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The anesthetic goals for laryngeal endoscopy include profound muscle paralysis to provide masseter muscle relaxation for introduction of the suspension laryngoscope and an immobile surgical field, adequate oxygenation and ventilation during surgical manipulation of the airway, and cardiovascular stability during periods of rapidly varying surgical stimulation.- During jet ventilation, it is crucial to monitor chest wall motion and to allow sufficient time for exhalation in order to avoid air trapping and barotrauma.
- The greatest concern during laser airway surgery is an endotracheal tube fire. This risk can be minimized by using a technique of ventilation that does not involve a flammable tube or catheter (eg, intermittent apnea or jet ventilation through the laryngoscope side port), or by using a laser-resistant endotracheal tube and lowering the fraction of inspired oxygen (ideally, as close to 21% as possible, consistent with adequate tissue oxygenation, as monitored by pulse oximetry) and not using nitrous oxide.
- Techniques to minimize intraoperative blood loss include the use of cocaine or an epinephrine-containing local anesthetic for vasoconstriction, maintaining a slightly head-up position, and providing a mild degree of controlled hypotension.
- As always, if there is serious preoperative concern regarding potential airway problems, an intravenous induction may be avoided in favor of awake direct or fiberoptic laryngoscopy (cooperative patient) or an inhalational induction while maintaining spontaneous ventilation (uncooperative patient). In any case, the appropriate equipment and qualified personnel required for an emergency tracheostomy must be immediately available.
- The surgeon may request the omission of neuromuscular blockers during neck dissection or parotidectomy to identify nerves (eg, spinal accessory, facial nerves) by direct stimulation and to preserve them.
- Manipulation of the carotid sinus and stellate ganglion during radical neck dissection (the right side more than the left) has been associated with wide swings in blood pressure, bradycardia, dysrhythmias, sinus arrest, and prolonged QT intervals. Infiltration of the carotid sheath with local anesthetic will usually ameliorate these problems. Bilateral neck dissection may result in postoperative hypertension and loss of hypoxic drive because of denervation of the carotid sinuses and bodies.
- Patients undergoing maxillofacial reconstruction or orthognathic surgical procedures often pose the greatest airway challenges to the anesthesiologist. If there are any anticipated signs of problems with mask ventilation or tracheal intubation, the airway should be secured prior to induction of general anesthesia.
- If there is a chance of postoperative edema involving structures that could obstruct the airway (eg, tongue), the patient should be carefully observed and perhaps should be left intubated.
- Nitrous oxide is either entirely avoided during tympanoplasty or discontinued prior to graft placement.
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Anesthesia for Otorhinolaryngologic Surgery: Introduction
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In few other circumstances are cooperation and communication between surgeon and anesthesiologist more important than during airway surgery. Establishing, maintaining, and protecting an airway in the face of abnormal anatomy and simultaneous surgical intervention are demanding tasks. An understanding of airway anatomy (see Chapter 19) and an appreciation of common otorhinolaryngologic and maxillofacial procedures are invaluable in handling these anesthetic challenges.