Heat, Cold and High Altitude Related illness By Dr Usama Ragab Lecturer of Medicine Topics are heat and cold related illness and high altitude medical disorders

1. Heat, Cold and High-Altitude
Related Illness
Usama Ragab Youssif, MD
Lecturer of Medicine
Email: usamaragab@medicine.zu.edu.eg
Slideshare: https://www.slideshare.net/dr4spring/
Mobile: 00201000035863

2. References
MKSAP 19 Cases and Discussions

3. Case 1
• A 37-year-old woman is evaluated in the
emergency department for headache,
dyspnea, and cough.
• Two days ago, she traveled from her home at
300 meters (984 feet) above sea level to a
mountain ski resort where the slopes are as
high as 3914 meters (12,841 feet).
• She developed the headache yesterday, and
today it is worse, and she has shortness of
breath and a cough.

4. Case 1 (cont.)
On physical examination, temperature is 37.0 °C, blood pressure is
124/72 mm Hg, pulse rate is 115/min, and respiration rate is 28/min.
Oxygen saturation is 82% with the patient breathing ambient air.
Inspiratory crackles are present bilaterally.
Chest radiograph demonstrates patchy alveolar infiltrates. High flow
supplemental oxygen by nasal cannula is initiated.

5. Which of the
following is
the most
appropriate
additional
treatment?
A. Acetazolamide, orally
B. Ceftriaxone, intravenously
C. Descent to a lower altitude
D. Dexamethasone, orally
E. Furosemide, intravenously

6. Correct Answer is C- Descent to a lower altitude
The most appropriate additional treatment is descent to a lower altitude
(Option C) as soon as possible.
The patient is experiencing high-altitude pulmonary edema (HAPE), which
is caused by exaggerated hypoxic pulmonary vasoconstriction and
abnormally high pulmonary artery and capillary pressures.
The resulting leakage of edema fluid into the alveolus causes hypoxemia
and may evoke an inflammatory response.

7. Risk factors
and
presentations
• Risks for this disorder include rapid ascent to
altitudes greater than 2500 meters (~8200 feet),
the actual altitude attained, time spent at
altitude, and a history of high-altitude illness.
• The typical symptoms of HAPE (cough,
shortness of breath, and fatigue) can be difficult
to distinguish from pneumonia.
• As HAPE progresses, patients can develop pink
frothy sputum, hemoptysis, and life-threatening
hypoxemia.

8. Treatment
Treatment of HAPE focuses on promptly reducing the pulmonary artery pressure.
This can be done by providing supplemental oxygen, limiting the patient's physical exertion and
cold exposure, and advising the patient to descend to a lower altitude as soon as possible.
This patient has received supplemental oxygen and should descend to a lower altitude.
Some clinicians suggest the use of nifedipine as adjunctive therapy, but there is a paucity of
data to confirm its benefit.

9. Other Answers
• Acetazolamide (Option A) is commonly
used for prophylaxis against HAPE, but
it has no role in treatment.
• Ceftriaxone (Option B) would be
appropriate if the patient had a
concurrent pneumonia along with
HAPE. However, given the symptoms
and timing of onset in this otherwise
healthy patient, there is nothing to
suggest a concurrent pneumonia or
the need for antibiotics.

10. Other Answers
• Dexamethasone (Option D) has been
shown to have a role in prophylaxis for
high altitude-related illnesses and as
treatment for high altitude cerebral
edema but not for HAPE.
• Furosemide (Option E) is a loop diuretic
that is commonly used in pulmonary
edema secondary to heart failure.
However, the typical patient with HAPE is
not volume overloaded. The use of
diuretics in these patients has no role in
HAPE and may cause harm by depleting
intravascular volume and further reducing
oxygen delivery to hypoxic tissues.

11. Final Bottomline
of this case
• Treatment of high-altitude
pulmonary edema focuses on
promptly reducing the pulmonary
artery pressure; the patient should
be given supplemental oxygen and
advised to descend to a lower
altitude as soon as possible and to
limit physical exertion and cold
exposure.
Luks AM, Swenson ER, Bdrtsch P Acute high altitude sickness. Eur Respir Rev. 2017;26. [PMID: 28143S79] doi:lO.ll83/1600Q617.0096-2016

12. High Altitude- Related lllnesses
Diminishing barometric pressure associated with
an ascent to altitude reduces the amount of
ambient oxygen available for gas exchange, a
condition known as hypobaric hypoxia.
Physiologic responses to hypobaric hypoxia
mechanistically underlie many disorders
collectively referred to as high altitude
illness

