US 4151844

US Patent 4151844: Automated Blood Component Separation

Title: Method and apparatus for separating whole blood into its components and for automatically collecting one component.

Assignee: The current assignee is Baxter International Inc., with the original assignee being Baxter Travenol Laboratories Inc.

Inventors: Herbert M. Cullis, Anthony L. Almond, Michael B. Uffer, Mirza A. Kohja, and Rodolfo R. Rodgriguez.

Filing Date: November 11, 1977.

Issue Date: May 1, 1979.

Abstract: The patent describes a method and apparatus for centrifugally separating whole blood into at least three components. Whole blood is withdrawn from a donor, passed through a fluid system, and centrifuged. One component, typically white blood cells (buffy coat), is withdrawn at a fixed volumetric rate for collection, while the other two components (red blood cells and plasma containing platelets) are withdrawn at variable rates. An optical sensing device monitors the collected component to detect contamination from the other two. If contamination is sensed, the system automatically adjusts the withdrawal rates of the other two components (red blood cells and plasma) to maintain the desired composition and minimize contamination of the collected component. The other two components are then recombined and returned to the donor.

Independent Claims Overview:

Independent Claim 1 (Method):
This claim outlines a method for separating whole blood into at least three components. It involves drawing whole blood from a donor, centrifuging it within a fluid system to achieve separation, and then withdrawing each component during centrifugation. A key aspect is the withdrawal of one specific component (e.g., white blood cells) at a constant, fixed rate, while the other two components (e.g., red blood cells and plasma) are withdrawn at adjustable rates. These other two components are then recombined and returned to the donor. The method further includes sensing the composition of the component being collected at a fixed rate to detect any mixing with the other two components. If such mixing is detected, the withdrawal rates of one or both of the other two components are adjusted to ensure the collected component has minimal contamination, and a specified amount of this desired component is collected.

Independent Claim 7 (Apparatus):
This claim describes an apparatus designed to perform the blood separation method. It includes mechanisms for drawing whole blood from a donor and supplying it to a centrifuge for separation. The apparatus features a first withdrawing means for a first blood component, a second withdrawing means for a second blood component (the one to be collected), and a third withdrawing means for a third blood component. Crucially, it includes a means for recombining the first and third blood components for return to the donor. The apparatus also comprises a sensing means to determine the composition of the second blood component being withdrawn. In response to sensing a mixing of the first or third components with the second component, an adjusting means modifies the withdrawal rates of the first and third withdrawing means. Finally, there is a means for collecting the second blood component.

CAFC 2026 Dockets:
A direct search of the CAFC 2026 dockets for specific patent number US4151844 through available search tools did not yield specific case information for the year 2026. The provided search results offer general access to Federal Circuit case information, filings, records, and opinions, but do not allow for a direct query by patent number for current dockets. Therefore, I cannot definitively report on any ongoing legal challenges related to this patent in the CAFC for 2026 with the current information.

As a patent attorney, I have conducted a search for known litigation involving US patent 4151844, focusing on patent litigation databases and court records such as Unified Patents, CAFC, and PACER.

Based on the performed searches, no specific litigation cases involving US patent 4151844 are known. The search results provided general information about patent litigation firms and processes, but did not identify any direct legal challenges or enforcement actions for this particular patent number.

Proceedings overview

There are no AIA trial proceedings currently on file for US Patent 4151844, based on the USPTO ODP API and web search. This indicates that the patent has not been subjected to inter partes review (IPR), post-grant review (PGR), or covered business method (CBM) patent review proceedings. The absence of PTAB activity means all claims of the patent remain untested by these particular challenges.

Strategic summary

As no AIA trial proceedings were found for US Patent 4151844, all claims (1-20) remain untested by IPR, PGR, or CBM challenges. This means there is no estoppel landscape established under 35 U.S.C. § 315(e)(2) for any potential petitioner or its privies regarding this patent. All prior art grounds are theoretically available for a new challenge, subject to statutory time bars (e.g., one year from service of an infringement complaint for IPRs).

