
environmental temperature exceeds skin
temperature (typically 35ºC or 95ºF).

7.  Children differ from adults with respect to
their anatomical and physiological response
to heat stress
 Children and infants are more vulnerable to
deltrious effects of heat due to
 higher surface area to weight ratio,
 inability to control environmental stresses
 and compromised sweating mechanisms

8.  Fever is elevation of body temperature above the normal
circadian variation as the result of a change in the
thermoregulatory center located in the anterior
hypothalamus.
 Fever is often a result of pyrogens , either exogenous or
endogenous in response to infection or inflammation
 On the other hand, hyperthermia is elevated body
temperature that occurs in presence of an unchanged
hypothalamic set point
 Exogenous heat exposure and endogenous heat
production (vigorous exercise, certain pharmacological
agents) are two mechanisms by which hyperthermia can
result in dangerously high internal temperature
 Hyperthermia must be distinguished from fever as
hyperthermia can be rapidly fatal and its treatment differs
from that of fever.

9. FEVER HYPERTHERMIA
Setting Of infection Of environmental
exposure to heat
Sweating profuse Rare or minimal
Skin moist Dry, flushed
Shivering present absent
Hyperpyrexia rare common
CNS dysfunction Not because of
fever itself .
Febrile seizures
common
Multiorgan dysfunction Not because of
fever itself
present
Response to antipyertics marked absent

10. Heat illness may be viewed as a continuum of
illnesses relating to the body's inability to cope
with heat.
 It includes minor illnesses, such as
 heat edema,
 heat rash (ie, prickly heat),
 heat cramps, and tetany,
 heat syncope ,
 heat exhaustion and
 Heatstroke which is the most severe form of the
heat-related illnesses

11. Heat cramps
 Cramps of most worked muscles after
exertion
 This can be prevented and relieved by
consumption of salt containing fluids.
 In severe cases, infuse normal saline.
Heat edema
 characterized by swelling of feet and ankles
 seen in elderly after long periods of sitting or
standing
 Simple leg elevation helps in most cases and
edema resolves after several days of
acclimatization.

12.  characterized by pooling of blood in
periphery and cardiac output while standing
for protracted periods in hot and humid
environments.
 This setting is commonly observed in
students attending school prayer assemblies.
 It is a self-limiting
 Maintaining the horizontal position and leg
elevation cures the pathology.

13.  is common in children as a result of blockage of sweat pores by
macerated stratum corneum
 These rashes undergo four stages.
Miliaria crystallina ( very small pruritic vesicles on an
erythematous base)
Miliaria rubra (deeper obstruction of sweat duct)
Miliaria profunda (deeper vesicle in dermis )
Miliaria pustulosa (secondary staphylococcal infection)

14.  is characterized by volume (water) or salt
depletion during conditions of heat stress.
 fatigue, headache, malaise, nausea, vomiting and
vertigo.
 Tachycardia, orthostatic hypotension and clinical
dehydration
 treated by rest in a cool environment and
oral replacement of fluids by water and electrolyte
solution
 Patients with clinical , dyselectrolytemia and
orthostatic hypotension should receive slow
infusion of saline

15.  Heat stroke is defined as a body temperature
higher than 41.1°C (106°F) associated with
neurologic dysfunction.
 Heat stroke is diffrentiated from heat
exhaustion by presence cns abnormalties

17.  Infants, children, and elderly persons have a
higher incidence of heatstroke than young,
healthy adults.
 Heatstroke affects all races equally.
 Heatstroke affects both genders equally.
However, because of gender differences in the
workforce, the annual death rate due to
environmental conditions is 2 times higher in
men than in women
 With the influence of global warming, it is
predicted that the incidence of heatstroke cases
and fatalities will also become more prevalent

18.  1- Classic, or nonexertional, heatstroke
(NEHS) • Classic heatstroke, which occurs
during environmental heat waves, is more
common in the very young and the elderly
and should be suspected in children, elderly
persons, and chronically ill individuals who
present with an altered sensorium. Classic
heatstroke.
 Classic heatstroke occurs because of failure
of the body's heat dissipating mechanisms

19.  . • EHS affects young, healthy individuals who
engage in strenuous physical activity, and
EHS should be suspected in all such
individuals who exhibit bizarre, irrational
behavior or experience syncope.
 EHS results from increased heat production,
which overwhelms the body's ability to
dissipate heat
 Both types of heatstroke are associated with
high morbidity and mortality, especially when
cooling therapy is delayed.

