High-Altitude Illness: Updates in Prevention, Identification, and Treatment

Table of Contents

 

About This Issue

The increase in travel to high-altitude destinations (>2500 m) and often-compressed travel schedules can cause even the fittest individuals to suffer from high-altitude illness (HAI). In addition, some medical conditions put patients at greater risk for HAI. This issue reviews the latest guidelines and advises clinicians – even those who typically work at sea level – on how to counsel patients on pretravel preparation and what to do when encountering, at altitude, a patient who is experiencing HAI.

What are the key signs of illnesses on the HAI spectrum: acute mountain sickness, high-altitude cerebral edema (HACE), and high-altitude pulmonary edema (HAPE)?

Safe ascent: how many meters in how many days are recommended?

How can the calculation of the Lake Louise score assist in determining the risk for HAI?

What are the “climb high, sleep low” recommendations?

Does age, gender, fitness level, or previous altitude exposure affect a patient’s chances for getting HAI?

What are the medical conditions that make altitude travel dangerous?

Are there cautions for patients with respiratory or cardiovascular conditions?

What are the drugs that can be given to prevent HAI? HAPE? Can they also be used to treat HAI?

1. About This Issue
2. Abstract
3. Case Presentations
4. Introduction
5. Critical Appraisal of the Literature
6. Background and Definitions
7. Pathophysiology
8. Prevention of Altitude Illness
   1. Behavioral Acclimatization
   2. Pharmacologic Prophylaxis
      1. Acetazolamide
      2. Dexamethasone
      3. Medications for High-Altitude Pulmonary Edema Prevention
   3. Supplemental Preventive Measures
9. Clinical Features and Diagnosis
10. Risk Factors for Altitude Illness
    1. Home Elevation
    2. “Climb High, Sleep Low”
    3. Exertion and Fitness Level
    4. Latitude
    5. Gender and Age
    6. Individual Susceptibility
    7. Previous Exposure to Altitude
    8. Medications/Alcohol
11. Prehospital Care
    1. Acute Mountain Sickness
    2. High-Altitude Cerebral Edema
    3. High-Altitude Pulmonary Edema
12. Emergency Department Evaluation
    1. History
    2. Physical Examination
13. Diagnosis and Treatment
    1. Acute Mountain Sickness
       1. Diagnosis
       2. Treatment
    2. High-Altitude Cerebral Edema
       1. Diagnosis
       2. Treatment
    3. High-Altitude Pulmonary Edema
       1. Diagnosis
       2. Treatment
14. Counseling Travelers With Comorbidities or Other Medical Conditions
    1. Respiratory Disease
       1. Asthma
       2. Chronic Obstructive Pulmonary Disease
       3. Interstitial Lung Disease
       4. Pneumothorax
    2. Cardiovascular Disease
       1. Coronary Artery Disease
       2. Congenital Heart Disease
       3. Congestive Heart Failure
       4. Hypertension
       5. Stroke
    3. Other Medical Considerations
       1. Diabetes Mellitus
       2. Sickle Cell Disease
       3. Pregnancy
       4. Obesity
       5. Migraine
       6. Carotid Body Damage
       7. Down Syndrome
15. Controversies and Cutting Edge
    1. Clinical Trials for High-Altitude Illness
    2. Preacclimatization and Genetics
    3. Ultrasound
16. Time- and Cost-Effective Strategies
17. Summary
18. Risk Management Pitfalls for Acute Mountain Sickness
19. Case Conclusions
20. Clinical Pathway for Diagnosis and Management of High-Altitude Illness
21. Tables and Figures
    1. Table 1. Major Clinical Categories of High-Altitude Illness
    2. Table 2. Risk Categories for Altitude Illness
    3. Table 3. 2018 Lake Louise Acute Mountain Sickness Score
    4. Table 4. Lake Louise Consensus on High-Altitude Cerebral Edema
    5. Table 5. Differential Diagnosis of Acute Mountain Sickness/High-Altitude Cerebral Edema
    6. Table 6. Lake Louise Consensus on High-Altitude Pulmonary Edema
    7. Table 7. Differential Diagnosis of High-Altitude Pulmonary Edema
    8. Table 8. Hospital Admission Considerations for Patients With High-Altitude Pulmonary Edema
    9. Table 9. Precautions at Altitude for Travelers with Respiratory Conditions
    10. Table 10. Precautions at Altitude for Travelers with Cardiovascular Conditions
    11. Table 11. Precautions at Altitude for Travelers with Other Common Medical Conditions
    12. Figure 1. Gamow Bag
22. References

Abstract

High-altitude illness is a continuum of syndromes that includes the potential for death. Understanding how to prevent altitude illness and how to treat it if it occurs is fundamental to trip planning and is an important role of medical advisors to travelers. Gradual ascent, along with pharmacotherapy where indicated, are the mainstays of prevention. Travelers with certain chronic medical conditions may require additional pretravel counseling and preparation. Diagnostic recognition of the differing manifestations of high-altitude illness as well as recommendations on appropriate therapeutic options are discussed in detail.

