Multiple Choice
In the context of lung physiology, what is the typical state of intrapleural pressure during normal breathing?
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22. The Respiratory System
Pressure in the Lungs and Pleural Cavity
Multiple Choice
In the context of pressure changes in the pleural cavity, thoracentesis is most accurately described as a procedure performed to accomplish which of the following in a patient with a collapsed lung (pneumothorax)?
A
Inject air into the pleural cavity to increase intrapleural pressure and keep the lung inflated
B
Remove air or excess fluid from the pleural cavity to help restore a negative intrapleural pressure and allow the lung to re-expand
C
Create an opening in the trachea to bypass upper airway obstruction and improve ventilation
D
Remove air from the alveoli to reduce alveolar pressure and prevent overexpansion
Verified step by step guidance1
Understand the normal physiology of the pleural cavity: The pleural cavity normally has a negative pressure relative to atmospheric pressure, which helps keep the lungs inflated by creating a suction effect.
Recognize what happens in a pneumothorax: Air enters the pleural cavity, causing the intrapleural pressure to become less negative or even positive, which leads to lung collapse because the suction effect is lost.
Identify the goal of thoracentesis in this context: The procedure aims to remove the air (or excess fluid) from the pleural cavity to restore the negative intrapleural pressure.
Explain how restoring negative intrapleural pressure helps: When the negative pressure is re-established, it re-creates the suction effect that pulls the lung outward, allowing it to re-expand and improve breathing.
Conclude that thoracentesis does not involve injecting air or creating openings in the trachea, but specifically involves removing air or fluid from the pleural space to correct pressure changes caused by pneumothorax.
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