NOTE: Pursuant to Fed. Cir. R. 47.6, this disposition is not citable as precedent. It is a public record. 

## United States Court of Appeals for the Federal Circuit

04-1546

TRANSONIC SYSTEMS, INC., Plaintiff -Appellant,

v. NON-INVASIVE MEDICAL TE CHNOLOGIES CORPORATION (doing business as In-Line Diagnostics Corporation), Defendant-Appellee.

_______________________ DECIDED: July 25, 2005

_______________________ Before SCHALL, GAJARSA, and PROST, Circuit Judges

. GAJARSA, Circuit Judge

. Transonic Systems, Inc. appeals from the district court’s judgment of no infringement, in favor of Non-Invasive Medica l Technologies Corporation, on claims 1, 9, 24, and 32 of U.S. Patent No. 5,685,989 (issued Nov. 11, 1997). Transonic Sys., Inc. v. Non-Invasive Medical Techs. Corp. , No. 1:99cv41 B, 1:00cv46 ST (D. Utah Aug. 9, 2004). The district court erred in construing, a nd applying, the claim term “calculating”. As set forth herein, the court reverses the di strict court’s claim co nstruction, vacates thejudgment of no infringement, and remands fo r further proceedings concerning both t he “Delta H” and “Go / No-Go” methods, and NMT products, at issue. The district court further determined that Transonic was esto pped from asserting infringement under the doctrine of equivalent s for all four claims. We vacate the district court’s prosecution history estoppel ruling and remand for further proceedings. Finally, we clarify that the “calc u lating means” in c l aims 24 and 32 require the function of “calculating” as defined in claims 1 and 9. On remand the district court should evaluate the means-plus-function terms in claims 24 and 32 for infringement using a section 112, paragraph 6 analysis, in light of the meaning of “calc u lating” as explained herein. I. Transonic Systems, Inc. (“Transonic”) and Non-Invasive Medi cal Technologie s Corporation (“NMT”) make kidn ey dialysis equipment. Transon ic owns U.S. Patent No. 5,685,989 (“the ’989 patent”) to a “Method and Ap paratus to Measure Blood Flow and Recirculation In Hemodialysis Shunts.” A dialysis machine takes blood f r om a su rgically implanted shunt, cleans it, and returns the blood to the body. The shunt event ually suffers from cl otting or clogging; if allowed to progress past a certain point, the normal blood flow through the shunt is impaired and the dialysis is subj ect to “recirculation.” Recirculation means that blood is drawn in m u ltiple pass e s through the dialysis mach ine. The effect of recircul ation is to reduce the machine’s efficiency, because the recirculation displaces blood that needs dialys is. Eventually a new shunt must be implanted, but the nu mber of times and places this can be done is limited.

04-1546 - 2 -The ’989 patent addr esses this problem by teaching methods, and dev ices , for ascertaining the blood flow through the shunt. If reduced blood flow is identified early enough, doctors can intervene and address the reduced flow before a new shunt is required. The patent approaches this probl em by a method termed “dilut i on,” which relates the observable properties of volume , concentration, and measurable d u ration of an “indic a tor” to the shunt blood fl ow of interest. An indicato r is a substance that alters a measurable property of bl ood, added during flow through the dialysis loop. The ’989 patent describes eight equations setting fo rth specific relations between thes e observables – or measures derived from observable parameters – and the shunt blood flow of interest. Independent c l aims 1 and 9 are directed to processes for ascertaining the blood flow through a shunt, and indep endent claims 24 and 32 are directed to devices for doing the same. NMT makes a “Crit-Line Monitor” that moni tors patient’s blood during dialy s is. NMT further teaches two methods for ascertaini ng shunt blood flow. The first, “Delta H”, relates to the hematocrit (red blood cell concent ration) in dialyzed blood as a function of varying the dialysis filtration rate. The second, “Go / No-Go”, ca lls for comparing one measured parameter, called “reve rse-line recirculation” (the percentage of treated blood that recirculates through the dialyzer when blood flow thr ough the dialyzer is reversed), to a reference (33%). If greater than 33%, the method teaches that shunt blood flow has fallen below 600 ml / min, indicating a problem. Transonic sued NMT for infringing claims 1, 9, 24, and 32 of th e ’989 patent. The disputed c l aim term is “calc u lating.” T h is court has, on t w o occas i ons, already addressed the meaning of “calculating.” Fir s t, in Transonic Sys., Inc. v. Non-Invasive

