heat 1. heat and related illness ppt.ppt

heat 1. heat and related illness ppt.ppt

1. Dr. Ahmed Balshi
Dr. Muhammad Asim Rana

2. HEAT-
RELATED
ILLNESSES
DR.VYJAYANTHI
KADAMBI S

8. –Normally, the body dissipates heat into the
environment via four mechanisms.
–Conduction
–Covection
–Radiation
–Evaporation

10. Examples
▶ dripping of sweat off
the skin
▶ constrictive or
occlusive clothing,
▶ dehydration, and
▶ excessive humidity

11. •ACCLIMATIZATION TO HEAT REFLECTS A CONSTELLATION
OF PHYSIOLOGIC ADAPTATIONS THAT PERMIT THE BODY
TO LOSE HEAT MORE EFFICIENTLY.
•THIS PROCESS OFTEN REQUIRES ONE TO SEVERAL WEEKS
OF EXPOSURE AND WORK IN A HOT ENVIRONMENT

12. ■Heat waves exacerbate the mortality rate, particularly among the
elderly and poor and among persons lacking adequate
nutrition and access to air-conditioned environments.
■Exertional heat illness continues to occur when laborers,
military personnel, or athletes exercise
strenuously in the heat.
■preadolescentsandteenagersareatrisksincethey
mayusepoorjudgmentwhenvigorouslyexercisinginhighhumidity
andheat.Otherriskfactorsincludeobesity,poorconditioningand
lackofacclimatization,andmilddehydration.

13. Heat edema is characterized by mild swelling of the
hands, feet, and ankles during the first few days of
significant heat exposure
–The principal mechanism involves cutaneous
vasodilation and pooling of interstitial fluid in
response to heat stress.
–resolves without treatment in several days

16. –maculopapular, pruritic, erythematous rash that
commonly occurs in clothed areas.
–Blockage of the sweat pores by debris from macerated
stratum corneum causes inflammation in the sweat
ducts. As the ducts dilate, they rupture and produce
superficial vesicles.
–The predominant symptom is pruritus.
–antihistamines, chlorhexidine
–Clothing should be clean and loose fitting, and activities
or environments that induce diaphoresis should be
avoided

18. –exercise-associated collapse
–Endurance exercise
–prolonged standing while stationary in the heat
–Sudden standing after prolonged exposure to heat.
–relative volume depletion, decreased vasomotor tone,
and peripheral vasodilation postural hypotension
–non-acclimated elderly individuals.
–removal from the heat source coolingrehydration.

21. –Hyperventilation tetany occurs in some individuals
when exposure to heat stimulates hyperventilation,
producing respiratory alkalosis, paresthesias, and
carpopedal spasm
–providing reassurance
–moving the patient out of the heat
–addressing the hyperventilation.

23. –intermittent,
–Painful
–Involuntary
–spasmodic contractions of skeletal muscles.
–unacclimated individual who is at rest after vigorous
exertion in a humid, hot environment.
– In contrast, cramps that occur in athletes during
exercise last longer, are relieved by stretching and
massage, and resolve spontaneously.

24. –replacingfluidlosseswithcopiouswaterorother
hypotonicfluidscause
–DefofNAKrhabdomyolysis
–Treatment=commerciallyavailableelectrolyte
solutions

25. The physiologic hallmarks of heat exhaustion—in
contrast to heatstroke—are the maintenance of
thermoregulatory control and CNS function.
Laborers, athletes, and elderly individuals exerting
themselves in hot environments, without adequate
fluid intake, tend to develop water depletion heat
exhaustion.
In contrast, salt-depletion heat exhaustion occurs
more slowly in unacclimated persons who have been
consuming large quantities of hypotonic solutions.

28. •Heatrash
•Sunburn
•Heatcramps
•Heatexhaustion
•Heatstroke
Severity
American Meteorological Society
Central North Carolina Chapter
April 21, 2005

29. •A core temperature ≥40°C accompanied by CNS
dysfunction in patients with environmental heat
exposure. This condition represents a failure of the
body's ability to maintain thermoregulatory
homeostasis.

30. •Classic (nonexertional) heat stroke : more
common in younger children who are unable to
escape from hot environments and those with
underlying chronic medical conditions that impair
thermoregulation.
•Exertional heat stroke : generally occurs in
healthy individuals who engage in heavy exercise
during periods of high temperature and humidity.
Typical patients are athletes and military recruits
in basic training.

31. Children
Outdoor workers
(construction, roofers,
migrant workers)
Military
Elderly

32. •The diagnostic criteria are elevated core
temperature (≥40°C) and (CNS)
abnormalities following environmental
heat exposure.
•Children with elevated body temperature
and CNS abnormalities should be treated
as victims of heat stroke.

