Book contents
- Basic Physiology for Anaesthetists
- Basic Physiology for Anaesthetists
- Copyright page
- Dedication
- Contents
- Foreword
- Preface to the Second Edition
- Preface to the First Edition
- Abbreviations
- Section 1 The Basics
- Section 2 Respiratory Physiology
- Chapter 6 The Upper Airways
- Chapter 7 The Lower Airways
- Chapter 8 Oxygen Transport
- Chapter 9 Carbon Dioxide Transport
- Chapter 10 Alveolar Diffusion
- Chapter 11 Ventilation and Dead Space
- Chapter 12 Static Lung Volumes
- Chapter 13 Spirometry
- Chapter 14 Hypoxia and Shunts
- Chapter 15 Ventilation–Perfusion Relationships
- Chapter 16 Ventilation–Perfusion Zones in the Lung
- Chapter 17 Oxygen Delivery and Demand
- Chapter 18 Alveolar Gas Equation
- Chapter 19 Oxygen Cascade
- Chapter 20 Lung Compliance
- Chapter 21 Work of Breathing
- Chapter 22 Control of Ventilation
- Chapter 23 Pulmonary Circulation
- Chapter 24 Oxygen Toxicity
- Chapter 25 Ventilatory Failure
- Chapter 26 Anaesthesia and the Lung
- Section 3 Cardiovascular Physiology
- Section 4 Neurophysiology
- Section 5 Gastrointestinal Tract
- Section 6 Kidney and Body Fluids
- Section 7 Blood and Immune System
- Section 8 Energy Balance
- Section 9 Endocrine Physiology
- Section 10 Developmental Physiology
- Section 11 Environmental Physiology
- Index
- References
Chapter 15 - Ventilation–Perfusion Relationships
from Section 2 - Respiratory Physiology
Published online by Cambridge University Press: 31 July 2019
- Basic Physiology for Anaesthetists
- Basic Physiology for Anaesthetists
- Copyright page
- Dedication
- Contents
- Foreword
- Preface to the Second Edition
- Preface to the First Edition
- Abbreviations
- Section 1 The Basics
- Section 2 Respiratory Physiology
- Chapter 6 The Upper Airways
- Chapter 7 The Lower Airways
- Chapter 8 Oxygen Transport
- Chapter 9 Carbon Dioxide Transport
- Chapter 10 Alveolar Diffusion
- Chapter 11 Ventilation and Dead Space
- Chapter 12 Static Lung Volumes
- Chapter 13 Spirometry
- Chapter 14 Hypoxia and Shunts
- Chapter 15 Ventilation–Perfusion Relationships
- Chapter 16 Ventilation–Perfusion Zones in the Lung
- Chapter 17 Oxygen Delivery and Demand
- Chapter 18 Alveolar Gas Equation
- Chapter 19 Oxygen Cascade
- Chapter 20 Lung Compliance
- Chapter 21 Work of Breathing
- Chapter 22 Control of Ventilation
- Chapter 23 Pulmonary Circulation
- Chapter 24 Oxygen Toxicity
- Chapter 25 Ventilatory Failure
- Chapter 26 Anaesthesia and the Lung
- Section 3 Cardiovascular Physiology
- Section 4 Neurophysiology
- Section 5 Gastrointestinal Tract
- Section 6 Kidney and Body Fluids
- Section 7 Blood and Immune System
- Section 8 Energy Balance
- Section 9 Endocrine Physiology
- Section 10 Developmental Physiology
- Section 11 Environmental Physiology
- Index
- References
Summary
Lung perfusion1 increases linearly from the top to the bottom of the lungs (Figure 15.1, lung perfusion line). The difference in perfusion at the top and bottom of the lung can be explained by the effect of gravity on the alveolar volume, which in turn determines the pulmonary capillary pressure. The difference in pulmonary capillary pressure between the lung apex and base is equivalent to the hydrostatic pressure exerted by a column of blood. The distance from apex to base is 30 cm, so the pressure difference is 30 cmH2O (equivalent to 22 mmHg). The pulmonary circulation is a low-pressure system: mean pulmonary artery pressure (MPAP) is typically just 15 mmHg. A pressure difference of 22 mmHg between the top and the bottom of the lungs is therefore potentially significant (this is discussed further in Chapter 16).
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- Basic Physiology for Anaesthetists , pp. 68 - 70Publisher: Cambridge University PressPrint publication year: 2019