04-1546 - 3 -Medical Techs. Corp. , 10 Fed. Appx. 928 (Fed. Cir. 2001) (“Transonic I ”), the court vacated and remanded the grant of preliminary injunction fo r Transonic. In Transonic I , the court explained that “calculat i ng . . . mu st be construed as requiring the use of at least one of the equations set forth in the specification of the ’989 patent.” Id. at 934. Second, in Transonic Sys., Inc. v. Non-Invasive Medical Techs. Corp. , 75 Fed. Appx

. 765 (Fed. Cir. 2003) (“Transonic II ”), the court vacated and re manded the dis t rict court’s summary judgment for NMT of non-infringement. Id. at 778. The court clarified its claim construction and further directed the district c ourt to consider the doctrine of equivalents in view of the intervening S upreme Court decision in Fest o Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co. , 535 U.S. 722 (2002). Id. at 775-79. On remand the district court interpreted this court’s clarification of “ c alculating” in Transonic II as meaning “requir[ing] calculation of a dilution curve.” Turning to the “Delta H” method, the district court found no literal infr ingement of method claims 1 or 9. The court further determined that, as to “c al culating means” under device claims 24 and 32, “NMT technology does not use the mat hematical principles disc los ed in the Transonic patent.” The court un derstands this as a ruling that the accused devices lack an identical function, namely, “calculating” as defined in claims 1 and 9. Turning to the “Go / No-Go” method, the court found no ev idence that the method “used” an equation relating to the teachings of the ’ 989 patent, and implicated by the term “calculating. ” Finally, the district court det ermined that “the difference between [Delta H] and the ’989 patent is s ubstantial” and f ound Transonic barred from asse rting infringem ent under t he doctrine of equivalents

.

04-1546 - 4 -On August 6, 2004, the district court granted partial summary judgment of no infringement for Transonic on all four clai ms. Transonic filed its notice of appeal on August 17, 2004, asserting jurisdiction unde r 28 U.S.C. § 1292( c)(1). On March 18, 2005, the parties stipulated to final j udgment in the trial court, nunc pro tunc to August 6, 2004. The court has jurisdicti on under 28 U.S.C. § 1295(a)(1). II. A. The court reviews de novo the district court’s grant of partial summary judgment. The court will affirm the partial s u mmary judgm ent of no infringement in fav o r of NMT if, drawing all reasonable factual inferences in fa vor of Transonic, the court concludes that the district court made the proper legal determinations and no genuine is sue of fact prevented the determination of no infringement. Fed. R. Civ. P. 56(d); Anderson v. Liberty Lobby, Inc. , 477 U.S. 242, 255 (1986). The infringement analysis follows two well- traveled steps. First, the court must review the district court’s r eading of “calculating”. See Cybor Corp. v. FAS Techs., Inc. , 138 F.3d 1448, 1454 (Fed. Cir. 1998) (en banc). This is a le gal is sue reviewed de nov o

. Id. Second, the court reviews the district court’s application of the properly construed claims to the accused product. The co mparison is a factual issue. See Teleflex , Inc. v

. Ficosa Nor t h America Corp. , 299 F.3d 1313, 1323 (Fed. Cir . 2002). Reviewing partial summary judgment of literal infri ngement this court assesses, de novo , whether the district court correctly found no genuine issue of material fa ct precluding the judgment of no infringement.

