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In re Bair Hugger Forced Air Warming Devices Products Liability Litigation

United States District Court, D. Minnesota

December 13, 2017




         In judicial districts across the nation, Plaintiffs have sued Defendants 3M Company and Arizant Healthcare Inc. These lawsuits have been transferred or consolidated into this multidistrict litigation for pretrial. Generally, Plaintiffs allege that Defendants' Bair Hugger Forced Air Warming Device (“the Bair Hugger”) caused their deep-joint infections as a sequela to orthopedic-implant surgery. Some Plaintiffs have sued alleging other surgical infections related to the Bair Hugger. The Bair Hugger, a device for keeping surgical patients warm, has a central unit, hose and blanket. The central unit draws in operating-room air through an inlet filter. It then heats and forces that air through the hose. The hose feeds the forced air into passageways within the blanket. During surgery, the blanket covers the patient's torso, with perforations facing the patient. The forced air then exits the blanket through these perforations, thereby transferring heat to the patient.

         Plaintiffs allege theories about how the Bair Hugger's forced-air warming can cause deep-joint infection. After warming the patient, the Bair Hugger's forced air flows into the operating room at large. Because this effluent forced air is warmer than the air-conditioned operating-room air, it convects. This convection stirs the operating-room air, allegedly lifting squames (skin flakes shed from people) and preventing them from safely settling away from the surgical wound. The parties agree that squames can carry skin bacteria, some of which can cause deep-joint infection. Plaintiffs also have a theory about bacteria that reside within the Bair Hugger's central unit or hose. These bacteria allegedly get out riding the forced air, thereby increasing the bacterial threat within the operating-room air.

         The parties have moved to exclude expert testimony about whether the Bair Hugger can cause deep-joint infection. Defendants move to exclude Plaintiffs' engineering experts Said Elghobashi, Daniel Koenigshofer, Michael Buck and Yadin David. Dkt. No. 794. Defendants move to exclude David's regulatory opinions separately. Dkt. No. 758. Defendants also move to exclude Plaintiffs' medical experts Jonathan M. Samet, William Jarvis and Michael J. Stonnington. Dkt. No. 745. Plaintiffs move to exclude Defendants' rebuttal experts John Abraham, Dkt. No. 821, Jonathan B. Borak, Dkt. No. 778, Jim Ho, Dkt. No. 733, Alexander A. Hannenberg, Dkt. No. 727, Theodore R. Holford, Dkt. No. 801, Antonia Hughes, Dkt. No. 826, Michael Keen, Dkt. No. 738, Thomas Kuehn, Dkt. No. 787, Samsun Lampotang, Dkt. No. 743, Michael Mont, Dkt. No. 796, Gary Settles, Dkt. No. 832, Timothy Ulatowski, Dkt. No. 755, and Richard Wenzel, Dkt. No. 812. The Court heard oral argument at an October 24-26, 2017 hearing. The Court DENIES the Motions, except for Defendants' Regulatory Motion about David, which the Court GRANTS IN PART and DENIES IN PART. The Court also denies Defendants' dependent Motion for Summary Judgment, Dkt. No. 759.

         Under Federal Rule of Evidence 702, the Court need only exclude expert testimony that is so fundamentally unsupported that it can offer no assistance to the jury.

         Expert testimony is governed by Rule 702. The expert-testimony proponent must prove facts supporting admissibility as more likely than not. Polski v. Quigley Corp., 538 F.3d 836, 841 (8th Cir. 2008). Under Rule 702:

A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if:
(a) the expert's scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue;
(b) the testimony is based on sufficient facts or data;
(c) the testimony is the product of reliable principles and methods; and
(d) the expert has reliably applied the principles and methods to the facts of the case.

         If relevant and reliable, a qualified expert's testimony need not be excluded. Children's Broad. Corp. v. Walt Disney Co., 357 F.3d 860, 864 (8th Cir. 2004). “Only if the expert's opinion is so fundamentally unsupported that it can offer no assistance to the jury must such testimony be excluded.” Id. at 865.

         The opponent's “full opportunity to cross-examine” and to “present[] expert testimony to rebut” weighs in favor of admission. See id.; Bonner v. ISP Techs., Inc., 259 F.3d 924, 932 (8th Cir. 2001) (“[Once the] methodology was scientifically valid, the scientific questions were best addressed by allowing each side to present its experts . . . to the jury.”). Better than exclusion at the threshold, these trial tools address issues that can go to how the jury should weigh the testimony or whether the jury should believe the expert. Children's Broad., 357 F.3d at 864-65 (affirming admission when trial court ruled that opponent's objections “were better directed to the weight of the testimony rather than admissibility”). The Motions are disposed of below, by expert.

