49 F.3d 1575 (Fed. Cir. 1995), 93-1284, Baxter Healthcare Corp. v. Spectramed, Inc.

Docket Nº:93-1284, 93-1302.
Citation:49 F.3d 1575
Party Name:34 U.S.P.Q.2d 1120 BAXTER HEALTHCARE CORPORATION and Utah Medical Products, Inc., Plaintiffs-Appellants, v. SPECTRAMED, INC., Defendant/Cross-Appellant.
Case Date:March 17, 1995
Court:United States Courts of Appeals, Court of Appeals for the Federal Circuit

Page 1575

49 F.3d 1575 (Fed. Cir. 1995)

34 U.S.P.Q.2d 1120


Inc., Plaintiffs-Appellants,


SPECTRAMED, INC., Defendant/Cross-Appellant.

Nos. 93-1284, 93-1302.

United States Court of Appeals, Federal Circuit

March 17, 1995

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[Copyrighted Material Omitted]

Page 1577

        H. Ross Workman, Workman, Nydegger & Jensen, Salt Lake City, UT, argued, for plaintiffs-appellants. With him on the brief were Larry R. Laycock and Todd E. Zenger. Also on the brief was Debra D. Condino, Baxter Healthcare Corp.

        James W. Geriak, Lyon & Lyon, Costa Mesa, CA, argued, for defendant/cross-appellant. With him on the brief was Kurt T. Mulville. Also on the brief were Allan W. Jansen, Lyon & Lyon, Los Angeles, CA, Steven D. Hemminger, Lyon & Lyon, San Jose, CA, and Larry R. Cassett and Roger M. Rothbun, BOC Group, Inc., Murray Hill, New Providence, NJ.

        Before MICHEL and PLAGER, Circuit Judges, and MESKILL, Senior Circuit Judge. 1

        PLAGER, Circuit Judge.

        This is a patent infringement case. In addition to deciding the merits of the judgment rendered by the trial court, we must also examine the question of a trial court's options when a jury decides some, but not all, of the special interrogatories submitted to it. Both parties object to the trial court's disposition of the issues.

        Plaintiffs Utah Medical Products, Inc. and Baxter Healthcare Corporation (hereafter collectively "Baxter") appeal, and defendant Spectramed, Inc. ("Spectramed") cross-appeals the March 3, 1993 judgment of the United States District Court for the Central District of California in Civil Action 89-0131. The district court entered judgment for plaintiff Baxter on the issues of inequitable conduct and certain issues of validity regarding U.S. Patent No. 4,610,256 (the '256 patent), but granted Spectramed's post-trial motions for judgment as a matter of law (JMOL) on all issues of infringement.


        The subject matter of this suit is a blood pressure transducer which is part of a system that continually and directly monitors a patient's blood pressure. In this monitoring system a catheter, placed inside a patient's blood vessel, transmits periodic pressure pulses through a fluid-filled tube in the catheter to a pressure transducer. A thin diaphragm in the pressure transducer deflects to a degree proportionate to the pressure of the pulses through the fluid. The transducer converts the strength of the pulse into a corresponding electrical signal, and transmits this signal through electrical cabling to a monitor, thus allowing continual measurement of the patient's blood pressure.

        The accuracy of the measurements in a direct monitoring system is highly dependent on the transducer; a method of calibration is necessary to ensure that the transducer is functioning properly. Historically, calibration was performed by connecting a known pressure source to the transducer's diaphragm via a special port in the transducer, on the same side of the instrument as the connection for the patient's catheter (patient side calibration). The pressure exerted by this source against the fluid in the chamber adjacent to the diaphragm causes the diaphragm to deflect. If the measurement on the monitor differs from the known pressure source, appropriate adjustments are made to the monitor.

        This method of calibration is not without some risk to the patient. Although a stopcock shuts off direct contact with the patient during calibration, the known pressure source does come into contact with the same side of the diaphragm as the tube leading to the patient while monitoring blood pressure. This introduces the risk of contaminants entering the patient's bloodstream once the stopcock is released. Moreover, should the person calibrating the transducer fail to close off the connection to the patient, air bubbles could directly enter into the patient's bloodstream, possibly leading to an air embolism.

