Court Opinion

ID: 209426
Source: CourtListenerOpinion
Date Created: 2011-03-13 07:34:38+00
Date Added: 2024-06-11T17:27:56.365386
License: Public Domain

NOTE: This disposition is nonprecedential.

 United States Court of Appeals for the Federal Circuit
                                   2008-1164, -1193

                 RESPIRONICS, INC. and RIC INVESTMENTS, LLC,

                                                      Plaintiffs-Appellants,

                                           v.

                                  INVACARE CORP.,

                                                      Defendant-Cross Appellant.

        W. Thomas McGough, Jr. Reed Smith LLP, of Pittsburgh, Pennsylvania, argued
for plaintiffs-appellants. With him on the brief were Gene A. Tabachnick and Joshua S.
Bish.

        Charles B. Lyon, Calfee, Halter & Griswold LLP, of Cleveland, Ohio, argued for
defendant-cross appellant. With him on the brief were John T. Wiedemann, Nenad
Pejic, Georgia E. Yanchar, and Jennifer B. Wick. Of counsel on the brief was Eric G.
Soller, Pietragallo, Bosick & Gordon, of Pittsburgh, Pennsylvania.

Appealed from: United States District Court for the Western District of Pennsylvania

Judge Gary L. Lancaster
                       NOTE: This disposition is nonprecedential.

 United States Court of Appeals for the Federal Circuit
                                   2008-1164, -1193

                 RESPIRONICS, INC. and RIC INVESTMENTS, LLC,

                                                       Plaintiffs-Appellants,
                                            v.

                                  INVACARE CORP.,

                                                       Defendant-Cross Appellant.

Appeal from the United States District Court for the Western District of Pennsylvania in
case no. 04-CV-0336, Judge Gary L. Lancaster.

                           __________________________

                            DECIDED: December 16, 2008
                           __________________________

Before SCHALL, CLEVENGER, and LINN, Circuit Judges.

LINN, Circuit Judge.

      Respironics, Inc. and RIC Investments, LLC (collectively “Respironics”) appeal

from a final judgment of noninfringement by Invacare, Inc. (“Invacare”) of Respironics’s

U.S. Patents No. 5,148,802 (“the ’802 patent”), No. 5,433,193 (“the ’193 patent”), and

No. 6,105,575 (“the ’575 patent”). Invacare cross-appeals from the final judgment of

literal infringement of U.S. Patent No. 6,609,517 (“the ’517 patent”) and also cross-

appeals from the final judgment that all four patents-in-suit are not invalid. Respironics

v. Invacare, No. 04-CV-0336 (W.D. Pa. Jan. 7, 2008) (“Judgment”). Because the district

court correctly construed the claims of the ’802 and ’193 patents and found them not

infringed, we affirm the judgment with respect to those two patents. Because the district
court erred in construing the term “shape” in the ’575 patent and erred in granting

summary judgment of no anticipation of the ’575 and ’517 patents, we vacate the grant

of summary judgment of noninfringement of the ’575 patent, reverse the grant of

summary judgment of validity of the ’575 and ’517 patents, and remand.

                                   I. BACKGROUND

      Respironics’s four patents-in-suit are directed to the treatment of obstructive

sleep apnea (“OSA”). A common method for treating OSA is the use of a continuous

positive airway pressure (“CPAP”) device to supply a constant pressure of air to the

patient to keep the patient’s airway open.     To ease patient discomfort, Respironics

developed and patented a variety of apparatuses and methods that detect when the

patient is exhaling and then lower the pressure of incoming air provided during

exhalation.

      The first two patents—’802 and ’193—are directed to “Bi-level” therapy. Unlike

CPAP, which supplies only one pressure, Bi-level therapy delivers a higher pressure

during inhalation and a lower pressure during exhalation.       These higher and lower

pressures are referred to as inhalation positive airway pressure (“IPAP”) and exhalation

positive airway pressure (“EPAP”), respectively.        See ’802 patent col.6 ll.45-59;

’193 patent col.6 ll.53-67. The third and fourth patents—’575 and ’517—are directed to

a more sophisticated therapy called proportional positive airway pressure (“PPAP”)

therapy. See ’575 patent col.6 ll.3-4; ’517 patent col.6 ll.3-4. Instead of supplying only

one pressure during a given exhalation, PPAP therapy provides varying pressures

during exhalation.   It can do so in one of two ways: (1) in accordance with a

predetermined pressure profile, which has a shape that is set independent of the

2008-1164, -1193                        2
patient’s breathing efforts; or (2) in proportion to the patient’s breathing, such that the

supplied pressure varies with how deeply the patient is breathing.        In general, the

appealed claims of the ’575 patent are directed to the former, “predetermined”

embodiment, and the appealed claims of the ’517 patent are directed to the latter,

“proportional” embodiment.

       Respironics sued Invacare for patent infringement.             Respironics’s final

infringement contention was that Invacare’s commercialization of a product (“the

Commercial Device”) infringed the ’802, ’193, and ’575 patents; and that Invacare’s

demonstration of a prototype device (“the Tradeshow Device”) infringed the ’517 patent.

Following a Markman hearing, the district court issued a claim construction order in

which it construed various contested terms of the patents. Respironics v. Invacare, No.

04-CV-0336 (W.D. Pa. Aug. 30, 2006) (“Claim Construction Order”). On cross-motions

for summary judgment, the district court ruled in favor of Respironics that all four

patents are not invalid as a matter of law and, in particular, that the ’575 and ’517

patents are not anticipated by a publication authored by Dr. Magdy Younes.