04-1546 - 5 -B. 1. In Transonic II this court examined the relation between the “d ilution principles” discussed in the ’989 patent spec ification, t he equations set fo rth in that s p ecificatio n, and the meaning of “calculating” and “determining” in the asse rted claims. Rejecting the notion that infringem ent lay on ly in solv ing for shunt blood flow us ing the “exact equations” in the ’989 patent s pecification, this court re cognized that the specific arguments of the various equatio ns might vary depending on the choice of indicator and the properties ins pected to ascertain indic a to r density at any given time. As the court explained, [T]he specification is always highly re lev ant to the claim construction analys is. Usually, it is dispos itive; it is the single best guide to the meaning of a disputed term.” Vitr onics Corp. v. Conceptronic, Inc. , 90 F.3d 1576, 1582 (Fed. Cir. 1996). In th is case, the patentee’s statements made in the SUMMARY OF THE INVENTION, and reproduced in pertinent part below, are instructive: Blood flow, Q, measured by t he dilution method (A.C. Guyton Textbook of Medical Ph ysiology, Sixth Edition, p. 287, 1981) is given by: Q=V/S (Eq.1) where V is the amount of inject ed indicator and S is the area under a dilution curve and is equal t o the average concentration of indic a tor in th e blood for the duration of the curve, multi p lied by the duration of the curve. * * * The change of characteristics is measured by known sensors, such as sound velocity s ensors, electrical impedance sensors, optical s ensors, thermal sensors, isotope sensors, or t he like, and the blood flow relationships are calculat ed in accordanc e with the foregoing equations.

04-1546 - 6 -’989 patent , col. 1, ll. 56- 61 & col. 4, ll. 26- 27. . . . [T]he spec ific ation [of the ’989 patent] does not disc lose “c alculating” or “determining” without the use of one of the disclos ed relations hips. * * * During prosecution of the ’989 patent, in response to an Offic e Action rejecting the pending claims, Transonic id entified several “primary features of the invention.” Included in these f eatures was “the c a lculation of shunt blood flow (line blood flow) from the sa mple via dilution principles as is taught in the present applicat ion. ” As discussed above, the only “calculation . . . via diluti on principles” taught in the specification of the ’989 patent revolves around the disclos ed equatio ns. In the same response, Transonic argued that the di sclosed equations are c r itical t o achiev ing t he purpose of the invention an d are novel ov er the prior art. It stated in pertinent part as follows : The purpos e of the inv ention is to measure s h unt (blood line) blood flow, and for this purpose the application sets out the flow relatio n ships which permit calculation of the line blood flow from other meas urements. These re lationships are not taught in the prior art. . . . Moreover, Transonic disti nguished a prior art refe rence during pr osecution by ex plaining that, “in the present inv ention[,] shunt flow is calculated from a dialysis flow and a c oncentration curve measurement.” Based upon the claim, the specification, and the prosecution hist ory, we again conclud e that Transonic “disc l aimed any interpre tations of the terms ‘calculating’ and ‘determining’ that do not reflec t the stated signific anc e of the disclos ed equations to the invention as a whole.” Transonic II , 75 Fed. Appx. at 775-76. The court concluded: [T]he terms “calculating” and “determini ng” must use at least one of the equations set forth in the specif ication of the ’989 pat ent, i.e. , “Q = V/S”, but that the claims also cover the use of indicators other than saline. In other words, the elements of the equation, “V” and “S”, may be altered to account for the characteristics of di fferent indicators , such as saline , temperature, etc., so l ong as the rela tionships set forth i n the equations in the specification are still e x presse d. Id. at 776-77.

