Perioperative Acid–Base Disturbances: Evaluation and Management

As perioperative physicians, anesthesiologists regularly face dilemmas in patients who have gas exchange and acid–base abnormalities. Even in the absence of technical problems, some individuals are difficult to oxygenate and ventilate intraoperatively. Hypoxemia and hypercapnia commonly occur in the postanesthesia care unit and on the surgical wards. Intensive care unit patients with respiratory failure and metabolic derangements may require operative intervention and pose significant management problems. Furthermore, the effects on patient physiology of a variety of perioperative metabolic insults must be considered. Assessment of acid–base and metabolic derangements requires evaluation of blood gases, electrolytes, and other laboratory data. This chapter discusses acid–base physiology as it applies to the perioperative period, and provides an approach to the interpretation of arterial blood gases and electrolytes with a focus on acid–base disorders.