ENT Procedures Anesthesia Notes

Ear Surgery

• Procedures include myringotomy for middle ear effusion (resulting in conductive hearing loss) and procedures on the mastoid process for mastoiditis (which may occur due to untreated or failed antibiotic response to chronic otitis media).
• Important considerations:
  • Many patients are pediatric.
  • Upper respiratory tract infection is common.
  • Postoperative nausea and vomiting are frequent.
• Ear surgery may involve dissection and preservation of the facial nerve, which has a long intra-osseous course and may be vulnerable to injury.
• The middle ear communicates with the oropharynx via the Eustachian tube, which may be blocked by trauma, edema, inflammation, infection, and large adenoids in children.
• The normal ability to equalize pressures between the inner and outer ear is disturbed if there is a blocked Eustachian tube, which usually allows air to vent into the pharynx.. The pressure in the middle ear may become raised leading to conduction deafness in the chronic situation and tympanic membrane rupture if the pressure rises acutely.
• Nitrous oxide can diffuse into air-filled cavities, including the middle ear, causing expansion of the cavity, leading to an increase in middle ear pressure.
• At the end of the anesthetic, rapid absorption of nitrous oxide can result in profound negative pressure. These changes in middle ear pressure can result in a decline in hearing, tympanic membrane rupture, graft disruption, and nausea and vomiting.
• Positioning during ear surgery usually involves a slight elevation of the head (to reduce bleeding) and turning the patient's head to the contralateral side. The patient's normal range of head movement should be assessed before surgery.
• Access to the airway may be limited during long procedures.
• The endotracheal tube must be carefully secured.
• In procedures such as stapedectomy and mastoidectomy, facial nerve monitoring may be performed, so it is important that neuromuscular paralysis has worn off.
• The need for the patient to be immobile in operations on the ossicles requires deep anesthesia.
• Emergence from anesthesia needs to be smooth so that there is no increase in venous pressure.
• After mastoidectomy, a head bandage will be applied, and much movement of the head can result in coughing and bucking on the endotracheal tube, which is not desirable due to the risk of bleeding, so a deep plane of anesthesia is maintained until the bandage has been applied.
• Postoperative nausea and vomiting can disrupt grafts and prostheses and needs to be controlled.

Nasal Surgery

• Nasal and sinus surgery carries the risk of bleeding into the airway and aspiration of blood.
• It is usually performed under general anesthesia with an endotracheal tube and a throat pack, but some procedures can be carried out under local anesthesia.
• When a throat pack is used, the anesthetist must be certain that it has been removed at the end of surgery. Some anesthetists like to tie the end of the throat pack to the endotracheal tube to ensure it is not left behind.
• Local anesthesia and vasoconstrictors are commonly used to reduce bleeding, even with general anesthesia techniques. Surgeons may infiltrate with adrenaline and apply cocaine. (The maximum cocaine dose should not exceed $1.5 \frac{mg}{kg}$).
• Both adrenaline and cocaine can cause tachycardia, hypertension, and dysrhythmias, especially when used with halothane. Patients must be monitored with an ECG.
• Swallowed blood after emergence will increase the risk of postoperative nausea and vomiting.
• Care should be taken to limit the dose of adrenaline in the presence of halothane anesthesia, as arrhythmias will occur.
• Nasal operations are not usually very painful.
• After the procedure, a direct laryngoscopy is performed, and the pharynx is suctioned under vision.
• There may be some blood in the nasopharynx, so the head is lifted, and the nasopharynx is suctioned after turning the Yankauer sucker through 180 degrees to suction behind the uvula and soft palate.
• Some surgeons will pack the nose after surgery, which can be distressing to the patient after emergence.
• A guedel airway will encourage the patient to breathe through the mouth at this time.
• Mask ventilation may be difficult on emergence, as the surgeon will not want pressure on the nose, particularly after rhinoplasty.
• Reduction of a nasal fracture is a brief procedure that can be performed under brief but deep general anesthesia. This can be achieved in the slight head-up position after adequate pre-oxygenation using fentanyl for analgesia and a bolus dose of propofol, allowing the surgeon to perform the reduction.
• If there is expected to be blood loss, the airway needs to be protected with either a laryngeal mask or endotracheal tube.
• Patients with severe epistaxis may present for internal maxillary artery ligation. They may have lost a substantial amount of blood and commonly have other co-existing diseases, particularly hypertension. Adequate preoperative hydration is important, and it is assumed that they have a full stomach (rapid sequence induction).
• The nasal sinuses may require drainage, and this sometimes requires a surgical approach. The important considerations are the risks of hemorrhage, eye injury, venous air embolism, cerebrospinal fluid leak, and permanent neurologic injury.

