Anesthesia for Otolaryngologic Surgery

Significant obstruction and anatomic distortion caused by tumor, infection, or trauma may be present in a patient with minimal evidence of disease because clinically evident upper airway obstruction is a late sign (Ferrari LR, Nargozian C. Anesthesia for otolaryngologic surgery. In: Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Ortega R, Stock MC, eds. Clinical Anesthesia. Philadelphia: Lippincott Williams & Wilkins; 2013:1356–1372). In the presence of tumor or infection in the airway, radiologic evaluation, computed tomography, and magnetic resonance imaging studies of the airway may help the anesthesiologist determine the most appropriate technique for securing the airway.

I. Anesthesia for Pediatric Ear, Nose, and Throat Surgery

Tonsillectomy and Adenoidectomy. Patients with cardiac valvular disease are at risk for endocarditis from recurrent streptococcal bacteremia secondary to infected tonsils. Tonsillar hyperplasia may lead to chronic airway obstruction, resulting in obstructive sleep apnea (OSA) syndrome, carbon dioxide retention, and cor pulmonale.

Preoperative evaluation includes a thorough history (antibiotics, aspirin-containing medications, sleep apnea) and physical examination (wheezing, stridor, mouth breathing, tonsillar size). In children with a history of cardiac abnormalities, an echocardiogram may be indicated.
Sleep disordered breathing (SDB) and obstructive sleep apnea syndrome (OSAS) is a spectrum of disorders ranging from primary snoring (10% of the population) to obstructive sleep apnea (1%–4% of the population).
- Proper screening and diagnosis of OSAS before surgery is essential in reducing the associated risks (STOP questionnaire for adults) (Table 47-1).
  
  Table 47-1 Stop Questionnaire to Screen Adult Patients for Obstructive Sleep Apnea
  
  Snoring, daytime somnolence
  Tiredness
  Observation of apnea during sleep
  Pressure elevations
- Obesity is a predisposing physical characteristic (changes craniofacial anthropometric characteristics) that increases the risk of OSAS.
- Pharyngeal muscle contraction is controlled by neural mechanisms that determine pharyngeal airway size. Increased neural activity can compensate during wakefulness, but suppression during sleep or anesthesia may result in narrowing of the pharyngeal airway.
- The long-term effects of OSAS are not limited to the airway (cognitive dysfunction from episodic hypoxia, metabolic syndrome, systemic and pulmonary hypertension).

Anesthetic Management (Table 47-2)

Sedative premedication should be avoided in children with OSA. Premedication often includes an antisialagogue.

Induction of anesthesia is usually with a volatile anesthetic and nitrous oxide (parental presence is a consideration, especially with an anxious child) followed by administration of a nondepolarizing muscle relaxant to facilitate tracheal intubation.

Table 47-2 Goals of Anesthesia for Tonsillectomy and Adenoidectomy

Render the patient unconscious in the most atraumatic manner possible.
Provide the surgeon with optimal operating conditions.
Establish IV access for volume expansion (when necessary) and medications.
Ensure rapid emergence (ability to protect the recently instrumented airway).

IV = intravenous.

A specially designated laryngeal mask airway that easily fits under the mouth gag permits surgical access while the lower airway is protected from exposure to blood during the procedure. Positive-pressure ventilation should be avoided, although gentle assisted ventilation is both safe and effective if peak inspiratory pressure is kept below 20 cm H₂O.
Emergence should be rapid, and the child should be able to clear blood or secretions from the oropharynx. (Maintenance of a patent upper airway and pharyngeal reflexes is important in the prevention of aspiration, laryngospasm, and airway obstruction.)
It is recommended that patients be observed for early hemorrhage for the first 6 hours and be free from significant nausea, vomiting, and pain before discharge.

Complications (Table 47-3)
- Preoperative preparation of the patient who requires return to the operating room for surgical hemostasis includes hydration. (The practitioner should check for orthostatic changes.)
- A rapid sequence induction of anesthesia with a styletted endotracheal tube is often recommended.
- Dependable suction is mandatory because blood in the pharynx may impair visualization.

Hospital Discharge. Patients undergoing adenoidectomy may be safely discharged on the same day after recovering from anesthesia. The trend is also to discharge patients undergoing tonsillectomy on the day of surgery.

Table 47-3 Postoperative Complications of Tonsillectomy

Emesis: Occurs in 30%–65% of patients; mechanism unknown but may include the presence of irritant blood in the stomach
Dehydration
Hemorrhage: 75% occurs in first 6 hrs after surgery; if surgical hemostasis is required, a full stomach and hypovolemia should be considered
Pain: Minimal after adenoidectomy and severe after tonsillectomy
Postobstructive pulmonary edema: Rare but possible if the patient has had a prior acute upper airway obstruction; treatment may include supplemental oxygen and administration of diuretics