Abstract
This chamber is designed for use with conscious or unconscious patients requiring treatment with oxygen under high pressure. It can be pressurised to a maximum of 45 pounds per square inch above ambient (60 pounds per square inch absolute).
The unit consists of two parts, the pressure chamber and the control console, connected together by flexible hose. The chamber can be operated up to a distance of 100 feet from the control console and both parts are mobile.
The chamber consists of two concentrically mounted transparent cylinders, closed at the ends by domed metal caps. One end cap is detachable and can be removed, complete with the bed. The bed will accommodate a patient 6 feet 6 inches tall. The fully transparent chamber allows a complete view of the patient during treatment.
A communication system is provided between the patient and operators. A loud speaker and microphone are built into the door of the chamber and two external pick-up points are situated on the console and the fixed end cap of the chamber. Two-way or three-way conversation is possible and the patient can be temporarily isolated from the system if required.
Oxygen and electrical services must be coupled to the console. The chamber will operate directly from oxygen cylinders charged to a maximum of 1,800 pounds per square inch or from any piped supply with a minimum pressure of 75 pounds per square inch absolute.
A self-contained 12-volt direct current battery supplies the necessary electrical power. A charging unit is incorporated in the control console and this is normally connected to an alternating current supply to keep the battery fully charged. If initially the battery is fully charged the unit can be operated in a continuous pressurisation-depressurisation cycle for at least twenty-four hours without further charging.
Pressurisation and depressurisation are achieved by means of a motorised valve on the outlet of the pressure chamber. During pressurisation a variable speed motor applies a gradually increasing load to a helical spring. This in turn loads the outlet valve. By this means smooth pressure changes are obtained and the motor speed can be used to control the rate of pressure change.
Operating the pressure chamber is simple. After the patient has been placed in the chamber and the door sealed by screw-down knobs, pressurisation is started by turning a selector switch on the control console. The required working pressure can be preset or the pressure can be held at any point between ambient and the top working pressure of 45 pounds per square inch above ambient. Pressurisation stops automatically when the preset level is reached or at 45 pounds per square inch. The rate of pressurisation is selected on the console and can be varied up to a maximum of approximately 8 pounds per square inch per minute. In the same manner, depressurisation can be controlled at any rate up to 8 pounds per square inch per minute down to ambient pressure, or held at any intermediate pressure according to the wishes of the operator.
Coloured lights on the control panel indicate whether the chamber is ready for use, in the pressurisation or depressurisation state, holding a steady pressure or holding at the chosen maximum pressure.
This pressure chamber is run as an open circuit. A continuous ventilating flow of oxygen passes through the chamber to wash out carbon dioxide and water vapour.
In the event of an emergency affecting the patient, fast depressurisation controls are provided on both the chamber and the console. An electrically operated dumping valve can be triggered from the control console or the same valve operated manually from the end of the chamber. A pressure drop of one pound per square inch per second is obtained when this valve is used, and it is possible to reduce from maximum pressure and remove the patient from the chamber in approximately one minute. If a total power failure should occur, a manually operated, slow depressurisation valve can be opened on the control console.
A number of sealed electrical plugs are provided in the door of the chamber. With suitable apparatus these allow electro-physiological monitoring of the patient throughout the course of the treatment.
