Negative pressure pulmonary oedema is a life threatening condition which may e caused due to an obstruction in upper airway. Thus as a result of this obstruction there will be a decrease in the intrathoracic pressure and this ill consequently lead to an increase in the hydrostatic pulmonary capillary pressure Thus as a result of this central mechanism a large aspiratory force will be generated.
In case there is more increase in the pulmonary capillary pressure, this will result in distention of the right ventricle and consequently the there is less ventricular compliance which indicates that the cardiac septum shifts to the left. Therefore it is due to negative pressure pulmonary oedema that the there is an increase in the pressure in left ventricle that causes a further decreases in the incidence of left ventricular stroke. Hypoxia leads to instant sympathetic response that causes constriction of the pulmonary capillaries. As a result of this a negative pressure pulmonary edema is caused due to increase in pulmonary capillary wedge pressure leading to collection of fluid in the pulmonary instertitium leading to pulmonary edema. There are two type of negative pressure pulmonary oedema. The type I is related to acute obstructing conditions while the type II negative pressure pulmonary oedema is mainly concerned with relief in the upper airways obstruction that may have been caused due to the presence of a tumor.