Searle Cardio-pulmonary Systems Inc.

Thoratec Laboratories Corporation

Robert B Fraser

Keith Evan Buck

Clive Miles

Irving C Chase

Kenneth J Baker

A flow controller primarily for breathing gas analysis has a gas flow circuit leading from a breathing air inlet to a gas analyzer and to a vacuum source. Another gas is bled into the circuit between the breathing air inlet and a point upstream of the vacuum source. Such other gas is precluded from flowing upstream in the circuit toward the gas analyzer by making the intervening flow path or conduit of suitable dimensions to have a Peclet number at least equal to 4 and preferably greater than 4 and about 6.

Flow controller

A breathing gas analyzer, especially for pulmonary use, has a frame supporting a centrally mounted radiation or analyzing chamber of about 1 and one-half to 25 millimeters (0.06 to 1.0 inches) substantially uniform inside diameter, having a circular-cylindrical transparent wall with closed ends connected in an electrical circuit and providing an anode of brass or stainless steel and a cathode of tantalum and constituting a discharge tube. Leading from a patient's breathing tube is a conduit passing axially through the cathode, the conduit having an inside diameter of about 0.03 to 0.25 inches (0.7 to 6.4 millimeters). The chamber is subjected to subatmospheric pressure of about 0.2 to 10.0 torr through a duct from about one thirty-second to one-quarter inches (0.8 to 6.4 millimeters) inside diameter, passing through the anode to a vacuum pump. Arrayed equidistantly from the axis and around the chamber are one or more radiation detection devices positioned opposite the negative glow region of the discharge. The detection devices may be connected to a display device. There are individual apertures and filters interposed between the chamber and each of the detecting devices.

Breathing gas analyzer

A gas analyzer especially for pulmonary use has a frame supporting a centrally mounted radiation chamber of about 10 to 30 millimeters (0.4 to 1.2 inches) substantially uniform inside diameter, having a circular-cylindrical glass wall closed by molybdenum protected aluminum ends connected in an electrical circuit to constitute an anode and a cathode. Leading from a patient's breathing tube is a conduit passing through a regulating valve and axially through the cathode, the conduit having an inside diameter of about 0.060 inches. The chamber is subjected to subatmospheric pressure through a duct of from about one-eighth to one-quarter inches inside diameter, passing through the anode to a vacuum pump. Arrayed equidistantly from the axis and around the chamber are several radiation detection devices, each connected to a display device. There are individual filters interposed between the chamber and at least some of the detecting devices.

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El Cerrito, CA, United States of America

Robert B Fraser