Medical ventilator system

A ventilator system for providing artificial ventilation to a patient, comprising:

• means for providing a pressure regulated source of respiratory gas;
• flow control means for controlling the flow rate of the respiratory gas in accordance with a predetermined flow rate-versus-time function, the flow control means including adjustable valve means through which the respiratory gas flows to the patient and a stepper motor having a rotatable shaft, an asymmetrical cam mounted to the shaft, and a cam follower mounted for linear movement in relation to the valve means and operating the valve means to control the flow rate, the stepper motor being responsive to a first electric signal;
• flow rate sensing and transducing means disposed downstream of the flow control means and in fluid communication therewith for sensing the flow rate of the respiratory gases and for generating a second electric signal indicative of the instantaneous flow rate of the respiratory gases;
• exhalation valve means being in fluid communication with the patient and with the flow control means for providing an outlet to the ambient for the proximal gases of the patient, said proximal gases including respiratory gas made available for breathing of the patient and gases exhaled by the patient, the exhalation valve means receiving an input pressure signal and being adapted for closing said outlet to the ambient when the input pressure signal exceeds the pressure of the proximal gases;
• pressure control means operatively connected with the exhalation valve for providing said input pressure signal in accordance with a predetermined pressure-versus-time function, and
• computer means for receiving the second electric signal from the flow rate sensing and transducing means, for storing the predetermined flow rate-versus-time function, for comparing the value required by said function to the second electric signal generated by the flow rate sensing and transducing means, and for generating and sending the first electric signal, responsive to the second electric signal, to the stepper motor to regulate the valve means to adjust the flow rate to an instantaneous value required by the predetermined flow rate-versus-time function.

In a ventilator system for providing artificial ventilation to a patient including a pressure regulated source of respiratory gas;

• flow control means for controlling the flow of the respiratory gas in accordance with a predetermined flow rate-versus-time function;
• exhalation valve means in fluid communication with the flow of the respiratory gas and the patient for providing an outlet to the ambient for proximal gases of the patient, said proximal gases including the respiratory gas and the gases exhaled by the patient, and mixtures thereof, the exhalation valve means including means for receiving a pilot pressure and being adapted for closing the outlet to the ambient when the pilot pressure exceeds the instantaneous pressure of the proximal gases;
• pressure control means operatively connected with the exhalation valve means for providing the pilot pressure in accordance with a predetermined pressure-versus-time function;
• pressure transducer means for sensing the instantaneous pressure of the proximal gases and for generating a first electric signal indicative of said instantaneous pressure of the proximal gases, and computer means for receiving the first electric signal, for providing the predetermined pressure-versus-time function, for comparing the value required by the predetermined pressure-versus-time function to the instantaneous pressure of the proximal gases as indicated by the first electric signal, and for generating and sending a corrective second electric signal to the pressure control means to regulate the pilot pressure generated by the pressure control means, the improvement comprising:
• means for providing a source of pressurized gas in addition to the respiratory gases provided for the patient;
• venturi jet means included in the pressure control means for receiving the pressurized gas and having an outlet port to the ambient whereby a stream of gas flows through the venturi jet means, the venturi jet means further including a static pressure port wherefrom the pilot pressure for the exhalation valve means is tapped, and
• adjustable valve means included in the venturi jet means for regulating the stream of gas to the ambient whereby the pilot pressure is regulated, the adjustable valve means being controlled by the corrective electric signal generated by the computer means.

In a ventilator system for providing artificial ventilation to a patient including a pressure regulated source of respiratory gas;

• flow control means for controlling the flow of the respiratory gas to the patient in accordance with a predetermined flow rate-versus-time function;
• flow sensing and transducer means for measuring the flow rate of the respiratory gas downstream of the flow control means and for generating a first electric signal indicative of said flow rate;
• exhalation valve means in fluid communication with the flow of the respiratory gas and with the patient for providing an outlet to the ambient to proximal gases of the patient;
• pressure control means operatively connected with the exhalation valve means for controlling the exhalation valve means to maintain the proximal pressure in accordance with a predetermined pressure-versus-time function;
• and computer means for receiving the first electric signal, for providing the predetermined flow rate-versus-time function, for comparing the value required by the predetermined flow rate-versus-time function to the instantaneous flow rate as indicated by the first electric signal, and for generating and sending a corrective second electric signal to the flow control means to regulate the flow control means, the improvement comprising:
• a stepper motor included in the flow control means and having a rotatable shaft, an asymmetric cam mounted to the rotatable shaft and a cam follower operatively mounted to follow the cam in a substantially linear motion, the stepper motor being controlled by the corrective second electric signal, and
• an adjustable flow control valve included in the flow control means and having an orifice interfacing with a valve body which is connected to the cam follower, whereby the stepper motor controls the flow rate.