Abstract: A modular drainage apparatus has a plurality of preformed plastic bodies supported by a header. One of the bodies includes a collection chamber connected to the pleural cavity of a patient and connected to a first passage formed in the header. A second body includes a U-shaped liquid seal chamber having one end connected to the first passage and its other end connected to a second passage formed in the header. The second passage is connected to a vacuum pump, which creates a suction within the collection chamber through the liquid seal chamber. A third body includes a U-shaped chamber to regulate the negative pressure produced by the vacuum pump to a desired negative pressure. The second body also includes a second U-shaped chamber having one end connected to the atmosphere and its other end connected to the liquid seal chamber adjacent its connection to the first passage.

Abstract: A drainage apparatus has a collection chamber connected to the pleural cavity of a patient with a vacuum pump connected through a water seal chamber to the collection chamber. A pressure regulating chamber maintains the negative pressure created by the vacuum pump in the water seal chamber at a desired negative pressure. When there is an increase in negative pressure within the pleural cavity of the patient, atmospheric pressure is transmitted through a liquid at a selected level in an excess negativity chamber to the collection chamber to reduce the negative pressure in the collection chamber and the pleural cavity of the patient connected thereto to a selected maximum above the negative pressure maintained in the collection chamber by the vacuum pump and regulated by the pressure regulating chamber.