20.  EHS is characterized by hyperthermia,
diaphoresis, and an altered sensorium, which
may manifest suddenly during extreme
 A number of symptoms (eg, abdominal and
muscular cramping, nausea, vomiting, diarrhea,
headache, dizziness, dyspnea, weakness)
commonly precede the heatstroke and may
remain unrecognized.
 Syncope and loss of consciousness also are
observed commonly before the development of
EHS.

21.  NEHS is characterized by hyperthermia, anhidrosis, and an
altered sensorium, which develop suddenly after a period
of prolonged elevations in ambient temperatures (ie, heat
waves).
 Core body temperatures greater than 41°C are diagnostic,
although heatstroke may occur with lower core body
temperatures.
 Classic heatstroke most commonly occurs during
episodes of prolonged elevations in ambient temperatures.
 It affects people who are unable to control their
environment and water intake (eg, infants, elderly persons,
individuals who are chronically ill), people with reduced
cardiovascular reserve, and people with impaired sweating
(e.g., from skin disease or ingestion of anticholinergic or
psychiatric drugs).

22.  Excessive heat denatures proteins, destabilizes
phospholipids and lipoproteins, and liquefies
membrane lipids, leading to cardiovascular
collapse, multiorgan failure, and, ultimately.
 In a simplified model, thermosensors located in
the skin, muscles, and spinal cord send
information regarding the core body temperature
to the anterior hypothalamus, where the
information is processed and appropriate
physiologic and behavioral responses are
generated. •
 Hypothalamic dysfunction may alter temperature
regulation and may result in an unchecked rise n
temperature and heat illness

23. The etiology of heatstroke may involve any of the following
 Increased heat production
 Decreased heat loss
 Reduced ability to acclimatize
 Reduced behavioral responses
Increased heat production
 : Increased muscular activity
 Increased metabolism
 Infections
 Convulsions
 Sepsis
 Tetanus
 Encephalitis
 Strychnine poisoning
 stimulant drugs, including cocaine and amphetamines, can
generate excessive amounts of heat by increasing metabolism
and motor activity through the stimulatory effects of dopamine,
serotonin, and norepinephrine.
 Thyroid storm

24. Reduced ability to acclimatize
 Persons at the extremes of age (ie, toddlers
and young children, the elderly) may be less
able to generate adequate physiologic
responses to heat stress.
Reduced behavioral responsiveness
 Infants, patients who are bedridden, and
patients who are chronically ill are at risk for
heatstroke because they are unable to control
their environment and water intake.

25. • Reduced sweating can result from any of the following:
 Dermatologic diseases
 Drugs
• Burns
Drugs that can result in decreased heat loss include the following:
• Anticholinergics • Neuroleptics • Antihistamines
• Exogenous factors that can decrease heat loss include the
following:
• High ambient temperatures • High ambient humidity
Reduced cardiovascular reserve
Advanced age
Beta-blockers
• Calcium channel blockers
• Diuretics
• Cardiovascular drugs - Interfere with the cardiovascular
responses to heat and, therefore, can interfere with heat loss

26.  The onset of symptoms is usually sudden but a
preceeding fever of 1 to 2 days duration is not
unusual.
 Cases of heatstroke have occurred in young
infants who were overclothed in a febrile illness.
 Prodromal symptoms like headache, nausea,
vomiting, diarrhea and dizziness may be
observed in few cases.
 Core temperature is usually more than 41°C but
sometimes may be lesser especially in newborns
and young children where symptoms of
heatstroke come at a lower threshold

27.  The classical feature of heatstroke is presence of dry
flushed kin with absent sweating
 sweating may persist in infants and children and
presence of sweating does not preclude the diagnosis
of heatstroke.
 Young children sometimes present with shock with
no cutaneous features of classical heatstroke.
 rectal temperature reveals the exact cause of shock
 is understood.
 Hence rectal temperature is taken in all cases of
shock (with or without dehydration), especially in
summer months.