04-1546 - 7 -2. Although the court explained t hat “calculating” or “deter mining” required the “ u se of at least one equation” set fo rth in the ’989 patent specification, it did not delve into what it meant to “use” an equation or relation. Based on the ’989 patent specification’s frequent reference to dilution curv es, on remand following Trans onic II the trial court concluded that “calculating” m eans that the accused inf r inger has to “calculat e a dilution curve.” Transonic contends that the tr ial court erred in this claim construction. I n particular, Transonic contends that the construction is not required by the plain language of the claims, and, i ndeed, violates the canon of claim differentiation by making superfluous the specific reference to dilu tion c u rves in claim 18. Nor is the trial court’s reading c o mpelled by the ’989 pat ent’s written descrip tion, whic h discusse s dilution cur v es in the context of explaining various mathemat ical relations but does not suggest that a curve must actually be dr awn, or the area under a cur v e must be measured from a graph, in order to make use of the relations set forth in the specification. Finally, Transonic maintains t hat the trial c ourt erred in ign o ring the effect of a broadening amendm ent during prosec ution, in whic h s pecific reliance on dilutio n

curves was moved to issued claim 18 as a spec ial cas e of the asserted claims. As set forth below, we agree with Transonic. 3. For this analysis the court focuses on language, and prosecut ion history, of issued claims 1, 9, and 18. See Vitronics Corp. v. Conceptronic, Inc. , 90 F.3d 1576,

04-1546 - 8 -1582 (Fed. Cir. 1996); Bell Communications Re search, Inc. v. Vitalink Com m unication s Corp. , 55 F.3d 615, 619-20 (F ed. Cir. 1995). As originally filed, claim 1 required: [1] measuring the [a] amount and [b] duration of said changed physica l property in said arterial line and [2] producing a dilution curve from said measurement; and [3] determi ning from the area of sa id dilution curve the blood flow in said arterio-venous shunt. (ll. 21-25). Responding to a June 19, 1996 Office Ac tion (and ex aminer interview), the inventors cancelled or iginal claim 1 and add ed new independent claims (43 and 52) that issued as independent claims 1 and 9. The inv entors explai ned that the new independent claim 43 was “revised to more clear ly high light the features of the invention which distinguish it over the prior art of record[.]” Argui ng that new indepe ndent claims 43 and 52 (issued as 1 and 9) “define the pr imary features of the invention,” the inventors defined t hose features as: - “The sampling of the mixture downstream in the shunt using the intake of the hemodialys is circulating system;” and - “The calculation of shunt blood flow (line blood f l ow) from the sample via dilution principles as is taught in the present application. ” As issued, claim one requires: measuring the amount of disti nguishable blood characteristic in sa id removed portion of mi xed blood; and calculating the rate of flow of said shunt blood flow in said arterio-venous shunt from said measured amount of distinguishable blood characteristic. ’989 patent , col. 8, ll. 51-55 (emphases added) . For this analysis, claim 9 differs only by reciting “determining” instead of “calculating. ”

04-1546 - 9 -The district court, Transonic argues, limit ed “calculating” in a m anner cons istent with the originally filed clai m, but incons istent with t he broadened language that actually issued in claims 1 and 9. By comparison, Transonic points to issued claim 18. It reads: 18. The process of claim 9, further including: [1] producing from the changed parameter measurement an indic a tor dilution cur v e representing said distinguish able blood characteristic; and [2] determining from said indicator dilution curve said blood flow rate in said shunt. ’989 patent , col. 10, ll. 9-13 (emphases added) . As Transonic ar gues, issued claim 18 basically appends to claim 9 (w hich, with issued claim 1, r eplac ed original claim 1) the limitations from original claim 1. In view of t h is record, two long-standing principles of claim construction sup p ort the view that “calculating” is not limited to “produci ng a dilution curv e,” nor to “calculating a dilution curve. ” First, this court’s case law prec ludes a reading that restricts “calculating” to the limit ations removed by broadening amendment. See Un ite d States v. Telectronic s , Inc. , 857 F.2d 778, 783 (Fed. Cir. 1988) (“[C]ourts are not permitted to read bac k into the c l aims limita tions which were originally there and wer e removed during prosecution of the application through t he Patent Office.” [cit. omitted]); Kistler Instrumente AG v. United States , 628 F.2d 1303, 1308 (Ct. Cl. 1980) (“It is signific ant that none of the claims in the patent which ultimately issue d contain t he narrow limitation of original cl aim . . . . It must be concluded that the Patent Office did not feel that this was a critic al limitation. Thus, defendant's insis t ence upon this court's reading back into the claims limitations whic h were originally there and were removed

