Altitude sickness overview

# Overview
Chronic mountain sickness (CMS) is also known as Monge's disease, after its first description in 1925 by Carlos Monge. High Altitude Flatus Expulsion was first described by Joseph Hamel in c. 1820. It was rediscovered in 1981 by Paul Auerbach and York Miller. Altitude sickness may be classified according to clinical symptoms and the pathological changes of principally encroached organs into 2 groups acute and chronic. Altitude sickness caused by an increase in pulmonary artery pressure due to the normal pulmonary vasoconstriction induced by hypoxia. Hypoxia leads to increase oxygen delivery to the tissues and increases ventilation, cardiac output and haemoglobin concentrations. These changes improve ventilation-perfusion matching and gas exchange and lead to high altitude pulmonary hypertension. Altitude sickness is brought on by the combination of reduced air pressure and lower oxygen concentration that occur at high altitudes. Common risk factors in the development of altitude sickness include underlying lung disease, substances or conditions that interfere with acclimatization, previous history of high altitude sickness, lack of acclimatization. There is insufficient evidence to recommend routine screening for altitude sickness which include cold pressor test, heart rate variability, pulmonary function test. The important complications of altitude sickness are high altitude pulmonary edema and cerebral edema. Prognosis is generally good, and the 5 year mortality rate of patients with altitude sickness is approximately 12%. Patients with altitude sickness may have a positive history of underlying lung disease and substances or conditions that interfere with acclimatization. Common symptoms of altitude sickness include headache, dizziness, fatigue, cyanosis. Laboratory findings consistent with the diagnosis of altitude sickness include increased the level of hemoglobin, hematocrit and blood urea nitrogen and decreased level of bicarbonate, creatinine and PCO2. An ECG may be helpful in the diagnosis of altitude sickness. Findings on an ECG suggestive of altitude sickness include shortening of R-R interval, shortening of the lengthening of Q-T and in particular for the ST-T flattening and Increase of P wave. X-ray may be helpful in the diagnosis of complications of altitude sickness which include patchy alveolar infiltrates, predominantly in the right central hemithorax, asymmetric pattern of airspace consolidation. CT scan may be helpful in the diagnosis of complications of altitude sickness pulmonary edema and it shows patchy alveolar infiltrates, predominantly in the right central hemithorax. Pharmacologic medical therapies for altitude sickness include acetazolamide, dexamethasone. Pharmacologic therapy for nausea and vomiting of altitude sickness include promethazine, ondansetron. Effective measures for the primary prevention of altitude sickness include avoiding alcohol ingestion, high carbohydrate in diet, adequate hydration, vigorous exertion during the first few days at high altitude, oxygen Enrichment.

# Historical Perspective
Chronic mountain sickness (CMS) is also known as Monge's disease, after its first description in 1925 by Carlos Monge. High Altitude Flatus Expulsion was first described by Joseph Hamel in c. 1820. It was rediscovered in 1981 by Paul Auerbach and York Miller.

# Classification
Altitude sickness may be classified according to clinical symptoms and the pathological changes of principally encroached organs into 2 groups acute and chronic.

# Pathophysiology
Altitude sickness caused by an increase in pulmonary artery pressure due to the normal pulmonary vasoconstriction induced by hypoxia. Hypoxia leads to increase oxygen delivery to the tissues and increases ventilation, cardiac output and haemoglobin concentrations. These changes improve ventilation-perfusion matching and gas exchange and lead to high altitude pulmonary hypertension.

# Causes
Altitude sickness is brought on by the combination of reduced air pressure and lower oxygen concentration that occur at high altitudes.

# Differentiating Altitude Sickness from Other Diseases

# Epidemiology and Demographics
The incidence of altitude sickness is approximately 53,000 per 100,000 individuals worldwide. The prevalence and mortality rate of altitude sickness depends on altitude. Patients of all age groups may develop altitude sickness. The incidence of altitude sickness increases with age; the median age at diagnosis is 26-45 years. There is no racial predilection to altitude sickness. The majority of altitude sickness cases are reported in Kilimanjaro, Everest region of Nepal.

# Risk Factors
Common risk factors in the development of altitude sickness include underlying lung disease, substances or conditions that interfere with acclimatization, previous history of high altitude sickness, lack of acclimatization.

# Screening
There is insufficient evidence to recommend routine screening for altitude sickness which include cold pressor test, heart rate variability, pulmonary function test.

# Natural History, Complications, and Prognosis
The important complications of altitude sickness are high altitude pulmonary edema and cerebral edema. Prognosis is generally good, and the 5 year mortality rate of patients with altitude sickness is approximately 12%.

# Diagnosis

## History and Symptoms
Patients with altitude sickness may have a positive history of underlying lung disease and substances or conditions that interfere with acclimatization. Common symptoms of altitude sickness include headache, dizziness, fatigue, cyanosis.

## Physical Examination
Physical examination of patients with altitude sickness is usually remarkable for headache, nausea, vomiting and lightheadedness.

## Laboratory Findings
Laboratory findings consistent with the diagnosis of altitude sickness include increased the level of hemoglobin, hematocrit and blood urea nitrogen and decreased level of bicarbonate, creatinine and PCO2.

## EKG
An ECG may be helpful in the diagnosis of altitude sickness. Findings on an ECG suggestive of altitude sickness include shortening of R-R interval, shortening of the lengthening of Q-T and in particular for the ST-T flattening and Increase of P wave.

## X Ray
X-ray may be helpful in the diagnosis of complications of altitude sickness which include patchy alveolar infiltrates, predominantly in the right central hemithorax, asymmetric pattern of airspace consolidation.

## CT
CT scan may be helpful in the diagnosis of complications of altitude sickness pulmonary edema and it shows patchy alveolar infiltrates, predominantly in the right central hemithorax.

## MRI
] may be helpful in the diagnosis of complications of high altitude pulmonary edema and it shows increased T2 signal in the white matter of the splenium of the corpus callosum.

## Other imaging findings
There are no other imaging findings associated with altitude sickness.

## Other diagnostic studies
There are no other diagnostic studies associated with altitude sickness.

# Treatment

## Medical Therapy
Pharmacologic medical therapies for altitude sickness include acetazolamide, dexamethasone. Pharmacologic therapy for nausea and vomiting of altitude sickness include promethazine, ondansetron.

## Surgery
Surgical intervention is not recommended for the management of altitude sickness.

## Primary Prevention
Effective measures for the primary prevention of altitude sickness include avoiding alcohol ingestion, high carbohydrate in diet, adequate hydration, vigorous exertion during the first few days at high altitude, oxygen Enrichment.

## Secondary Prevention
There are no established measures for the secondary prevention of altitude sickness.

## Future or Investigational Therapies
In order to help understand the factors that make some individuals susceptible to high altitude pulmonary edema (HAPE), the International HAPE Database was set up in 2004. Individuals who have previously suffered from HAPE can register with this confidential database in order to help researchers study the condition.