ANATOMY

Detailed explanation-1: -The expiratory reserve volume (ERV), about 1, 200 ml, is the additional air that can be forcibly exhaled after the expiration of a normal tidal volume.

Detailed explanation-2: -Function Residual Capacity(FRC) It is the amount of air remaining in the lungs at the end of a normal exhalation. It is calculated by adding together residual and expiratory reserve volumes. The normal value is about 1800 – 2200 mL. FRC = RV+ERV.

Detailed explanation-3: -As lung volume increases, pressure decreases as per Boyle’s law. The resulting sub-atmospheric intra-alveolar pressure then draws air into the alveoli based on the pressure difference. Once the pressure equalized, a tidal volume of approximately 500 mL is delivered.

Detailed explanation-4: -Tidal volume is a measure of the amount of air a person inhales during a normal breath. Traditional preset tidal volumes higher than 10 ml/kg have been proved to be associated with increased risk of pulmonary barotrauma and should be avoided. High tidal volumes also decrease venous return and reduce cardiac output.

Detailed explanation-5: -The volume exhaled in a normal breath is the tidal volume. The volume that can be inhaled above tidal volume is the inspiratory reserve volume.