Respironics v. Invacare, 511 F. Supp. 2d 587 (W.D. Pa. Apr. 26, 2007). The district

court also granted summary judgment in favor of Invacare that the Commercial Device

does not infringe the ’802, ’193, and ’575 patents. Id. at 604. However, the district

court identified one key factual dispute precluding summary judgment as to infringement

of the ’517 patent: “whether the Vscale factor in the Unloading Equation converts the

valve position measurements into flow rate signals.”       Id.   A trial was conducted to

resolve that question. Answering in the affimative, a jury concluded that the Tradeshow

Device literally infringed claims 29, 30, and 32 of the ’517 patent. Following post-verdict

2008-1164, -1193                         3
briefing, the district court denied Invacare’s motion for judgment as a matter of law

(“JMOL”) and denied Respironics’s motion for a permanent injunction. Respironics v.

Invacare, No. 04-CV-0336 (W.D. Pa. Jan. 7, 2008) (“JMOL Opinion”). The district court

entered judgment in accordance with both the summary judgment order and the jury’s

verdict, and further stayed the bifurcated damages portion of the case pending

resolution of any appeal. Judgment at 1.

      Respironics appealed from the judgment on issues relating to noninfringement of

the ’802, ’193, and ’575 patents.     Invacare cross-appealed on issues relating to

infringement of the ’517 patent and validity of the ’575 and ’517 patents. Because the

judgment “is final as to all issues except for a determination of damages, we have

jurisdiction under 28 U.S.C. § 1292(c)(2).” Cent. Admixture Pharmacy Servs., Inc. v.

Advanced Cardiac Solutions, P.C., 482 F.3d 1347, 1353 (Fed. Cir. 2007).

                                   II. DISCUSSION

                                    A. Infringement

      “The determination of infringement is a two-step process, wherein the court first

construes the claims and then determines whether every claim limitation, or its

equivalent, is found in the accused device.” Roche Palo Alto LLC v. Apotex, Inc., 531

F.3d 1372, 1377 (Fed. Cir. 2008). Claim construction is a question of law, which we

review de novo. Cybor Corp. v. FAS Techs., Inc., 138 F.3d 1448, 1456 (Fed. Cir. 1998)

(en banc). Infringement is a question of fact, which we review for substantial evidence

when tried to a jury, Finisar Corp. v. DirecTV Group, Inc., 523 F.3d 1323, 1332 (Fed.

Cir. 2008), but which we review without deference when decided on summary judgment,

2008-1164, -1193                       4
Bd. of Regents of the Univ. of Texas Sys. v. BENQ Am. Corp., 533 F.3d 1362, 1367

(Fed. Cir. 2008).

                                 1. Commercial Device

      We first address whether the district court properly concluded, on summary

judgment, that the Commercial Device did not infringe the ’802, ’193, and ’575 patents.

       a. Claim Construction of “selected higher and lower pressure magnitudes”

      Respironics challenges the district court’s construction of the term “selected

higher and lower pressure magnitudes” in method claims 3 and 24 of the ’802 patent

and method claims 9, 44, and 53 of the ’193 patent. The district court construed this

term identically for all claims, and the parties do not urge different constructions for

different claims. Claim 3 of the ’802 patent recites, with disputed term emphasized:

          A method of medical treatment for a patient comprising the steps of:
             [1] providing a flow of breathing gas from a source for delivery to
                    the airway of such a patient at selected higher and lower
                    pressure magnitudes at least as great as ambient
                    atmospheric pressure;
             [2] continually detecting the instantaneous flow rate of said
                   breathing gas flowing between said source and the airway of
                   such a patient;
             [3] continually processing selected parameters including said
                   instantaneous flow rate to provide a reference indicia
                   corresponding to an average flow rate of breathing gas
                   flowing between said source and said patient; and
             [4] utilizing said instantaneous flow rate and said reference indicia
                      to select one of said higher and said lower pressure
                      magnitudes for said flow of breathing gas to be applied in the
                      airway of such a patient.

(bracketed numbers added).

      The district court construed the term “selected higher and lower pressure

magnitudes” in step one to require the pressure magnitudes to be “chosen prior to

2008-1164, -1193                        5
operation of the computer circuitry that is used to determine whether the patient is

inhaling or exhaling.” Claim Construction Order at 16 (emphasis added). Respironics

argues that this construction impermissibly imports a temporal limitation into the claims.

It argues that the method steps are not set forth in any chronological sequence and,

accordingly, the pressure magnitudes need not be selected at any particular time in the

sequence.    Invacare defends the district court’s construction, arguing that the word

“select” appears twice in the claims: in the past tense “selected” in step one, and in the

present tense “to select” in step four.       These two occurences of the word “select,”

coupled with step four’s refererence back to “said” magnitudes in step one, convinces

Invacare that the magnitudes in step one are selected before any of steps two, three, or

four are performed.

       The claim language itself provides little insight as to when the pressure

magnitudes in step one are “selected.”           Because steps two and three must be

performed “continually,” it cannot be said that the claim language itself requires all steps

to be performed in the order written. Also, the mere fact that step four refers back to

“said higher and said lower pressure magnitudes” of step one does not, as a rule,

require step one to be performed before step four. Indeed, in Interactive Gift Express,

we held that step one of a method claim can be performed after step four, even though

step four referred to “the catalog code” introduced in step one. Interactive Gift Express,

Inc. v. Compuserve Inc., 256 F.3d 1323, 1328 (Fed. Cir. 2001) (emphasis added); id. at

1343 (“[T]here is no reason why step one[ ] . . . must occur before step four[ ] . . . .).