         Said Elghobashi

         Plaintiffs' expert Elghobashi opines that the Bair Hugger's forced air convects particles ten microns in diameter from just above the operating-room floor to the surgical wound. Elghobashi Rpt. ll. 825-27. The parties agree that, because ten-micron particles include squames, these particles can carry enough bacteria in a permissive package to cause a deep-joint infection if, during surgery, they reach the prosthetic joint. See Defs.' Mem. Excl Pls.' Eng'g Experts (“Eng'rs Mem.”) 32 (diminishing expert's finding because “he found few, if any, particles larger than 5µm, and even fewer over 10µm.”). Elghobashi simulates the Bair Hugger's forced air in a model operating room by large-eddy simulation, the reliability of which Defendants concede. Elghobashi Rpt. ll. 832-33; see Eng'rs Mem. 55 (conceding “that CFD[, or, computational-fluid dynamics, ] evidence can be admissible, if properly supported by reliable boundary conditions.”). To simulate the Bair Hugger's alleged operating-room convection, Elghobashi had to learn about the device. First, by watching Defendants' videos and reading their internal documents, he learned how hot the forced air leaves the device's blanket. Eng'rs Mem. 40. Then, while he observed an active Bair Hugger, “he simply ran his hand under” its blanket to learn where the forced air comes out. Id.

         Defendants challenge Elghobashi's testimony under Rules 702 and 403. They argue that Elghobashi speculated about how hot and where the Bair Hugger's forced air enters the operating room at large. They also argue that his simulated images are unduly prejudicial and likely to confuse the jury because the images could seem to show bacteria invading the surgical wound and because the images were simulated. See Fed. R. Evid.

         Elghobashi's testimony is admissible. Elghobashi has tested his opinion by simulation, the physics of which Defendants concede is reliable. As for the simulation's inputs, Elghobashi's testimony is not so fundamentally unsupported that it can offer no assistance to the jury. Elghobashi may rely on Defendants' representations. Bonner, 259 F.3d 924, 931 (affirming admission when expert relied on opponent's “consumer information”). And generally, the credibility of an expert's basis goes to weight. So too here. Elghobashi has bases for how hot and where the Bair Hugger's forced air goes; the jury may weigh his testimony as it believes those bases. Defendants may back away from their representations in rebuttal. They may cross-examine Elghobashi to test what, exactly, he felt with his hand during his observations. They may contradict Elghobashi's inputs by presenting their own fluids expert Abraham, see below. The Court thus DENIES Defendants' Motion as to Elghobashi because his testimony meets Rule 702.

         Elghobashi's testimony is not unduly prejudicial or likely to confuse the jury. Elghobashi consistently describes his simulated particles as squames, not bacteria, e.g., Elghobashi Rpt. l.815, and, anyway, Defendants have conceded that ten-micron particles can be dangerous. Defendants have also conceded the physics of large-eddy simulation, so objections to the simulation as simulation are without merit. The Court thus DENIES Defendants' Motion as to Elghobashi also because his testimony does not offend Rule 403.

         Daniel Koenigshofer

         Plaintiffs' expert Koenigshofer opines that the Bair Hugger detracts from air quality in the operating room and at the surgical wound, thus increasing infection risk. Koenigshofer Rpt. 23. Among other qualifications, Koenigshofer wrote a chapter about “Infection Control” in a published book about operating-room design. Id. at 2. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) selected him to be this chapter's author. Id. Koenigshofer relies on Elghobashi's testimony, among other sources, and describes what this testimony means for infection risks in the operating room. Id. at 20. He adds that the Bair Hugger can suck in particles from the air near the operating-room floor, citing a 1968 study to note that some of these particles can carry bacteria. Id. at 21-22. To say that squames can be near the floor, he cites an ASHRAE figure, which says that a ten-micron particle takes 8.2 minutes to settle five feet in still air. See Id. fig.5. Defendants object that Koenigshofer is unqualified and has insufficient factual basis.

