| 摘要 |
A volume ventilator (10) has a ballon valve type (180, 182) exhalation valve for permitting release of gases to the ambient during exhalation period or when there is excess proximal pressure in the ventilator system. The instantaneous proximal pressure in the ventilator system is sent to a microcomputer controller (38). The pressure in the ballon (180), which is the pilot pressure of the exhalation valve (164), is regulated through a jet venturi type pressure controller (80) by a ball valve (204). The ball valve is controlled by a stepper motor (216) in response to the difference between the instantaneously sensed proximal pressure, and the pilot pressure required to be present in the ballon in accordance with an algorithm, or preselected pilot pressure-versus-time function. Accurate servo control of the flow of respiratory gas to the patient is accomplished by a flow control subsystem (86) which incorporates a flow control valve (90) controlled by a second stepper motor (108). |
