This document provides information about high altitude areas and their effects on the human body. It discusses the characteristics of high altitude terrain, such as low oxygen levels, extreme temperatures, and difficult terrain. It then describes the various physiological effects of high altitudes, including lack of oxygen, fatigue, and psychological impacts. The document outlines different medical problems that can occur at altitude, such as altitude sickness, pulmonary edema, cerebral edema, and frostbites. It provides details on prevention, treatment, and the process of acclimatization to high altitude conditions.

1. HIGH ALITUDE AREA

2. AIM
TO FAMILIARISE THE OFFICER
TRAINEES WITH DIFFERENT
ASPECTS OF
HIGH ALTITUDE AREA

3. PREVIEW
Part 1 – Characteristics of HAA
Part 2 – Effects of HAA
Part 3 – Precautions
Part 4 – Mitigation
Part 5 – Medical Aspects

4. CHARACTERISTICS
OF
HIGH ALTITUDE AREA

5. TERRAIN AND WEATHER
• Altitude
• Vegetation
• Lack of water
• Paucity of roads and tracks
• Time
• Space
• Variation in temperature
• Speed of wind
• Wind chill
• Movement on snow difficult

6. TERRAIN AND WEATHER
• Glacier
– Hanging glaciers and avalanche
– Ice walls
– Crevasses
– Blizzards
– Pillaring effects

7. EFFECTS
OF
HIGH ALTITUDE

8. EFFECTS
• Lack of oxygen
• Movement
• Limited lines of communication
• Weather changes shortly
• UV rays
• Mental and physical stress
• Fatigue
• Motivation

9. EFFECTS
• Altitude > 2700 m (9000 ft)
• Main problem: decreased availability of oxygen causing
a disorder of normal breathing
• Other factors: low temperature
low air humidity
high UV radiation
low atmospheric pressure
8 850 m / 29 000 ft
5 500 m / 18 000 ft
2 700 m / 9 000 ft
pA = 1 [atm]
0 m
pA = 0.75
pA = 0.5
pA = 0.3
O2 - 21 %

10. PSYCHOLOGICAL EFFECTS
• Disinterest
• Irritability
• Irrational reaction
• Lengthening reaction time
• Dementia (irreversible at low altitude)
• Impotence & Sterility
• Insubordination

11. MEDICAL PROBLEMS
• Abnormal response to acclimatization
– Early – AMS, HAPO, HACO
– Intermediate – SAMS, HAPH
– Late – CMS
• Effects of extreme cold
– Chilblains
– Frostbite
– Hypothermia

12. CHILBLAIN

13. CHILBLAIN
• Poor blood circulation
• Family history of chilblains
• Regular exposure to cold, damp or draughty conditions
• Poor diet or low body weight.
• Long-term condition that causes swelling in the body's tissues– a
common condition that affects the blood supply to certain parts of the
body, usually the fingers and toes.
• People who smoke are more at risk as nicotine constricts blood vessels.
• Areas of the feet exposed to pressure, such as a toe that's squeezed by
tight shoes.
• Abrupt temp changes.
• People with diabetes are at higher risk.

14. FROSTBITE

15. FROSTBITE
• Exposure to severe cold or cold objects.
• Affects fingers, toes, cheeks, nose and ears.
• Tissues freezes at sub zero temperatures.
• May cause gangrene.
• Susceptible to future frostbite.
• Amputation or loss of function.

16. MEDICAL PROBLEMS
• Related to blood clotting disorder
– DVT
– Pulmonary thromboembolism
– CVA
• Eye & skin problems
• Others
– GI disorders
– Neurological & sleep disorders
– Misc & exacerbation of existing disorders

17. OTHER EFFECTS
• Dimness of vision
• Loosening of teeth
• Loss of weight
• Flatulence
• Indigestion
• Loose bowels
• Anemia

18. ETIOLOGY
• Multifactorial
• No gender difference
• All ages affected
• Hypoxic ventilatory response reduced
• Fluid electrolyte imbalance
• Raised intracranial pressure