14. High Altitude- Related illnesses (cont.)
Susceptibility to high altitude illness is individualized and difficult to predict. Although
high altitude illnesses can occur at all ages regardless of fitness level, patients with a
history of high altitude-related illness are at risk for recurrence.
Other risk factors include rapid ascent (more than 3500 m in less than 2 days or more
than 500 m per day above altitudes of 3000 m) and medical comorbidities that impair
oxygenation, such as interstitial lung disease, COPD, and pulmonary hypertension.
Acetazolamide and gradual ascent to altitude can be used prophylactically in patients
who have previously suffered high altitude illness or have other risk factors

15. Case 2
• A 22-year-old man is evaluated in the
emergency department (ED) after being
pulled from a partially frozen lake.
• Immersion time is estimated to be 2 hours.
• He was found by emergency medical
services and was unresponsive and
pulseless.

16. Case 2
(cont.)
• He was intubated and advanced life support
was initiated.
• On arrival at the ED, pulse had returned, and
cardiopulmonary resuscitation was stopped.
• Mechanical ventilation was initiated, and
intravenous fluids were administered. Wet
clothes were removed.

17. Case 2 (cont.)
On physical examination, blood pressure is 92/60 mm Hg.
Temperature by an esophageal probe is 27.6 °C.
There are no signs of trauma.
Laboratory studies: Glucose 88 mg/dL, Potassium 5.4 mEq/L
Arterial blood gas studies: pH 7.28, Pco2 36 mmHg, Po2 110 mmHg

18. Which of the
following is
the most
appropriate
warming
technique?
A. Active internal rewarming
B. Cardiopulmonary bypass warming
C. Hemodialysis
D. Passive rewarming

19. Answer is A-
Active
Internal
Rewarming
• The most appropriate treatment is active
internal rewarming (Option A).
• This patient has severe hypothermia,
defined by a core temperature of less than
28.0 °C in the setting of ongoing coma or
cardiovascular collapse.
• Other findings in severe hypothermia are
absent reflexes, ventricular arrhythmia,
asystole, and apnea.

20. How to proceed
• If a severely hypothermic patient becomes pulseless and requires resuscitation, it
is reasonable to continue cardiopulmonary resuscitation for a prolonged period
until the patient can be rewarmed.
• Methods of internal rewarming include infusion of heated intravenous crystalloid
solution as well as lavage of the peritoneal or pleural cavities with warm fluids.
• During active rewarming, core temperature should be monitored with an
esophageal temperature probe, as rectal and bladder temperatures will lag
behind the rising core temperature during the rewarming process.

21. Other
Answers
• Extracorporeal support, including cardiopulmonary
bypass (Option B), is recommended for severely
hypothermic patients in cardiac arrest because it
maximizes the rewarming rate and can provide
hemodynamic support.
• Hemodialysis (Option C) can be used for warming,
depending on the clinical circumstances. Acid base and
electrolyte abnormalities are common in hypothermia.
These values, along with markers of coagulopathy, will
improve with rewarming but should be serially
measured.
• The patient has metabolic acidosis and hyperkalemia, but
neither is severe enough to warrant hemodialysis, and
rewarming can be accomplished by other means.

22. Other Answers
• Hypothermic patients who are shivering will passively rewarm themselves
(Option D) if they are removed from the cold environment and given adequate
insulation to prevent heat loss, but as hypothermia progresses, shivering stops.
• For core temperatures of 28.0 °C to 35.0 °C, active external warming is usually
sufficient. This consists of warming blankets and forced warm air.
• For temperatures less than 28.0 °C and for patients who fail to respond
adequately to active external rewarming, active internal rewarming methods
should be applied.

23. Final Bottomline
• Severe hypothermia is defined by a core temperature of less than 28.0 °C in the
setting of ongoing coma or cardiovascular collapse.
• For temperatures less than 28.0 °C and for patients who fail to respond adequately to
active external rewarming, active internal rewarming methods, including infusion of
heated intravenous crystalloid solution and lavage of the peritoneal or pleural cavities
with warm fluids, should be applied.
Paal P, Brugger H, Strapazzon G. Accidental hypothermia. Handb Clin Neurol. 2018;157:547-563.

24. Hint on hypothermia
• Accidental hypothermia, defined by a core temperature below 35 °C,
is classically associated with winter in cold climates but can occur in
more temperate weather if the exposure is sufficient (such as in wet
conditions).
• In mild hypothermia, shivering is an effective compensatory
mechanism, but in more severe cases (core temperature lower than
32 °C), it eventually ceases.

26. Symptomatology
• Early signs of hypothermia include tachycardia, hyperventilation,
poor judgment, and diuresis.
• Later findings include hypotension, bradycardia and other cardiac
arrhythmias, and further depression of mental status with eventual
coma,
• In moderate to severe hypothermia, Osborne waves may be present
on electrocardiogram tracings.

