Table 1.

Pathophysiologic responses to high altitude^{10,21,23,24,27,49,64,73}

System	Acute Exposure	Chronic Exposure
Pulmonary	Hypoxemia, ↑ventilation, ↓arterial oxygen saturation	Hypoventilation, pulmonary hypertension, ↑lung capillary blood volume, ↑lung diffusion capacity, exacerbation of chronic lung disease, HAPE on renascent of altitude residents
Cardiovascular	Transient ↑blood pressure, ↑heart rate, ↑venous tone, ↑cardiac output, peripheral edema	↓Systolic/diastolic blood pressure, right ventricular hypertrophy, right heart failure, arterial oxygen desaturation, ↑plasma triglyceride level, exacerbation of congenital heart disease
Hematologic	↑Hemoglobin concentration, ↓plasma volume, ↑erythropoietin, ↑D-dimer	Polycythemia, ↑O2 carrying capacity of blood
Renal	↑Bicarbonate excretion, ↓plasma calcium and phosphate, hypocapnic respiratory alkalosis, ↑diuresis	Hyperuricemia, microalbuminuria, ↓renal plasma flow, ↑filtration fraction (preserved or mildly ↓glomerular filtration rate), glomerular hypertrophy
Neuropsychologic	↓Synthesis of neurotransmitters, cerebral vasodilation, mood changes, ↓cognitive function, ↓motor/sensory function	Cerebral hypoxia, biochemical dysfunction, ↓sleep quality, ↑mood disorders, ↓cognitive function
Exercise	↓Maximal oxygen consumption, ↓VO2max	↓Aerobic exercise capacity
Other	Retinopathy, anorexia

HAPE, high altitude pulmonary edema.