3Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada.2Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, AB, Canada.1Clinical Physiology Laboratory, Division of Pulmonary Medicine, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB, Canada.These problems are discussed further in Chapter 40 in relation to pulmonary gaseous exchange and in Chapter 43 in relation to certain pulmonary diseases. In a normal person, the anatomical and physiological dead spaces are nearly equal because all alveoli are functional in the normal lung, but in a person with partially functional or nonfunctional alveoli in some parts of the lungs, the physiological dead space may be as much as 10 times the volume of the anatomical dead space, or 1 to 2 liters. When the alveolar dead space is included in the total measurement of dead space, this is called the physiological dead space, in contradistinction to the anatomical dead space. Therefore, from a functional point of view, these alveoli must also be considered dead space. On occasion, some of the alveoli are nonfunctional or only partially functional because of absent or poor blood flow through the adjacent pulmonary capillaries. The method just described for measuring the dead space (see slide 36) measures the volume of all the space of the respiratory system other than the alveoli and their other closely related gas exchange areas this space is called the anatomic dead space. In a normal person, the anatomical and physiological dead spaces are nearly equal because all alveoli are functional in the normal lung, but in a person with partially functional or nonfunctional alveoli in some parts of the lungs, the physiological dead space may be as much as 10 times the volume of the anatomical dead space, or 1 to 2 liters.Īnatomical Versus Physiological Dead Space. Total dead space = physiological dead space Physiological dead space = all space other than alveoli/gas exchange areas + alveoli that don’t do gas exchange (due to absent or poor perfusion) Anatomic dead space = all space other than the alveoli/gas exchange areas Alveolar dead space = the alveoli that can’t do gas exchange (due to absent or poor blood flow through the adjacent pulmonary capillaries) Dead space is the parts of the airway that don’t exchange gas
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