19. PRECAUTIONS
&
MITIGATION

20. PRECAUTIONS / MITIGATION
• Knowledge
• Acclimatization
• Special equipment
• Training
• Discipline
• Hygiene and sanitation
• First aid
• Casualty evacuation
• Treatment

21. adequate  acclimatization
insufficient  high altitude illness
REACTION TO HIGH ALTITUDE
5 000 m
16 500 ft
7 000 m
24 000 ft
2 500 m
8 000 ft
high altitude illness
tolerance zone
current acclimatization
no problems
adaptation

22. PREVENTION OF HAI
1. Gradual ascent within the tolerance zone
2. Full acclimatization
3. Descent when develop symptoms AMS
4. Avoiding medications that cause depression
of breathing
• alcohol, sleeping pills, sedatives, strong
painkillers
5. Prophylaxis

23. • A gradual process of the body adaptation to high altitude
ACCLIMATIZATION
Changes :
1. Breathing:  Hyperventilation (breathing deeper and faster)
 Shortness of breath during exertion
 Changed breathing pattern (periodic breathing)
and frequent awakening at night
2. Blood circulation:  Tachycardia (increased heart rate)
 Decreased maximum heart rate
 Higher number of red blood cells
3. Body fluid :  Increased urination (altitude diuresis)

24. ACCLIMATIZATION
• A reversible, non inheritable change in the
anatomy or physiology of an organism that
enables it to survive in stressful environment
• Altitude tolerance
• Qualitatively similar to adaptation

25. PHYSIOLOGICAL CHANGES
• The main features of acclimatization are
related to changes in :
– Respiratory system
– Cardiovascular system
– Oxygen transport and delivery system
• Others
– Endocrines
– Renal functions
– Coagulation

26. ADAPTATION
• Involves biochemical, physiological and
anatomical changes in the organism which
have a genetic basis and is inheritable
• Native highlanders

27. Physiological Adaptation
• Changes usually >2500m (30% decrease in atm
pressure)
• Physiological changes in early adaptation
– Changes in RBCs
• Increased number
• Increase in size and volume
• Increased Hb concentration in RBC
– Increase in pulmonary ventilation and vital capacity
– Increase in Heart rate, Blood volume and Cardiac output

28. Physiological Adaptation
• “Rapid acclimatization” may manifest as early
mountain sickness
• The beneficial adaptive response becomes
aberrant and disease process starts when :
– Acclimatization is inadequate or breaks down
– Ascent is too rapid (more than 3000 ft in a day)
– Heavy physical exertion (un-acclimatized)
– Lag in adjustment of body to increasing hypoxia
– Pronounced symptoms in night due to pooling of blood in
lungs (horizontal position)

29. ACCLIMATIZATION SCHEDULE
• STAGE 1 ( 9000ft – 12000ft ) : 6 DAYS
Day 1& 2 – Rest, short walk , no climb
Day 3& 4 - Slow pace walk for 1.5 km, no
steep climb
Day 5& 6 - 5 km walk with climb of 300m
within the same

30. • STAGE 2 ( 12000ft – 15000ft ) : 4 DAYS
Day 1 & 2 – Slow walk for 1.5 km, no steep
climb
Day 3 - Slow walk upto 3 km & slow
climb of 300m in 3 km without
equipment
Day 4 - Slow walk upto 3 km & slow
climb of 300m in 3 km with
equipment and steep climb of 100m
without equipment

31. • STAGE 3 ( > 15000ft ) – 4 DAYS
Same as in stage 2
RE - ENTRY
Absence from high altitude area for :
• > 4 weeks : full acclimatization
• < 10 days : no acclimatization
• 10 days - 4 weeks : 4 days acclimatization
required at each stage
Day 1 & 2 - rest , short walk
Day 3 - slow walk of 1-2 km , no climb.
Day 4 - slow walk of 3 km , with climb of 300 m

32. PHYSIOLOGICAL ADAPTATION
• Interstitial fluid into vascular compartment >
hypevolemia > overload of pulmonary circulation
• Hyperventilation>>tissue CO2 washout >>hypocapnia
& alkalosis
• Increase in 2,3 DPG brings about major changes -
restores O2 delivery to tissues

