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Mechanical Properties of the Lungs
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
This is the change in volume of the lung produced by a unit change in transmural pressure gradient (alveolar pressure-pleural pressure), the flow of gas having ceased, with the lungs held at a fixed volume for as long as is practicable. This is to allow the fast and slow alveoli to fill (inflate) completely. For example, a subject can inspire a known volume of gas and then relax against a closed airway for as long as possible, while intrapleural pressure is measured (usually by observing oesophageal pressure). During the respiratory pause (breath-holding) adequate time is provided for all the alveoli to fill.
High-altitude protection
Published in Nicholas Green, Steven Gaydos, Hutchison Ewan, Edward Nicol, Handbook of Aviation and Space Medicine, 2019
Nicholas Green, Steven Gaydos, Hutchison Ewan, Edward Nicol
Raised intrapleural pressure: Intrapleural pressure rises with intrapulmonary pressure during pressure breathing.If lung distension occurs, rise in intrapleural pressure will be less than applied intrapulmonary pressure.Rise in intrapleural pressure determines the degree of pressure applied to the heart and great vessels.
The respiratory system
Published in Laurie K. McCorry, Martin M. Zdanowicz, Cynthia Y. Gonnella, Essentials of Human Physiology and Pathophysiology for Pharmacy and Allied Health, 2019
Laurie K. McCorry, Martin M. Zdanowicz, Cynthia Y. Gonnella
Intrapleural pressure (Ppl) is the pressure within the pleural cavity. Under equilibrium conditions, the chest wall tends to pull outward and the elastic recoil of the lungs tends to pull them inward (like a collapsing balloon). These opposing forces create a subatmospheric or negative pressure within the pleural space. In between breaths, intrapleural pressure is −5 mmHg. During inspiration, the lungs follow the chest wall as it expands. However, the lung tissue resists being stretched so that the intrapleural pressure becomes even more negative and is −8 mmHg.
Optimal diagnostic strategies for pleural diseases and identifying high-risk patients
Published in Expert Review of Respiratory Medicine, 2023
D N Addala, P Denniston, A Sundaralingam, N M Rahman
There has been growing interest in pleural manometry (the change in intrapleural pressure during drainage) in recent years, in particular to diagnose the presence of non-expansile lung (NEL). NEL occurs when an excessive negative pleural pressure is generated during pleural aspiration, often causing pain during the procedure. In MPE, this occurs due to either obstructive endobronchial lesions or visceral pleural thickening, preventing lung re-expansion. Pleural manometry has shown promising results in predicting NEL, although does not appear to reduce procedural pain[96,97]. Early identification of NEL has the potential to guide definitive interventions earlier, as those patients with NEL and thus lack of pleural apposition require indwelling pleural catheter insertion and attempts at chemical pleurodesis are likely to be unsuccessful.
Endobronchial valve therapy for severe emphysema: an overview of valve-related complications and its management
Published in Expert Review of Respiratory Medicine, 2020
T. David Koster, Karin Klooster, Nick H. T. Ten Hacken, Marlies van Dijk, Dirk-Jan Slebos
Another potential manifestation is the ‘pneumothorax ex vacuo’, which means there is air in the pleural space, but no active air leak. There are two hypotheses as to how this develops. It is possible that there is a trauma of the treated lobe in which a part of the volume expands to the pleural cavity, but the valves prevent an active air leak. Most often, the size of the pneumothorax is small [42]. Another hypothesis is that due to the increase in negative intrapleural pressure after the acute lobar collapse, air from the surrounding tissue and blood is drawn into the pleural space. In this case, the pleura remains intact and there is no bronchopleural fistula [42,43]. In case of a pneumothorax ex vacuo, drainage is normally not necessary and a ‘wait-and-see’ policy can be successful in these patients as the pneumothorax will slowly resolve (Figure 8).
Pleural Pressure Differences Before Removal Are Greater in Patients Who Develop Residual Pneumothorax Post Chest Drain Removal
Published in Journal of Investigative Surgery, 2020
Vasileios K. Kouritas, Charalambos Zissis, Ion Bellenis
Traditionally, a “big swing” observed on the fluid column of the underwater drainage system has intrigued clinicians regarding the safety of its removal [6, 11]. In such cases, for increased safety, some clinicians prefer to clamp the drain for a period of time before removal [11]. The association of wide intrapleural pressure differences with prolonged air leak has previously been published [8]. Another reason for a “big swing” is historically perceived to be the presence of a space within the pleural cavity or atelectasis of the lung parenchyma. Results from the present study show that a “big swing”, observed as a wide ΔP, without an obvious space or atelectasis on the chest radiograph before drain removal, was predictive of the presence of residual pneumothorax, especially if it is more than 8 cm H2O. A ΔP more than 12 cm H2O was predictive of the requirement for re-insertion of the chest tube, although no air leak could be identified clinically and no abnormalities were seen on the chest radiograph prior to removal.