The lack of PTAB challenges for a patent that was granted in 1979 and expired in 1997 is not unusual, as AIA trial proceedings (IPR, PGR, CBM) were introduced much later, with IPR and CBM becoming available in September 2012, and PGR for patents granted under AIA provisions. Given the patent's expiration, the opportunity for new AIA trials is generally moot, as these proceedings primarily aim to challenge the patentability of active patent claims. There are no observable patterns of repeated petitions or aggressive appeals from this record.

Recommended next steps

Given that US Patent 4151844 expired in 1997 and has no recorded AIA trial proceedings, there are no active PTAB trial-stage milestones to monitor. For a defendant facing assertion of this patent today, the primary defensive posture would involve arguments related to its expired status, which typically precludes injunctive relief and limits damages to pre-expiration infringement. No PTAB-specific defenses are available as no claims have been invalidated or sustained in such proceedings.

Inventors

• Herbert M. Cullis (Employer: Baxter Travenol Laboratories Inc.)
• Anthony L. Almond (Employer: Baxter Travenol Laboratories Inc.)
• Michael B. Uffer (Employer: Baxter Travenol Laboratories Inc.)
• Mirza A. Kohja (Employer: Baxter Travenol Laboratories Inc.)
• Rodolfo R. Rodgriguez (Employer: Baxter Travenol Laboratories Inc.)

No unusual patterns, such as inventors departing the original assignee shortly after filing, were observed. All inventors are presumed to have been employed by Baxter Travenol Laboratories Inc. at the time of filing.

Original assignee

The entity named on the issued patent is Baxter Travenol Laboratories Inc. This company was a prominent manufacturer of medical products, including blood processing systems, and it shipped products embodying the claims. The company later underwent a corporate name change, becoming Baxter International Inc., which is currently a major operating company in the healthcare industry, active in the fields of medical devices, pharmaceuticals, and biotechnology.

Assignment timeline

• 1982-12-31 (executed) / recorded 1986-07-28 — Reel 004050/0675
  • Conveyance: Assignment
  • Assignor: BAXTER TRAVENOL LABORATORIES INC.
  • Assignee: BAXTER INTERNATIONAL INC.
  • Correspondent: MCDOUGALL, HERSH & GOODMAN, 135 S. LASALLE STREET, CHICAGO IL 60603
  • Context: Internal reorganization/corporate name change.

The USPTO Patent Assignment Search returned only one assignment record for US4151844, indicating that the ownership chain has been straightforward since its issuance.

Timeline diagram

timeline
    title Ownership of US 4151844
    1977 : Filed by Baxter Travenol
    1979 : Issued
    1982 : Assigned to Baxter Intl Inc

NPE / troll-pattern signals

1. Shell-entity transfer — Not present. The assignment was from "BAXTER TRAVENOL LABORATORIES INC." to "BAXTER INTERNATIONAL INC.", both of which are recognized operating companies in the healthcare sector, indicating a corporate restructuring or name change rather than a transfer to a non-practicing entity. [cite: 004050/0675]
2. Known asserter in the chain — Not present. Neither Baxter Travenol Laboratories Inc. nor Baxter International Inc. are identified as known NPEs or patent asserters on public lists.
3. Repeat correspondent across the chain — Unclear. There is only one assignment record for this patent, filed by MCDOUGALL, HERSH & GOODMAN. Therefore, it is not possible to observe a pattern of repeat correspondents within this specific chain.
4. Cascading transfers — Not present. Only a single assignment is recorded for this patent, which does not constitute multiple consecutive transfers within a short period. [cite: 004050/0675]
5. Pre-litigation transfer — Unclear. While the assignment was executed in 1982 and recorded in 1986 [cite: 004050/0675], there is insufficient data from the provided sources (patent text, Google Patents legal events, USPTO PEDS/ODP) to determine if this transfer occurred within six months of any first infringement suit involving this patent. Given the dates, it's unlikely to be a pre-litigation transfer as typically associated with NPEs acquiring patents for immediate assertion.
6. Bankruptcy fire-sale — Not present. The transfer appears to be part of a standard corporate name change or reorganization rather than a sale stemming from bankruptcy proceedings.
7. Privateering — Not present. The assignment is between related operating entities, not to an NPE acting on an operating company's behalf.
8. Defensive aggregator (anti-NPE) — Not present. The current assignee, Baxter International Inc., is an operating company, not a defensive aggregator like RPX or Allied Security Trust.