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  1. The '256 Patent

            On September 25, 1984, Dr. William D. Wallace, a physician at Utah Medical, filed a patent application for an apparatus and method for calibrating transducers in a different manner. 2 Instead of introducing a positive pressure on the patient's side of the transducer, with its corresponding risks, Dr. Wallace's invention avoids contact with the patient's side of the transducer diaphragm by providing a negative or vacuum pressure to be drawn on the backside of the diaphragm (backside calibration). Since the transducer is a differential device and typically balanced to zero pressure, a negative pressure on the backside of the diaphragm will result in the same pressure reading on the monitor as an equal and opposite positive pressure on the front side of the transducer. This known negative pressure deflects the diaphragm which then triggers the previously-mentioned conversion into an electrical signal. On September 9, 1986 this application issued as U.S. Patent No. 4,610,256 (the '256 patent) with Claim 1, which is illustrative of the '256 patent, reading:

    1. In a direct blood pressure monitoring system including an indwelling catheter and pressure tubing filled with a fluid for communicating blood pressure pulses to a diaphragm of a pressure transducer, and a monitor for displaying data corresponding to said blood pressure pulses, an apparatus comprising means for placing one side of said diaphragm in communication with said blood pressure pulses in said pressure tubing and catheter, means for venting the other side of said diaphragm to atmospheric pressure, and means for introducing a calibration pressure on the side of said diaphragm that is vented.

            On May 27, 1987 the Patent and Trademark Office (PTO) granted Spectramed's request for reexamination of the '256 patent in light of a newly discovered piece of prior art--a published article entitled "A Calibration System for Catheter Transducer Pressure Measurement," Biomedical Engineering, May 1976, at 180-82, by R.H.S. Murray and N.A. Howe (hereafter Murray/Howe). Unlike other cited prior art references, this reference taught, inter alia, a means for calibrating on the backside of a transducer diaphragm. The patentee, in his response, argued that although this reference taught backside calibration of a transducer, it did so in a way different from that claimed by the '256 patent. Specifically, the Murray/Howe reference taught backside calibration by physically modifying the transducer, whereas the '256 patented invention utilized a cable both for introducing pressure to the backside of the transducer as well as for transmitting the electrical signal to the monitor. According to the patentee, the use of this cable was neither disclosed nor contemplated in the Murray/Howe reference. 3 In light of this distinction the patentee amended his claims. 4 Based on this reasoning the examiner allowed the claims as amended, and a Reexamination Certificate issued on June 21, 1988.

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  2. Defendant's Products

            The defendant in this action, Spectramed, began selling its DTX line of transducers as early as May 1983. This device and its accompanying white cable, discussed infra, were on sale in this country more than one year prior to the filing date of the '256 patent, and therefore are prior art under 35 U.S.C. Sec. 102(b). The device consisted of a transducer housing with an attached cable (referred to hereafter as a "pigtail" cable) having both electrical wiring and a vent passage for venting the backside of the transducer diaphragm. The other end of the pigtail cable, i.e., the side not connected directly to the transducer housing, was attached to an electrical connector. Along with this transducer Spectramed sold a corresponding white cable which served essentially as an extension cord from the electrical connector on the pigtail cable to a monitor for reading the blood pressure (referred to hereinafter as "white cable"). This product--DTX with white cable--was not designed or equipped to perform backside calibration.

            In 1985, after the commercial embodiment of the '256 patented invention was put on the market, Spectramed modified its white cable. Specifically, Spectramed altered the female connector on the white cable, which attaches to the electrical connector on the transducer's pigtail cable, by designing an O-ring to fit around the female connector for the purpose of sealing the connection, and inserting a tube through the central portion of the female connector venting six or eight inches down the cable. The resulting product--the gray cable--when used with the unmodified prior art DTX transducer was capable of performing backside calibration.

            Utah Medical, believing that Spectramed's new product infringed their '256 patent, invited Spectramed to enter into a licensing agreement both prior and subsequent to issuance of the '256 patent. Spectramed declined, and instead filed the previously discussed request for reexamination of the '256 patent. In July 1989, shortly after the Reexamination Certificate issued, Utah Medical and Baxter Healthcare Corporation, which had obtained a license for the '256 patent, filed suit against Spectramed alleging that Spectramed's various transducer models--the DTX, DTX Plus, P10EZ, and P23XL models--infringed the '256 patent.

  3. District Court Proceedings...

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