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  • Image not available.In a patient with an acute asthma attack, a normal or high Paco2 indicates that the patient can no longer maintain the work of breathing and is often a sign of impending respiratory failure. A pulsus paradoxus and electrocardiographic signs of right ventricular strain (ST-segment changes, right-axis deviation, and right bundle branch block) are also indicative of severe airway obstruction.
  • Image not available.Asthmatic patients with active bronchospasm presenting for emergency surgery should be treated aggressively whenever possible. Supplemental oxygen, aerosolized β2-agonists, and intravenous glucocorticoids can dramatically improve lung function in a few hours.
  • Image not available.Intraoperative bronchospasm is usually manifested as wheezing, increasing peak inflation pressures (plateau pressure should remain unchanged), decreasing exhaled tidal volumes, or a slowly rising waveform on the capnograph.
  • Image not available.If the bronchospasm does not resolve after deepening the anesthetic, less common causes should be considered before administering more specific drugs. Obstruction of the tracheal tube from kinking, secretions, or an overinflated balloon; bronchial intubation; active expiratory efforts (straining); pulmonary edema or embolism; and pneumothorax can all simulate bronchospasm.
  • Image not available.In patients with chronic obstructive pulmonary disease (COPD), chronic hypoxemia leads to erythrocytosis, pulmonary hypertension, and eventually right ventricular failure (cor pulmonale).
  • Image not available.Oxygen therapy can dangerously elevate Paco2 in patients with CO2 retention; elevating Pao2 above 60 mm Hg can precipitate respiratory failure.
  • Image not available.Preoperative interventions in patients with COPD aimed at correcting hypoxemia, relieving bronchospasm, mobilizing and reducing secretions, and treating infections may decrease the incidence of postoperative pulmonary complications. Patients at greatest risk for complications are those with preoperative pulmonary function measurements less than 50% of predicted.
  • Image not available.Patients with pulmonary bullae are at high risk of developing pneumothoraxes intraoperatively, particularly if ventilated with positive pressure.
  • Image not available.Restrictive pulmonary diseases are characterized by decreased lung compliance. Lung volumes are typically reduced, with preservation of normal expiratory flow rates. Thus, both forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) are reduced, but the FEV1/FVC ratio is normal.
  • Image not available.Intraoperative pulmonary embolism usually presents as unexplained sudden hypotension, hypoxemia, or bronchospasm. A decrease in end-tidal CO2 concentration is also suggestive of pulmonary embolism but not specific.


The impact of preexisting pulmonary disease on respiratory function during anesthesia and in the postoperative period is predictable: Greater degrees of preoperative pulmonary impairment are associated with more marked intraoperative alterations in respiratory function (see Chapter 22) and higher rates of postoperative pulmonary complications. Failure to recognize patients who are at increased risk is a frequent contributory factor leading to complications, as patients may not receive appropriate preoperative and intraoperative care. This chapter examines pulmonary risk in general and then reviews the anesthetic approach to patients with the most common types of respiratory disease.


Pulmonary Risk Factors


Six risk factors (Table 23–1) predispose patients to postoperative pulmonary dysfunction, the most common postoperative complication. The incidence of atelectasis, pneumonia, pulmonary embolism, and respiratory failure following surgery is quite ...

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