Verdict

Insufficient data.
The single recorded assignment (Reel 004050/0675, recorded 1986-07-28) shows a transfer from Baxter Travenol Laboratories Inc. to Baxter International Inc., which is consistent with a corporate name change or internal reorganization of the original operating company. There are no clear signals indicating a transfer to a Non-Practicing Entity based on the available assignment records.

USPTO Assignment Center Search for US4151844

Here is an analysis of the most relevant prior art cited in US Patent 4151844, based on the provided patent text.

The present invention (US4151844) relates to a method and apparatus for separating whole blood into its components, specifically featuring automatic monitoring of one component (e.g., white blood cells/buffy coat) using an optical sensing device and automatic adjustment of the withdrawal rates of other components (red blood cells and plasma) to maintain a desired composition [Abstract, Description: "Summary of the Invention"]. This automation aims to overcome the prior art requirement for constant operator attention and manual adjustment of pump speeds [Description: "Background of the Invention", "Description of the Prior Art"].

The following patent citations are listed as prior art for US4151844:

Prior Art Analysis:

1. US2876769A

• Full Citation: US2876769A, Cordova Jose Juan, "Apparatus for oxygenating, centrifuging and changing the temperature of blood"
• Publication/Filing Date: Priority date: 1955-10-11, Publication date: 1959-03-10
• Brief Description: This patent describes an apparatus for oxygenating, centrifuging, and changing the temperature of blood. The title suggests a focus on a multi-functional device for blood processing, including centrifugation.
• Potentially Anticipates Claims (35 U.S.C. § 102):
  • Claims 1, 7 (General Method/Apparatus for Blood Separation): This patent potentially anticipates the general concept of centrifuging blood to separate components (Claim 1: "centrifuging the blood to separate same into at least three components thereof"; Claim 7: "An apparatus for separating whole blood into at least three blood components thereof comprising: ... a centrifuge device"). However, it does not appear to anticipate the automatic monitoring and adjustment features central to US4151844 without further details of its internal control mechanisms. A full anticipation assessment would require reviewing the complete patent text of US2876769A.

2. US3489145A

• Full Citation: US3489145A, Surgeon General Of The Public, "Method and apparatus for continuous separation of blood in vivo"
• Publication/Filing Date: Priority date: 1966-08-08, Publication date: 1970-01-13
• Brief Description: This patent describes a method and apparatus for continuous separation of blood in vivo. The term "continuous separation" suggests a flow-through centrifugation system, which is a foundational aspect of US4151844.
• Potentially Anticipates Claims (35 U.S.C. § 102):
  • Claims 1, 7 (Continuous Blood Separation and Component Withdrawal): The concept of continuously separating blood and withdrawing components (Claim 1: "withdrawing each of the components during the centrifugation thereof"; Claim 7: "first withdrawing means...second withdrawing means...third withdrawing means for withdrawing a third blood component") could be generally anticipated. However, the specific automatic optical sensing and proportional adjustment claimed in US4151844 (Claims 3, 4, 5, 6, 8-20) are not evident from the title or general description. A full anticipation assessment would require reviewing the complete patent text of US3489145A.

3. US3519201A

• Full Citation: US3519201A, Us Health Education & Welfare, "Seal means for blood separator and the like"
• Publication/Filing Date: Priority date: 1968-05-07, Publication date: 1970-07-07
• Brief Description: This patent focuses on "Seal means for blood separator and the like," suggesting a technical solution for fluid integrity within blood processing devices, possibly for rotating components like centrifuges.
• Potentially Anticipates Claims (35 U.S.C. § 102):
  • This patent, based on its title, likely addresses a mechanical detail (seal means) rather than the overall control method or apparatus for automatic component collection. It is less likely to anticipate the method or control system claims (Claims 1-6, 9-20) of US4151844, though the underlying apparatus (Claim 7) might incorporate such sealing mechanisms. No direct anticipation of the unique features of US4151844 is apparent from the title. A full anticipation assessment would require reviewing the complete patent text of US3519201A.