34. HIGH ALTITUDE ILLNESS
1. High altitude and Pa O2
2. Acclimatization
3. High altitude illness: AMS
HACO
HAPO
4. Treatment of HAI
5. Prevention of HAI

35. Altitude, Partial pressure &
% of Oxygen
Altitude Pressure Temp PO2 02 %
Feet Mtrs mmHg Cel mmHg Effective
0 0 760 15 160 21
5000 1525 632 5 132 17
10000 3050 523 -3 114 15
15000 4575 430 -15 91 12
20000 6100 350 -25 73 10

36. Relationship of altitude,
barometric pressure and PaO2

38. Respiration
• Involves
– Ventilation
– Diffusion
– Gas transport
– Tissue diffusion
• Oxygen moves in a diffusion gradient
• HA alters this gradient (becomes less steep)
• Acclimatization tries to correct this alteration

39. Ventilatory changes
• Hyperventilation within few hours in response to
hypobaric hypoxia (peripheral chemoreceptor
mediated)
• Increase in respiratory rate and subsequently in
amplitude
• Increase in tidal volume
• Drop in arterial CO2 tension – resp alkalosis

40. • Inhibition of central medullary chemo
receptors
• Peripheral chemo receptors are strong and
override the central receptors
• Sensitivity of central receptors to carbon
dioxide returns to normal within 8 days of
ascent

41. Hypoxic ventilatory response
• A basic response to hypoxia via chemo-
receptors
• The foundation of successful
acclimatization
• Sub normal HVR leads to alveolar
hypoventilation causing pulmonary
vasoconstriction

42. Pulmonary diffusion
• The alveolar to arterial difference in oxygen tension
is 6 mm Hg at sea
• This alveolar to arterial difference in oxygen tension
is reduced at HA
• This leads to better arterial oxygen tension
• Also there is an increase in ventilation perfusion ratio
and pulmonary arterial pressure

43. Systemic circulation
• Tachycardia due to increased sympathetic
activity
• Drop in cardiac output and the stroke volume
(up to 20-25% drop)
• Decrease in plasma volume due to diuresis
• Total blood volume increase due to increase in
hematocrit after two to three weeks of stay

44. Oxygen transport
• Oxygen transport and release depends on CO, SaO2
and affinity of Hb with oxygen
• To ensure adequate oxygen to tissue –
– Increase in hemoglobin
– Increase in cardiac output
– Decrease affinity of Hb with oxygen
• Initial Rise in Hb is due to hemo-concentration
resulting from diuresis
• Absence of this diuresis leads to fluid retention and has
been implicated in pathogenesis of AMS

45. • Hb rises within few days
• The rise in Hb and hamatocrit is due to increased
erythropoiesis mediated through erythropoietin
• Erythropoietin also rises within few hours of
ascent
• Hb comes back to normal within 20 days of
descent

46. Tissue diffusion
• Increased oxygen availability from the blood to
the tissues
• Increase in capillary density and decrease in
muscle fiber size
• Myoglobin levels in muscles increase
• Myoglobin facilitates diffusion of oxygen to the
cells

47. Syndromes due to hypobaric hypoxia
• Acute mountain sickness syndrome
– Benign acute mountain sickness
– High altitude pulmonary edema
– High altitude cerebral edema
• Sub acute mountain sickness syndrome
– Adult SAMS
– Infantile SAMS
• Chronic mountain sickness

48. • Others
– High altitude pulmonary arterial hypertension
– High altitude retinopathy
• Other medical problems
– High altitude syncope
– Stroke at HA
– High altitude induced hypertension

49. Forms of HAI:
HIGH ALTITUDE ILLNESS (HAI)
I. Acute mountain sickness (AMS)
II. High altitude cerebral edema (HACO)
III. High altitude pulmonary edema (HAPO)
• A disease caused by hypoxia in high altitude that is
beyond the ranges the body can tolerate

50. ACUTE MOUNTAIN SICKNESS
(AMS)
• Symptoms caused by mild brain swelling (fluid
retention) due to hypoxia
• Mild to severe
incidence 25 – 85 %
usually appears 6 – 12 hours after an ascent

