title: Decompression induced bubble dynamics on ex vivo fat and muscle tissue surfaces with a new experimental set up.
abstract: Vascular gas bubbles are routinely observed after scuba dives using ultrasound imaging, however the precise formation mechanism and site of these bubbles are still debated and growth from decompression in vivo has not been extensively studied, due in part to imaging difficulties. An experimental set-up was developed for optical recording of bubble growth and density on tissue surface area during hyperbaric decompression. Muscle and fat tissues (rabbits, ex vivo) were covered with nitrogen saturated distilled water and decompression experiments performed, from 3 to 0bar, at a rate of 1bar/min. Pictures were automatically acquired every 5s from the start of the decompression for 1h with a resolution of 1.75μm. A custom MatLab analysis code implementing a circular Hough transform was written and shown to be able to track bubble growth sequences including bubble center, radius, contact line and contact angles over time. Bubble density, nucleation threshold and detachment size, as well as coalescence behavior, were shown significantly different for muscle and fat tissues surfaces, whereas growth rates after a critical size were governed by diffusion as expected. Heterogeneous nucleation was observed from preferential sites on the tissue substrate, where the bubbles grow, detach and new bubbles form in turn. No new nucleation sites were observed after the first 10min post decompression start so bubble density did not vary after this point in the experiment. In addition, a competition for dissolved gas between adjacent multiple bubbles was demonstrated in increased delay times as well as slower growth rates for non-isolated bubbles.
authors.affiliation: Department of Bioengineering, Imperial College London, London, UK; Environmental & Occupational Physiology Lab., Haute Ecole Paul Henri Spaak, Brussels, Belgium. Electronic address: virginie.papadopoulou07@imperial.ac.uk.
authors.forename: Virginie
authors.initials: V
authors.lastname: Papadopoulou
authors.affiliation: Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: Sotiris
authors.initials: S
authors.lastname: Evgenidis
authors.affiliation: Imaging Sciences & Biomedical Engineering Division, King's College London, London, UK.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Eckersley
authors.affiliation: Hyperbaric Department, St. Paul General Hospital of Thessaloniki, Thessaloniki, Greece.
authors.forename: Thodoris
authors.initials: T
authors.lastname: Mesimeris
authors.affiliation: Environmental & Occupational Physiology Lab., Haute Ecole Paul Henri Spaak, Brussels, Belgium; DAN Europe Research Division, Belgium.
authors.forename: Costantino
authors.initials: C
authors.lastname: Balestra
authors.affiliation: Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: Margaritis
authors.initials: M
authors.lastname: Kostoglou
authors.affiliation: Department of Bioengineering, Imperial College London, London, UK.
authors.forename: Meng-Xing
authors.initials: MX
authors.lastname: Tang
authors.affiliation: Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki, Greece. Electronic address: karapant@chem.auth.gr.
authors.forename: Thodoris D
authors.initials: TD
authors.lastname: Karapantsios
mesh_terms: D000273:Adipose Tissue / Q000737:chemistry* / Q000378:metabolism; D000818:Animals; D003664:Decompression; D004058:Diffusion; D005740:Gases / Q000378:metabolism*; D008297:Male; D045423:Microbubbles; D009132:Muscles / Q000737:chemistry* / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D011817:Rabbits
chemical_list: D005740:Gases; D009584:Nitrogen
keywords: Decompression sickness; Degassing; Diving; Mass transfer; Micronuclei; Nuclei