Chapter 37: Anesthesia for Otolaryngology–Head & Neck Surgery

KEY CONCEPTS

• The anesthetic goals for laryngeal endoscopy include an immobile surgical field and adequate masseter muscle relaxation for introduction of the suspension laryngoscope (typically profound muscle paralysis will be sought), adequate oxygenation and ventilation, and cardiovascular stability despite periods of rapidly varying surgical stimulation.

• During jet ventilation, chest wall motion must be monitored and sufficient exhalation time allowed in order to avoid air trapping and barotrauma.

• The greatest concern during laser airway surgery is an airway tube fire. This risk can be moderated by minimizing the fraction of inspired oxygen (FiO₂ <30% if tolerated by the patient) and can be eliminated when there is no combustible material (eg, flammable endotracheal tube, catheter, or dry cotton pledget) in the airway.

• Techniques to minimize intraoperative blood loss include topical vasoconstriction with cocaine or an epinephrine-containing local anesthetic for vasoconstriction, maintaining a slightly head-up position, and providing a mild degree of controlled hypotension.

• If there is serious preoperative concern regarding potential airway problems, intravenous induction may be avoided in favor of awake direct or fiberoptic laryngoscopy (cooperative patient) or direct or fiberoptic intubation following an inhalational induction, maintaining spontaneous ventilation (uncooperative patient). In any case, the appropriate equipment and qualified personnel required for emergent tracheostomy must be immediately available.

• The surgeon may request the omission of neuromuscular blockers during neck dissection, thyroidectomy, or parotidectomy to allow nerve identification (eg, spinal accessory, facial nerves) by direct nerve stimulation and thereby facilitate their preservation.

• Manipulation of the carotid sinus and stellate ganglion during radical neck dissection has been associated with wide swings in blood pressure, bradycardia, arrhythmias, sinus arrest, and prolonged QT intervals. Infiltration of the carotid sheath with local anesthetic will usually moderate these problems. Bilateral neck dissection may result in postoperative hypertension and loss of hypoxic drive due to denervation of the carotid sinuses and bodies.

• Patients undergoing maxillofacial reconstruction or orthognathic surgical procedures often pose airway challenges. 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 risk of postoperative edema involving structures that could obstruct the airway (eg, tongue, pharynx), the patient should be closely observed and perhaps kept intubated.

• Nitrous oxide is either entirely avoided during tympanoplasty or discontinued prior to graft placement.