The physiologic ventilatory dead space fraction (VD/VTphys) is usually defined as the fraction of tidal volume (VT) that does not participate in gas exchange. Dead space comprises two separate components: airway dead space (the volume of areas that do not contribute to gas exchange) and alveolar dead space (the volume of well-ventilated alveoli that receive minimal blood flow). So thanks for watching and I hope to see you again soon.Dead space refers to lung areas that are ventilated but not perfused. If you want to learn how Medmastery can help you become a great clinician, make sure to watch the about mastery video. Absolutely, make sure to check out the course this video was taken from and to register for a free trial account which will give you access to select the chapters of the course. So, an elevation in arterial carbon dioxide tension would only be seen when the patient can't sustain the overall level of ventilation necessary to compensate. These individuals can compensate for the increase in Dead Space by increasing the overall level of ventilation to keep pa co2 constant. However, in most disorders characterized by an increase in lung areas with high v Q hypercapnia does not occur. Conceptually, any alveolar units with v Q greater than one, but not infinity, can be described as if the units were functionally equivalent to areas of Deadspace.Īreas of high v Q or physiologic Deadspace represent regions of wasted ventilation as far as carbon dioxide elimination is concerned.
Another form of abnormal ventilation perfusion relationship can be seen as a result of alveolar units with ventilation, but no persistent perfusion.
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