Pulmonary Gas Exchange

The lung receives the entire cardiac output from the right heart and must load oxygen onto and unload carbon dioxide from perfusing blood in the correct amounts to meet the metabolic needs of the body. It does so through the process of passive diffusion. Effective diffusion is accomplished by intricate parallel structures of airways and blood vessels designed to bring ventilation and perfusion together in an appropriate ratio in the same place and at the same time. Gas exchange is determined by the ventilation-perfusion ratio in each of the gas exchange units of the lung. In the normal lung ventilation and perfusion are well matched, and the ventilation-perfusion ratio is remarkably uniform among lung units, such that the partial pressure of oxygen in the blood leaving the pulmonary capillaries is less than 10 Torr lower than that in the alveolar space. In disease, the disruption to ventilation-perfusion matching and to diffusional transport may result in inefficient gas exchange and arterial hypoxemia. This volume covers the basics of pulmonary gas exchange, providing a central understanding of the processes involved, the interactions between the components upon which gas exchange depends, and basic equations of the process. Table of Contents: Introduction / Anatomy of the Gas Exchanger / Gas Carriage / Gas Exchange by Diffusion / Gas Exchange and the Matching of Ventilation and Perfusion / Evaluating Pulmonary Gas Exchange / Summary / References

G. Kim Prisk, PhD, DSc, is a Professor of Medicine and Radiology at the University of California, San Diego, where he has been since completing his PhD at the University of Otago, New Zealand in 1983. He has been extensively involved in studies of pulmonary function and gas exchange in weightlessness on the Space Shuttle and International Space Station. His current research focuses on the use of proton MRI to perform quantitative functional imaging of the lung. He is a Fellow of the American Institute of Medical and Biological Engineering and is an Associate Editor of the Journal of Applied Physiology. Susan R. Hopkins, MD, PhD, is a Professor of Medicine and Radiology at the University of California, San Diego (UCSD). She completed MD training at Memorial University of Newfoundland in St. John's Canada and practiced Family Medicine in rural British Columbia, before returning to complete a Fellowship in Sports Medicine (1986) and a PhD in Exercise Physiology (1993) at the University of British Columbia in Vancouver, Canada. She joined UCSD in 1993. An avid cyclist, skier, and rock climber, her research involves pulmonary function and gas exchange in hypoxia and exercise. Together with Dr. Prisk, her current research focuses on the use of proton MRI to perform quantitative functional imaging of the lung. She is an Associate Editor of Applied Physiology Nutrition and Metabolism, and on the Editorial Board of the Journal of Applied Physiology.