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Intrapleural pressure depends on the ventilation phase, atmospheric pressure, and the volume of the intrapleural cavity. [2] At rest, there is a negative intrapleural pressure. This provides a transpulmonary pressure, causing the lungs to expand. If humans didn't maintain a slightly negative pressure even when exhaling, their lungs would ...
As water molecules pull together, they also pull on the alveolar walls causing the alveoli to recoil and become smaller. But two factors prevent the lungs from collapsing: surfactant and the intrapleural pressure. Surfactant is a surface-active lipoprotein complex formed by type II alveolar cells.
The pleural cavity, or pleural space (or sometimes intrapleural space), is the potential space between the pleurae of the pleural sac that surrounds each lung.A small amount of serous pleural fluid is maintained in the pleural cavity to enable lubrication between the membranes, and also to create a pressure gradient.
The alveolar pressure is estimated by measuring the pressure in the airways while holding one's breath. [2] The intrapleural pressure is estimated by measuring the pressure inside a balloon placed in the esophagus. [2] Measurement of transpulmonary pressure assists in spirometry in availing for calculation of static lung compliance.
Dynamic compression of the airways results when intrapleural pressure equals or exceeds alveolar pressure, which causes dynamic collapsing of the lung airways. It is termed dynamic given the transpulmonary pressure (alveolar pressure − intrapleural pressure) varies based on factors including lung volume, compliance, resistance, existing pathologies, etc. [1]
The active maintenance of an intrapleural negative pressure via chest drains builds the basis of chest drain management, as an intrapleural pressure lower than the surrounding atmosphere allows easier lung expansion and thus better alveolar ventilation and gas exchange.
Pulmonary compliance is calculated using the following equation, where ΔV is the change in volume, and ΔP is the change in pleural pressure: = For example, if a patient inhales 500 mL of air from a spirometer with an intrapleural pressure before inspiration of −5 cm H 2 O and −10 cm H 2 O at the end of inspiration.
NPPE develops as a result of significant negative pressure generated in the chest cavity by inspiration against an upper airway obstruction. These negative pressures in the chest lead to increase venous supply to the right side of the heart while simultaneously creating more resistance for the left side of the heart to supply blood to the rest of the body (). [4]