Anesthesia for Airway Surgery
- Coexisting pulmonary and cardiac diseases increase susceptibility to the detrimental effects of sympathetic stimulation, hypoxemia, and hypercarbia that may accompany airway procedures. Pulmonary function needs to be optimized preoperatively. Perioperative management, including the preoperative medical regimen, can be tailored to reduce the risk of adverse myocardial events.
- Flow-volume loops are useful for assessing the severity of obstructive pulmonary disease and for the categorization of intrathoracic and extrathoracic airway obstructions. Inhalational induction of anesthesia may be indicated in patients with large-airway obstruction. Muscle relaxants are avoided until the site of airway compromise has been crossed by an endotracheal tube or rigid bronchoscope.
- Modern anesthetics can provide deep planes of anesthesia while preserving the possibility of rapid emergence with little residual respiratory depression. Total intravenous maintenance techniques are often required in airway surgeries. Short-acting neuromuscular blockers, β-adrenergic blockers, and vasodilators are useful adjuncts in airway surgery but provide no protection against patient awareness.
- Airway surgeries often require the use of alternative ventilatory strategies including jet ventilation modes, use of the ventilating rigid bronchoscope, cross-table ventilation, and selective bronchial intubation. Both anesthesiologist and surgeon must be knowledgeable regarding the limitations of these techniques, including the possibility of hypoxemia, hypercarbia, or barotrauma.
- Respiratory insufficiency after airway surgery may result from drug effects (e.g., residual neuromuscular blockade), large-airway pathology (e.g., vocal cord dysfunction, tracheomalacia), or intrinsic lung injury (e.g., atelectasis, lobar collapse, aspiration pneumonitis). In patients with large-airway obstruction, inhaled racemic epinephrine or ventilation with helium-oxygen mixtures may provide relief.
One of the most challenging tasks during surgery of the airway is ensuring adequate ventilation of the respiratory tree. Because the airway is shared between surgeon and anesthesiologist, successful oxygenation and ventilation of the patient can only be accomplished through collaboration during the stages of airway surgery. This includes periods in which surgical airway manipulation compromises adequate ventilation and periods in which ventilation interferes with the surgical environment. With continuous communication between the surgeon and anesthesiologist and careful preparation for these challenging cases, optimal outcomes can be achieved.
The anesthetic techniques for airway surgeries are determined by the surgical procedure itself and the degree of urgency for intervention. Considerations in the anesthetic technique include but are not limited to the preoperative evaluation of the patient, choice of ventilation, anesthetic agents, and anticipated postoperative complications.
Clinicians have responded to the challenge of ventilating these patients with a host of innovative techniques. Additionally, advances in monitoring and anesthetic agents have allowed patients with increasing comorbidities to be candidates for higher risk procedures. Still, despite these advances, the complexity of these operations continues to require special expertise in anesthetic and patient management. The preoperative, intraoperative, and postoperative aspects of anesthetic management for airway surgeries are reviewed in this chapter.
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