Intrapulmonary pressure >Inspiratory phase:<1 atm >Expiratory phase:>1 atm >At the end of inspiration or expiration:=1 atm Intrapleural pressure >Concept Changes during respiratory cycle More negative as inspiratory processing Less negative as expiratory processing >Measurement Expression Direct Indirect measurement 775 mmHg or-5 mmHg Always 1 atm under static condition
Intrapulmonary pressure ➢Inspiratory phase: <1 atm ➢Expiratory phase: >1 atm ➢At the end of inspiration or expiration: =1 atm Intrapleural pressure ➢Concept & Changes during respiratory cycle More negative as inspiratory processing Less negative as expiratory processing ➢Measurement & Expression Direct & Indirect measurement 775 mmHg or −5 mmHg Always < 1 atm under static condition
吸气 1呼气 肺内压 胸膜腔内压 气容积 。 容积 1234 时间(s) Changes of intrapulmonary intrapleural pressure during respiratory cycle
Changes of intrapulmonary & intrapleural pressure during respiratory cycle
>Formation IAP PRF has opposite directions,so IPP=IAP-PRF At the end of insp-expiration,so IPP=ASP-PRF If ASP=0,IPP=0-PRF=-PRF IPP:intrapleural pressure IAP:intra alveolar pressure PRF:pulmonary recoil force ASP:atmospheric pressure
➢Formation IAP & PRF has opposite directions, so IPP=IAP−PRF At the end of insp- & expiration, so IPP=ASP−PRF If ASP=0, IPP=0−PRF= −PRF IPP: intrapleural pressure IAP: intra alveolar pressure PRF: pulmonary recoil force ASP: atmospheric pressure
Formation of intrapleural negative pressure
Formation of intrapleural negative pressure
>Significance Physiological Distend the lung Make inspiration easier Promote venous lymph return in the chest Pathological (Pneumothorax) Collapse the lung Make inspiration difficult Affect venous lymph return Fatal in pulmonary circulatory failure cases Importance Keep the interpleural cavity hermetically sealed
➢Significance Physiological ~ Distend the lung & Make inspiration easier Promote venous & lymph return in the chest Pathological ~ (Pneumothorax) Collapse the lung & Make inspiration difficult Affect venous & lymph return Fatal in pulmonary & circulatory failure cases Importance Keep the interpleural cavity hermetically sealed