33. •CNS symptoms can be manifested as
–Impaired judgment
–inappropriate behavior
•Children commonly present with more significant
neurologic symptoms such as
–seizures
–delirium
–hallucinations
–ataxia
–coma

34. •Tachycardia
•Tachypnea
•The skin may be flushed and warm or diaphoretic.
•Vomiting and diarrhea are also common.
•Those patients with coagulopathy may
demonstrate
–purpura,
–hemoptysis,
–hematemesis,
–melena,
–hematochezia.

36. •Clinical assessment:
•The diagnosis of heat stroke is based
upon a careful history and physical
examination.

37. •Should be determined in all patients and
continuously monitored.
•Rectal temperature is the most commonly
obtained core temperature measurement,
although esophageal, central venous, pulmonary
artery, or bladder probe temperature are potential
alternatives.
•Oral, axillary, or tympanic membrane
temperatures are unreliable in treating heat
illness.

38. ●Rapid blood glucose to identify hypoglycemia
●Blood gas (venous or arterial) to evaluate for the presence and
severity of metabolic acidosis
●CBC,(PT), (PTT), INR and Serum electrolytes .
●Liver enzymes to assess for liver injury
●Urea and creatinine to identify prerenal azotemia or renal
failure resulting from myoglobinuria
●Serum (CK), ionized or total calcium, and phosphate to detect
rhabdomyolysis , hypocalcemia and
hyperphosphatemia
●Urine rapid dipstick and urinalysis to diagnose myoglobinuria
●Toxicologic screening for drugs of abuse or prescribed
medications

39. Chest radiograph:
Helps identify pulmonary edema and is useful in
patients for whom pulmonary aspiration is a concern.
Electrocardiogram:
Should be obtained in patients with electrolyte
abnormalities (eg, hyperkalemia, hypokalemia,
hypocalcemia) and/or rhabdomyolysis.
Computed tomography:
CT-Brain should be obtained if a child has persistently
altered mental status despite cooling or shows signs of
increased intracranial pressure suggestive of cerebral
edema or intracranial hemorrhage.

40. Dysrhythmias
14

41. 15

42. •Cooling might have occurred prior to the
arrival of the hospital.
•Removal from the source of heat stress
and rapid initiation of cooling, as the risk of
morbidity and mortality for patients with
heat-related illness is associated with the
duration of hyperthermia.

43. •Patients with heat stroke should be treated
with either ice water immersion or
evaporative external cooling in the field.
•Pre-hospital cooling measure should be
initiated prior to / or simultaneously with
activation of emergency medical services.

44. •Evaporative cooling may be accomplished
in the field by spraying patients with water or
saline and fanning these patients, either
manually or with ambulance fans or air-
conditioners. Application of ice packs to the
neck, axillae, and groin.
•The institution of pre-hospital cooling should
not delay timely transportation to definitive
care.

45. 21

46. •Stabilization: In addition to the careful assessment and
support of airway, breathing, and circulation, the
clinician should anticipate and aggressively manage
hyperthermia, dehydration, rhabdomyolysis, DIC, high
output cardiac insufficiency, renal and hepatic failure.
•Alteredmentalstatustypicallyresolvesonce
oxygenation,adequatetissueperfusion,and
normothermiaareachieved.
•Seizuresshouldbetreatedwithbenzodiazepines
(lorazepam0.1mg/kg,IV)

47. •Evaporative cooling:
is achieved by spraying patients with tepid water (to
minimize shivering) while fanning with high-flow fans
to maximize air circulation. Cooling rates approaching
0.15ºC per minute have been achieved in adults.
Alternatively, the patient may be placed on a cooling
blanket. If tolerated, selective application of ice packs
to the neck, axillae, and groin during evaporative
cooling may be of additional benefit.

48. Cold water immersion:
Cold water immersion is another adjunctive
cooling modality when evaporative cooling with
or without selective ice application is not
possible.

49. The most effective method of lowering the
core body temperature quickly is the use of
cardiopulmonary bypass; however, this
highly specialized intervention is not
rapidly available at most institutions.
Newer, less invasive devices such as
intravascular cooling catheters have been
utilized to rapidly induce therapeutic
hypothermia .

50. •Gastric, rectal, and/or bladder lavage with
cold isotonic fluids (eg, normal saline that
has been iced) have been proposed as
additional means of invasive cooling.
However, it is not clear that these methods
are any more effective than evaporative
cooling or cold water immersion alone.
Thus, these methods are not routinely
employed.

51. •Decreases in core body temperature as
measured by rectal temperature generally
lag behind the actual drop in core
temperature at the hypothalamus. For this
reason, cooling measures are generally
stopped in pediatric heat stroke victims once
the core temperature reaches approximately
38ºC to prevent overshoot hypothermia.

