MAE Seminar (ZOOM): Effect of Forced-air Warming on Pathogens

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Said Elghobashi

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Abstract: This lecture describes a detailed large-eddy simulation (LES), accurately capturing the three-dimensional temporal flow evolution and the trajectories of millions of squames (skin flakes of 10-micron diameter), in a realistic medical operating-room (OR) environment with an operating table, side tables, surgical lamps, medical staff and a patient.

Perioperative patient warming is an important clinical practice to prevent patient temperature below 36oC and minimize the risk of hypothermia. Forced air warming (FAW) maintains a safe temperature. These FAW devices blow heated air through a tube to a plastic blanket covering the patient. The warm air flows through many small holes on the blanket side facing the patient seeping into the sterile space adjacent to the operating table (OT), creating rising thermal plumes that interact with the turbulent ceiling ventilation air in the OR. This complex turbulent flow interaction enhances the squames dispersion toward the surgical site.

Two cases are studied, one with the hot air blower off and the other with the blower on, together with Lagrangian trajectories of three million squames initially placed on the floor surrounding the OT. The LES results show that with the blower off, squames are quickly transported by the ventilation air away from the table and toward the exit grilles. In contrast, with the hot air blower turned on, the ventilation air flow above and below the OT is disrupted significantly. The rising thermal plumes from the hot air blower drag the squames above the OT and the side tables before they are advected downward toward the surgical site.


M.Sc., University of Southern California (1971)
Ph.D., Imperial College, University of London (1974)
D.Sc., Imperial College, University of London (1999)

HONORS (partial list)
Member of the National Academy of Engineering
Fellow of the American Physical Society
Fellow of the American Association for the Advancement of Science
Fellow of the American Society of Mechanical Engineers
Senior Award of International Conference on Multiphase Flow, 2016
Visiting Fellow Cambridge University, England, 1999
DIC: Diploma of membership of Imperial College, 1974
British Science Research Council (SRC) Scholarship (1971-1974)