Thus, in a method claim, a step that recites “said” or “the,” referring to an earlier object,

does not always have to be performed after the step that first introduces the object.

2008-1164, -1193                          6
       We turn then to the specification, which we have called “‘the single best guide to

the meaning of a disputed term.’” Phillips v. AWH Corp., 415 F.3d 1303, 1315 (Fed. Cir.

2005) (en banc) (quoting Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1582

(Fed. Cir. 1996)). In this case, the specification discloses only one way to select the

higher and lower pressure magnitudes: via pressure adjustment controls (labeled “90”

and “92”), which are depicted as a pair of dials in Figure 4, reproduced below.

These dials, according to the specification, are used “for setting the respective [higher]

IPAP and [lower] EPAP pressure levels.” ’802 patent col.13 ll.30-31. Throughout the

specification, the pressure magnitudes are referred to as being “predetermined,” id.

col.2 l.68-col.3 l.1, col.7 l.40, or “preselected,” id. col.3 l.27. See also ’194 patent col.3

ll.3-4, l.30.   When pressed at oral argument to identify an embodiment in the

specification where the pressure magnitudes are not preselected, counsel for

Respironics was unable to do so.                Oral Arg. at 5:35-6:10, available at

http://oralarguments.cafc.uscourts.gov/mp3/2008-1164.mp3. Similarly, the district court

found, and we agree, that “[t]here is no indication in the patents that the lower pressure

magnitude can somehow be changed breath by breath.” Claim Construction Order at

2008-1164, -1193                          7
19. The preselection of higher and lower pressure magnitudes is not merely a preferred

embodiment; it is the patents’ only embodiment.

       The prosecution history also supports the district court’s construction.          As

originally filed, claims 3 and 24 of the ’802 patent used the word “alternately” in place of

the now-disputed word “selected.” In response to an obviousness rejection, Respironics

amended the term to its current form and carried it over to the claims of the ’193 patent.

J.A. 935, 939. Respironics offers no explanation for this amendment. But, to whatever

extent the word “alternately” might have permitted selection of pressure magnitudes on

a breath-by-breath basis, a capability nowhere disclosed in the patents, Respironics’s

decision to replace “alternately” with “selected” forecloses the broader construction.

       Thus, we conclude that the district court correctly construed the term “selected

higher and lower pressure magnitudes” to require the pressure magnitudes to be

chosen prior to operation of the computer circuitry that is used to determine whether the

patient is inhaling or exhaling. See Loral Fairchild Corp. v. Sony Corp., 181 F.3d 1313,

1322 (Fed. Cir. 1999) (“Although not every process claim is limited to the performance

of its steps in the order written, the language of the claim, the specification and the

prosecution history support a limiting construction in this case.”).

                         b. Infringement of ’802 and ’193 Patents

       We also conclude that that district court correctly determined that the

Commercial Device does not infringe the ’802 and ’193 patents under the district court’s

proper claim construction. As previously discussed, the claims require both higher and

lower pressure magnitudes to be selected at the outset of operation. The Commercial

Device, however, preselects only the higher pressure magnitude when operated under

2008-1164, -1193                          8
normal conditions, not the lower magnitude.        Respironics, 511 F. Supp. 2d at 596

(quoting Respironics’s expert as admitting that “the magnitude of unloading is a function

of the [SoftX] setting . . . and peak inspiratory flow of the preceding inspiration (patient-

determined quantity)”). Because the Commercial Device does not perform every step of

the asserted claims, we agree with the district court that the Commercial Device does

not infringe these patents.

       Respironics argues, alternatively, that operating the Commercial Device in so-

called “Standby Mode” might still infringe the ’802 and ’193 patents.          Although the

district court’s opinion did not expressly address this argument, we conclude that

Respironics’s evidence failed to create a genuine issue of material fact sufficient to

defeat the grant of summary judgment of noninfringement. Respironics relies on the

Supplemental Mascara Declaration for the assertion that the ΔV variable in the

Unloading Equation is given a predetermined value in Standby Mode, which is then

used to preselect the lower pressure magnitude before the device detects whether the

patient is inhaling or exhaling, as required by the claims. This statement is directly

belied by Respironics’s own brief, which expressly defines the ΔV variable as “the

change in valve position defined by (Peak – Median) for the inhalation of the previous

breathing cycle.” Appellant’s Br. 14 (emphasis added). Because ΔV presupposes the

detection of a previous breathing cycle, this operation cannot infringe.         A similarly

noninfringing definition of ΔV is found in the computer code cited in the Supplemental

Mascara Declaration. See J.A. 1985 (defining “ΔV = 10 (‘valve_change’ initial value)”)

(citing J.A. 4477 (“The valve_change value is the amount of movement the valve has

m[a]de from it[s] average position between breaths.”) (emphasis added)).           Because

2008-1164, -1193                          9
there is no genuine issue of material fact that ΔV requires at least one prior breath to

have been detected, operating the Commercial Device in Standby Mode does not

infringe as a matter of law. Accordingly, we affirm the judgment of noninfringement of

the ’802 and ’193 patents.

