Approach Considerations
Educate travelers with the following three Centers for Disease Control and Prevention (CDC) principles to prevent death or serious consquences from altitude illness [4] :
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Know the early symptoms of altitude illness, and be willing to acknowledge when they are present.
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Never ascend to sleep at a higher altitude when experiencing symptoms of altitude illness, no matter how minor they seem.
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Descend if the symptoms become worse while resting at the same altitude.
Supplemental oxygen and descent are the definitive therapy for all forms of altitude illness; however, descent may not always be possible due to climate, environmental, or logistic issues.
See the Guidelines section for prevention and treatment recommendations from the Wilderness Medical Society [2, 3] and the Centers for Disease Control and Prevention. [4]
Note that the coronavirus disease 2019 (COVID-19) pandemic has raised concerns over whether affected patients with respiratory distress have presentations more like high-altitude pulmonary edema (HAPE) than that of acute respiratory distress syndrome (ARDS). [20, 21] Therefore, the Guidelines section also contains the following COVID-19-related guidance:
For more COVID-19 information, please go to Medscape's Novel Coronavirus Resource Center, COVID-19 Clinical Guidelines, and Coronavirus Disease 2019 (COVID-19).
Medical Care
See also the Guidelines section for treatment recommendations from the Wilderness Medical Society [2, 3] and the Centers for Disease Control and Prevention. [4]
The treatment of high-altitude pulmonary edema (HAPE) includes rest, administration of oxygen (first line), and descent to a lower altitude (first line if oxygen is unavailable). [2, 3, 4, 7, 18] If diagnosed early, recovery is rapid with a descent of only 500-1000 m. A portable hyperbaric chamber (see the following image) or supplemental oxygen administration immediately increases oxygen saturation and reduces pulmonary artery pressure, heart rate, respiratory rate, and symptoms. In situations where descent is difficult, these treatments can be lifesaving. [5, 6]
High-altitude pulmonary edema (HAPE). Medical students demonstrate the use of a portable hyperbaric chamber. Courtesy of Wikipedia (https://en.wikipedia.org/wiki/File:Portable_hyperbaric_chamber.jpg).
In one study, 11 patients at 4240 m altitude in Pheriche, Nepal, were treated for HAPE with bed rest, oxygen, nifedipine, and acetazolamide. [25] Sildenafil and salmeterol were used in most, but not all patients. Seven of these had serious-to-severe HAPE (Hultgren grades 3 or 4). Oxygen saturation was improved at discharge (84% ± 1.7%) compared with admission (59% ± 11%), as was the ultrasound comet-tail score (11 ± 4 at discharge vs 33 ± 8.6 at admission), a measure of pulmonary edema for which admission and discharge values were obtained in 7 patients.
A randomized, double-blinded, placebo-controlled study showed that adults with previous HAPE who received prophylactic tadalafil (10 mg) or dexamethasone (8 mg) had significantly less HAPE compared with those who received placebo twice daily. The medications were administered during ascent and at a stay at 4559 m altitude. [26]
Two participants who received tadalafil developed severe acute mountain sickness upon arrival at 4559 m and withdrew from the study; they did not have HAPE at that time. HAPE developed in 7 of 9 participants who received placebo and in 1 of the remaining 8 participants who received tadalafil, but it did not develop in any of the 10 participants who received dexamethasone (P = .007 for tadalafil vs placebo; P< .001 for dexamethasone vs placebo). Eight of 9 participants who received placebo, 7 of 10 who received tadalafil, and 3 of 10 who received dexamethasone had acute mountain sickness (P = 1.0 for tadalafil vs placebo; P = .020 for dexamethasone vs placebo).
At high altitude, systolic pulmonary artery pressure increased less in participants who received dexamethasone (16 mm Hg [95% confidence interval, 9-23 mm Hg]) and tadalafil (13 mm Hg [95% confidence interval, 6-20 mm Hg]) than in those who received placebo (28 mm Hg [95% confidence interval, 20-36 mm Hg]) (P = .005 for tadalafil vs placebo; P = .012 for dexamethasone vs placebo).
The conclusion was that both dexamethasone and tadalafil decrease systolic pulmonary artery pressure and may reduce the incidence of HAPE in adults with a history of HAPE. [27] Dexamethasone prophylaxis may also reduce the incidence of acute mountain sickness in these adults.
Portable hyperbaric chambers (Gamow, CERTEC) are in wide use by trekkers. A physiologic (simulated) descent of approximately 2000 m may be achieved in a few minutes. Patients are typically treated in 1-hour increments. Patients should be closely observed for rebound symptoms after hyperbaric treatments.