04-1546 - 10 -during prosecution of the application through the Patent Office can not be permitted.” )

. Thus, “calculating” in issued claim 1 is broader than “calculating” in originally filed claim 1. The district court’s construction is consis t ent with th e plain lan guage of the originally filed claim, but not the issued claim. Second, by the doctrine of claim diffe rentiation the court presumes that “determining” in claim 9 must have a different scope from the narrow limitations set forth in claim 18. See Liebel-Flarsheim Co. v. Medrad, Inc. , 358 F.3d 898, 910 (Fed. Cir.), cert. denied , 125 S. Ct. 316 (2004) (“[T]he presenc e of a dependent claim t hat adds a particular limitation raises a presumption that the limitation in question is not found in the independent claim.”). “Ther e is presumed to be a difference in meaning and scope when different words or phrases are used in separate claims. To the extent that the absence of such difference in meaning and sc ope wou l d make a claim superfluous, the doctrine of claim differentiati on states the pres umption that the difference between claims is s i gnific ant.” Tandon Corp . v. United States Int'l Trade Comm'n , 831 F.2d 1017, 1023 (Fed. Cir. 1987). Claim 18 plainly req u ires “producing ... an indic a tor dilution curve” and “determining” the shunt blood flow from it. By strai ghtforward application of this doctrine, “determining” in claim 9 (and “calculating”) has broader scope; it does not require “producing an i ndicator dilution c u rve.” Although claim differentiation is only an interpretative pres umption, NMT identifies no substantive reason to foreclose its application here. Cf. Comark Communications, Inc. v. Harri s Corp. , 156 F.3d 1182, 1187 (Fed. Cir. 1998). The ’989 patent specification is f u lly c ons istent with a reading of “calculating” or “determining” that does not require creating a dilution cu rve or measuring the area

04-1546 - 11 -underneath it. In the Summary of Invention, Transonic introduces its use of dilution methods to ascertain shunt blood flow. Di scussin g blood flow Q as a function o f indic a tor volume V and defined variabl e “S”, the specific ation explains: S is the area under a dilution cu rve and is equal to the average concentration of indicator in the bl ood for the duration of the curve, multiplied by the durati on of the curve. ’989 patent, col. 1, ll. 62-65. As this passage explain s , t he area under a dilution curv e can be asc e rtained without actually drawing s u ch a curv e and measuring the area under it. Put differently, the parameter relevant to the claims at bar, “S”, represents the product of average indicator conc entration over a specific in terval, and the duration of that interval. In short, although “S” may ha ve meaning as an area in the c ontext of a dilution curve, charti ng indicator concentra tion over time, the fact that S may be graphica lly illustrated does not r equire that an infring e r actua lly plot the curve. Aside from claim 18, whic h specific ally requires “ p roducing ... an i ndic a tor dilution curve,” the claims at bar do not s o require . The ’989 patent specificat ion, both at claim 18 and the written description explaining dilution prin ciples, thus does not support the district court’s analysis. The trial court erred in r eading “calcula ting” and “determining” to mean “calculation of a dilution curve.” As this court explained in Transonic II , an infringer “calculates” or “determines” shunt flood blow within the meaning of the asserted claims by “using” at least one equation s e t forth in the ’989 pat ent. A met hod or device “calculates” shunt blood flow within the meaning of the asserted claims if it solves f o r the flow as a funct i on of the parameters set forth in t he relevant question.