                             c. Claim Construction of “shape”

       Respironics challenges the district court’s construction of the word “shape” in

claims 21 and 43 of the ’575 patent. That word is used in the following phrase: “a shape

of said predetermined pressure profile is set independent of any monitored respiratory

characteristics of such a patient.” (emphasis added).        The district court construed

“shape” to mean “magnitude and duration.” Claim Construction Order at 26. We agree

with Respironics that this construction is unduly narrow. As the intrinsic record makes

clear, a pressure profile is defined not only by its magnitude and duration, but also by its

shape, which is a different characteristic reflective of the way the pressure changes over

time, independent of the particular magnitude and duration of the profile.

       We look first to the claims. The claims themselves suggest that a profile’s shape

is a separate characteristic that can be set independent of the profile’s magnitude and

duration. Claims 22 and 44, which depend directly from claims 21 and 43, each recites

a single additional limitation: “setting at least one of a magnitude and a duration of said

pressure profile.” (emphases added). Because parent claims 21 and 43 recite that the

profile’s “shape” is set independent of any monitored respiratory characteristics of a

patient, the further setting of the profile’s “magnitude” and/or “duration” in claims 22 and

44 would be redundant if “shape” meant “magnitude and duration,” as construed by the

district court.

2008-1164, -1193                         10
       Like the claims, the specification refers separately to each of these three

characteristics: “[T]he defined pressure profile has a shape that generally corresponds

to a patient’s normal flow,” ’575 patent col.20 ll.23-25 (emphasis added); “Multiple

predefined pressure profiles, having different magnitudes, durations or both can be

stored in a CPAP/PPAP device,” id. col.20, ll.53-55 (emphases added). A drawing best

captures the point. The patent’s Figure 11B, reproduced below, shows three pressure

profiles (P1, P2, P3) with different magnitudes (M1, M2, M3) and different durations (D1,

D2, D3). But, despite having different magnitudes and durations, all three pressure

profiles have the same general shape (a left-of-center “U”-shape), which “drops off

quickly at the start of expiration then rises slowly.” Id. col.20 ll.63-64.

The specification thus illustrates that a pressure profile is defined by its duration,

magnitude, and shape. These three characteristics—duration, magnitude, and shape—

are interrelated, but are different factors in the overall makeup of the pressure profile.

The profile’s duration (e.g., D1, D2, D3 in Fig. 11B) is the time difference measured from

the start to the end of the profile. The profile’s magnitude (e.g., M1, M2, M3 in Fig. 11B)

is the pressure difference between the profile’s maximum and minimum pressures. But

duration and magnitude alone do not define how quickly or slowly the profile drops off to

2008-1164, -1193                          11
arrive at the minimum pressure, how long it might stay at any particular pressure, or

how quickly or slowly the profile rises up to arrive back at the maximum pressure.

These are considerations that relate to the “shape” of the profile.          As shown in

Figure 11B, the profile’s shape is the contour along which the pressure changes over

time, independent of the particular magnitude and duration of the profile.

      The prosecution history does not contradict the claims or the specification. The

disputed term was added to claims 21 and 43 in response to an anticipation rejection

over U.S. Patent No. 5,598,838 (“Servidio”).       Distinguishing Servidio, Respironics

explained to the examiner that “the shape of [Servidio’s] expiratory model waveform is

generated based on the inspiratory waveform, which is determined by monitoring the

patient flow during inspiration. . . . Furthermore, it would not be obvious to modify the

teachings of [Servidio] so that the shape of the expiratory waveform model is not based

on the monitored respiratory characteristics of the patient.”      J.A. 3719 (emphases

added). This statement says nothing about the waveform’s magnitude or duration. It

merely shows that Respironics understood that a “waveform” can have a “shape.”

      We conclude that a profile’s “shape” is not limited to its “magnitude and duration.”

We therefore modify the construction of the word “shape” to mean “contour along which

the pressure changes over time, describing the way in which the profile drops off to

arrive at the minimum pressure and then rises up to arrive back at the maximum

pressure, independent of the exact values of magnitude and duration.”

                             d. Infringement of ’575 Patent

      Based on an incorrect construction of the word “shape,” the district court held on

summary judgment that the Commercial Device did not infringe claims 21, 43, and 44 of

2008-1164, -1193                        12
the ’575 patent.     Because the Commercial Device supplies a pressure whose

magnitude is based on the patient’s previous breath, the court determined that the

pressure profile’s “shape” cannot be set independent of the patient’s respiratory

characteristics. Respironics, 511 F. Supp. 2d. at 587. This would be true if “shape”

were tied to “magnitude,” as it was under the district court’s construction.        But, as

previously explained, “shape” should not have been so limited. Moreover, Respironics

points to record evidence that it believes shows that the Commercial Device utilizes a

predetermined pressure profile having a so-called “bath-tub”-shape that is set

independent of any monitored breathing characteristics. J.A. 1443 (Respironics’s claim

chart accusing the Commercial Device of employing a “predetermined pressure profile

‘bath-tub’ shape”); id. 2334, 2420.       Under our modified construction of “shape,”

Respironics’s evidence may raise a genuine issue of material fact. We therefore vacate

the grant of summary judgment with respect to noninfringement of the ’575 patent and

remand the issue for consideration by the district court in the first instance under the

modified construction.

                      e. Disclaimer of CPAP and Bi-level Therapy

       On cross-appeal, Invacare challenges the district court’s claim construction of the

’802, ’193, and ’575 patents, which Invacare argues should be construed to expressly

disclaim CPAP and Bi-level therapy from the scope of the claims. Because the district

court found no infringement of these patents, Invacare’s cross-appeal admittedly seeks

only “a second ground for non-infringement.” Cross-Appellant’s Br. at 1. This is an

improper cross-appeal. See Chiron Corp. v. Genentech, Inc., 363 F.3d 1247, 1252

(Fed. Cir. 2004) (“A cross-appeal is only proper if ‘a party seeks to enlarge its own rights

2008-1164, -1193                         13
under the judgment or to lessen the rights of its adversary under the judgment.’”)

