Gas Bubble Dynamics in the Human Body

Saul Goldman, Manuel Solano-Altamirano, Kenneth Ledez

• Publisher: Academic Press
• Year: 2017
• Print ISBN: 9780128105191
• eBook ISBN: 9780128105207
• Topic: Medicine
• Subtopic: Medical Theory, Practice & Reference

Gas Bubble Dynamics in the Human Body provides a broad range of professionals, from physicians working in a clinic, hospital or hyperbaric facility, to physical scientists trying to understand and predict the dynamics of gas bubble behavior in the body, with an interdisciplinary perspective on gas-bubble disease. Both iatrogenic and decompression-induced gas bubbles are considered. The basic medical and physiological aspects are described first, in plain language, with numerous illustrations that facilitate an intuitive grasp of the basic underlying medicine and physiology. Current issues in the field, particularly microbubbles and microparticles, and their possible role in gas-bubble disease are included. The physical and mathematical material is given at several levels of sophistication, with the "hard-core" math separated out in sections labelled "For the Math Mavens", so that the basic concepts can be grasped at a descriptive level. The field is large and multi-disciplinary, so that some of the discussion that is at a greater depth is given separately in sections labelled "In Greater Detail". Skipping these sections for whatever reason, shouldn't materially hamper acquiring an overall appreciation of the field.- Demonstrates how physical and mathematical tools help to solve underlying problems across physiology and medicine- Helps researchers extend their competence and flexibility to the point that they can personally contribute to the field of hyperbaric medicine and physiology, or to other related biological problems that may interest them- Provides clinicians with explicit examples of how mathematical modelling can be integrated into clinical treatment and decision-making

1

Bubbles in the body: The not so good, the bad, and the ugly

Abstract

Understanding the anatomy and physiology of the cardiovascular and pulmonary systems is essential to appreciate the dynamics of bubbles in the body, including the structure of arterial and venous vessels, cell membranes and the transport of gases. Bubbles may be spherical, but if larger than the diameter of an enclosing vessel will become “sausage-shaped” (cylindrical with hemispherical end-caps). Microbubbles and microparticles play important roles in decompression sickness (DCS) and arterial gas embolism (AGE). Bubbles may be stabilized by a surrounding skin of molecules and thereby persist much longer than would be expected otherwise. The pulmonary bubble filter is a crucial defense against venous bubbles entering the arterial circulation, but may be bypassed by a patent foramen ovale and other mechanisms. The uptake and elimination of inert gases may be described by “washin” and “washout” exponentials. The appendix describes fundamental concepts of gas pressures in the body.

Keywords

Microbubble; Microparticle; Patent foramen ovale; Pulmonary bubble filter; Bubble; Alveolus; Circulation; Cell membrane; Inert gas; Diffusion; Oxygen; Oxygen 93; Carbon dioxide; Nitrogen; Argon

We hate to be the ones to burst your bubble, but…

The authors

Main Topics

• Causes and origins of bubbles in the body

• Anatomy and function of the circulatory system

• Branching structure of the circulation

• Pulmonary bubble filter

• Pressures and gas tensions

Medical Matters

• Formation and role of microparticles

• Vascular vulnerabilities

• Inflammatory responses to bubbles

• Ischemia/reperfusion injury due to bubbles

1.1 Introduction

Bubbles in the human body are not just from diving but also arise from medical procedures, trauma, and other situations. There is no definitely known physiologic role for bubbles in the body. Evolution has provided defenses against many biologic threats although for bubbles these may be somewhat limited. Many sections of this book contain calculations and equations of varying complexity. One rule or “equation” that holds generally true in the human body is:

Bubbles = Bad.

How bad depends on many factors that are discussed in this book.

1.2 Causes and origins of bubbles in the body

Gas bubbles can form in or enter the tissues or blood from a number of sources [1, 2]:

• Depressurization/decompression.

• Disruption or trauma to gas cavities within the body.

• Injection into the bloodstream by various mechanisms, many due to medical interventions.

• Rupture of alveoli (lung sacs) and the vessels that surround them due to over-pressurization or other injury.

• Being injected or forced into the body from other exogenous sources, such as industrial compressed gas tool accidents.

• Counterdiffusion, where an inert gas is breathed that is different than the one that is supersaturating tissues.

The source of the gas may result directly in bubbles, or the bubbles may form as a consequence of a reduction in ambient pressure or other physical influences. When breathing compressed gases, such as in SCUBA or other diving, the gas is inhaled through the lungs. The term gas-bubble disease will be used when necessary to encompass all circumstances when medical disorders are related to the presence of gas bubbles in the body. In most cases of decompression sickness (DCS) the location of bubbles is not known. This chapter deals primarily with circulation and the pulmonary system, with particular emphasis on their relation to the formation, dissolution, and transport of gas bubbles in the body. Blood circulation is driven by pressure differences, while the formation, growth, and dissolution of gas bubbles can be driven by pressure and/or gas tension differences. The main concepts are first explained and illustrated descriptively, with the more quantitative physical underpinnings described subsequently. But because of the complexity of the body and the variety of conditions encountered, we will have to distinguish between: absolute and relative (or gauge) pressure, ambient pressure, hydrostatic pressure, gas partial pressure, and gas tension (in addition to arterial, venous, and tissue gas tensions). All this can be a confusing distraction. So to maintain continuity of the conceptual material, we separate the discussion of the measures of pressure and tension from the main text, and describe them separately in Appendix of this chapter. A more detailed discussion of gas tension and its relation to the chemical potential and bubble growth and dissolution is reserved for Chapter 2.

1.3 Circulation fundamentals

The human body is an immensely complex structure. It is important to be familiar with the overall anatomy and function of the circulation (Fig. 1.1) and the general configuration of gas and blood flow in the lungs (Fig. 1.2) (see also [3–6]). Blood flows from the left atrium into the left ventricle from which it is pumped into the main artery (aorta), then the arteries, arterioles, and then to tiny capillaries from where oxygen and nutrients pass to the cells and tissues. A small percentage of fluid is collected into lymphatic vessels but most of the circulating blood passes from the capillaries into venules, veins, and the...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Dedication
• List of figures
• About the authors
• Preface
• Acknowledgments
• 1: Bubbles in the body: The not so good, the bad, and the ugly
• 2: Driving force of gas-bubble growth and dissolution
• 3: Rates of gas-bubble growth and dissolution in simple liquids
• 4: Estimating the radii and lifetimes of small gas bubbles suspended in simple liquids
• 5: AGEs in scuba diving and in DCS-like problems in breath-hold diving
• 6: Gas bubbles in soft tissue-like solids
• 7: The evils that bubbles do…
• 8: Compartmental decompression models and DCS risk estimation
• 9: Treating the evils that bubbles do
• 10: Gas-bubble dynamics in the treatment of gas-bubble disease: Merging medicine and math
• Appendix: Solutions to problems
• Index