28.  cardiovascular manifestations include a
hypercirculation, tachycardia and shock.
 Jaundice may occur
 Elevation of transaminases occur early in the
course of the disease.
 Coagulation abnormalities
 purpura, poor prognosis
 Conjunctival hemorrhage,
 orificial bleeds and malena

29.  Renal
 Acute oliguric renal failure .
 urine is scanty&brownish and examination
reveals proteinuria, abundant granular casts and
rbc
 Metabollic derangements
 Respiratory alkalosis,
 lactic acidosis,
 hypoglycemia, judiciously managed
 hypokalemia, hypernat-
 remia and hypocalcemia

30.  CNS dysfunction is a hallmark of heatstroke.
 confusion,
 tremors,
 delirium,
 coma or
 seizures.
 Profound muscular rigidity with tonic contractions,
 Opisthotonus
 decerebrate rigidity,
 oculogyric crisis and dystonic movements.
 Pupils may be fixed and dilated.
 These changes are potentially reversible, although
permanent damage can occur in severe caseses

31.  The diagnosis of heatstroke is mainly clinical
 Blood glucose
 complete bloodcount,
 electrolytes,
 blood urea,
 transaminases,
 calcium and
 arterial blood gas.
 The patient should be catheterized and urine
output is to be measured

32.  meningitis, encephalitis, cerebral malaria
 and Reye’s syndrome should be considered
when temprature and sensorium of child
doesn’t respond to the cooling meausres
intiated.
 Lumbar puncture should be performed in
cases of doubt.
 The CSF in heatstroke is crystal clear with
occasional lymphocytic pleocytosis and mildly
elevated protein

33.  Certain drug overdoses like anticholinergic
(Atropine),
 amphetamines and haloperidol
 Other serious systemic Infections
,typhoid fever and CNS hemorrhage sometimes
resemble heatstroke.

34.  • Temperature: exceeds 41°C. •
 Pulse: Tachycardia, exceeding 130 beats per
minute is common.
 Blood pressure: normotensive, with a wide
pulse pressure;
 hypotension is common and may result from
a number of factors, including vasodilation of
the cutaneous vessels, pooling of the blood in
the venous system, and dehydration.

35.  Heat hyperpyrexia is a medical emergency
and must be managed aggressively to reduce
the complications and mortality associated
with it.
General Measures
 1.Airway should be secured.
 2.Oxygen administration at 5-10 liters/min.
is provided
 Circulatory support

36.  External cooling methods are the mainstay of
treatment
 must be initiated as soon as possible.
 The patient is immediately removed from the
hot environment and all clothing should be
removed.
 Rectal temperature is monitored every 5
minutes
 search for cause should be done later

37.  Immersion in ice-water
keeping the head above is the preferred cooling modality
and brings down the temperature rapidly (<39°C in 10-
40min)
 Evaporative cooling
means of large circulating fans and skin wetting is also
very effective but requires complex set-up
 Adjunctive measures:
application of ice packs
vigorous skin massage to prevent vasoconstriction
cooling blankets,
rectal, gastric or peritoneal lavage with cold water
 Should used in conjunction with the immersion or
evaporative methods

38.  Cooling measures should be discontinued
once core temperature reaches 39°C to avoid
hypothermic overshoot
 Antipyretics like paracetamol and salicylates
are not indicated in heat related illnesses and
may be harmful as these worsen hepatic and
hematological damage

39.  Hypotension
 Convulsions
 Coagulopathy
 Renal failure
 Metabolic derrangements
 Vigorous shivering due to rapid cooling
methods
Convulsions

40.  A high index of suspicion is required as
appropriate management of this condition
markedly reduces the mortality.
 Liberal fluid and salt intake, avoidance of
prolonged exposure to high ambient
temperatures,
 avoidance of strenuous play in hot and humid
conditions and
 early recognition and management of heat
illnesses is important for preventing
heatstroke and the damage associated with it.

41.  IAP TEXTBOOK OF EMERGENCIES,
 NELSON TEXT BOOK OF PEDIATRICS.