28. Severe cases
• If a severely hypothermic patient becomes pulseless and requires
resuscitation, it is reasonable to continue cardiopulmonary
resuscitation for a prolonged period until the patient can be
rewarmed.
• There are reports of cardiopulmonary resuscitation lasting hours and
resulting in full recovery when a severely hypothermic patient has a
cardiac arrest.

29. Case 3
• A 72-year-old man is evaluated in the emergency department for
decreasing responsiveness after he spent the day at the zoo.
• The outside temperature was 38.9 °C.
• He also has hypertension. Medications are hydrochlorothiazide and
lisinopril.

30. Case 3
(cont.)
• On physical examination, temperature is
40.5 °C, blood pressure is 97/54 mm Hg,
pulse rate is 117/min, respiration rate is
22/min, and oxygen saturation is 96% with
the patient breathing ambient air.
• He is somnolent. His skin is flushed, warm,
and dry.
• Other than tachy-cardia, cardiac and
pulmonary examinations are normal.
Laboratory results are pending.

31. Which of the
following is
the most
appropriate
treatment?
A. Acetaminophen
B. Dantrolene
C. Evaporative cooling
D. Immersion in ice water

32. Answer is C- Evaporative
cooling
• The most appropriate treatment is evaporative
cooling with water mist, fans, and ice packs
(Option C).
• Heatstroke is a failure of the body's thermal
regulatory system caused by dysfunction, as in
elderly patients taking anticholinergic
medications; volume depletion (diuretics,
insensible water loss); or overwhelming of the
system, as in athletes or military recruits who
train strenuously in hot, humid weather.

33. Symptoms
• They may also experience hypotension, nausea,
and muscle weakness.
• This patient has non exertional heat stroke. It is
generally defined by a core body temperature
above 40 °C along with encephalopathy.
• Additional complications of heat stroke can
include kidney and liver injury, DIC, and
rhabdomyolysis.
• The elderly are particularly vulnerable, with
added risk from comorbidities and medications.

34. Treatment of
heatstroke
• If untreated, mortality in heatstroke can reach 60%.
• Treatment of non-exertional heatstroke includes
evaporative cooling (with water mist and fans) with
or without ice packs to lower the core temperature
to a safe temperature, usually 38.5 °C.
• Evaporative cooling is effective, non-invasive, easily
performed, and does not interfere with other
aspects of patient care. It is associated with
decreased morbidity and mortality when used to
treat elderly patients with classic heatstroke.

35. Other Answers
Centrally acting antipyretics such as
acetaminophen (Option A) are not
effective for heatstroke because the
underlying mechanism does not involve
a change in the hypothalamic set point.
Furthermore, acetaminophen may
exacerbate complications such as
hepatic injury and should be avoided.

36. Other Answers
• Malignant hyperthermia is a rare cause of severe hyperthermia in response to inhaled
anesthetic agents (e.g., halothane and isoflurane) or depolarizing paralytic agents (e.g.,
succinylcholine) (Option B).
• When a patient with inherited susceptibility is exposed to one of these agents, he or she
may develop muscle rigidity, rhabdomyolysis, cardiac arrhythmias, and core body
temperature elevation to 45.0 °C or more. Mortality can reach 10%.
• Treatment consists of discontinuing the triggering agent, active cooling, and
administration of the muscle relaxant dantrolene every 5 to 10 minutes until muscle
rigidity and hyperthermia resolve.
• Dantrolene is ineffective in patients with severe temperature elevation not caused by
malignant hyperthermia.

37. Other Answers
Immersion in ice water (Option D) may be
necessary for young persons with exertional
heatstroke when they remain severely
symptomatic despite evaporative cooling,
but it is not first-line therapy because it may
be complicated by hypothermia.
In older persons with non-exertional
hyperthermia, ice water immersion is
associated with increased mortality and
should not be used.

38. Final bottom-line
• Treatment of non-exertional heatstroke includes evaporative cooling (with water mist
and fans) with or without ice packs to lower the core temperature to a safe
temperature, usually 38.5 °C
• In older persons with non-exertional hyperthermia, ice water immersion is associated
with increased mortality and should not be used.

39. Case 4
• A 49-year-old man is transferred from a
psychiatric hospital to the emergency
department because of a change in vital signs
and encephalopathy.
• He has schizophrenia and depression. He was
hospitalized 3 days ago for acute psychosis and
attempted suicide.
• In the psychiatric hospital, he was treated with
risperidone and fluoxetine. He subsequently
developed nausea and vomiting and was
prescribed promethazine.

