ABSTRACT
Adequate gas exchange may be matched with the systemic circulation; however, it is necessary to coordinate the functioning of the lung (including the conducting airways, the pulmonary circulation, and the gas exchanging regions), the ventilatory pump (diaphragm and chest wall), and the central ventilatory controller with its afferent inputs and neural connections to the respiratory muscles. The control of breathing is influenced by drugs with side-effects that can cause or relieve pulmonary dysfunction and drugs that can be used to treat pulmonary dysfunction caused by disease or surgical and anesthetic procedures. This chapter is organized on the basis of respiratory system structure and function, and in it the significant effectsof pharmacologic agents used in anesthesia for the control of ventilation both in normal individuals and in patients with respiratory compromise are discussed. The chapter is designed to enable the reader to understand the respiratory pharmacology of common drugs and conditions as they relate to anesthesiology. Further information concerning the general physiology and pharmacology of the regulation of breathing can be found in authoritative monographs.'>
Experiments with animals, generally cats, have provided most of the information about the anatomy and physiology of central respiratory centers. Although early studies required destruction or sectioning of brain areas, more recent studies have provided greater detail and information concerning these anatomical structures. Some noninvasive techniques, such as functional magnetic resonance imaging (MRI), have also provided data from human studies. Extracellular recordings of neural spike trains have allowed primary classification of neurons as inspiratory, if they fire in synchrony with the phrenic nerve discharge, and expiratory, if they fire during phrenic nerve silence.There are many variations in these basic patterns that permit numerous subclassifications.'