(quoting Bailey v. Dart Container Corp. of Mich., 292 F.3d 1360, 1362 (Fed. Cir. 2002).

We shall therefore treat Invacare’s claim construction argument as an alternative

ground for affirming the judgment of noninfringement, and shall disregard Invacare’s

noncompliant Reply Brief on this issue. See Chiron, 363 F.3d 1252 (“Although styled as

a cross-appeal, this court treats this claim construction issue as an alternative ground

for affirming the judgment.”). Moreover, because we have affirmed, supra, the judgment

of noninfringement of the ’802 and ’193 patents, we shall limit our review to the

’575 patent.

      Having considered Invacare’s argument, we decline to read an express

disclaimer into the claims, but nevertheless modify the construction of the term

“predetermined pressure profile” in claims 21 and 43 of the ’575 patent to reflect the

way this term was later used on summary judgment. Originally, Invacare had urged the

district court to construe the term to require, among other things, that the pressure

profile “is used to reduce the CPAP or bi-level pressure.” J.A. 1441 (chart of claim 21);

id. 1465 (chart of claim 43). That construction was never expressly adopted in the

Claim Construction Order. Id. at 25 (construing “predetermined pressure profile” only

with regard to means-plus-function language). Later, on summary judgment, the district

court apparently adopted Invacare’s earlier proposed construction, stating that “the

predetermined pressure profile reduces the constant pressure of CPAP or the reduced

EPAP pressure of bi-level therapy once the device detects the expiratory breathing

phase.” Respironics, 511 F. Supp. 2d. at 603. On that basis alone, the district court

held that claims 21 and 43 were not anticipated by two prior art patents.             Id.

2008-1164, -1193                       14
Respironics does not dispute the district court’s summary judgment interpretation,

presumably because doing so would jeopardize the validity rulings. We agree with the

district court’s summary judgment interpretation and find it to be entirely consistent with

the way the term is used throughout the specification. E.g., ’575 patent col.20 ll.20-25

(distinguishing “predetermined pressure profile” from straight-line CPAP); id. col.21

ll.12-18 (distinguishing it from straight-line Bi-level EPAP). Thus, in order to maintain

consistent claim constructions for both validity and infringement, we shall modify the

construction of “predetermined pressure profile” to require, as the district court later did,

that “the predetermined pressure profile reduces the constant pressure of CPAP or the

reduced EPAP pressure of bi-level therapy once the device detects the expiratory

breathing phase.” Respironics, 511 F. Supp. 2d. at 603. See Kim v. ConAgra Foods,

Inc., 465 F.3d 1312, 1324 (Fed. Cir. 2006) (“The same claim construction governs for

validity determinations as for infringement determinations.”).

       Despite the above modification, we nevertheless deny Invacare an alternative

ground for affirming the grant of summary judgment of noninfringement of the

’575 patent. Invacare’s noninfringement argument is premised on the assertion that the

Commercial Device is a standard CPAP device whose pressure remains constant. That

fact, however, is in dispute.    See J.A. 2975, Respironics’s Opp. Def.’s Mot. Partial

Summ. J. 26 (“[H]owever, the accused device is not a standard CPAP device.”)

(emphasis in original). Invacare’s own User Manual states that the Commercial Device

“decreas[es] the pressure that the patient must exhale against” and contains “three (3)

settings allow[ing] the user to adjust the extent of the pressure drops.” J.A. 5323. The

User Manual goes on to explain that, in addition to the three adjustable settings, the

2008-1164, -1193                         15
device “can be set for standard CPAP operation.” Id. The presence of the other three

settings creates a genuine issue of material fact as to whether the Commercial Device

can only operate as a standard CPAP device. We therefore conclude that Invacare’s

CPAP argument does not provide an alternative basis to affirm the grant of summary

judgment of noninfringement of the ’575 patent.

                                   2. Tradeshow Device

       We next turn to Invacare’s cross-appeal of the jury’s finding that the Tradeshow

Device infringed claims 29, 30, and 32 of the ’517 patent.

                            a. Claim Construction of “controlling”

       Invacare challenges the district court’s construction of the “controlling” step in

claim 29 of the ’517 patent, which the district court declined to interpret as a step-plus-

function limitation under 35 U.S.C. § 112 ¶ 6. Claim Construction Order at 34-35. The

“controlling” step reads:

              controlling a pressure of the flow of breathing gas delivered
              to a patient based on a product of the expiratory gain and
              the fluid characteristic during at least a portion of an
              expiratory phase of such a patient’s breathing cycle, so that
              a pressure of the flow of breathing gas delivered to the
              patient during at least a portion of the expiratory phase
              varies with fluctuations of the fluid characteristic.

Without pointing to anything in the claim language itself that would dictate construction

under § 112 ¶ 6, Invacare relies entirely on the prosecution history.         Specifically,

Invacare asserts that Respironics urged the examiner to interpret the “controlling” step

as a step-plus-function limitation and that the examiner adopted this interpretation.

Neither assertion is persuasive.