         Koenigshofer's testimony is admissible. Defendants do not dispute Koenigshofer's published book chapter about operating-room infection, which appears to qualify him for his testimony's scope. Cf. Wheeling Pittsburgh Steel Corp. v. Beelman River Terminals, Inc., 254 F.3d 706, 715 (8th Cir. 2001) (reversing admission of warehousing testimony because, although expert had dealt with other facilities, he had never published about, worked for or studied warehouses). And Koenigshofer's testimony is not so fundamentally unsupported that it can offer no assistance to the jury. Defendants do not dispute that the Bair Hugger's central unit sucks in operating-room air and can sit on the operating-room floor. They do not attack the ASRAE figure. And they only object to the 1968 study's age. The jury may decide whether to believe that study. Likewise, Defendants may contradict it with their particle expert Ho's testimony, see below. The Court thus DENIES Defendants' Motion as to Koenigshofer because his testimony meets Rule 702.

         Michael Buck

         Plaintiffs' expert Buck opines that the Bair Hugger emits particles, some of which are ten-micron particles. Buck Rpt. 16-17. By measuring what comes out of a Bair Hugger's blanket when the device is on with a commercially available particle counter, Buck counts emitted particles by size. Id. at 14. He adapts a plastic storage container to capture the device's post-blanket forced air. Before counting particles, he sets his particle counter to “a zero point [by] zeroing the machine.” Buck Dep. 203:16-18. Defendants object that Buck's testimony is irrelevant because he did not sterilize the container before counting particles and because he did not measure bacteria directly.

         Bucks testimony is admissible because it is not so fundamentally unsupported that it can offer no assistance to the jury. Buck zeroed his particle counter, which should reduce background from his container, sterilized or not. If he should have done a more thorough test, that issue goes to weight, not admissibility. Defendants may cross-examine Buck and may submit rebuttal about whether zeroing is adequate. And Buck's lack of bacterial testing is harmless because he found some ten-micron particles. Defendants argue that these particles are experimental artifacts. With the benefit of adversarial presentation, the jury may decide whether to credit this argument or, alternatively, accept Buck's testimony for what he says. The Court thus DENIES Defendants' Motion as to Buck because his testimony meets Rule 702.

         Jonathan M. Samet

         Plaintiffs' expert Samet opines that, compared to warming devices that warm patients through modes other than forced air, the Bair Hugger increases the risk of deep-joint infection from orthopedic-implant surgery. Samet Rpt. 4. He cites an observational study that found a drop-off in these infections over time at a hospital. Id. at 11 (citing McGovern et al, Forced-Air Warming and Ultra-Clean Ventilation Do Not Mix: An Investigation of Theatre Ventilation, Patient Warming and Joint Replacement Infection in Orthopaedics, 93 J. Bone Joint (Br.) 1537 (2011) [hereinafter the Observational Study]). At the Observational Study's hospital, the drop-off happened when the hospital discontinued using the Bair Hugger. To ascribe that drop-off to this discontinuation, and not alternative explanations, Samet draws on Elghobashi's testimony, buttressed by scientific publications. Samet relies on Elghobashi for a mechanistic, causal link between the drop-off and discontinuing the Bair Hugger. E.g., Samet Rpt. at 15-16. Recall that, Elghobashi simulates, using accepted physical principles, how the Bair Hugger could convect squames to the surgical wound. To Samet, this physics-based simulation justifies pointing to the Bair Hugger, instead of alternative explanations, as the cause of the observed hospital's high rate of deep-joint infections while it was using Bair Huggers to warm patients. Defendants argue that the Observational Study is not scientifically convincing and that Elgobashi's testimony about convection is too unreliable to support Samet's causal inference.

         Samet's testimony is admissible. First, Defendants acknowledge the drop-off in infections; they dispute why the drop-off occurred. See Defs.' Mem. Excl. Pls.' Med. Experts (“Med. Experts Mem.”) 22, Dkt. No. 750. But the Court may not exclude expert testimony for disagreeing with a conclusion about why something happened. See Smith v. BMW N. Am., Inc., 308 F.3d 913, 920 n.9 (8th Cir. 2002) (reversing exclusion for “attack[ing] . . . conclusion”). Second, to support his causal inference, Samet relies on, among other things, Elghobashi's testimony about Bair Hugger convection. Samet may rely on admissible expert testimony. Elghobashi's testimony is admissible, see above. Samet thus may rely on Elghobashi's testimony. Defendants apparently concede that, once admitted, Elghobashi's testimony is sufficient to support Samet's causal inference. See Med. Experts Mem. 24. And anyway, Samet need not rule out every alternative explanation for the observed hospital's drop-off in infections. Johnson v. Mead Johnson & Co., LLC, 754 F.3d 557, 563 (8th Cir. 2014) (reversing exclusion because “we have ...

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