What anesthetic alternatives are available for patients undergoing adenotonsillectomy?
The anesthetic alternatives for adenotonsillectomy are varied. Induction of anesthesia may proceed following the application of a blood pressure cuff, precordial stetho-scope, pulse oximeter, electrocardiogram, and temperature probe. The primary concern is airway patency, necessitat-ing early initiation of capnography. Establishment of intra-venous access is ideally accomplished before induction of anesthesia, but if not, this becomes a top priority after induction. Sometimes, uncooperative children and adults require inhalation induction without the benefit of prehy-dration or rapid-acting medications. Anticipated difficult mask airways and difficult intubations suggest the need for awake intubation under topical anesthesia. An inhalation induction with assisted ventilation represents an alterna-tive approach. As anesthetic depth increases, pharyngeal muscles and soft tissues become lax, resulting in exacer-bated airway obstruction. Oral or nasal airway placement carries the potential for worsening obstruction if sufficient anesthetic depth has not yet been achieved. A popular maintenance anesthetic in children includes sevoflurane, nitrous oxide, oxygen, and muscle relaxant. Propofol hastens the early return of airway reflexes, lucidity, and cooperation. Substituting rofecoxib, a selective COX-2 inhibitor, for opiates can minimize postoperative respiratory depression. Rofecoxib does not alter central respiratory drive and does not have significant antiplatelet effects. Its current major drawback may be cost.
Although 4% lidocaine spray to the larynx as well as lidocaine injection into the tonsillar bed helps to reduce afferent sensory input from the surgical field, they are potentially detrimental. Reduced airway sensation predis-poses to aspiration pneumonia.
Over the years, recurrent problems with intraoperative endotracheal obstruction have popularized the use of preformed tubes, which adapt well to many mouth gags and minimize interference with surgical manipulations. Although the endotracheal tubes are unlikely to be kinked at the level of the mandibular incisors, potential still exists for endotracheal tube compression by the tongue blade in the hypopharynx. The increased risk for endotracheal tube dis-lodgement, kinking, and compression predisposes patients to hypoxia and hypercarbia, underscoring the importance of capnography and pulse oximetry. Precor-dial stethoscopes may detect a mainstem endobronchial intubation.
Ventricular dysrhythmias are a recognized complication of adenotonsillectomy. Their appearance frequently signals inappropriate depth of anesthesia, hypoxia, hypercarbia, or absorption of dysrhythmogenic drugs. Deepening the anesthetic readily treats light levels of anesthesia. Surgeons may administer epinephrine into the operative field. The resulting dysrhythmias are usually short-lived and generally require no treatment.
Swallowed blood frequently culminates in nausea and vomiting. To help minimize this problem, an orogastric tube is placed and the stomach contents aspirated before emergence. An awake extubation is preferable to protect against aspiration, but deep extubation is sometimes chosen. Deep extubation helps prevent violent coughing, profound straining, and bronchospasm during emergence. After deep extubation, the patient is placed in the lateral decubitus position, the table is moved to a slight head-down position, the head is turned to the side, and the upper hand is situated under the patient’s chin. Administering intravenous lidocaine, which may also slightly impair emer-gence, can reduce the risk of laryngospasm. Humidified oxygen is administered in the postanesthesia care unit.