       First, Respironics never urged the examiner to apply § 112 ¶ 6 to method

claim 29 (then-claim 73). When that claim was added during prosecution, together with
2008-1164, -1193                          16
apparatus claim 24 (then-claim 68), the pending application already included apparatus

claim 1 (then-claim 45) and method claim 9 (then-claim 53).      J.A. 3790-801.    Both

apparatus claims recite a “processing means . . . for producing a command signal,” and

both method claims recite “controlling a pressure of the flow of breathing gas delivered

to a patient.” Notably, the apparatus limitations are written in “means for” format; by

contrast, the method steps lack the words “step for,” thus triggering a presumption that

§ 112 ¶ 6 does not apply to the method steps. See Generation II Orthotics Inc. v. Med.

Tech. Inc., 263 F.3d 1356, 1368 (Fed. Cir. 2001) (stating that “there is a presumption

that . . . limitations are not subject to section 112, paragraph 6” when they do not use

the words “means for” or “step for”). When Respironics added new claims 68 and 73

(now 24 and 29, respectively), Respironics told the examiner that “[n]ew independent

claims 68 and 73 are similar to existing independent claims 45 and 53” (now 1 and 9,

respectively). J.A. 3788. Although Invacare now seizes upon Respironics’s “similar to”

language in this statement, it is clear, based on the above comparison of common

terms, that Respironics was referring to the common language used respectively in the

two apparatus claims (“processing means . . . for producing a command signal”) and in

the two method claims (“controlling a pressure of the flow of breathing gas delivered to

a patient”), not to any alleged similarity between apparatus and method claims. Thus,

contrary to Invacare’s assertion, Respironics did not urge the examiner to import a

meaning under § 112 ¶ 6 from the apparatus claims into the method claims.

      Second, the examiner never adopted any step-plus-function interpretation. In the

reasons for allowance, the examiner set forth the various limitations of the apparatus

claims, referring to the “processing means” limitation in the apparatus claims, but not

2008-1164, -1193                       17
the “controlling” step in the method claims. J.A. 3806. After setting forth the apparatus

limitations, the examiner referred to the “abovementioned” (apparatus) limitations only

as “means plus function” limitations. Id. (emphasis added). Nowhere in the reasons for

allowance does the examiner mention the patent’s “controlling” steps, or refer to them

as step-plus-function limitations. Accordingly, we reject Invacare’s argument that the

prosecution history compels a different construction.

                        b. Exclusion of Noninfringement Opinion

         Invacare asks us to vacate the jury’s verdict regarding the Tradeshow Device

because the district court ruled that Invacare could not introduce into evidence a prior

opinion by Respironics’s sole testifying witness, who had opined that the Commercial

Device does not infringe the ’517 patent. The district court sustained Respironics’s

objection that this evidence was “[i]rrelevant,” J.A. 220, which we interpret as an

exclusion under Rule 402 of the Federal Rules of Evidence (“Evidence which is not

relevant is not admissible.”). “We review a district court’s evidentiary rulings under the

law of the regional circuit.” Proveris Scientific Corp. v. Innovasystems, Inc., 536 F.3d

1256, 1267 (Fed. Cir. 2008). The Third Circuit reviews the district court’s evidentiary

rulings for abuse of discretion. United States v. Williams, 458 F.3d 312, 315 (3d Cir.

2006).

         Because the sole issue at trial was infringement by the Tradeshow Device, we

see no abuse of discretion in the district court’s decision to exclude the noninfringement

opinion regarding the Commercial Device. Other available evidence shows that these

two devices operate quite differently. For example, Invacare’s own product manager,

Ms. Hanley, testified that she had detected deep exhalation unloading when she used

2008-1164, -1193                        18
the Tradeshow Device, but detected virtually none with the Commercial Device. J.A.

2323.       Because independent claim 29 requires that the accused device provide

breathing gas whose pressure “varies with fluctuations of the fluid characteristic,” the

Commercial Device’s lack of appreciable variations in unloading (in contrast to that of

the Tradeshow Device) would have been a critical difference for purposes of

infringement. Given this key difference, the district court did not abuse its discretion in

concluding that noninfringement by the Commercial Device was not probative of

whether the Tradeshow Device infringed. See Fed. R. Evid. 401 (defining “relevant

evidence” as “evidence having any tendency to make the existence of any fact that is of

consequence to the determination of the action more probable or less probable than it

would be without the evidence”).

        Invacare’s reliance on Petree v. Victor Fluid Power, Inc., 887 F.2d 34 (3d Cir.

1989), is misplaced.      Evidence in that case was relevant under Rule 402 but was

excluded by the district court under Rule 403. 1 Petree, 887 F.2d at 37-38. The appeal

there focused solely on admissibility under Rule 403. Id. at 40-41 (holding that the

evidence was admissible for impeachment purposes). Here, by contrast, the district

court sustained Respironics’s objection that the noninfringement opinion was

“[i]rrelevant.”   J.A. 220.   Because we affirm this ruling under Rule 402, the parties’

arguments regarding unfair prejudice and jury confusion are, themselves, irrelevant.