Finally, the use of an expiratory positive airway pressure mask improves oxygenation and may be useful as a temporizing measure.
Admission to a hospital is warranted for significant arterial desaturation and clinical deterioration despite outpatient management of HAPE.
Prevention
See also the Guidelines section for prevention guidance from the Wilderness Medical Society [2, 3] and the Centers for Disease Control and Prevention. [4]
Prophylaxis for high-altitude pulmonary edema (HAPE) is indicated for persons who have been identified (from past experience) as being susceptible to developing high-altitude illness or who must ascend rapidly to a high altitude. Acetazolamide and dexamethasone have been shown to be effective agents for prophylaxis against high-altitude illness. These agents must be started 24 hours before ascent and continued for 48-72 hours at altitude. Acetazolamide, which appears to hasten acclimatization, is considered the drug of choice because of a low incidence of significant adverse effects. [28]
Because acetazolamide hastens acclimatization, it should be effective at preventing all forms of acute altitude illness. It has been shown to blunt hypoxic pulmonary vasoconstriction but there are no data specifically supporting a role in HAPE prevention. Clinical observations suggest acetazolamide may prevent reentry HAPE, a disorder seen in individuals who reside at high altitude, travel to lower elevation, and then develop HAPE upon rapid return to their homes. [2]
Based on a single randomized, placebo-controlled study [29] and extensive clinical experience, the Wilderness Medical Society recommends nifedipine for HAPE prevention in high risk individuals. [2, 3]
Other preventive measures include:
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Eating a high-carbohydrate diet
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Avoiding heavy exertion at high altitude
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Slow ascent
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Avoiding abrupt ascent to sleeping elevations higher than 3000 m: If possible, spend 2 nights at altitudes of 2500-3000 m before further ascent.
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Avoiding alcohol and sedatives
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High-altitude pulmonary edema (HAPE). Plain chest x-ray (radiograph) of a patient diagnosed with HAPE. There are patchy infiltrates throughout the lung tissue, with predominant changes in the right middle lobe/right central hemithorax. Courtesy of Wikipedia (https://en.wikipedia.org/wiki/File:Chest_XR_of_HAPE.png).
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High-altitude pulmonary edema (HAPE). Medical students demonstrate the use of a portable hyperbaric chamber. Courtesy of Wikipedia (https://en.wikipedia.org/wiki/File:Portable_hyperbaric_chamber.jpg).
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High-altitude pulmonary edema (HAPE). Initial chest x-ray showing pulmonary infiltrates in the right lung especially in the right mid and lower lung zones indicative of pulmonary edema. The patient was a middle-aged woman trekker who was emergency air-lifted from an altitude of 4410 m in the Nepal Himalayas to 1300 m in Kathamandu. She had continued ascending despite experiencing mild altitude symptoms at Namche (3440 m), with considerably worsened symptoms at Tengboche (3860 m). Courtesy of Extreme Physiology & Medicine (PMID: 24636661, online at https://extremephysiolmed.biomedcentral.com/track/pdf/10.1186/2046-7648-3-6).
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High-altitude pulmonary edema (HAPE). Repeat chest x-ray after 2 days showing rapid resolution of the pulmonary edema in the same Himalayan trekker discussed in the previous image. The patient received bed rest, supplemental oxygen, and oral sustained-release nifedipine 20 mg twice daily. Courtesy of Extreme Physiology & Medicine (PMID: 24636661, online at https://extremephysiolmed.biomedcentral.com/track/pdf/10.1186/2046-7648-3-6).
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High-altitude pulmonary edema (HAPE). Pulmonary embolism masquerading as HAPE. Axial computed tomography (CT) pulmonary angiogram showing thrombi as filling defects in the right main pulmonary artery (right arrow) extending into its branch and in the distal left pulmonary artery (left arrow) with extension into its superior branch. Courtesy of High Altitude Medicine & Biology (PMID: 27768392, online at https://www.liebertpub.com/doi/full/10.1089/ham.2016.0008).
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- HAPE Prevention and Treatment Guidelines (WMS, CDC)
- FDA Policy for Face Masks, Face Shields, and Respirators in COVID-19 (2020)
- COVID-19–Related Airway Management Clinical Practice Guidelines (SIAARTI/EAMS, 2020)
- COVID-19 Ventilation Clinical Practice Guidelines (ESICM, 2020)
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