The Respiratory System: Physiologic Assessment and Real-world Application

The respiratory system is an elegant physiologic mechanism that provides the most basic support of the body, oxygenation and ventilation. Oxygen must be absorbed and delivered to the tissues to continue with oxidative metabolism while the byproduct of carbon dioxide must be expelled in a delicate balance to maintain an acid/base equilibrium. Complete understanding of oxygen content, delivery, and consumption is essential as a provider caring for the critically ill patient. The respiratory system can be closely monitored through a variety of helpful adjuncts including pulse oximetry, capnometry, and pulmonary function testing. These additional data points are useful for assessing a patient’s clinical condition in conjunction with the patient’s overall pulmonary status, underlying pathology, and environmental factors. A thorough understanding of the respiratory system guided by diagnostic testing and an assessment of patient factors are helpful in mitigating risk of pulmonary complications in the perioperative environment. This review contains 2 figures, 2 tables, and 54 references. Key Words: capnometry, pulse oximetry, respiratory system, oxygenation, ventilation pulmonary, pulmonary function testing, pulmonary complications, preoperative pulmonary optimization, smoking cessation