        1
              Federal Rule of Evidence 403 provides, with emphasis added, “Although
relevant, evidence may be excluded if its probative value is substantially outweighed by
the danger of unfair prejudice, confusion of the issues, or misleading the jury, or by
considerations of undue delay, waste of time, or needless presentation of cumulative
evidence.”
2008-1164, -1193                          19
                                           c. JMOL

       Invacare appeals the denial of its JMOL motion, asserting that the jury’s verdict

regarding the Vscale variable used in the Tradeshow Device did not amount to a finding

of infringement of the ’517 patent. We review the denial of a JMOL motion under the

law of the regional circuit. 800 Adept, Inc. v. Murex Sec., Ltd., 539 F.3d 1354, 1366

(Fed. Cir. 2008). In this regard, the Third Circuit asks “whether viewing the evidence in

the light most favorable to the nonmovant and giving [the nonmovant] the advantage of

every fair and reasonable inference, there is insufficient evidence from which a jury

reasonably could reach the conclusions that it did.” Rinehimer v. Cemcolift, Inc., 292

F.3d 375, 383 (3d Cir. 2002) (internal quotation marks omitted).

       We conclude that Invacare’s JMOL motion was properly denied. In that motion,

Invacare argued that the question sent to the jury was not dispositive of infringement

because it pertained only to a single claim element, and that there was no finding as to

all other claim elements. 2     The district court held that Invacare had waived this

argument because it had not been raised (and no missing claim elements had been

identified) in opposition to Respironics’s motion for summary judgment of infringement.

JMOL Opinion at 10-11. Moreover, the district court held that Invacare had a duty of

candor to come forward and help the court identify any remaining factual issues, rather

than permit the court to conduct the entire proceeding on an issue the court thought was

the sole issue in dispute. Id. at 11-12.

       2
             The question on the verdict form asked, “Has Respironics proven by the
preponderance of the evidence that the Vscale variable in the Unloading Equation
converts valve position information into flow rate units, that is, the volume of breathing
gas moving per unit of time?” The jury checked “YES,” above “Respironics wins.” J.A.
2183.
2008-1164, -1193                           20
       We agree: “Counsel must remember that they are not only advocates for their

clients; they are also officers of the court and are expected to assist the court in the

administration of justice, particularly in difficult cases involving complex issues of law

and technology.” Allen Eng’g Corp. v. Bartell Indus., Inc., 299 F.3d 1336, 1356 (Fed.

Cir. 2002). In this case, the district court went to great lengths to understand a complex

algorithm and to distill the myriad issues down to those issues in material dispute. The

district court identified a single factual issue—unit conversion by the Vscale variable—

which precluded entry of summary judgment and which would be resolved by a jury.

Respironics, 511 F. Supp. 2d. at 598 (“If it does [convert valve position information into

flow rate units], then defendant’s trade show device infringed this patent. If it does not,

then defendant’s trade show device did not infringe this patent.”). In response, Invacare

filed a motion for reconsideration that was focused solely on the Vscale variable, nowhere

addressing any other claim elements. When the district court denied this motion, it

again stated that the Vscale variable was the sole issue for trial. Later, at an August 2007

status conference, both parties agreed that the only way to bring the infringement case

to a close was for a jury to answer the question regarding the Vscale variable. See JMOL

Opinion at 7-8 (recounting history of case). Invacare never filed any motion in limine

indicating that there were additional issues for trial. Nor did it so indicate in either its

proposed jury instruction or its proposed verdict form. Six weeks after the August 2007

status conference, and a mere three weeks before trial was scheduled to begin,

Invacare stated that it wanted to present its new noninfringement defense, but again

failed to identify any particular claim element that was missing from the Tradeshow

Device. Id. at 9. Under these circumstances, we agree with the district court that

2008-1164, -1193                         21
Invacare should not be permitted to overturn a judgment of infringement based on claim

limitations that Invacare itself apparently conceded were met.

                                      B. Anticipation

         Invacare appeals the grant of Respironics’s motion for summary judgment, which

sought a determination that claims 21 and 43 of the ’575 patent and claims 29, 30, and

32 of the ’517 patent are not anticipated by a publication authored by Dr. Magdy Younes

et al., titled “An apparatus for altering the mechanical load of the respiratory system,” 62

J. Appl. Physiol. 2491 (1987) (“the Younes Article”). We review a district court’s grant of

summary judgment de novo. Leggett & Platt, Inc. v. VUTEk, Inc., 537 F.3d 1349, 1352

(Fed. Cir. 2008). “A patent is invalid as anticipated if every limitation in a claim is found

in a single prior art reference.” Nystrom v. TREX Co., 424 F.3d 1136, 1149 (Fed. Cir.

2005).     “While anticipation is a question of fact, ‘it may be decided on summary

judgment if the record reveals no genuine dispute of material fact.’” Leggett & Platt, 537

F.3d at 1352 (quoting Golden Bridge Tech., Inc. v. Nokia, Inc., 527 F.3d 1318, 1321

(Fed. Cir. 2008)).

         We agree with Invacare; the grant of summary judgment was improper because

neither Respironics nor the district court identified any claim limitation that was not

disclosed in the Younes Article. When Respironics moved for summary judgment, it

identified the following distinctions between the patents and the Younes Article:

               a. The device disclosed [in the Younes Article] does not
                  deal with the use of any of the illustrated functions for
                  treatment of any particular condition (i.e., matching
                  specific function with specific disease states) (id.);
               b. The Younes article discloses a generic apparatus that
                  can deliver various desired pressure functions using a
                  piston as the gas delivery source (id.); and

2008-1164, -1193                         22
              c. The apparatus has no means to detect and compensate
                 for leaks (id.).