04-1546 - 12 -For example, the ’989 patent expresses the basic relation between shunt blood flow (Q) and ‘dilution’ as a ra tio of indic a tor volume (V) and the pr oduct of a measuring interval and the av erage indic a tor concentration ov er that interval (S). I.e., Q = V / S. This expression captures an in tuitive rela tionship in wh ic h a high blood flow rate suggests a briefer int e rval over which indi c a tor can be detected, or a lower average concentration as the indicator rapidly dissi pates in the presence of a high blood flow rate (and vice versa). A method or device t hat solves for shunt blood flow by measuring or deriving indic a tor volume, i dentifying a measuring interval ov er which th e ind i cator is detectable, and obtaining the av erage indicator concentration over that interval, and combining this information accor d ing to a re lation desc ribed in the ’989 patent, therefore “uses” that relation. A met hod that obtains S by plotting a dilution curve and measuring the area beneath it provides one way of “u sing” this relation or equation, but the asserted claims are not limited to that approach. The court further reaffirms the analysis in Tr ansonic II , where the court held t h at such “use” of an equation s e t forth in th e ’989 patent inc l udes va rying the spec ific parameters at issue to account for different indicators or different indicator or blood properties that are inspected to ascertain indicator density. That i s , “the elements of the equation, ‘V’ and ‘S’, may be al tered to account for the ch aracteristics of different indic a tors . . . so long as the relationships set forth in the equations in the specification are still expressed.” 75 F ed. Appx. at 777. The el ements of the equation may be altered to account for use of a different i ndicator, a different wa y of introducing that indic a tor to the bloodstream at the upstr eam location, and a different changed bloo d characteristic measured at t he downstream location, s o lo ng as the resulting equation

04-1546 - 13 -utilizes indicator dilution princip l es to estima te shunt blood flo w

. Thus, so long as an equation that embodies indicator dilution principles is used to estimate shunt blood flow, use of a different indic a tor, a different way of introducin g the indic a tor to the blood, and a different changed blood charac teristic do not mean that shunt blood flow is not “determined” or “calculated.” In sum, the court reverses the trial court’s claim c onstruction. The asserted claims do not require “producing a dilution curve.” Instead, “c alculating” in claim 1, and “determining” in claim 9, m eans solving or estimating shunt blood flow, using at least one of the equations set forth in the ’989 patent. A method or device “uses” an equation in the ’989 patent when it s o lves for shunt blood flow by combining measured parameters according to a partic u lar relation specified in a relev ant equation from the ’989 patent

. C. The court next c onsiders whet her, under the prope r claim construction, the district court properly gr anted judgment of no infringem ent. The partial summary judgment is proper only when no reasonable trier of fact coul d find that every limitation recited in a properly construed claim is found in the accused device or method eithe r literally or under the doctr ine of equivalents. See Bai v. L & L Wings, Inc. , 160 F. 3d 1350, 1353-54 (Fed. C i r. 1998). 1. The district court stated that “[b]ecause indicator dilution equatio ns are not the relationship contemplated by the Federal Cir cuit, the court need not consider whether ∆ H equations are indicator dilution equations.” Under this court’s construction of

04-1546 - 14 -“calculating” and “determining,” however, the fact-finder must co nsider whether the Delta H method utiliz es an equa tion that embodies indicator dilution princ i ples. Upo n review of the evidenc e, we conclude that a summary judgment was improper. With this record a reasonable fact-finder could find t hat determining shunt blood flow using the Delta H m e thod is “c alculating” or “determi ning” shunt blood flow within the meaning of the asserting claims. As noted above, the Delta H method calls for assessi ng s h unt blood flow by analyz ing hematocrit as a functi on of a dialysis ultrafiltration rate. One of Transonic ’ s experts, Dr. Spergel, ex plained in more detail how Delta H method works: [I]n order to measure [shunt] blood flow, the clinician sets the ult r afiltration rate in the dialyz er first at a mi nimum speed, then at a maximum speed, and then at a minimum speed at very precise time intervals. It is my understanding that changing the ultrafiltration rate changes the hematocrit (i.e., the percentage of red blood cell ma ss in the blood). The CRIT-LINE reads the hematocrit at each speed. T hen the clin icia n reverses the lines, and repeats the same procedure with the lines in the reversed position. From these various hematocrit le vels, [ s hunt] blood flow would be manually c a lculated using a com p licat ed for m ula provided by NM T in its literature. (J.A. at 936). This “complicated formu la” appears in one of NMT’s Technical Notes : ABF = (UF R max x R max ) / ( ∆ H R – ∆ H N ), where ∆ H R = R max – [(R 1 + R 2 ) / 2)] and ∆ H N = N max – [(N 1 + N 2 ) / 2)]. Importantly, the NMT Te chnic a l Note defines ∆ H R in terms of th ree measurements of hematocrit when the lines of the dialyzer are r e versed: (1) R max , which is a measurement of hem atocrit at max i mum ultr afiltration speed; (2) R 1 , which is a firs t measurement of hematocrit at mi nimum ultrafiltration speed; and R 2 , which is a second measurement of hematocrit at the minimum ultrafiltrati on speed. By comparing R max to the average of R 1 and R 2 , the formula appears to take into a ccount the change in