4. US3655123A

• Full Citation: US3655123A, Us Health Education & Welfare, "Continuous flow blood separator"
• Publication/Filing Date: Priority date: 1966-08-08, Publication date: 1972-04-11
• Brief Description: This patent describes a "Continuous flow blood separator," reinforcing the concept of continuously processing blood to separate its components.
• Potentially Anticipates Claims (35 U.S.C. § 102):
  • Claims 1, 7 (Continuous Blood Separation Apparatus): Similar to US3489145A, this patent likely anticipates the general elements of a continuous flow blood separation apparatus. However, there is no indication from the title alone that it includes the automatic optical sensing and adjustment of withdrawal rates as taught by US4151844 (Claims 3, 4, 5, 6, 8-20). A full anticipation assessment would require reviewing the complete patent text of US3655123A.

5. US3802432A

• Full Citation: US3802432A, I Djerassi, "Apparatus for filtration-leukopheresis for separation and concentration of human granulocytes"
• Publication/Filing Date: Priority date: 1972-05-18, Publication date: 1974-04-09
• Brief Description: This patent describes an apparatus for "filtration-leukopheresis" for the separation and concentration of human granulocytes (a type of white blood cell). This indicates prior art in separating specific blood components, particularly white blood cells.
• Potentially Anticipates Claims (35 U.S.C. § 102):
  • Claim 2 (Separation of White Blood Cells/Buffy Coat): This patent directly addresses the separation and concentration of white blood cells (granulocytes), which aligns with Claim 2 of US4151844 where the desired component is white blood cells/buffy coat. While it deals with collecting white blood cells, the title suggests a "filtration-leukopheresis" approach, which is different from the centrifugation and optical density sensing mechanism of US4151844. Thus, the specific method of automatic optical sensing and adjustment of US4151844 (Claims 3, 4, 5, 6, 8-20) is unlikely to be anticipated. A full anticipation assessment would require reviewing the complete patent text of US3802432A.

6. US3812482A

• Full Citation: US3812482A, Primary Childrens Hospital, "Air emboli detector"
• Publication/Filing Date: Priority date: 1973-02-26, Publication date: 1974-05-21
• Brief Description: This patent describes an "Air emboli detector." This suggests a safety or monitoring device for detecting air bubbles in fluid systems, which is relevant to extracorporeal blood circuits. US4151844 mentions "suitable low and high pressure sensors are provided in the tubing 21 to sense high and low pressure conditions indicating a leak... or an occluded vein" [Description: "The first tubing 21"]. While related to system safety, it's not directly about blood component separation control.
• Potentially Anticipates Claims (35 U.S.C. § 102):
  • This patent primarily addresses a safety feature (air emboli detection) which is distinct from the core inventive concept of US4151844 concerning automatic optical density-based control of blood component withdrawal rates. No direct anticipation of the claims of US4151844 related to automatic separation control is apparent from the title. A full anticipation assessment would require reviewing the complete patent text of US3812482A.

7. US3892236A

• Full Citation: US3892236A, Isaac Djerassi, "Apparatus for filtration-leukopheresis for separation and concentration of human granulocytes"
• Publication/Filing Date: Priority date: 1973-04-02, Publication date: 1975-07-01
• Brief Description: This patent is identical in title and inventor to US3802432A, describing an "Apparatus for filtration-leukopheresis for separation and concentration of human granulocytes." It likely represents a continuation or related work to US3802432A.
• Potentially Anticipates Claims (35 U.S.C. § 102):
  • Claim 2 (Separation of White Blood Cells/Buffy Coat): Similar to US3802432A, this patent directly addresses the separation and concentration of white blood cells. As noted previously, while it deals with collecting white blood cells, the "filtration-leukopheresis" method is distinct from the centrifugation and optical density sensing and automated control of US4151844. Therefore, the specific automatic monitoring and adjustment features of US4151844 (Claims 3, 4, 5, 6, 8-20) are unlikely to be anticipated. A full anticipation assessment would require reviewing the complete patent text of US3892236A.

