title: Dual-frequency ultrasound for detecting and sizing bubbles.
abstract: ISS construction and Mars exploration require extensive extravehicular activity (EVA), exposing crewmembers to increased decompression sickness risk. Improved bubble detection technologies could help increase EVA efficiency and safety. Creare Inc. has developed a bubble detection and sizing instrument using dual-frequency ultrasound. The device emits "pump" and "image" signals at two frequencies. The low-frequency pump signal causes an appropriately-sized bubble to resonate. When the image frequency hits a resonating bubble, mixing signals are returned at the sum and difference of the two frequencies. To test the feasibility of transcutaneous intravascular detection, intravascular bubbles in anesthetized swine were produced using agitated saline and decompression stress. Ultrasonic transducers on the chest provided the two frequencies. Mixing signals were detected transthoracically in the right atrium using both methods. A histogram of estimated bubble sizes could be constructed. Bubbles can be detected and sized transthoracically in the right atrium using dual-frequency ultrasound.
authors.affiliation: Department of Medicine, Dartmouth Medical School, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03756, USA. jay.buckey@dartmouth.edu
authors.forename: Jay C
authors.initials: JC
authors.lastname: Buckey
authors.forename: Darin A
authors.initials: DA
authors.lastname: Knaus
authors.forename: Donna L
authors.initials: DL
authors.lastname: Alvarenga
authors.forename: Marc A
authors.initials: MA
authors.lastname: Kenton
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Magari
mesh_terms: D000818:Animals; D003665:Decompression Sickness / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000517:prevention & control; D004618:Embolism, Air / Q000000981:diagnostic imaging*; D005118:Extraterrestrial Environment; D018478:Extravehicular Activity; D005260:Female; D013026:Space Flight; D013552:Swine; D014159:Transducers; D014465:Ultrasonics; D014463:Ultrasonography; D014893:Weightlessness / Q000009:adverse effects*