04-1546 - 15 -hematocrit when the lines of the dialyz er ar e reversed. Moreover, according to the Technical Note, these measurements of hemato crit are made at four minut e intervals, which seemingly cor r espond to the “very pr ecise time intervals” referred to by Dr. Spergel. In light of this evidence, we cannot say that a reasonable jury could not conclude that the Delta H method measur es a changed blood characteristic over time and utilizes a formula that mathematically relates particular v a riables according t o indic a tor dilution principles. Thus, the question of whether the Delta H me thod infringes the claims of the ’989 patent must be remanded for further proceeding s consistent with this court’s claim construction. 2. The district court also granted judgment that NMT’s “Go / No-Go” method does not infringe the asserted claims of the ’ 989 patent. The trial court relied on an absence of any genuine issue of fact concerning whether the NMT method “uses” a specific equation from the ’989 patent relating reverse-li ne recirculation to shunt blood flow. In particular, Transonic argued that NMT’s “G o / No-Go” method relies on the relation Q a = Q b (1 / R re v – 1), the relation between s hunt blood flow (Q a ), dialyzer blood flow (Q b ), and revers ed-line recirculation or percentage of recirc ulation with reversed lines (R rev ), that NMT discloses in material describing it s “saline dilut i on” method. Transonic further argued that this relation is “mathematically equivalent” to “the e quations disclosed” in the ’989 patent. The trial court focused on equation 5 from the ’989 patent. That equation pr ovides: Q shunt = Q dial (V ven / V ca l * S ca l / S art – 1)

04-1546 - 16 -’989 patent , col. 2, l. 67. The eq uation expr esses shunt blood flow (Q shunt ) as a function of dialyzer blood flow (Q dial ), the volume of indicator in jected into the venous line (V ven ), the quantity of indicator used in a calibration injection (V cal ), the area under the diluation curve generated by a calibration (S cal ), and the “absolute concentration of indicator in the arterial blood line” (S art ). Id. at ll. 18-64. The district court characterized T r ansonic’s infringement argument as resting on mere “a ssumption ” that the latter equation restates equation 5 in the ’989 patent, and further determined that Transonic “has not established the use of this equation in t he ‘Go-No Go method’.” Finding no genuine issue of fact, the trial court gr anted summary judgment for NMT. Transonic argues that the trial court misread the record and ignored genuine issues of fact supporting infringement. We agree. First, there is no genuine dispute that NMT’s “Go / No-Go” method is a spec ial cas e of NMT’s “saline dilution” method in which the dialyz er blood flow (Q b ) is simply fixed at 300 ml / min, and the calculated shunt blood flow is simply compared to a re ference point of 600 ml / min. NMT’s own documents indicate that NMT drew its s h unt bl ood flow relation, for the saline dilution method, from a 1995 ar ticle by Krivitski. I n a tech note describing its “Go / No-Go” screening c r iteria, NMT explained that Review of published data pr oves that at a dialyz er blood flow rate of 300 ml / min, a reversed-line recirculation [R re v ] of approximately 33% is equivalent to an Access Blood Flow [s hunt blood flow] of 600 ml / min. Using the t e ch note as a starting point, Transonic ’ s expert opined that the only “published data” establishing a “quantitative relations hip between access blood flow, dialyz er blood flow rate, and reversed-line reci rculation” was the “formul a recited” in NMT’s literature concerning its “s aline dilution” method. In vi ew of this evidence, NMT’s