52. Medications have a limited role in the
management of heat stroke. However,
pharmacologic measures taken to prevent
shivering.
We suggest that patients with heat stroke
receive benzodiazepines (eg, midazolam0.05 to
0.1 mg/kg iv ) to prevent shivering during
cooling measures.
Although antipsychotic agents (chlorpromazine)
have been used in adults to prevent shivering,it
may exacerbate hypotension in heat stroke
victims. They also have a greater propensity to
cause dystonia in children. Thus, they should be

53. •DantroleneAlthough initial evidence suggested
that dantrolene shortened cooling times in adults
with heat stroke, additional small trials have not
identified a consistent benefit. Thus, dantrolene is
not routinely used.
•Antipyretic medications (acetaminophen,
ibuprofen) are ineffective for the treatment of
hyperthermia in heat stroke victims and should
not be used because they may exacerbate liver
injury (acetaminophen) or compound coagulation
disorders (nonsteroidal antiinflammatory agents,
ibuprofen).

54. After stabilization and rapid cooling, the victim
with heat stroke remains at high risk for multiple
organ failure, metabolic abnormalities, and
disorders of coagulation.

55. •Rhabdomyolysis with hyperkalemia,
hypocalcemia, and hyperphosphatemia
•DIC
•Acute kidney injury
•Hyponatremic dehydration
•Cardiogenic shock with low systemic vascular
resistance
•Cardiogenic and noncardiogenic pulmonary
(ARDS)
•Liver failure : Treatment is supportive. Rarely,
liver transplantation has been necessary in
teenagers with heat stroke-associated liver
failure.
•Cerebral edema

56. •Respiratory dysfunction:
–Trachealintubationandmechanicalventilationareoften
necessary.Inareviewof28patientsadmittedwithheat
stroke,24(86percent)developedrespiratoryfailurewith
mostrequiringmechanicalventilation.

57. •Potential cardiac complications include
acute decompensated heart failure and
myocardial injury .ECG abnormalities
include sinus tachycardia , conduction
abnormalities, prolonged QT interval,
transient Brugada pattern, and nonspecific
ST-T changes. Rapid cooling is essential;
cardiac dysfunction and tachyarrhythmias
generally resolve with cooling.

58. •Hypotension associated with heat stroke results
from peripheral vasodilation, cardiac dysfunction,
and volume depletion. Treatment consists primarily
of discrete intravenous (IV) boluses of isotonic
crystalloid (eg, isotonic saline 250 to 500 mL).
Given the risk of pulmonary edema, excessive fluid
administration should be avoided.

59. •Seizures:
•Seizures are common. Initial treatment consists of short-
acting benzodiazepines, while cooling measures are
initiated. Midazolam0.1 to 0.2 mg/kg IV, to a maximum
dose of 4 mg, has an onset of action one to five minutes
and duration of action of 1 to 6 hours. Lorazepam0.1
mg/kg IV, to maximum dose of 4 mg, is a second-line
option, as the duration of action may be prolonged from
12 to 24 hours. Barbiturates should be avoided. Rapid
cooling is essential to treatment.

60. •Acute kidney injury & Rhabdomyolysis:
•Renal function studies and serum electrolyte
should be followed closely over the first few
days of illness; renal replacement therapy
may be needed.

61. •Hepatic injury:
•Generally self-limited but in some
cases may progress to acute liver
failure, with a subset of patients
requiring liver transplantation.

62. •DIC
•can develop during the first 3 days of illness
and coagulation studies should be
monitored during this period. Replacement
of clotting factors with FFP and platelets
may be necessary.

63. Morbidity or mortality are directly related to
duration and degree of hyperthermia.
Thus, heat stroke must be treated aggressively.
In addition, prognosis depends on the patient
population and type of heat stroke.

64. Mortality of up to 63 % has been reported in
elderly adults with classic heat stroke. In
contrast, mortality is much lower(1 to 15 %)
in adolescents and young adults with exertional
heat stroke. Additional poor prognostic
indicators for mortality include the height of the
initial core body temperature and the number of
organ systems affected during the course of
treatment.

65. •Permanent neurologic damage is more commonly
seen in patients with core temperatures >42ºC
(107.6ºF) and consist of
–spasticity,
–ataxia,
–dysarthria,
–poor coordination,
–impaired memory, and
–behavioral changes.
•Patients recovering from rapidly treated exertional or classic
heat stroke with core body temperatures below this level may
manifest some of these neurologic findings but typically
recover fully.

66. •Dress for the heat : Wear lightweight, light-coloured
clothing. It is also a good idea to wear hats or to use an
umbrella.
•Drink water : Carry water or juice with you and drink
continuously even if you do not feel thirsty. Avoid
alcohol and caffeine, which dehydrate the body.
•Avoid foods that are high in protein, which increase
metabolic heat.
•Stay indoors when possible.
•Take regular breaks when engaged in physical activity
on warm days.
•Take time out to find a cool place.
42

67. •Children with elevated body temperature and CNS
abnormalities should be treated as victims of heat stroke.
•Rectal temperature is the most commonly obtained core
temperature measurement.
•Morbidity or mortality are directly related to duration and
degree of hyperthermia.
•The institution of prehospital cooling should not delay
timely transportation to definitive care.
•The most effective method of lowering the core body
temperature quickly is the use of cardiopulmonary bypass.