40. Case 4
(cont.)
• On physical examination, temperature is 39.5 °C,
blood pressure is 173/112 mm Hg, pulse rate is
132/min, respiration rate is 26/min, and oxygen
saturation is 99% with the patient breathing
ambient air.
• He is diaphoretic and tachypneic, with clear lungs.
• He has tachycardia without murmur, gallops, or
rubs.
• Muscles are rigid. Deep tendon reflexes are normal.
Promethazine is discontinued.

41. Which of the
following is the
most
appropriate
initial
treatment?
A. Discontinue fluoxetine
B. Discontinue risperidone
C. Start cyproheptadine
D. Start dantrolene

42. Answer is B-
Discontinue
risperidone
• The most appropriate initial treatment is the
discontinuation of risperidone (Option B).
• This patient developed neuroleptic malignant
syndrome as a result of risperidone (an atypical
antipsychotic) and promethazine (an antiemetic
agent).
• Neuroleptic malignant syndrome is characterized by
fever, mental status changes, muscle rigidity, and
dysautonomia.

43. Answer is B-
Discontinue
risperidone
• The syndrome is seen both with first-
generation antipsychotics and with newer
atypical antipsychotics and anti-emetics.
• It is most common at times of medication
initiation or escalation of medication doses.
It can also be caused by the rapid withdrawal
of dopaminergic medications.

44. Supportive
treatment
In addition to discontinuation of the
triggering agents, active cooling and
supportive care (including
intravenous fluids) may be used.
The mortality rate associated with
neuroleptic malignant syndrome
may exceed 10%.

45. Other Answers
• Serotonin syndrome is most commonly associated with the use of selective
serotonin reuptake inhibitors (SSRIs) such as fluoxetine (Option A) and is typically
precipitated by the addition of a second medication that affects the release or
uptake of serotonin.
• Serotonin syndrome is characterized by mental status changes, dysautonomia,
hyperthermia, myoclonus, and hyperreflexia.
• The two features that are most helpful in distinguishing serotonin syndrome from
neuroleptic malignant syndrome are the presence of hyperreflexia and
myoclonus.

46. Other
Answers
• Initial management includes removal of the
offending agents and supportive care,
includinging benzodiazepines.
• Cyproheptadine (Option C) may also be used
off-label for serotonin syndrome if
symptoms persist despite benzodiazepines.
• Because this patient does not have serotonin
syndrome, these medications are not
appropriate.

47. Again,
Malignant
Hyperthermia
• Malignant hyperthermia is AD condition resulting from
deranged intracellular calcium metabolism in response to
inhaled anesthetic agents and succinylcholine.
• It is characterized by severe hyperthermia, muscle
rigidity, rhabdomyolysis, and arrhythmias.
• Treatment includes cessation of the triggering agent,
active cooling, and administration of dantrolene (Option
D).
• This patient has not received agents known to trigger
malignant hyperthermia, and the patient's symptoms are
not consistent with this diagnosis.

48. Final Bottomline
• Neuroleptic malignant syndrome is
characterized by fever, mental
status changes, muscle rigidity, and
dysautonomia and is seen with
both first-generation antipsychotics
and newer atypical antipsychotics
and antiemetics.
• Treatment of neuroleptic malignant
syndrome includes discontinuation
of the triggering agent, active
cooling, and supportive care.

49. Case 5
• A 48-year-old man is evaluated in the hospital
for acute onset of hyperpyrexia and muscle
rigidity.
• He was hospitalized 12 hours ago for upper
gastrointestinal bleeding. Within the last hour
he underwent upper endoscopy using rapid
sequence intubation with succinylcholine and
etomidate.
• Soon after completion of the procedure, he
developed fever, tachypnea, and tachycardia.

50. Case 5 (cont.)
On physical examination, temperature is 40.6 °C, blood pressure is 112/68
mm Hg, pulse rate is 130/min, respiration rate is 26/min., and oxygen
saturation is 99% breathing oxygen, 2 L/min by nasal cannula.
He has generalized muscle rigidity and cannot open his mouth.
Neurologic examination is otherwise normal. Cooling measures are
implemented.

51. Which of the
following is the
most
appropriate
pharmacologic
treatment?
A. Acetaminophen
B. Cyproheptadine
C. Dantrolene
D. Diltiazem

52. Correct Answer is D
• Malignant hyperthermia is a rare cause of severe hyperthermia in
response to inhaled anesthetic agents or depolarizing paralytic agents
such as succinylcholine, resulting in muscle rigidity, rhabdomyolysis,
cardiac arrhythmias, and significant core body temperature elevation.
• Treatment of malignant hyperthermia consists of discontinuing the
triggering agent, active cooling, and administration of the muscle
relaxant dantrolene.

54. Thank You