Cerebral gas embolism absorption during hyperbaric therapy: theory

Abstract

Cerebral gas embolism is a serious consequence of diving. It is associated with decompression sickness and is assumed to cause severe neurological dysfunction. A mathematical model previously developed to calculate embolism absorption time based on in vivo bubble geometry is used in which various conditions of hyperbaric therapy are considered. Effects of varying external pressure and inert gas concentrations in the breathing mixtures, according to US Navy and Royal Navy diving treatment tables, are predicted. Recompression alone is calculated to reduce absorption times of a 50-nl bubble by up to 98% over the untreated case. Lowering the inhaled inert gas concentration from 67.5% to 50% reduces absorption time by 37% at a given pressure. Bubbles formed after diving and decompression with He are calculated to absorb up to 73% faster than bubbles created after diving and decompression with air, regardless of the recompression gas breathed. This model is a useful alternative to impractical clinical trials in assessing which initial step in hyperbaric therapy is most effective in eliminating cerebral gas embolisms should they occur.

In vivo microvascular mosaics show air embolism reduction after perfluorocarbon emulsion treatment

“…In contrast with previous studies, we produced massive AGE by injecting air into a cremaster preparation that had all microcirculatory networks available for perfusion. In addition, the air bubble volumes of our study (over 200 nL/individual intravascular bubble, over 600 nL/studied embolized network) were up to 20 times larger than the volumes produced previously in similar preparations (Branger andEckmann, 1999, 2002;Eckmann and Diamond, 2004;Eckmann and Lomivorotov, 2003).…”

“…In many cases, pictures are produced but a number of technical issues related to image quality and acquisition of the angiograms prevent accurate measurements of bubble dimensions (Herren et al, 1998;Parsons et al, 2009;Soga et al, 1999). The quantification of the microbubble dynamics at microvascular level in vivo is more challenging and has been successfully attempted only in a few instances (Branger andEckmann, 1999, 2002;Yamaguchi et al, 2003). In previous reports using intravital microscopy and arteriolar gas embolism (AGE), arterial vessels nearby the studied vessels were cauterized before small air bubbles (up to 5 μL) were injected (Branger andEckmann, 1999, 2002;Eckmann and Lomivorotov, 2003).…”

“…The quantification of the microbubble dynamics at microvascular level in vivo is more challenging and has been successfully attempted only in a few instances (Branger andEckmann, 1999, 2002;Yamaguchi et al, 2003). In previous reports using intravital microscopy and arteriolar gas embolism (AGE), arterial vessels nearby the studied vessels were cauterized before small air bubbles (up to 5 μL) were injected (Branger andEckmann, 1999, 2002;Eckmann and Lomivorotov, 2003). Therefore, the observed areas were restricted and the intravascular bubble volume only ranged 5-10 nL.…”

Diagnostic Cerebral Angiography

“…Quick and readily available (though unproven) methods include the use of in small series) to result in good outcomes. [41][42][43][44] One report indicated a bene fi t even after a delay in initiated hyperbaric therapy. 45 However, a larger series showed 67% good outcome when hyperbaric treat-…”

Electric analogue for the dynamics of decompression sickness bubbles: Numerical results

“…The evolution of the bubbles formed in the tissues during the ascent, both in real diving or simulated with air, has been inferred from theoretical models and clinical observation [11][12][13]. Branger et al [14] developed a mathematical model to study the evolution of the absorption of the bubbles and the effects of the variations in external pressure and of inert gases in breathable mixtures, using decompression tables of the American and British navies, based on an analysis of the structure of the bubbles that are formed.…”