Case Presentations

At 3400 m altitude you meet a woman who says she has a headache and feels “run-down”…

You have flown into Cusco, Peru (3400 m) to join a tour group that plans to hike the Inca Trail to Machu Picchu. During the evening of your arrival, you attend a welcome dinner with your group, where you meet a 29-year-old female fellow traveler from Miami who also flew in earlier in the day. As she gets up to leave the dinner early, she says she has a mild headache and feels generally run-down. You wonder if you should be concerned for her...

At 4730 m altitude, you meet a man who is having difficulty walking and is vomiting…

You are on an expedition to trek Mount Kilimanjaro. You have limited time, so you decided to do the 5-day Marangu route. At the end of day 3, you arrive at Kibo Hut (4730 m). As you are settling in to sleep for the night, you notice a 57-year-old man, also on your trek, who is walking with an unsteady gait and is vomiting. The expedition lead guide is unable to communicate with medical command, and he asks you for advice. You consider the options but know there is only one good one...

At 2860 m altitude, you meet a man who is coughing and says he has “caught a cold”…

While embarking on your own guided trek into the Mount Everest region, you run into a 45-year-old man who had arrived into the Tenzing-Hillary Airport in Lukla, Nepal (2860 m) a few hours prior. He appears to be struggling hauling his backpack. When you ask him if he needs assistance, he mentions that he flew from London into Kathmandu 2 days prior and states that he seems to have “caught a cold” during his travels. He appears short of breath and you notice he is coughing up pinkish-white sputum. You wonder if he has more than just a cold and whether you should intervene...

Clinical Pathway for Diagnosis and Management of High-Altitude Illness

Subscribe to access the complete flowchart to guide your clinical decision making.

Table and Figures

Subscribe for full access to all Tables and Figures.

Key References

Following are the most informative references cited in this paper, as determined by the authors.

1. “How many tourists visited Machu Picchu in 2018?“ 2019. Peru Telgraph. Accessed August 10, 2021. (News website)

2. Croughs M, Van Gompel A, Rameckers S, et al. Serious altitude illness in travelers who visited a pre-travel clinic. J Travel Med. 2014;21(6):403-409. (Prospective questionnaire; 401 subjects)

3. * Luks AM, Auerbach PS, Freer L, et al. Wilderness Medical Society clinical practice guidelines for the prevention and treatment of acute altitude illness: 2019 update. Wilderness Environ Med. 2019;30(4S):S3-S18. (Clinical practice guidelines) DOI: 10.1016/j.wem.2019.04.006

44. * Luks AM, Swenson ER. Travel to high altitude with pre-existing lung disease. Eur Respir J. 2007;29(4):770-792. (Review) DOI: 10.1183/09031936.00052606

47. * Flaherty GT, Kennedy KM. Preparing patients for travel to high altitude: advice on travel health and chemoprophylaxis. Br J Gen Pract. 2016;66(642):e62-e64. (Clinical guideline review) DOI: 10.3399/bjgp16X683377

48. * Mieske K, Flaherty G, O’Brien T. Journeys to high altitude--risks and recommendations for travelers with preexisting medical conditions. J Travel Med. 2010;17(1):48-62. (Clinical guideline review) DOI: 10.1111/j.1708-8305.2009.00369.x

Subscribe to get the full list of 66 references and see how the authors distilled all of the evidence into a concise, clinically relevant, practical resource.

Keywords: acute mountain sickness, high-altitude illness, HAI, high-altitude cerebral edema, HACE, high-altitude pulmonary edema, HAPE, acclimatization, acetazolamide, dexamethasone, nifedipine, ascent, descent, Lake Louise, headache, ataxia, hypoxia, nausea, vomiting, dizziness, Gamow, respiratory, cardiovascular, sickle cell, Downx