ENT surgery requires exquisite cooperation between the anesthesiologist and surgeon. ENT operations entail several unique considerations, which are best thought of in terms of timing.
Of all patient groups, ENT patients have the highest likelihood of having a difficult airway. As with other patients, IV induction should be avoided if the airway is suspicious – the cooperative patient may be amenable to an awake intubation, whereas the uncooperative patient may require an inhalational induction. Tracheostomy equipment should be immediately available.
If paralytics are deemed safe for intubation, consider using SCh for two reasons – first, many of these patients will have a relatively difficult airway, and second, ENT surgeons often stimulate nerves intraoperatively, and require kinesis to properly identify them.
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.
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 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), thus the anesthesiologist may want to consult preoperative imaging and should pay particular care 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 mg/kg, 25% recovery in 18 mins) or cisatracurium (0.2 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 microlaryngeal 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) are greatly smooth the hemodynamic profile.
Foreign Body Removal
Often accomplished using direct laryngoscopy and/or rigid bronchoscopy and in the absence of positive pressure ventilation. Humidified oxygen combined with TIVA (to avoid exposure of the surgeon) is recommended.
Laser Surgery and Airway Fires
Can be accomplished with (volatile anesthetics may be used) or without (TIVA + jet ventilation) endotracheal intubation. PVC endotracheal tubes must be avoided, as they are flammable.
YAG lasers have a 10-fold shorter wavelength (1065-1320 nm) than CO2 lasers (10,600 nm), and therefore has much better tissue penetration. The greatest fear during laser airway surgery is an airway fire, thus an armored tube is usually indicated – fill the proximal cuff with saline/methylene blue. FiO2 should be minimized, saline-soaked pledgets should be placed in the airway, and water should be immediately available in a 60 cc syringe.
If an airway fire occurs 1) disconnect the circuit 2) remove the ETT and 3) if the fire continues, flood the field with saline. Direct examination with bronchoscopy is indicated, followed by reintubation following assessment of damage.
All OR personnel should wear special glasses and both special masks and a smoke evacuator should be used.
Common Surgical Procedures
Tonsils and Adenoids
Patients who present for T&A often have OSA, which manifests as snoring, enuresis, somnolence, personality changes, and growth disturbances. Their airway management is complicated by obesity, large tongues, short thick necks, and redundant tissue. Patients for T&A frequently suffer from URIs, in which case surgery is often postponed 7-14 days in order to reduce the risk of laryngospasm. Some T&A patients will also suffer from GERD because they generate supranegative intrathoracic pressures.
During induction, it may be prudent to have an otolaryngologist present. Consider placing an oral RAE for surgical convenience. Pack the supraglottic area with gauze (minimizes aspiration of blood), and place an OG tube prior to extubation.
Post-operatively, dexamethasone may alleviate pain. Children under four should probably be observed for 24 hours postoperatively, as there have been case reports of airway obstruction as far as 24 hours after surgery.
Nasal and Sinus Surgery
Common pathologies include polyps, deviated septi, or infections, all of which lead to obstruction (hence the diagnosis) and can lead to difficult mask ventilation.
Often, nasal operations can be performed under exclusively local anesthesia and sedation in the ENT office – the anterior ethmoidal and sphenopalatine nerves can be blocked by packing these nose with local anesthetic-soaked gauze for at least 10 minutes, although subsequent SQ injections are often required (cocaine or LA with epi).
Because local blocks often require additional injections, some surgeons prefer general anesthesia, in which case oral airways, oral RAE tubes, and deep paralysis (movement while working in the sinus can lead to severe ophthalmologic complications) are recommended.
Placement of a posterior pack and supplementing LA with epinephrine (or using cocaine, max dose 3 mg/kg) can help control blood loss.
Head and Neck Surgery
The major preoperative concern is the potential for difficult airway (due to radiation). SCh is often indicated because NMBDs will interfere with nerve monitoring. Meticulous planning should occur as many of these patients are elderly with long histories of smoking and multiple medical problems.
Because of medical comorbidities and the potential for major blood loss, an arterial line is often indicated (frequent lab draws, hemodynamic swings). Intraoperative hemodynamic management may be further complicated by carotid-bulb induced bradycardia (can be attenuated by local anesthetic infiltration into the carotid sheath). Always place a second IV, and if a central line is indicated, consider using the femoral vein.
Often an intraoperative tracheostomy is performed. Ventilate with 98% oxygen (~ 2% inhaled agent), suction the hypopharynx, then deflate the cuff after the surgeon as reached the trachea. Once the tracheal wall has been penetrated, pull the ETT back slightly, allowing the tracheal tube to be inserted, then remove entirely.
If a microvascular free flap is created, a relatively low hematocrit (27–30%) may be desirable.
Post-operatively, one should have a high suspicion for nerve injuries (facial, recurrent laryngeal, phrenic).
Parotid Gland Surgery
Parotid gland surgery often requires nerve monitoring (facial nerve) and may require nasotracheal intubation so that the mandible can be dislocated.
Maxillofacial Reconstruction & Orthognathic Surgery
Usually for trauma, to correct malformations, or for radical cancer operations. These patients often pose the greatest airway challenges, thus the anesthesiologist should consider securing the airway prior to induction. Many of these patients will require a nasal RAE (although not LeFort II-III). Take particular care securing the airway, as access will be limited during the operation.
Intraoperatively, substantial blood loss can occur, thus a second IV is mandatory (especially since arms are often tucked).
Requires GA and often requires neuromonitoring (thus avoidance of NMBDs). Nitrous oxide is either entirely avoided during tympanoplasty or discontinued prior to graft placement. Postoperatively, PONV is common, thus consider a TIVA.
Myringotomy/tube insertion is so rapid that premedication should be avoided (will outlast the procedure) – GA with facemask will usually suffice.
Middle ear and mastoid procedures are more extensive and often require intubation with a RAE tube. Patients are often extubated deep in order to prevent disruption of repairs / TM graft displacement. The stomach should be decompressed prior to extubation, and antiemetics should be strongly considered.
Often present with fever, dysphagia/drooling, muffled voice, head extension, retractions, difficulty breathing, and cyanosis. Do NOT attempt to visualize the epiglottis and minimize patient interactions. A tracheostomy tray should be immediately located, and induction should then proceed using sevoflurane (which is less irritating than other agents). Patients usually remain intubated for at least 48 hours.