title: Rapid and selective brain cooling method using vortex tube: A feasibility study.
abstract: Vortex tubes are simple mechanical devices to produce cold air from a stream of compressed air without any moving parts. The primary focus of the current study is to investigate the feasibility and efficiency of nasopharyngeal brain cooling method using a vortex tube. Experiments were conducted on 5 juvenile pigs. Nasopharygeal brain cooling was achieved by directing cooled air via a catheter in each nostril into the nasal cavities. A vortex tube was used to generate cold air using various sources of compressed air: (I) hospital medical air outlet (n = 1); (II) medical air cylinders (n = 3); and (III) scuba (diving) cylinders (n = 1). By using compressed air from a hospital medical air outlet at fixed inlet pressure of 50 PSI, maximum brain-rectal temperature gradient of -2°C was reached about 45-60 minutes by setting the flow rate of 25 L/min and temperature of -7°C at the cold air outlet. Similarly, by using medical air cylinders at fill-pressure of 2265 PSI and down regulate the inlet pressure to the vortex tube to 50 PSI, brain temperature could be reduced more rapidly by blowing -22°C ± 2°C air at a flow rate of 50 L/min; brain-body temperature gradient of -8°C was obtained about 30 minutes. Furthermore, we examined scuba cylinders as a portable source of compressed gas supply to the vortex tube. Likewise, by setting up the vortex tube to have an inlet pressure of 25 PSI and 50 L/min and -3°C at the cold air outlet, brain temperature decreased 4.5°C within 10-20 min.
authors.affiliation: Imaging Program, Lawson Health Research Institute, London, Ontario, Canada(1); Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada. Electronic address: mfazelb@uwo.ca.
authors.forename: Mohammad Fazel
authors.initials: MF
authors.lastname: Bakhsheshi
authors.affiliation: Imaging Program, Lawson Health Research Institute, London, Ontario, Canada(1).
authors.forename: Lynn
authors.initials: L
authors.lastname: Keenliside
authors.affiliation: Imaging Program, Lawson Health Research Institute, London, Ontario, Canada(1); Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada; Department of Medical Imaging and Biophysics, Western University, London, Ontario, Canada.
authors.forename: Ting-Yim
authors.initials: TY
authors.lastname: Lee
mesh_terms: D000818:Animals; D001921:Brain; D058868:Compressed Air; D005240:Feasibility Studies; D007036:Hypothermia, Induced / Q000295:instrumentation / Q000379:methods*; D007440:Intubation / Q000295:instrumentation / Q000379:methods; D009305:Nasopharynx; D013552:Swine