Throat Surgery

• Throat surgery involves the sharing of the airway with the surgeon.
• Good management requires excellent communication with the surgeon.
• Patients can present with an abnormal airway that is congenital or acquired (such as infection, tumor, radiation, and foreign body).
• Perioperative airway management must be carefully designed.
• Extubation after airway surgery must be planned.
• Throat packs must be removed, the pharynx suctioned under direct vision, the patient oxygenated, and only extubated after full protective airway reflexes have returned.
• Excessive bleeding, edema, or extensive surgery may make extubation unsafe.

ENT Anesthesia Considerations

• Preoperative Considerations:
  • ENT patients have the highest likelihood of having a difficult airway.
  • IV induction should be avoided if the airway is suspicious. A cooperative patient may be amenable to an awake intubation, whereas an uncooperative patient may require an inhalational induction.
  • Tracheostomy equipment should be immediately available.
  • If paralytics are deemed safe for intubation, consider using SCh because:
    • Many of these patients will have relatively difficult airways.
    • ENT surgeons often stimulate nerves intraoperatively and require this to properly identify them
• Intraoperative considerations:
  • Blood loss can be hidden in the oropharynx and stomach. To minimize blood loss, encourage the use of either cocaine (a vasoconstrictor) or local anesthetics containing epinephrine. Some authors also recommend maintaining a slightly head-up position and providing mild hypotension.
  • Manipulation of the carotid sinus and/or stellate ganglion can cause hemodynamic instability and a variety of dysrhythmias. Injection of the carotid sheath with local anesthetic may be indicated.
  • It is crucial to monitor chest wall motion constantly and to allow sufficient exhalation time to avoid air trapping and barotrauma.
• Postoperative considerations:
  • If there is a chance of postoperative edema involving structures that could obstruct the airway (e.g., tongue), the patient should be carefully observed and perhaps should be left intubated.

Endoscopy

• Endoscopy includes laryngoscopy, esophagoscopy, and bronchoscopy and often entails the use of a laser.
• Many of these patients are being evaluated for hoarseness, stridor, or hemoptysis and may have had airway trauma, an obstructing tumor, vocal cord dysfunction, or tracheal stenosis (some of whom are exceedingly difficult to mask ventilate). The anesthesiologist may want to consult preoperative imaging and should pay particular attention to the airway exam.
• Many of these patients underwent indirect laryngoscopy in the ENT clinic, thus the surgeon may be able to offer valuable anatomical insight
• Profound muscle paralysis is needed for introduction of the suspension laryngoscope and to create an immobile surgical field. Strongly consider mivacurium ($0.2 \frac{mg}{kg}$, 25% recovery in 18 mins) or Cisatracurium ($0.2 \frac{mg}{kg}$. 25% recovery in 55 minutes), both of which allow rapid recovery.
• Adequate oxygenation and ventilation during surgical manipulation of the airway is critical but can be difficult.
• The ideal technique is to connect a jet ventilator to the side port of the laryngoscope, directing 1-2s of 40 psi oxygen towards the glottis, followed by 4-6s of exhalation. Older techniques include intubation with a 4-6 mm tube micro laryngeal tracheal (MLT) tube, intermittent apnea, and insufflation through a small catheter.
• Cardiovascular stability is difficult to achieve secondary to the rapidity with which surgical stimulation varies.
• These procedures are essentially a series of intubations.
• The recommended anesthetic regimen is to maintain a light baseline of TIVA followed by intermittent boluses of propofol or Remifentanil. Regional nerve blocks (ex. glossopharyngeal) greatly smooth the hemodynamic profile