Search results
Results from the WOW.Com Content Network
The standard drug treatment of dexamethasone does not alter the hypoxia or the consequent vasoconstriction, but stimulates fluid reabsorption in the lungs to reverse the edema. Additionally, several studies on native populations remaining at high altitudes have demonstrated to varying degrees the blunting of the HPV response.
By contrast, in the lungs, the response to hypoxia is vasoconstriction. This is known as hypoxic pulmonary vasoconstriction, or "HPV", and has the effect of redirecting blood away from poorly ventilated regions, which helps match perfusion to ventilation, giving a more even oxygenation of blood from different parts of the lungs. [81]
Increased pulmonary arterial and capillary pressures (pulmonary hypertension) secondary to hypoxic pulmonary vasoconstriction. [9] [11] Increased capillary pressure (hydrostatic pressure) with over-distention of the capillary beds and increased permeability of the vascular endothelium, also known as "stress failure."
To be classified as pulmonary heart disease, the cause must originate in the pulmonary circulation system; RVH due to a systemic defect is not classified as pulmonary heart disease. Two causes are vascular changes as a result of tissue damage (e.g. disease, hypoxic injury), and chronic hypoxic pulmonary vasoconstriction. If left untreated, then ...
This is the most frequent type of altitude sickness encountered. Symptoms often manifest within ten hours of ascent and generally subside within two days, though they occasionally develop into the more serious conditions. Symptoms include headache, confusion, fatigue, stomach illness, dizziness, and sleep disturbance. [9]
The physiological responses to high altitude include hyperventilation, polycythemia, increased capillary density in muscle and hypoxic pulmonary vasoconstriction–increased intracellular oxidative enzymes. There are a range of responses to hypoxia at the cellular level, shown by discovery of hypoxia-inducible factors (HIFs), which determine ...
The second is OHS primarily due to "sleep hypoventilation syndrome"; this requires a rise of CO 2 levels by 10 mmHg (1.3 kPa) after sleep compared to awake measurements and overnight drops in oxygen levels without simultaneous apnea or hypopnea. [4] [11] Overall, 90% of all people with OHS fall into the first category, and 10% in the second. [5]
Many people with chronic obstructive pulmonary disease have a low partial pressure of oxygen in the blood and high partial pressure of carbon dioxide.Treatment with supplemental oxygen may improve their well-being; alternatively, in some this can lead to the adverse effect of elevating the carbon dioxide content in the blood (hypercapnia) to levels that may become toxic.