1) High altitude illness includes acute mountain sickness (AMS), high altitude cerebral edema (HACE), and high altitude pulmonary edema (HAPE). AMS causes headache, nausea, fatigue, and dizziness. HACE is a neurological deterioration in someone with AMS. HAPE causes cough, dyspnea, and chest tightness. (2) Risk factors for these illnesses include rapid ascent, exertion, prior history, age under 50, and underlying lung/heart conditions. (3) Treatment depends on the illness but may include descent, oxygen, medications like dexamethasone or nifedipine, and hyperbaric bags that simulate lower altitudes.

1. HIGH ALTITUDE
ILLNESS
Dr. Partha Das
ER, Fortis Hospital, Kolkata

3. TYPES

4. Lake Louise self-assessment
AMS scoring system
Each symptom is graded on a scale of 0–3; the
presence of headache plus a score greater than or equal
to 3 is usually considered positive for AMS.
Mild AMS 2-4, Moderate AMS 5-9, Severe AMS >10
Ref: Rambam Maimonides Medical Journal
January 2011w Volume 2w Issue 1w e0022
Headache None (0) to anticipating (3)
GI symptoms None (0), mild nausea (1),
moderate nausea/vomiting (2),
severe nausea/vomiting (3)
Fatigue/ Weakness None (0) to severe or
incapacitating (3)
Dizziness/ light headedness None (0) to incapacitating (3)
↓ sleep last night Slept well (0) to no sleep at all (3)

5. BLOOD GASES & ALTITUDE
Ref: Tintinalli’s Emergency Medicine, 6th
ed.
Altitude (meters) PaO2 (mmHg) SaO2 % PaCO2 (mmHg)
Sea level 90-95 96 40
1524 (5000 ft.) 75-81 95 35.6
2286 (7500 ft.) 69-74 92-93 31-33
4572 (15000 ft.) 48-53 86 25
6096 (20000 ft.) 37-45 76 20
7620 (25000 ft.) 32-39 68 13
8848 (29029 ft.) 26-33 58 9.5-13.8

6. RISK FACTORS
Rapid ascent
Physical exertion at high altitudes (including
climbing)
P/H/O high altitude sickness
Younger individuals (<50 years)
Obesity
Pre existing lung/cardiac disease
Sleeping @ 7000-9000 ft.

7. AMS
Typically occurs @ altitudes > 2500m/8200ft
C/F headache/dizziness
Nausea/vomiting
Fatigue/irritability
(Often misdiagnosed as hangovers from alcohol)
Generally benign & self limiting
Onset : 4-12 hours after ascent

8. HACE
• Cytotoxic rather than vasogenic
• Progressive neurological deterioration in
someone with AMS or HAPE.
(seen rarely as an isolated entity)
• May occur 12 hours after onset of AMS &
requires 2-4 days for development
• C/F: Headache
Altered mental status
Ataxia
Nausea/vomiting
Papilledema/ Retinal Hemorrhages
CN palsies

9. FREQUENCY OF NEUROLOGIC FEATURES IN 44
PATIENTS WITH HACE
Table 1 lists the neurological findings in the largest series published to date
(Dickinson, 1983)
HIGH ALTITUDE MEDICINE & BIOLOGY
Volume 5, Number 2, 2004
© Mary Ann Liebert, Inc.
Disturbance of consciousness 31 (70%)
Ataxia 27 (61%)
Papilledema 23 (52%)
Urinary retention/ incontinence 21 (48%)
Abnormal plantar reflexes 15 (34%)
Abnormal limb tone/ power 6 (14%)
Abducens Nerve palsy 2
Anisocoria 2
Visual field loss 2
Speech difficulty 1
Hearing loss 1
Flapping tremor 1

10. HAPE
• Usually occurs 2-4 days after ascent
• Life threatening
• Usually at altitudes >2300m
• C/F cough (usually dry→frothy +/- blood stained)
Dyspnea (even at rest)
Chest tightness
Orthopnea/ Tachypnea
Fever +/-
Coarse crepitations on auscultation
Cyanosis

