The lifetimes of small arterial gas emboli, and their possible connection to Inner Ear Decompression Sickness

Solano-Altamirano, J. Manuel; Goldman, Saul

doi:10.1016/j.mbs.2014.03.008

Cited by 14 publications

(11 citation statements)

References 7 publications

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“…The medium was taken here to represent uniformly perfused tissue that allows absorption or release of gas by the blood at every point in the tissue (67a, 67b). More recently, a three-region model that can be conveniently used to estimate bubble lifetimes has been proposed by Solano-Altamirano and Goldman (67) and is described by Eq. 1:…”

Section: Mathematical Modelingmentioning

confidence: 99%

“…Ϫ f͒P e R o ϩ 2␥ ͪͮ , (1) where T (diss) is time to dissolution, R is the radius of the bubble, Ro is the initial radius of the bubble, D is the diffusion constant, Pe is the external pressure, f is the undersaturation factor determined by the blood gas tensions with respect to atmospheric pressure, ␥ is the surface tension of the blood, and d ϭ BT/K H (Henry's solubility constant for an ideal gas), where B is the universal gas constant, T is temperature, and KH is Henry's constant, that is, K H ϭ P e ⁄C s ,where C s is the gas solubility in liquid phase (67). This model consists of an interfacial boundary, a diffusive region next to the bubble where diffusion is the sole solute transport mechanism, and a well-stirred region beyond the diffusion region, where mixing is assumed perfectly efficient, so by definition, there are no solute concentration gradients in this well-mixed region (67). Convection as a mechanism of transport is introduced indirectly and qualitatively by application of a three-region model (67) and the parameter .…”

Section: Mathematical Modelingmentioning

confidence: 99%

“…As previously mentioned, the models discussed above are two-region bubble models that were defined in METHODS. In the current study, we applied the three-region mathematical model of bubble dissolution proposed by Solano-Altamirano and Goldman (67).…”

Section: Mathematical Modelingmentioning

confidence: 99%

“…Because the density of air decreases with increasing altitude, creating saline contrast microbubbles from reduced-density air may further decrease the stability of contrast microbubbles in vivo. Moreover, reduced atmospheric pressure may result in further undersaturation of dissolved gases in the blood, which may affect in vivo bubble dynamics (67). A reduction of the persistence of air microbubbles would result in a more rapid dissolution of bubbles, thereby impairing ultrasonic detection of Q IPAVA using TTSCE.…”

Section: Introductionmentioning

confidence: 99%

“…Factors that may affect the stability of microbubbles in blood include the surface tension at the bubble/blood interfacial boundary, molecular weight of the gas, diffusivity of the gas, gas density, blood viscosity, and solubility (in blood) of the gas from which the bubble is composed (49,58). In the current study, we also applied a three-region mathematical model of bubble dissolution (67), which considers some of the factors affecting bubble stability (mentioned above) as part of the analysis and interpretation of our results.…”

Section: Introductionmentioning

confidence: 99%

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AltitudeOmics: effect of reduced barometric pressure on detection of intrapulmonary shunt, pulmonary gas exchange efficiency, and total pulmonary resistance

Petrassi

Davis

Beasley

et al. 2018

Journal of Applied Physiology

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Blood flow through intrapulmonary arteriovenous anastomoses (Q) occurs in healthy humans at rest and during exercise when breathing hypoxic gas mixtures at sea level and may be a source of right-to-left shunt. However, at high altitudes, Q is reduced compared with sea level, as detected using transthoracic saline contrast echocardiography (TTSCE). It remains unknown whether the reduction in Q (i.e., lower bubble scores) at high altitude is due to a reduction in bubble stability resulting from the lower barometric pressure (P) or represents an actual reduction in Q. To this end, Q, pulmonary artery systolic pressure (PASP), cardiac output (Q), and the alveolar-to-arterial oxygen difference (AaDO) were assessed at rest and during exercise (70-190 W) in the field (5,260 m) and in the laboratory (1,668 m) during four conditions: normobaric normoxia (NN; [Formula: see text] = 121 mmHg, P = 625 mmHg; n = 8), normobaric hypoxia (NH; [Formula: see text] = 76 mmHg, P = 625 mmHg; n = 7), hypobaric normoxia (HN; [Formula: see text] = 121 mmHg, P = 410 mmHg; n = 8), and hypobaric hypoxia (HH; [Formula: see text] = 75 mmHg, P = 410 mmHg; n = 7). We hypothesized Q would be reduced during exercise in isooxic hypobaria compared with normobaria and that the AaDO would be reduced in isooxic hypobaria compared with normobaria. Bubble scores were greater in normobaric conditions, but the AaDO was similar in both isooxic hypobaria and normobaria. Total pulmonary resistance (PASP/Q) was elevated in HN and HH. Using mathematical modeling, we found no effect of hypobaria on bubble dissolution time within the pulmonary transit times under consideration (<5 s). Consequently, our data suggest an effect of hypobaria alone on pulmonary blood flow. NEW & NOTEWORTHY Blood flow through intrapulmonary arteriovenous anastomoses, detected by transthoracic saline contrast echocardiography, was reduced during exercise in acute hypobaria compared with normobaria, independent of oxygen tension, whereas pulmonary gas exchange efficiency was unaffected. Modeling the effect(s) of reduced air density on contrast bubble lifetime did not result in a significantly reduced contrast stability. Interestingly, total pulmonary resistance was increased by hypobaria, independent of oxygen tension, suggesting that pulmonary blood flow may be changed by hypobaria.

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Section: Mathematical Modelingmentioning

confidence: 99%