What is intrathoracic pressure?

Intrathoracic pressure refers to the pressure within the chest cavity, which includes the lungs, heart, and other structures in the thoracic cavity. This pressure is crucial for breathing and heart function.

During inhalation, the diaphragm contracts and moves downwards, increasing the volume of the chest cavity and decreasing the intrathoracic pressure. This decrease in pressure allows air to rush into the lungs to equalize the pressure inside the lungs with the atmospheric pressure.

During exhalation, the diaphragm relaxes and moves back up, decreasing the volume of the chest cavity and increasing the intrathoracic pressure. This increase in pressure forces air out of the lungs.

Changes in intrathoracic pressure can also affect heart function. When intrathoracic pressure decreases during inhalation, it can increase blood flow back to the heart. Conversely, when intrathoracic pressure increases during exhalation, it can decrease blood flow back to the heart.

Disruptions in intrathoracic pressure can occur due to conditions such as pneumothorax (collapsed lung), pleural effusion (accumulation of fluid in the chest cavity), or conditions that restrict lung expansion, such as chronic obstructive pulmonary disease (COPD). Proper monitoring and management of intrathoracic pressure are essential for maintaining normal breathing and heart function.