[#3] MECÂNICA RESPIRATÓRIA: PNEUMOTÓRAX | MK Fisiologia

Summary

In this video, the host explains pneumothorax, a condition where air enters the pleural space between the lungs and chest wall, leading to lung collapse (atelectasis). Using a traumatic injury as an example, the script describes how the pressure in the pleural space changes, affecting lung function. The video also covers how to treat pneumothorax by restoring normal intrapleural pressure, either through mechanical ventilation or a catheter to remove the air. The host emphasizes the importance of understanding these physiological processes for better respiratory health.

Takeaways

• 😀 Pneumothorax refers to the presence of air between the pleuras, specifically in the intrapleural space, which can affect breathing.
• 😀 Pneumothorax can be caused by trauma, such as a stab wound, leading to a perforation of the chest wall and pleura.
• 😀 Normally, there is a negative pressure (around -5 cm of water) in the intrapleural space, which helps keep the lungs expanded.
• 😀 When the chest wall or pleura is punctured, air enters the intrapleural space, and the pressure becomes less negative, potentially reaching zero.
• 😀 The reduction of negative pressure in the pleural space leads to a decrease in transpulmonary pressure, which may cause the lung to collapse (atelectasis).
• 😀 Transpulmonary pressure is the difference between alveolar pressure and intrapleural pressure, and it is essential for keeping the lungs expanded.
• 😀 To re-expand the lung, it is necessary to increase transpulmonary pressure, which can be achieved by either increasing alveolar pressure or decreasing intrapleural pressure.
• 😀 One method for lung expansion in cases of pneumothorax is the use of positive pressure ventilation, which increases alveolar pressure and helps expand the lungs.
• 😀 Ventilation with positive pressure is a temporary measure to help the patient breathe but does not resolve the pneumothorax itself.
• 😀 To truly fix the pneumothorax, the intrapleural pressure must be restored to its normal resting value (around -5 cm of water) by removing the air through suction or other medical interventions.

Q & A

What is pneumothorax?

Pneumothorax refers to the presence of air between the pleurae, specifically in the intrapleural space or pleural cavity. It can occur due to trauma or injury to the chest, leading to a perforation of the pleura and allowing air to enter.

How does pneumothorax affect lung function?

Pneumothorax leads to a decrease in transpulmonary pressure, which is the pressure difference between the alveolar pressure and the intrapleural pressure. This reduction in transpulmonary pressure causes the lungs to collapse (atelectasis), as the lungs retract from the chest wall.

What is the relationship between intrapleural pressure and atmospheric pressure in pneumothorax?

Under normal conditions, the intrapleural pressure is lower than atmospheric pressure. However, in pneumothorax, air enters the intrapleural space, causing the intrapleural pressure to rise, potentially equalizing with atmospheric pressure, disrupting the negative pressure that keeps the lungs expanded.

What happens when the intrapleural pressure equals atmospheric pressure?

When the intrapleural pressure equals atmospheric pressure, the transpulmonary pressure becomes zero, leading to the collapse of the alveoli. Without the force that keeps the lungs expanded, the lung tissue retracts from the chest wall, resulting in atelectasis.

How can mechanical ventilation help in the case of pneumothorax?

Mechanical ventilation with positive pressure can help expand the lung by increasing the alveolar pressure. This, in turn, increases the transpulmonary pressure, allowing the lung to re-expand and prevent further collapse.

What is the primary goal when treating pneumothorax?

The primary goal in treating pneumothorax is to restore the intrapleural pressure to its normal negative value, usually around -5 cm of water. This allows the lung to expand again and reattach to the chest wall.

How is the air in the pleural space removed during treatment?

The air trapped in the pleural space can be removed through the insertion of a catheter, which performs suction to evacuate the air, restoring the normal intrapleural pressure and allowing the lung to re-expand.

What is the significance of transpulmonary pressure in lung mechanics?

Transpulmonary pressure is crucial for lung expansion. It is the difference between the pressure inside the alveoli and the intrapleural pressure. A positive transpulmonary pressure keeps the lung tissue stretched, preventing collapse.

What is the difference between pressure inside the alveoli and intrapleural pressure during a normal respiratory cycle?

During normal respiration, the alveolar pressure fluctuates with inhalation and exhalation, while the intrapleural pressure remains negative relative to atmospheric pressure, facilitating lung expansion. In pneumothorax, the intrapleural pressure increases, which can cause lung collapse.

Can mechanical ventilation completely resolve pneumothorax?

No, mechanical ventilation can assist in breathing by increasing alveolar pressure and supporting lung expansion, but it does not resolve the pneumothorax itself. The primary solution involves restoring the normal intrapleural pressure through the removal of air from the pleural space.