Methods of gas-balance control to be used with a portable hyperbaric chamber in the treatment of high altitude illness

Abstract

A portable fabric hyperbaric chamber (Gamow Bag TM ) has been designed for on site treatment of altitude illness. The chamber includes a manual pumping system, weighs 6.57 kg (14.5 pounds), and can be carried in a backpack. A laboratory study was undertaken to document safety, subject comfort and gas retention characteristics of the chamber. The chamber is designed to be used in one of three different modes: pump mode, bladder mode, and oxygen-scrubber mode. In the pump mode, 521 min –1 of fresh air is continuously supplied via an air pump. Using this technique, ten healthy volunteers were placed in the chamber for 90 min at pressures up to 16.0 kPa (120 mmHg) above ambient pressure. Ambient CO 2 and O 2 levels were found to be less than 1% and more than 20%, respectively. Testing the bladder mode, six subjects exhaled via a nasal mask into a latex bladder, not allowing CO 2 to accumulate in the chamber. Using this mode, the pumping rate can be decreased by a factor of ten, a great advantage when the pumper is working at altitudes above 5792 m (19000 ft). In the oxygen-scrubber mode, O 2 was continuously added via a pressure regulator. CO 2 accumulation was eliminated with a high efficiency CO 2 scrubber made of LiOH. One pound of scrubber and 150 1 of pressurized O 2 can keep an average person in an atmosphere of 21% O 2 with less than 1% CO 2 for 6 h. In this mode, all pumping, except the initial pressurization of the bag, is eliminated.