ABSTRACT
The major function of the cardiopulmonary system is delivery of oxygen to tissues and elimination of carbon dioxide generated by tissue metabolism. This chapter reviews these processes and provides the clinician with a logical framework for assessment of animals with cardiopulmonary dysfunction. The oxygen pathway is a clinically useful concept that provides a logical framework for evaluation and treatment of disturbances in the cardiopulmonary system. Adequate ventilation requires central respiratory centers, spinal pathways, peripheral respiratory nerves, primary respiratory muscles, pleural-pulmonary coupling, and pulmonary mechanical function to be intact or normal. Clinical assessment of ventilation should include observation of breathing. Total ventilation is measured directly with a Wright’s respirometer attached to an endotracheal tube or tight-fitting mask. There are three basic mechanisms of gas exchange impairment: diffusion impairment, shunt, and ventilation-perfusion mismatch. The most common method of assessing saturation in veterinary patients is pulse oximetry.