51. • Hypoxia - Increased secretion of atrial
natriuretic peptide
- Activation of renin - angiotensin –
Aldosteron system
• Both these lead to Fluid retention
• Arterial hypoxemia causes cerebral vaso-dilatation
responsible for headache

52. Predisposing factors:
1. Rate of ascent
2. Altitude reached (sleeping altitude)
3. Individual susceptibility (genetic)
4. Other: exertion
certain diseases (cardiopulmonary)
no significant association with: age
gender
physical fitness
ACUTE MOUNTAIN SICKNESS
(AMS)

53. DIAGNOSIS:
 Headache
+ 1 or more of the following symptoms:
 loss of appetite, nausea, vomiting
 fatigue, weakness
 dizziness, light-headedness
 difficulty sleeping
in the setting of a recent gain in altitude above 2500 m
ACUTE MOUNTAIN SICKNESS
(AMS)

54. The Lake Louise consensus
scoring of AMS
• AMS self assessment
• To diagnose patient should have
– History of recent gain of altitude
– Stay at that altitude for several hours
– Headache

55. • Headache 0 None at all
1 Mild headache
2 Moderate headache
3 Severe headache,
incapacitating

56. • Gastrointestinal symptoms
0 Good appetite
1 Poor appetite or nausea
2 Moderate nausea or vomiting
3 Severe, incapacitating nausea and
vomiting

57. • Fatigue and/or Weakness
0 Not tired or weak
1 Mild fatigue/weakness
2 Moderate fatigue/weakness
3 Severe fatigue/weakness

58. • Dizziness/light-headedness
0 None
1 Mild
2 Moderate
3 Severe, incapacitating

59. • Difficulty in sleeping
0 Slept as well as usual
1 Did not sleep as well as usual
2 Woke many times, poor night's sleep
3 Could not sleep at all

60. • Score of 3 or more is positive for AMS
• Score of more than 5 indicate severe
disease

61. • Severe swelling of the brain with deterioration of
brain functions
• The most severe form of AMS, end-stage of AMS
Incidence 0.1 - 5 %
often manifests at night
can progress rapidly, lethal in few hours to 2 days
HIGH ALTITUDE CEREBRAL EDEMA
(HACO)

62. HIGH ALTITUDE CEREBRAL EDEMA
(HACO)
Predisposing factors:
like in AMS
HACO usually develops from AMS

63. HIGH ALTITUDE CEREBRAL EDEMA
(HACO)
DIAGNOSIS:
at least 2 of the following symptoms:
 AMS
 ataxia (loss of coordination of movements)
 mental status changes (confusion, disorientation)
in the setting of a recent gain in altitude above 2,500 m

64. Clinical features of HACO
• Isolated HACO is uncommon
• Usually seen in combination with HAPO
• The onset is with AMS
• The transition from AMS to HACO may be
very subtle hence a high degree of suspicion is
needed for diagnosis

65. HACO should be suspected
• Truncal ataxia – tested by tandem walking
(heel to toe walking)
• Alteration in the level of consciousness

66. Other features
• Dimness of vision
• Dizziness and drowsiness
• Incontinence of urine
• Mood changes
• Confusion
• stupor and coma

68. HIGH ALTITUDE PULMONARY EDEMA
(HAPO)
• Leak and accumulation of fluid in the lungs leading
to respiratory failure
• May occur without signs of AMS
Incidence 0.1 - 5 %
often manifests at night (typically the second night of ascent)
progresses rapidly, lethal if untreated
may lead to development of HACO

69. HAPO
• Can be preceded by AMS
• Initial patho-physiology remains same
– Increase in blood volume
– Redistribution of blood from periphery to
centre
• Onset of HAPO is also seen immediately on
arrival to HA by air – direct role of hypoxia
on lungs

70. HIGH ALTITUDE PULMONARY EDEMA
(HAPO)
Predisposing factors:
1. Young fit males
2. Rate of entry (Entry by air – rapid)
3. Physical exercise even of moderate intensity (within 72
hrs of entry into HA)
4. Cold (need further study) Genetic factors
5. Re-exposure to HA