04-1546 - 17 -argument that “the [saline di lution] equation cited by Trans onic never appears in any literature describing or pr omoting the Go/No Go method” is misplaced. Second, Tr ansonic ’ s expert further opined t hat NMT’s reversed-line recirculation equation, f o r the “saline” method, and the rela tions set forth in the ’989 patent, wer e “equivalent.” Notwithstandi ng the trial court’s char acterizing this evidence on equivalenc e as a mere “assumption,” we find the expert testimony sufficient to raise a genuine iss ue of material fact resisting summary judgment. In short, a reasonable fact-finder coul d find that NMT’s “Go / No-Go” method infringes the asserted claims by “calculati ng” or “determining” sh unt blood f l ow on the basis of relations set forth in the ’989 patent. The trial court erred in granting judgment of no infringement on NMT’s “Go / No-Go” method. D. The court further notes that claims 24 and 32 both include limita t ions subject to the requirements of 35 U.S.C. § 112, ¶ 6 that are affected by our construction of the term “calculating.” “Literal infringement of a § 112, ¶ 6 limitation requir e s that the relevant structure in the accused devic e perf orm the identic al f unction rec i ted in the claim and be identical or equiv a lent to the corresponding st ructure in the specification.” Odetics, Inc. v. Stora ge Tech. Corp. , 185 F.3d 1259, 1267 (Fed. Cir. 1999). As the court explained in Transonic II , the functions of both “means fo r calculating” in claim 24 and “calculator means” in claim 32 require “calculating.” 75 Fed. Appx. at 778

. Therefore, on remand the distri ct court should reassess infr ingement of claims 24 and 32 under the construction of “calculating”, as cl arified above. If the district court finds that the accused devices perform the identical function of “c alculating” shunt blood flow,

04-1546 - 18 -then the district court must ascertain whet her the structures of those devices are identical or equivalent to the corresponding st ructure disclosed in the ‘989 patent. See Odetics , 185 F.3d at 1267. E. Finally, the district court determined that Tr ansonic was estopped from asserting infringement under the doctrine of equivalents. We find th is determination unsupported by the analysis in the district court’s opinion. As explai ned by t he Supreme Court in Festo , a narrowing amendment made to satisfy any requirement of the Patent Act invokes a presumption that the patentee surrendered all s ubject matter between the broader and the narrower claim language. 535 U.S. at 740. To overcome the presumption of surrender, the patentee b ears the burden of pr oving whether an exception applies. See id. at 740-41 (“The equivalent may have been unfor eseeable at the time of the applic ation; the r a tional e underlying the amendm ent may bear no more than a tangential relation to t he equivalent in question; or there may be some other reason suggesting t hat the patentee coul d not reasonably be expect ed to have described the insubst antial subs titute in questi on.”). From the dist rict court’s partial summary judgment order we ar e unable t o asce rtain: (1) what amendment is at issue; (2) what claim scope was deemed to be su rrendered; (3) what arguments Transonic made to overcome any presumption of surrender; and (4) why any such arguments were insufficient. Accordingl y, we vacate the ruling on pr osecution history estoppel and remand for analys is under Festo

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04-1546 - 19 -III. The district court’s construction of “calcu lat i ng” was in error. The court reverses the district court’s claim construction, and construes the claim as set forth in this opinion. T he infringement analy s is depending on this claim const r uction is flawed, and must be undertaken anew. Fur t hermore, the di strict court failed to conduc t a proper Festo analysis. Therefore, we vacate the j udgment of no infringement, and the ruling o n prosecution history estoppel, and remand for proceedings cons istent with this opinion. Each side shall bear its own costs. REV E RS E D -IN-PART , VACATE D AND RE MANDE D

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