<P> Müller's maneuver can temporarily significantly decrease the intrapleural pressure . </P> <P> The logic in intra-pulmonary pressure and the intra-pleural pressure is that the pressure becomes more negative during inspiration and allows air to get sucked in (Boyle' s law .) P vs V relationship...and during expiration the pressure becomes less negative and (greater than atmospheric pressure, Note: (the partial pressure of Carbon dioxide .)) and air is given out...The only difference in the pressures are intra-pleural pressure is more negative than intra-pulmonary pressure...Factors affecting are: Physiological effects - 1 .) mullers maneuver - forced inspiration against a closed glottis results in negative pressure...2 .) Deep inspiration Pathological effects: 1 .) Emphysema 2 .) Pneumothorax Condition . </P>

At the end of inspiration intrapleural pressure is