1. Field of the Invention
The present invention relates to a medical appliance driving apparatus designed to inflate and deflate a medical appliance such as an artificial heart pump or an intra-aortic balloon pump by alternatively supplying positive and negative pressures thereto. More particularly, the present invention pertains to an apparatus for driving an intra-aortic balloon pump.
2. Description of the Related Art
Medical appliance driving apparatus are required to increase the speed of inflation and deflation of the associated medical appliances. It is preferable, in order to meet such requirements, to have a sharp rise (or drop) of the pressure supplied to the medical appliances. For this reason, one type of driving apparatus employs an accumulator to prevent variations in pressure. However, it is necessary to considerably increase the capacity of the accumulator in order to absorb an increase or decrease in pressure produced in the accumulator when the state of the medical appliance is changed from inflation to deflation or vice versa. Accordingly, it is difficult to reduce the overall size of the driving apparatus.
There is another type of medical appliance driving apparatus wherein a solenoid valve is disposed in parallel to a pressure regulating valve and a pressure from a pressure source such as a compressor or a vacuum pump is directly supplied to the medical appliance by controlling the solenoid valve so as to be opened and closed at a predetermined timing, thereby providing compensation for the rise of pressure supplied to the medical appliance.
For example, a driving apparatus disclosed in Japanese Kokai No. 59-177062, published Oct. 6, 1984, is arranged such that, while a negative pressure is being supplied to a medical appliance, a positive pressure is directly supplied from a compressor through a solenoid valve and kept higher than a set pressure regulated by a pressure regulating valve to thereby compensate for the rise of pressure when a positive pressure is supplied to the medical appliance.
Driving apparatus disclosed in Japanese Kokai Nos. 59-206698, published Nov. 22, 1984, and 59-207158., published Nov. 24, 1984, respectively, are arranged such that, when a positive pressure is supplied to a medical appliance, a positive pressure from a compressor is directly supplied through a solenoid valve for a predetermined period of time to thereby compensate for the rise of pressure supplied to the medical appliance.
Driving apparatus disclosed in Japanese Kokai Nos. 59-206699, published Nov. 22, 1984, and 59-207158 are provided with an auxiliary accumulator for accumulating a positive pressure from a compressor in addition to an accumulator for accumulating a regulated pressure, and when the regulated pressure is supplied to the medical appliance, the pressure accumulated in the auxiliary accumulator is supplied together with said regulated pressure to thereby provide compensation for the rise of pressure supplied to the medical appliance.
A driving apparatus disclosed in Japanese Kokai No. 60-106462, published, June 11, 1985, is arranged such that, when a positive pressure is supplied to a medical appliance, a positive pressure from a compressor is directly supplied through a solenoid valve to thereby compensate for the rise of pressure supplied to the medical appliance, and when the pressure in the medical appliance reaches a predetermined value, the solenoid valve is closed.
In all of these driving apparatus a pressure from a pressure source is directly led to a medical appliance in order to compensate for the rise of pressure supplied to the medical appliance. Accordingly, when the medical appliance is to be inflated to a positive pressure fluid is needed to compensate for a negative pressure in the pipe line, whereas, when the medical appliance is to be deflated, a negative pressure fluid is needed to compensate for a positive pressure in the pipe line. For this reason, it has heretofore been unavoidable that the rise of pressure at the time of switching the state of the medical appliance from inflation to deflation and vice versa is somewhat slow.