baseniom.blogg.se - Anatomic dead space vs physiological dead space

The subject breathes in normal room air, and respiration (production of CO 2) happens everywhere, except in the volume occupied by the dead spaces. Physiological dead space is the sum of the anatomical dead space and the alveolar dead space. In the ideal healthy adult, this is zero. However, it is quick enough that it can be approximated (averaged out) as an abrupt transition.Īlveolar dead space includes those parts of the respiratory zone that do not participate in gas exchange. Note that in practice, O 2 is replaced by N 2 more gradually, as a sigmoid curve.

When the gas is expired, the pure O 2 is expired first.

The gas in the anatomical dead space remains as pure O 2 because it remains up in the conducting zone.

Most of the O 2 mixes with the air already in the alveoli (75% N 2).

It is measured by the nitrogen washout (Fowler) technique:

Positive pressure ventilation (i.e.Dead space is the volume of ventilated air that does not participate in gas exchange.Īnatomical dead space is the volume of air that fills the conducting zone, about 150 mL (~30% of normal tidal volume).

Neck extension and jaw protrusion (can increase it twofold).

General anesthesia – multifactorial, including loss of skeletal muscle tone and bronchoconstrictor tone.

The ratio of physiologic dead space to tidal volume is usually about 1/3. Alveolar dead space is the volume of gas within unperfused alveoli (and thus not participating in gas exchange either) it is usually negligible in the healthy, awake patient.

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 it is approximately 2 mL/kg in the upright position. Physiologic or total dead space is the sum of anatomic dead space and alveolar dead space. Dead space is the volume of a breath that does not participate in gas exchange.