Nellcor Puritan Bennett Incorporated

Aequitron Medical, Inc.

David B Lura

Michael B Jones

Eric P Bailey

Craig Schlawin

A piston ventilator is disclosed herein which uniquely includes an oxygen blending module which supplies oxygen enhancement for aiding patients requiring respiratory treatment. The oxygen blending module supplies a preselected enrichment of oxygen to a piston and cylinder assembly wherein the amount of oxygen permitted to flow therein is continuously monitored and controlled according to the volume above the piston in the cylinder as calculated by a controller. The oxygen blending module includes a flow sensor which monitors the flow of supplemental oxygen into the piston and cylinder assembly, and further includes a primary oxygen control valve which restricts the flow of oxygen through the flow sensor to the piston and cylinder assembly depending on the difference between the calculated desired amount of oxygen and the target amount of oxygen provided to the controller.

Oxygen blending in a piston ventilator

A patient ventilator is connected with two stand-by switches wherein activation of both switches is required for stopping the ventilating function. The preferred stand-by switches are in the form of membrane switches in which a conductive dome is positioned and spaced between respective layers having electrical traces thereon cooperating with the dome for defining the switches. The application of manual pressure closes the spaces between the layers and activates both switches.

Switch overlay in a piston ventilator

A piston ventilator is provided which advantageously monitors the positive end expiratory pressure (PEEP) in a patient circuit for supplying breathable gas to a patient, and controls a shiftable valve element in an exhalation valve to regulate the amount of resistance during the exhalation portion of the patient's breath. The shiftable element is preferably an inflatable diaphragm which receives a pneumatic signal through a signal conduit. The pressure provided by the signal conduit is controlled by the amount of gas vented by a PEEP valve, wherein the greater the opening of the PEEP valve, the greater the amount of gas from the patient circuit is vented therethrough and consequently the less the restriction is provided in the exhalation valve. The primary source of pressure for the breathable gas is provided by a piston ventilator, with make-up pressurization in the patient circuit provided by a secondary source such as a blower to compensate for leakage and to provide pressurization for the signal conduit during the retraction of the piston within the cylinder and consequent exhalation portion of the patient's breath. Supplemental oxygen is provided to the patient circuit during retraction of the piston to ensure adequate oxygen enrichment at the incipient portion of the inhalation portion of the patient's breath.

Peep control in a piston ventilator

The invention relates to an oxygen sensor which measures the concentration of oxygen based upon ultrasonic sound waves traveling through a binary gas. The measured sound-wave delay through the gases determines the concentration level for oxygen within the transducer chamber. The invention includes an L-shaped housing where a transmitter/transducer is attached to one end of the housing and the receiver/transponder is positioned at the junction between the two substantially straight portions of the L-shaped housing. A straight transducer chamber is thereby provided, while simultaneously provided a housing design which minimizes reflected standing waves for detection by the receiver/transponder. The invention includes a sonic baffle positioned at the opposite end of the L-shaped housing from the transmitter/transducer which minimizes standing waves thereby improving the performance of the gas detection device. The invention also includes a sound buffer affixed to the interior of the L-shaped housing which further reduces the existence and reflection of standing waves for detection by the receiver/transponder. Temperature is monitored within the transducer chamber by an angularly offset temperature sensor.

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Brooklyn Park, MN, United States of America

David B Lura