Bubble size on detachment from the luminal aspect of ovine large blood vessels after decompression: The effect of mechanical disturbance

Arieli, Ran; Arieli, Uri; Marmur, Abraham

doi:10.1016/j.resp.2015.05.001

Cited by 15 publications

(29 citation statements)

References 15 publications

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“…It has been suggested that the AHS are composed of lung surfactants deposited on the luminal aspect of blood vessels (Hills, 1992 ; Arieli, 2015 ). We recently confirmed the validity of this hypothesis, by showing that DPPC leaks from the lungs into the blood and settles to form AHS on the vessel (Arieli et al, 2015 ).…”

Section: Compatibility Of Ahs With Decompression From Divingmentioning

confidence: 58%

“…The combination of the early findings of Hills and our experiments on silicon wafers provided the impetus for our study of ovine blood vessels (Arieli and Marmur, 2013b , 2014 , 2016 ; Arieli et al, 2015 , 2016 ). The findings from these investigations eventually led us to propose a new physiological model for designing decompression procedures (Arieli and Marmur, 2017 ).…”

Section: Active Hydrophobic Spots (Ahs) On the Luminal Aspect Of Bloomentioning

confidence: 77%

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Nanobubbles Form at Active Hydrophobic Spots on the Luminal Aspect of Blood Vessels: Consequences for Decompression Illness in Diving and Possible Implications for Autoimmune Disease—An Overview

Arieli

2017

Front. Physiol.

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Decompression illness (DCI) occurs following a reduction in ambient pressure. Decompression bubbles can expand and develop only from pre-existing gas micronuclei. The different hypotheses hitherto proposed regarding the nucleation and stabilization of gas micronuclei have never been validated. It is known that nanobubbles form spontaneously when a smooth hydrophobic surface is submerged in water containing dissolved gas. These nanobubbles may be the long sought-after gas micronuclei underlying decompression bubbles and DCI. We exposed hydrophobic and hydrophilic silicon wafers under water to hyperbaric pressure. After decompression, bubbles appeared on the hydrophobic but not the hydrophilic wafers. In a further series of experiments, we placed large ovine blood vessels in a cooled high pressure chamber at 1,000 kPa for about 20 h. Bubbles evolved at definite spots in all the types of blood vessels. These bubble-producing spots stained positive for lipids, and were henceforth termed “active hydrophobic spots” (AHS). The lung surfactant dipalmitoylphosphatidylcholine (DPPC), was found both in the plasma of the sheep and at the AHS. Bubbles detached from the blood vessel in pulsatile flow after reaching a mean diameter of ~1.0 mm. Bubble expansion was bi-phasic—a slow initiation phase which peaked 45 min after decompression, followed by fast diffusion-controlled growth. Many features of decompression from diving correlate with this finding of AHS on the blood vessels. (1) Variability between bubblers and non-bubblers. (2) An age-related effect and adaptation. (3) The increased risk of DCI on a second dive. (4) Symptoms of neurologic decompression sickness. (5) Preconditioning before a dive. (6) A bi-phasic mechanism of bubble expansion. (7) Increased bubble formation with depth. (8) Endothelial injury. (9) The presence of endothelial microparticles. Finally, constant contact between nanobubbles and plasma may result in distortion of proteins and their transformation into autoantigens.

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Section: Compatibility Of Ahs With Decompression From Divingmentioning

confidence: 58%

Section: Active Hydrophobic Spots (Ahs) On the Luminal Aspect Of Bloomentioning

confidence: 77%

Nanobubbles Form at Active Hydrophobic Spots on the Luminal Aspect of Blood Vessels: Consequences for Decompression Illness in Diving and Possible Implications for Autoimmune Disease—An Overview

Arieli

2017

Front. Physiol.