J.A. 1535. The problem with this list is that none of the cited distinctions is reflected in

the claims of the patents. The first distinction is of no consequence because the claims

of the ’575 and ’517 patents are not limited to the treatment of any particular condition

or disease state, but generally recite “delivering pressurized breathing gas to an airway

of a patient.” The second misses the mark because the claims do not necessarily

preclude using pistons as the gas delivery source. As for the third, leak detection is not

recited in the claims. Respironics has never explained how these alleged differences

relate to the claims of the ’575 and ’517 patents.

       Moreover, in opposition to Respironics’s motion, Invacare submitted several

claim charts purporting to match each claim limitation with a specific disclosure in the

Younes Article. J.A. 4528 (Def.’s Br. Opp. Pl.’s Mot. Partial Summ. J. 7); id. 806-09

(charts of ’575 patent); id. 816-18 (charts of ’517 patent). The district court’s summary

judgment opinion, however, does not refer to these charts; nor does the opinion explain

which claim limitation(s) are missing in the Younes Article. We take no view on the

technical merits of Invacare’s claim charts, but note that the district court on remand

should determine whether Invacare has shown the existence of a genuine issue of

material fact. See Freedman Seating Co. v. Am. Seating Co., 420 F.3d 1350, 1363

(Fed. Cir. 2005) (stating that an accused infringer “only needed to show the existence of

a genuine issue of material fact in order to preclude summary judgment for” the

patentee) (citing Anderson v. Liberty Lobby, Inc., 477 U.S. 242, 252 (1986)).           We

therefore reverse the grant of summary judgment of validity with regard to claims 21 and

43 of the ’575 patent and claims 29, 30, and 32 of the ’517 patent. Although the district

2008-1164, -1193                         23
court erred by granting summary judgment on the grounds set forth in Respironics’s

motion, Respironics may move again for summary judgment more clearly setting forth

whatever patentable differences it believes exist over the Younes Article.

                           C. Additional Claim Constructions

       Respironics requests that we construe various other terms that were not

determinative in the district court’s infringement analyses.     We have, on occasion,

exercised our discretion to construe such terms in the interest of judicial efficiency.

Here, we decline to construe any additional terms in the ’802 and ’193 patents, because

the district court correctly found no infringement of those patents under the term

“selected higher and lower pressure magnitudes,” and because those patents do not

present any remaining issues on remand. See Inpro II Licensing, S.A.R.L. v. T-Mobile

USA, Inc., 450 F.3d 1350, 1352 (Fed. Cir. 2006) (declining to construe additional terms

where noninfringement was affirmed under dispositive term and where no validity issues

remained). However, because we have held, supra, that a remand is necessary to

reconsider both infringement of the ’575 patent and anticipation of the ’575 and ’517

patents, we shall review the disputed claim constructions of those patents. See Chimie

v. PPG Indus., Inc., 402 F.3d 1371, 1375 n.2 (Fed. Cir. 2005) (construing second term

after vacating summary judgment of noninfringement under first term, where “the

construction of this second disputed term was not dispositive to the district court’s

decision, but may be relevant on remand”).

                      1. Claim Construction of “fluid characteristic”

       Respironics argues that “fluid characteristic” in the claims of the ’575 and ’517

patents should not be limited to just “flow rate,” because the specification also discloses

2008-1164, -1193                        24
“volume” as a fluid characteristic.       See ’575 patent col.23 ll.65-67 (“said fluid

characteristic is one of a rate of said flow of gas within said patient interface and a

volume of gas to be exhaled”) (emphases added). We agree that the claim construction

should be modified to include volume. Although volume can be calculated from flow

rate, such a calculation would require additional steps to be performed: measuring time

and then multiplying time by average flow rate (or integrating a time-varying flow rate).

Aside from volume, however, Respironics points to no other fluid characteristic

disclosed in the specification. Nor do we see any. Thus, properly construed, “fluid

characteristic” means “flow rate or volume.”

                      2. Claim Construction of “corresponding to”

      Respironics also contends that the phrase “corresponding to” means something

more than just “equal to.” For the reasons stated above, our review here is limited to

the term’s use in the “sensing” step of the ’517 patent’s claim 29, which recites: “sensing

a fluid characteristic associated with the flow of breathing gas and outputting a signal

corresponding to the fluid characteristic.” (emphasis added). In this context, we agree

with Respironics that “corresponding to” is broader than “equal to.” This particular step

recites a “fluid characteristic,” which we have construed, supra, to mean flow rate or

volume. It would make no sense, then, to say that a flow rate or volume is “equal to” a

signal, when the specification speaks of electrical signals that are typically measured in

units of voltage or current. Two such things cannot be equal to one another. Rather, it

is more proper to say that the two are functionally related to one another: the magnitude

of the outputted signal varies as a function of the magnitude of the sensed flow rate or

volume.   These two things “correspond to” one another in the sense that they are

2008-1164, -1193                        25
“similar, comparable, and/or matching”—the term’s plain and ordinary meaning.

Because the modified construction is broader than the construction under which

infringement was found, our modification of “corresponding to” does not disturb the

finding of infringement.

                                   III. CONCLUSION

       For the foregoing reasons, we affirm the judgment in all but two respects: we

vacate the grant of summary judgment of noninfringement as to claims 21, 43, and 44 of

the ’575 patent; and reverse the grant of summary judgment of validity as to claims 21

and 43 of the ’575 patent and claims 29, 30, and 32 of the ’517 patent. We remand the

case for further proceedings consistent with this opinion.

 AFFIRMED-IN-PART, REVERSED-IN-PART, VACATED-IN-PART, AND REMANDED

2008-1164, -1193                        26