Dead Space Volume

The normal value for dead space volume in ml is approximately the lean mass of the body in pounds and averages about a third of the resting tidal volume 450 500 ml.

Dead space volume. Anatomic dead space is the volume of gas within the conducting zone as opposed to the transitional and respiratory zones and includes the trachea bronchus bronchioles and terminal bronchioles. In fowler s original study the anatomic dead space was 156 28 ml n 45 males or 26 of their tidal volume. It is approximately 300 ml in normal lungs. 150ml of tidal volume occupies anatomical dead space.

The volume of the lung that does not participate in gas exchange in normal lungs is equal to the anatomic dead space 150 ml. The normal value is in the range of 130 to 180 ml and depends on the size and posture of the subject. The value increases slightly with large inspirations because the radial traction exerted on the bronchi by the surrounding lung parenchyma increases their size. May increase in several lung diseases.

The anatomic dead space is the gas volume contained within the conducting airways. Alveolar dead space is the volume of gas which fills lung units which are underperfused not perfused not participating in gas exchange pick the description which produces the fewest furrows in the examiner s brow it is the difference between physiological dead space and anatomical dead space. Wests zone 1 contain alveolar dead space. There are two different ways to define dead space anatomic and physiologic.

It is ventilation without perfusion. 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. It is approximately 2 ml kg in the upright position. If the total volume of expired air be 500 ml and the dotted area represents the alveolar air and the hatched area be dead space air.

Dead space is the volume of a breath that does not participate in gas exchange. Dead space is the portion of each tidal volume that does not take part in gas exchange. Anatomical dead space volume represents an amount of air that does not participate in gaseous exchange because it is retained in the respiratory tract and can not reach vascularised alveoli. Physiologic or total dead space is the sum of anatomic dead space and alveolar dead space.

Let us assume that the area of dots 70 sq. Cm and the area of hatching 30 sq. 2 physiologic dead space fraction dead space divided by tidal volume v d v t as defined by bohr and enghoff is the sum of anatomic or airway dead space v d anat and alveolar dead space v d alv divided by the v t. Generally an young adult breathes in 500ml of air which is called tidal volume.