A biophysical vascular bubble model for devising decompression procedures

Abstract

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.

High Bubble Grade After Diving: The Role of the Blood Pressure Regimen

“…Indeed, it has been reported that the systemic infusion of an endogenous nitric oxide synthase inhibitor lead to an increase in vascular stiffness and a decrease in cerebral blood flow in healthy subjects (Kielstein et al, 2006). As suggested by Arieli and Marmur (2017), the reduction of peripheral blood flow, in divers with low arterial compliance, might enhance the diffusion of inert gas into the artery and therefore the expansion of microbubbles.…”

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

“…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 ).…”

“…Initiation is defined as the moment the first bubble from an AHS reaches a diameter of 0.1 mm, as a function of time from decompression. The dotted line is a suggested smooth function (taken from Arieli and Marmur, 2017 with permission).…”

“…It is therefore possible that decompression bubbles develop in distal arteries within the nervous system, and more so in the spinal cord. A detailed discussion of arterial bubbles was presented in the paper by Arieli and Marmur ( 2017 ).…”

Static Metabolic Bubbles as Precursors of Vascular Gas Emboli During Divers’ Decompression: A Hypothesis Explaining Bubbling Variability

“…Arieli was then able to visually observe the whole dynamics of bubble growth, detachment and the rate of bubble production. He derived a mathematical equation for conditional detachment which he based on buoyancy, and therefore, on reaching a critical bubble volume (Papadopoulou et al, 2015; Arieli and Marmur, 2017). He concluded that decompression bubbles in divers can develop only from pre-existing gas micronuclei (Arieli and Marmur, 2017), and that these could be nanobubbles appearing on active hydrophobic spots (AHS) as found on the endoluminal surface of blood vessels.…”