<P> In physiology, intrapleural pressure (also called intrathoracic pressure) refers to the pressure within the pleural cavity . Normally, the pressure within the pleural cavity is slightly less than the atmospheric pressure, in what is known as negative pressure . When the pleural cavity is damaged / ruptured and the intrapleural pressure becomes equal to or exceeds the atmospheric pressure, pneumothorax may ensue . </P> <P> Intrapleural pressure depends on the ventilation phase, atmospheric pressure, and the volume of the intrapleural cavity . </P>

What is the pressure in the intrapleural space