High-altitude pulmonary edema

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Highly elevated lung edema (HAPE) ( HAPO spelled edema in English English) is a life-threatening form of non-cardiogenic pulmonary edema (fluid accumulation in the lungs ) that occurs on healthy mountain climbers at altitudes usually above 2,500 meters (8,200 feet). However, cases have also been reported at lower altitudes (between 1,500-2,500 meters or 4,900-8,200 feet on highly vulnerable subjects), although what makes some people vulnerable to HAPE is currently unknown. HAPE remains a leading cause of death associated with high altitude exposure, with a high mortality rate in the absence of adequate emergency care.

Video High-altitude pulmonary edema

Signs and symptoms

Physiological changes and symptoms often vary according to the height involved.

The Lake Louise Consensus Definition for High-Altitude Pulmonary Edema has set widely used criteria for defining HAPE symptoms:

Symptoms: at least two of:

• Difficulty breathing (dyspnea) at rest
• Cough
• Weakness or decrease in sports performance
• Tension or chest congestion

Alerts: at least two of:

• Crackles or wheezing (at breathing) in at least one lung
• Central cyanosis (blue skin color)
• Tachypnea (shallow short breath)
• Tachycardia (rapid heartbeat)

The initial cause of HAPE is oxygen deprivation caused by lower air pressure at high altitudes. The mechanisms that cause this lack of oxygen cause HAPE is not well understood, but two processes are believed to be important:

1. Increased pulmonary artery and pulmonary pressure secondary to pulmonary vasoconstriction of hypoxia.
2. Increased idiopathic non-inflammation in vascular endothelium permeability.

Although higher pulmonary artery pressure is associated with HAPE development, the presence of pulmonary hypertension may not be sufficient to explain the development of edema: severe pulmonary hypertension may occur in the absence of clinical HAPE in subjects at high altitudes.

Maps High-altitude pulmonary edema

Predisposing factors

Individual susceptibility to HAPE is difficult to predict. The most reliable risk factor is the previous vulnerability to HAPE, and there is likely to be a genetic basis for this condition, possibly involving genes for angiotensin converting enzyme (ACE). Recently, scientists have found an equation between the low number of 2,3-BPG (also known as 2,3-DPG) with the occurrence of HAPE at high altitudes. People with sleep apnea are prone to irregular breathing patterns while sleeping at high altitudes.

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Treatment

The standard and most important treatment is to descend to lower heights as quickly as possible, preferably at least 1,000 meters. Oxygen should also be provided if possible. Symptoms tend to rapidly improve with decline, but more severe symptoms may persist for several days. Standard drug treatments that have strong clinical evidence are dexamethasone and nifedipine. Phosphodiesterase inhibitors such as sildenafil and tadalafil are also effective but may aggravate mountain disease headaches.

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Incident

The HAPE clinical incidence in non-acclimatized travelers exposed to high altitudes (~ 4,000m or 13,000ft) appears to be less than 1%. The US Army Pike Research Laboratory has exposed volunteers to sea level quickly and directly to high altitudes; during 30 years of research involving about 300 volunteers (and more than 100 staff members), only three have been evacuated with HAPE conjecture.

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Research

To help understand the factors that make some individuals vulnerable to HAPE, the International HAPE Database was established in 2004. The database is administered by APEX, a high-level medical research charity. Individuals who previously suffered HAPE may register with this confidential database to help researchers study the condition.

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See also

• Acetazolamide, a drug that accelerates acclimatization to high altitudes.
• Pulmonary edema
• Higher disease
• high altitude cerebral edema (HACE)
• Exposure to high altitude flat (HAFE)
• Pulse oximeter, a tool for measuring blood oxygen levels.
• Drug wilderness
• Wilderness Medical Society

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References

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External links

• International HAPE Database
• Altitude.org's description of HAPE and altitude sickness
• Training on Expedition Medicine
• GP Notebook HAPE

Source of the article : Wikipedia