ABSTRACT
The respiratory system responds to surgical stress and anesthetic interventions under influences of a variety of drugs used during the perioperative period in any surgical patient. A variety of respiratory complications may develop when the physiological responses fail to maintain respiratory homeostasis in patients at risk. Development of a respiratory complication is multi-factorial, and in turn, a risk factor can lead to a variety of respiratory complications. Some respiratory complications occur in patients without known risk factors, probably because of occasional failure to identify the risk factors. Depending upon the postoperative period, complication types vary as shown in Figure 18.1. In general, upper airway dysfunction and impairment of respiratory control occur in association with residual drug effects mostly on the day of the surgery. Constant hypoxemia due to impairment of lower airway and lung function usually peaks during days 1-3 after operation. Nocturnal oxygen desaturation, possibly related to alteration of postoperative sleep architecture, becomes evident during days 2-5 after operation.
