Comprehensive review and study of the buoyant air flow within positive-pressure hospital operating rooms

ABSTRACT

A comprehensive investigation is provided on the flow of air within a positive-pressure operating room during a simulated surgery. The simulated surgery made use of an over-body patient-warming blanket whose purpose is to maintain patient temperatures. One issue to be studied was whether a forced-air patient-warming unit with the blanket caused airflow disturbances at the surgical site that would otherwise not occur without the blanket. In the study, measurements from an operating room, including dimensions, flowrates, temperatures, and the positions of potential flow blockages were taken. Airflow simulated using the large-eddy simulation method showed that at no time, and under no conditions did the device cause potentially unclean air to intrude into the sterile surgical field during the operation of the warming device. In addition, a series of flow-visualization experiments made with neutrally buoyant tracers showed the surgical site was washed by ultraclean air from the ventilation system of the operating room regardless of whether the patient-warming device was being used. A comparison of the numerical simulations and experiments showed a near perfect match in temperature measurements and flow patterns. The mutually reinforcing simulations and experiments lend added credibility to the results.

Nomenclature

Co	=	courant number
p	=	pressure
t	=	time
ui	=	velocity in tensor form
xi	=	coordinate direction in tensor form
Greek symbols	=
γ	=	filtering function
ρ	=	density
τ	=	shear stress
ν	=	kinematic viscosity
φ	=	filtering variable

Nomenclature

Co	=	courant number
p	=	pressure
t	=	time
ui	=	velocity in tensor form
xi	=	coordinate direction in tensor form
Greek symbols	=
γ	=	filtering function
ρ	=	density
τ	=	shear stress
ν	=	kinematic viscosity
φ	=	filtering variable

Acknowledgment

This research was supported by 3 M Corporation.