Abstract: A hypobaric chamber apparatus and method are provided for removing excess fluid from the lungs of a patient. A cylindrical vessel is used having a hatch at one end to allow entry of a patient into the chamber. A patient is placed in the chamber and breathes oxygen-rich gas through a face mask while a vacuum pump reduces the pressure in the chamber to a predetermined pressure between 2 and 10 psi. A helium purge system is used to displace the atmospheric gas in the chamber and to replace it with a predetermined mixture of treatment gas. When the predetermined subatmospheric pressure is reached within the chamber, the patient removes the face mask and breathes the treatment mixture of gas at the predetermined subatmospheric pressure. The excess liquid in the lungs of the patient is evaporated into the treatment gases. The treatment gases are recirculated and exposed to ultraviolet radiation to kill bacteria therein and to prevent the patient from reinfecting himself or herself.