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“…As no pathological findings such as PFO or lung inflammation were detected in the experimental animals in the present study, we suggest that the discrepancy between these two mammalian models reflects differences in body size [the body size of the pig is 2 orders of magnitude (10 2 ) greater than that of the rat] and hence both in metabolism and in gas uptake and elimination. Differences in body size and metabolic rate may also affect the quantity of bubble micronuclei and the rate at which they emerge on well-defined hydrophobic spots on the inner walls of large blood vessels, including the aorta (1,2). We therefore suggest that with regard to the hazard of DCI following a "yo-yo" dive in the human diver, who weighs in the region of 70 kg, we may well be justified in extrapolating from our results for the pig.…”

Section: Discussionmentioning

confidence: 76%

Evidence for the infiltration of gas bubbles into the arterial circulation and neuronal injury following “yo-yo” dives in pigs

Ofir

Yanir

Mullokandov

et al. 2016

Journal of Applied Physiology

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"Yo-yo" diving may place divers at a greater risk of neurologic decompression illness (DCI). Using a rat model, we previously demonstrated that "yo-yo" diving has a protective effect against DCI. In the current study, we evaluated the risk of neurologic DCI following "yo-yo" dives in a pig model. Pigs were divided into four groups. The Control group (group A) made a square dive, without excursions to the surface ("peeps"). Group B performed two "peeps," group C performed four "peeps," and group D did not dive at all. All dives were conducted on air to 5 atm absolute, for 30-min bottom time. Echocardiography was performed to detect cardiac gas bubbles before the dive, immediately after, and at 90-min postdive. Motor performance was observed during the 5-h postdive period. Symptoms increased dramatically following a dive with four "peeps." Gas bubbles were detected in the right ventricle of all animals except for the sham group and in the left ventricle only after the four-peep dive. Neuronal cell injury was found in the spinal cord in each of the three experimental groups, tending to decrease with an increase in the number of "peeps." A four-peep "yo-yo" dive significantly increased the risk of neurologic DCI in pigs. Following a four-peep dive, we detected a higher incidence of bubbles in the left ventricle, supporting the common concern regarding an increased risk of neurologic DCI, albeit there was no direct correlation with the frequency of "red neurons" in the spinal cord.

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“…The inflammation, neutrophil activation, and platelet aggregation seen in DCI are due to microparticles composed of cell membranes, which we and others believe to have been stripped from the vasculature by bubbles (Arieli et al. ; Pontier et al. ; Yang et al.…”

Section: Introductionmentioning

confidence: 63%

A biophysical vascular bubble model for devising decompression procedures

Arieli

Marmur

2017

Physiological Reports

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Vascular bubble models, which present a realistic biophysical approach, hold great promise for devising suitable diver decompression procedures. Nanobubbles were found to nucleate on a flat hydrophobic surface, expanding to form bubbles after decompression. Such active hydrophobic spots (AHS) were formed from lung surfactants on the luminal aspect of ovine blood vessels. Many of the phenomena observed in these bubbling vessels correlated with those known to occur in diving. On the basis of our previous studies, which proposed a new model for the formation of arterial bubbles, we now suggest the biophysical model presented herein. There are two phases of bubble expansion after decompression. The first is an extended initiation phase, during which nanobubbles are transformed into gas micronuclei and begin to expand. The second, shorter phase is one of simple diffusion‐driven growth, the inert gas tension in the blood remaining almost constant during bubble expansion. Detachment of the bubble occurs when its buoyancy exceeds the intermembrane force. Three mechanisms underlying the appearance of arterial bubbles should be considered: patent foramen ovale, intrapulmonary arteriovenous anastomoses, and the evolution of bubbles in the distal arteries with preference for the spinal cord. Other parameters that may be quantified include age, acclimation, distribution of bubble volume, AHS, individual sensitivity, and frequency of bubble formation. We believe that the vascular bubble model we propose adheres more closely to proven physiological processes. Its predictability may therefore be higher than other models, with appropriate adjustments for decompression illness (DCI) data.

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Bubble size on detachment from the luminal aspect of ovine large blood vessels after decompression: The effect of mechanical disturbance

Cited by 15 publications

References 15 publications

Nanobubbles Form at Active Hydrophobic Spots on the Luminal Aspect of Blood Vessels: Consequences for Decompression Illness in Diving and Possible Implications for Autoimmune Disease—An Overview

Nanobubbles Form at Active Hydrophobic Spots on the Luminal Aspect of Blood Vessels: Consequences for Decompression Illness in Diving and Possible Implications for Autoimmune Disease—An Overview

Evidence for the infiltration of gas bubbles into the arterial circulation and neuronal injury following “yo-yo” dives in pigs

A biophysical vascular bubble model for devising decompression procedures

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