8. US4086924A

• Full Citation: US4086924A, Haemonetics Corporation, "Plasmapheresis apparatus"
• Publication/Filing Date: Priority date: 1976-10-06, Publication date: 1978-05-02
• Brief Description: This patent describes a "Plasmapheresis apparatus." Plasmapheresis involves the separation of plasma from whole blood, a key step in blood component separation, and often involves centrifugation.
• Potentially Anticipates Claims (35 U.S.C. § 102):
  • Claims 1, 7 (Blood Component Separation, particularly Plasma): This patent clearly falls within the field of blood component separation, specifically focusing on plasma. It likely anticipates the general apparatus and method for separating blood into components, including plasma, as outlined in Claims 1 and 7. Given the context of US4151844's problem statement (operator adjustment for buffy coat purity), it is possible that advanced plasmapheresis apparatus like this one might have some form of automated control, but the specific optical density sensing of the buffy coat and the responsive, differential adjustment of red blood cell and plasma pump speeds (Claims 3, 4, 5, 6, 8-20) is not apparent from the title. US4151844 distinguishes itself by focusing on the automatic collection of a specific component (white blood cells/buffy coat) with minimal contamination through optical feedback and differential pump control. A full anticipation assessment would require reviewing the complete patent text of US4086924A.

Conclusion on Anticipation:

Based solely on the titles and brief descriptions available in the US4151844 patent document, the cited prior art generally anticipates the broad concepts of:

• Centrifugal blood separation (US2876769A, US3489145A, US3655123A, US4086924A).
• Continuous flow blood processing (US3489145A, US3655123A).
• Separation and collection of specific blood components, including white blood cells (US3802432A, US3892236A) and plasma (US4086924A).

However, the core inventive contribution of US4151844, as explicitly stated in its summary and description, lies in the automatic optical monitoring of a collected blood component (like the buffy coat) and the responsive, differential, and graded adjustment of withdrawal rates of the other components to maintain a desired composition. This specific combination of optical sensing, determination of density and its trend (increasing/decreasing), and the nuanced control of multiple pumps in an inverse relationship (as detailed in Claims 3, 4, 5, 6, 9-20) does not appear to be directly anticipated by the titles or generalized descriptions of the cited prior art. The prior art descriptions provided within US4151844 indicate a problem with existing systems requiring constant manual operator intervention to achieve desired purity, which is precisely what US4151844 claims to overcome with its automated control system.

A definitive determination of anticipation under 35 U.S.C. § 102 for each claim would necessitate a thorough review of the full text of each cited prior art patent and a detailed element-by-element comparison.

US Patent 4151844 describes a method and apparatus for separating whole blood into at least three components (red blood cells, a buffy coat of white blood cells, and plasma with platelets) using centrifugation. The core of the invention lies in the automatic monitoring of the composition or optical density of the collected component (specifically the buffy coat of white blood cells) using an optical sensing device. Based on this sensing, the apparatus automatically adjusts the rates of withdrawal of the other two components (red blood cells and plasma) in opposite directions to maintain the desired composition of the collected component and minimize contamination. One component (e.g., buffy coat) is withdrawn at a fixed rate, while the other two are withdrawn at variable rates.

The patent states that the invention "overcomes this operator monitoring requirement by providing a method and apparatus wherein the composition or optical density of the buffy coat of white blood cells being withdrawn from a centrifuge device is automatically monitored and when changes occur therein an optical sensing device is operable to cause an adjustment in the rates of withdrawal of the red blood cells and the plasma containing platelets so as to maintain a desired composition or optical density of the white blood cells being withdrawn."

Prior Art References and their Disclosures:

1. US Patent 3,986,442 (U.S. Pat. No. 3,986,442): This patent is explicitly identified as prior art in the description of US4151844. It discloses a centrifugal liquid processing apparatus for separating whole blood into components (red blood cells, buffy coat, and plasma). It teaches the use of outlets at different radii for withdrawing these components via pumps. However, US4151844 highlights a significant drawback: "The rates of withdrawal by the various pumps depend upon the concentration of these components in the blood and upon changes in the radius at which these components collect during centrifugation." It further explains that "an operator must carefully observe the blood components while they are being withdrawn" and manually adjust pump speeds, which "requires constant attention by an operator and is somewhat tedious when the processing extends up to an hour or more." Thus, US3986442 provides the foundational centrifugal separation and component withdrawal, but requires manual intervention.

