Physiological Dead Space

No gas exchange is possible in these spaces.

Physiological dead space. Anatomical dead space is that portion of the airways such as the mouth and trachea to the bronchioles which conducts gas to the alveoli. 2003 by saunders an imprint of elsevier inc. Rather than representing it as a volume in ml kg it is better to represent it as a fraction of the tidal volume or minute volume largely because it tends to change together with the tidal volume. Physiological dead space is the combination of the anatomical and alveolar dead space components.

The total dead space in the entire respiratory system including the alveoli compare anatomical dead space. There are two different ways to define dead space anatomic and physiologic. In simple words physiological dead space is the combination of anatomical dead space and alveolar dead space. Physiological dead space is the part of the tidal volume which does not participate in gas exchange.

Anatomic dead space is the total volume of the conducting airways from the nose or mouth down to the level of the terminal bronchioles and is about 150 ml on the average in humans. Alveoli with no perfusion i e. Physiological dead space refers to the volume of air that fills conducting airways plus the volume of air that penetrates gas exchanging regions but does not involve in gas exchange. In the respiratory tract any nonfunctional alveoli that do not receive air that participates in gas exchange.

Possible causes include emphysema pneumothorax pneumonia pulmonary edema and constriction of bronchioles. Alveoli that fill with air but do not exchange gas to and from the capillaries contribute to physiologic dead space which ideally would be very low or almost zero. Measuring physiological dead space measure the amount of co2 eliminated from the lung in a single tidal volume collect one tidal volume of gas and measure the mixed expired co2 concentration physiological dead space equation. West s zone 1 the difference between anatomical dead space and physiological dead space is alveolar dead space.

What is physiological dead space. The total dead space also known as physiological dead space is the sum of the anatomical dead space plus the alveolar dead space. Its volume v d is determined by measuring the partial pressure of carbon dioxide in a sample of exhaled gas peco2 and in the arterial blood paco2 and with tidal volume of v t using the formula v d v t paco2 peco2 paco2. Physiologic dead space includes the dead space of the upper airways but also accommodates for the dead space in alveoli that do not partake in gas exchange for a number of reasons.

Physiologic dead space the sum of the anatomic and alveolar dead spaces.