Air flow modellization by computational fluid dynamics for optimizing control for airborne microbial contamination in an intensive care room for severely burned patients
Abstract number: P1523
Beauchêne C., Laudinet N., Choukri F., Rousset J., Larbre J., Bergeron V., Chaouat M., Benbunan M., Mimoun M., Lajonchère J., Derouin F.
Objective: Controlling airborne contamination is of major importance in burn units because of the high susceptibility of burned patients to infections. In this study, Computational Fluid Dynamics (CFD) modeling was used to optimize the design of an intensive care room for severely burned patients.
Methods: The study was carried out in 4 steps: 1) patient room design, 2) CFD simulations to model air flows throughout the patient room, adjacent anterooms and the corridor, 3) construction of a prototype room that simulates the hospital environment 4) validation experiments.
The free access computational program Code_Saturne® program was used to mesh the rooms, the medical staff and the equipment into 330 000 cells and to simulate airflows and diffusion of microbial contaminants originating from different sources. Experiments with inert aerosol particles followed by time resolved particle counting were conducted in the prototype room for testing the CFD observations.
Results: CFD studies allowed testing several scenarii simulating the consequences of introduced contaminations. When the surgical zone was artificially contaminated, most particles dispersed toward the peripheral part of the room and were rapidly cleared, but part of them was trained by convection currents to the upper part of the room. This resulted in delayed particulate clearance times and justified the increase of upper exhaust grilles flow rates. Simulating health care workers' traffic between rooms revealed that opening the door between rooms that are at different temperatures resulted in turbulent air exchanges between the rooms. This phenomenon bypassed the pressure differences between the rooms. Experiment conducted in a full-scale pilot room validated CFD findings with respect to levels of confinement, protection of the patient's zone, decontamination kinetics and particle transfer at door opening.
Conclusion: CFD analysis was an effective tool for the design of intensive care rooms for burn patients. The combination of a 15 Pa positive pressure, high air exchange rates with an efficient filtration (or inactivation) were efficient in preventing entry and spread of microbial contaminants in the room. The major protective role of negatively pressured anterooms was also confirmed, although opening between rooms that are at different temperature could bypass this protection. Spiking experiments realized in a prototype room confirmed these findings, thereby validating the CFD prediction.
|Session name:||Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases|
|Location:||Vienna, Austria, 10 - 13 April 2010|
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