11. PEOPLE AT RISK FOR HAPE
• Pulmonary hypertension
– Intra cardiac shunts
– Patent ductus arteriosus
– Drug-induced (Fenfluramine/ SSRIs)
– Chronic venous thrombotic disease

12. PATHOPHYSIOLOGY

13. PEDIATRIC
CONSIDERATIONS
• AMS in small children & infants can be
manifested by :-
• ↑ Fussiness
• ↑ Irritability
• ↓ Appetite & vomiting
• Sleep disturbances

14. INVESTIGATIONS
• HAPE
• Blood gas – E/o hypoxemia & respiratory
alkalosis
• CXR – Patchy alveolar infiltrates with
batwing distribution
Kerly B lines +/-
• ECG – Sinus tachy
E/o Right heart strain

15. HAPE Contd…
Ref: https://radiopaedia.org/cases/high-altitude-pulmonary-oedema

16. Contd…
• HACE
• CT/MR- Vasogenic edema of white
matter

17. DIFFRENTIALS
• AMS: Alcohol hangover
CO poisoning (from wood
combustions inside camps)
Viral syndrome
Encephalitis/ Meningitis
• HAPE: High altitude bronchitis
Pneumonia
PE (more rapid onset +
pleuritic chest pain)
• HACE: CVA/TIA
FND suggests vascular lesions

18. Grade based on ACCP classification of
clinical evidence for guidelines

19. MANAGEMENT
HAPE:
• Immediate evacuation to ↓ altitudes
• O2 delivery or simulated descent in hyperbaric
chamber/ Gamow bag
• ET intubation for airway protection
• Beta agonist inhalers & nebulization
• Tab. Nifedipine 10mg stat, then 20-30 mg TID
• Consider Furesemide
Ref – Tintinalli’s emergency medicine, 6th
ed.

20. Contd…
Grade based on ACCP classification of
clinical evidence for guidelines

22. GAMOW BAG
• Gamow bag uses ↑PaO2 for therapy of hypobaric
injury
• Inflated to simulate a ↓ altitude.
• Advantage: portable for field use.
• HAPE: 2-4 hours, HACE: 4-6 hours of treatment
• Named after its inventor, Dr. Igor Gamow

23. Contd…
HACE:
• Immediate evacuation to ↓ altitude
• Dexamethasone 8mg i/v stat, then 4mg i/v
QID
• Hyperbaric O2

24. Contd…
AMS:
• Acetazolamide 250-500mg BD (5mg/kg/day in 2-
3 divided doses)
• Prophylaxis 250mg BD (start 24 hours before
ascent)
• Peds 5mg/kg BD
• Paracetamol for headache
• Promethazine/ Ondansetron for vomiting
• Halt ascent until symptoms subside
• Supplemental O2

25. PREVENTION
• Gradual ascent (1000-1200 ft. per day) & also
allowing time for pre-acclimatization
• Low sleeping altitudes & avoid sleeping tablets
• Keep warm & well hydrated
• ↑ carb diet & avoid alcohol
• Gingko Bilboa extract (80-120mg BD)
• Acetazolamide 125-250mg BD or Dexa 4mg QID
– 24 hours before or after ascent
• Tadalafil (10mg BD to start 1 day prior ascent)

26. OTHER HIGH ALTITUDE
CONDITIONS
• High altitude bronchitis/ pharyngitis
• Chronic mountain polycythemia
• UV keratitis (snow blindness)
• Peripheral edema
• High altitude retinopathy
• Acute exacerbation of COPD/CAD
• Hypothermia

27. REFERENCES
• Hackett PH, Roach RC: High-altitude medicine, in PA
Auerbach (ed): Wilderness Medicine. St Louis, Mosby,
2001, p 2.
• Emedicine.medscape.com
• Tintinalli’s Emergency Medicine, 6th
ed.
• HIGH ALTITUDE MEDICINE & BIOLOGY
Volume 5, Number 2, 2004, © Mary Ann Liebert, Inc.
• www.radiopedia.com
• HAPE Diagnosis, Prevention & Treatment (Vol.12
Number 2 March/April 2013 - Andre Pennardt, MD,
FACEP, FAWM)