Tag: Hypoxia

High-altitude pulmonary edema (HAPE) is the leading cause of death from altitude illness. Chest ultrasonography using the comet-tail technique has recently been shown to effectively detect pulmonary edema and quantify extravascular lung water (EVLW) in hospitalized patients. This technique relies on the creation of “comet-tail” artifacts by multiple microreflections of the ultrasound beam within water-thickened […]

On the one hand, it is relatively easy to envision how a vigorous hypoxic response can be useful in an accidental hypoxic encounter occasioned by ascent or the misfortune of disease; but it is somewhat more difficult to account for the association of a low hypoxic response with prowess in endurance athletic events or with the […]

Further, in contrast to the behavior of low-altitude species, in which hypoxia produces right shifts in oxygen hemoglobin dissociation curve, the bai-headed goose and llama show strongly left-shifted curves. This presumably aids in oxygen loading in the lung but presents a potential disadvantage for its unloading in peripheral tissue. In low-altitude individuals, such left-shifting of […]

To this point, the information presented suggests that a brisk hypoxic ventilatory response may be advantageous with respect to adaptation to hypoxia, as illustrated by the association of a vigorous hypoxic ventilatory response with better performance and fewer symptoms following ascent to high altitude and better maintenance of ventilation in patients with COPD. However, this […]

In one, it was found that the PaC02 of patients with chronic obstructive pulmonary disease (COPD) during chronically stable intervals correlated with that found in their offspring, and that the Pa02 of the patients was positively correlated with the hypoxic ventilatory response of the offspring. Further, during acute exacerbations of COPD, arterial oxygen and carbon […]

Although a substantial number of studies employing a range of techniques have all produced concordant results suggesting a defect in the ventilatory effort response to chemical stimuli in hypoventilating patients with severe airway obstruction, there remain residual doubts about whether these findings reflect true differences in ventilatory drive. This reflects the possibility that differences in […]

If variation in ventilatory drive, both endowed and acquired, determines the extent and quality of adaptation to the hypoxia of high altitude, such variation might also contribute to the variable clinical profile of patients with hypoxic disease at low altitude, such as chronic obstructive pulmonary disease. It has long been known that such patients present […]

Over several days’ exposure to hypoxia there is a progressive rise in ventilation and increasing arterial oxygenation, often referred to as ventilatory acclimatization to hypoxia, which is well described but poorly understood. Numerous theories have been put forward to explain this phenomenon, including resolution of respiratory alkalosis in blood or brain, central neural excitation, and […]

To determine whether this ventilatory rolloff is a manifestation of changes in the carotid body, in central translation of chemoreceptor input into respiratory neural traffic, or in the peripheral respiratory apparatus, studies were done in cats that demonstrate a ventilatory rolloff during sustained hypoxia similar to that observed in humans. Measurements during sustained hypoxia showed […]

Does this variable chemosensitivity influence the nature and quality of adaptation to hypoxia at high altitude and in disease? In the case of high altitude, several studies suggest such an association. For example, individuals with the ability to climb to very high altitudes seem to have especially high hypoxic ventilatory responses, compared with climbers unable […]