2. US Patent 4,086,924 (Haemonetics Corporation): This patent, titled "Plasmapheresis apparatus," has a priority date of 1976-10-06, which predates the filing date of US4151844 (1977-11-11) and thus constitutes prior art. The abstract for US4086924 states: "An automatic control system for regulating the withdrawal of plasma from a centrifugal separation system used in plasmapheresis includes an optical detector for sensing red blood cells at the plasma withdrawal port, and a pump control system for maintaining the interface of red cells and plasma below the withdrawal port."

Obviousness Analysis under 35 U.S.C. § 103:

The independent claims of US4151844, such as Claim 1 (method) and Claim 7 (apparatus), cover the concept of automatically sensing the composition of a withdrawn blood component (e.g., buffy coat) and adjusting the withdrawal rates of other components (red blood cells and plasma) in response to this sensing to minimize contamination.

A combination of US3986442 and US4086924 would render the claims of US4151844 obvious to a person having ordinary skill in the art (PHOSITA).

Motivation for Combination:

1. Established Need for Automation: US3986442 explicitly identifies the problem of manual monitoring and adjustment during blood component separation as "tedious" and requiring "constant attention." This patent, therefore, itself provides a strong motivation for a PHOSITA to seek methods and apparatus for automating the process.
2. Known Solution for Contamination Control: US4086924 teaches an "automatic control system for regulating the withdrawal of plasma" in a centrifugal separation system. Crucially, this system "includes an optical detector for sensing red blood cells at the plasma withdrawal port, and a pump control system for maintaining the interface of red cells and plasma below the withdrawal port." This demonstrates that:
   • Optical sensing was a known technique for detecting blood components (specifically red blood cells to prevent their withdrawal with plasma).
   • Automatic pump control based on optical sensing was a known solution for maintaining component purity (preventing contamination) during centrifugal blood separation.
3. Predictable Application: Given the problem of manual monitoring described in US3986442 and the existing automatic optical sensing and pump control solutions shown in US4086924 for maintaining component purity during plasmapheresis, a PHOSITA would have been motivated to combine these teachings. The specific application in US4151844 involves sensing the buffy coat (instead of the plasma/RBC interface) and adjusting red blood cell and plasma pumps, but this is a straightforward application of known principles. The problem is a lack of automatic control to maintain a precise separation interface, and the solution from US4086924 is precisely that: automatic optical sensing coupled with pump control to maintain an interface.

Specific Obviousness Argument for Claim 1 and 7:

• Primary Reference (US3986442): Discloses the basic method and apparatus for centrifuging whole blood to separate it into three components (red blood cells, buffy coat, plasma), withdrawing each component, and recombining two for return to the donor. It also sets forth the problem of manual adjustment.
• Secondary Reference (US4086924): Teaches the use of an optical detector to sense blood components (e.g., red blood cells) at a withdrawal port during centrifugation and a pump control system that automatically adjusts pump speeds in response to the optical sensing to maintain a desired interface and prevent contamination.

A PHOSITA, facing the tedious manual adjustment problem explicitly noted in US3986442, would look for ways to automate the process. US4086924 provides a clear teaching of how to automatically monitor a blood component boundary using optical sensing and how to automatically adjust a pump (or pumps, by extension) to maintain component purity in a continuous flow centrifugal system. Extending this known automation technique to monitor the buffy coat (rather than plasma) and control the adjacent red blood cell and plasma pumps in a coordinated, inverse manner (as disclosed in US4151844) would be a logical and predictable step for a PHOSITA. The principle of using optical density to detect component boundaries and then using that information to automatically adjust pump rates to maintain separation is present in US4086924. Applying this principle to different component interfaces or to adjust multiple pumps in an inverse fashion would be an obvious design choice to solve the known problem of manual intervention.

Therefore, claims such as Claim 1 (method) and Claim 7 (apparatus) of US4151844 would be rendered obvious by a combination of the teachings of US3986442 and US4086924.