The Boc Group, Inc.

Ohmeda Inc.

William M Theisen

Charles D Wiseman

Duncan P Bathe

Robert Q Tham

A method and apparatus is disclosed for determining airway resistance and lung compliance using an electrical circuit model wherein at least one component parameter is non-linear. The system non-intrusively obtains pressure and flow data signals from a pressure transducer and a laminar flow element without interrupting or interfering with normal breathing and gas supply to a patient. An invariant exponential is determined empirically based on physical characteristics of the airway. The non-linear airway resistance and lung compliance can then be calculated based on the sensed flow rate, gas pressure, a calculated gas volume, and the invariant exponential using linear techniques. The resulting airway resistance can be normalized to a standard reporting flow rate value. The system is particularly useful in anesthesia applications, but is also useful in any breathing system where fresh gas is supplied constantly from a gas source other than a ventilator.

Method and apparatus for determining airway resistance and lung

A method is disclosed for producing a flexible microcircuit of a size usable in vivo in the arterial or venous tract of a human. The method comprises forming, by various photoresist techniques, conductive runs on a polyimide base of about 1-2 mils thickness. Each end of a flexible microcircuit has minute holes formed therein for connection to an electronic chip and to hard wiring. The method produces holes in the conductive runs for the electronic chip connection of about 0.002 inches in diameter and holes about 0.016 inches in diameter at the end for wiring.

Method of making a flexible microcircuit

A method is disclosed for bonding a minute semiconductor device to the freestanding end of a flexible microcircuit. The method generally comprises a series of steps including initially bonding the semiconductor device to a substrate for handling during the further progression of steps. An extremely minute conductive ball is bonded to one or more conductive surfaces of the semiconductor device and an upwardly depending pigtail is formed atop each of the conductive balls. The flexible microcircuit, having holes in predetermined locations and in numbers corresponding to the upwardly depending pigtails, is positioned atop those pigtails such that a portion of each pigtail protrudes through the flexible microcircuit. Another minute conductive ball is thereafter applied to each of those portions of pigtails protruding through the flexible microcircuit, thus sandwiching the microcircuit between the conductive balls. The final result is a semiconductor device attached to the distal, free end of the flexible microcircuit of sufficient minuteness such that the semiconductor and distal end of the microcircuit can be inserted into a patient's blood vessel for in vivo detection and monitoring of various parameters.

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Madison, WI, United States of America

William M Theisen