![]() ![]() Tidal volume + inspiratory reserve volumeĮxpiratory reserve volume + residual volumeĪffected by height, gender, posture, changes in lung compliance. Volume breathed in from quiet expiration to maximum inspiration Requires adequate compliance, muscle strength and low airway resistance Inspiratory reserve volume + tidal volume + expiratory reserve volume maximum inspiration to maximum expiration) Volume that can be exhaled after maximum inspiration (ie. These are fixed as they do not change with the pattern of breathing. These are composed of 2 or more lung volumes. ![]() ![]() Volume remaining after maximum expiration Reduced in pregnancy, obesity, severe obstruction or proximal (of trachea/bronchi obstruction) Relies on muscle strength and low airway resistance Relies on muscle strength, lung compliance (elastic recoil) and a normal starting point (end of tidal volume)Įxtra volume that can be expired below tidal volume, from normal quiet expiration to maximum expiration shallow breaths vs deep breathsĮxtra volume that can be inspired above tidal volume, from normal quiet inspiration to maximum inspiration Positive pressure ventilation (i.e.Volume that enters and leaves with each breath, from normal quiet inspiration to normal quiet expirationĬhanges with pattern of breathing e.g.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. ![]()
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