71. Pulmonary edema
• Caused by flow of fluid across capillary
membranes into the interstitial space and
hence in the alveoli
• This flow depends on
– Hydrostatic pressure in the capillary
– The integrity of capillary endothelium
– Rate of removal of fluid from interstitial
space

72. • Pulmonary vasoconstriction and pulmonary
arterial hypertension cause rise in
hydrostatic pressure
• Pulmonary hypertension also causes
epithelial dysfunction
• Epithelial dysfunction also caused by
mediators

73. Major changes
• Non uniform hypoxic pulmonary arteriolar vaso-
constriction
• Pulmonary arterial hypertension
• Increased pulmonary blood flow in regions not
affected by vaso-constriction
• Epithelial dysfunction

74. • Hypoxic vasoconstriction, associated with
increased pulmonary blood flow causes
STRESS FAILURE of the pulmonary
capillaries and with disruption of integrity
of the capillary-alveolar membrane it
leads to pulmonary edema

75. HAPO
DIAGNOSIS:
at least 2 of the following symptoms:
 Breathlessness at rest
 Cough
 Weakness, fatigue, drowsiness
 Chest tightness, fullness, congestion
at least 2 of the following signs:
 gurgling or rattling breaths, coarse crepts
 central cyanosis (blue or dark purple lips)
 fast breathing
 increased heart rate
in the setting of a recent gain in altitude above 2500 m

76. Diagnosis
• Based on clinical features
• Confirmed on X-ray chest
• Soft, fluffy, non homogenous shadows

79. Severity of HAPO
Mild Moderate Severe
Pulse <120 120 -140 >140
Cyanosis Nil +/- +/-
Resp rate <40 40 – 50 > 50
Conscious Yes Yes Yes/no
Crepitations <1/2 lung
fields
> ½ lung
fields
> ½ lung
fields

80. TREATMENT OF AMS
Mild to moderate forms
 NEVER continue ascent !
 Consider - rest at the same altitude
- descent
 Proper Fluid intake
 Mild analgesics (paracetamol, aspirin, ibuprofen)
 Acetazolamide (Diamox)- increases ventilation & arterial
O2
 Rest
Severe forms: treat like HACO

81. AMS – Specific Treatment
• Acetazolamide
– Prophylactic and curative
– Carbonic anhydrase inhibitor
– Causes bicarbonate diuresis and metabolic acidosis
– Increased ventilation and arterial oxygenation
– Dose 250 mg PO tid
• Dexamethasone
– Reduces cerebral edema
– Useful if acetazolamide not tolerated
– Dose 8mg IM/PO followed by 4mg IM/PO 6 h
• Ginkobiloba

82. TREATMENT OF HACO
 Immediate descent to lower altitude
 Oxygen inhalation
 Hyperbaric bag (HAPO Bag)
 Acetazolamide (Diamox)
 Dexamethasone

83. TREATMENT OF HAPO
 Evacuation to lower altitude
 Oxygen inhalation
 Hyperbaric bag
 Diuretics - Lasix
 Nifedipine

84. PORTABLE HYPERBARIC CHAMBER
(HAPO bag)
• Air-impermeable bags that can be inflated to high
pressure, simulating descent
• Main types: Gamow
Certec
PAC (Portable Altitude Chamber)

85. PORTABLE HYPERBARIC CHAMBER

86. PORTABLE HYPERBARIC CHAMBER
• Indications: HACO or HAPO when descent is impossible
• Contraindications:
Absolute - lack of spontaneous breathing
Relative - middle ear congestion, claustrophobia

87. Recompression
• Recompression in chamber – 1 atm X 16hrs
• All cases of HAPO/ HACO in portable one man
recompression bag
• 150 mm Hg (reduces altitude by 6000 ft); reduce to
50mm Hg every 5 min; recompress 150mm Hg
(ensures air circulation)
• Bring patient out of bag 2 hourly for 15-20 min -
monitoring/ nursing

90. “THE GOLDEN RULES”
If you feel unwell at High Altitude, it is high
altitude illness until proven otherwise
Never ascend with symptoms of AMS
If you are getting worse or have HACO or
HAPO, get down immediately

91. “DON’T
BECOME
GAMA IN
THE
LAND OF