What are the indications for adenotonsillectomy?

The most common indication for adenotonsillectomy (AT) in pediatric patients is sleep-disordered breathing. Obstructive sleep apnea (OSA) is an extreme form of sleep-disordered breathing. Other indications include recurrent pharyngitis, peritonsillar abscess, dysphagia, asymmetric tonsillar hypertrophy, halitosis, and posttransplant lymphoproliferative disorder. Indications for adenoidectomy without tonsillectomy are adenoidal hypertrophy, chronic sinusitis, adenoiditis, and recurrent otitis media.

What is the pathophysiology of obstructive sleep apnea, and how is it diagnosed?

Respiration involves chest wall expansion and diaphragm descension, both of which create negative intrapleural pressure. This negative pressure is distributed throughout the lower and upper airway. Negative pressure in the pharynx tends to draw soft tissues inward, predisposing to upper airway obstruction. During sleep, airway patency is maintained despite a decrease in pharyngeal muscle tone. This situation may be altered in the presence of neuromuscular hypotonia or craniofacial abnormalities or when alcohol or sedatives are taken ( Box 65-1 ). Tonsillar hypertrophy exacerbates upper airway obstruction in two ways. First, it encroaches on the airway, narrowing its cross-sectional area. Second, when the cross-sectional area is reduced sufficiently, airflow through the stenosed pharynx increases, which produces reduced pressure inside the pharynx by the Bernoulli effect. The additional decrease in pharyngeal pressure draws soft tissues farther into the airway and exacerbates upper airway obstruction. Patients with neuromuscular or craniofacial disorders are at increased risk for OSA, especially if tonsillar hypertrophy coexists.

BOX 65-1

Congenital Conditions Associated with Obstructive Sleep Apnea

  • Acromegaly

  • Apert syndrome

  • Crouzon syndrome

  • Goldenhar syndrome

  • Hurler syndrome

  • Hunter syndrome

  • Pierre Robin sequence

  • Treacher Collins syndrome

  • Trisomy 21

Airway obstruction results in hypoxia and hypercarbia that trigger the brainstem arousal reflex causing increased pharyngeal tone. When pharyngeal dilator muscles contract, soft tissues are moved out of the airway lumen, and airway patency is improved. This series of events occurs many times during sleep, disrupting the normal sleep cycle. Symptoms consist of snoring, breathing pauses, gasping, and use of accessory respiratory muscles. Enuresis and excessive sweating may also occur. If the sleep cycle is significantly disturbed, daytime somnolence is present as well.

Chronic hypoxia and hypercarbia lead to pulmonary vasoconstriction and pulmonary hypertension. Right atrial enlargement, right ventricular hypertrophy, and ultimately right-sided heart failure (cor pulmonale) develop if OSA is not treated early ( Figure 65-1 ). Polycythemia may occur in response to chronic hypoxia.

FIGURE 65-1 ■

Pathophysiology of OSA.

The “gold standard” for the diagnosis of OSA is polysomnography. Polysomnography is an overnight sleep study during which electroencephalogram, electromyogram, electrocardiogram (ECG), pulse oximetry, airflow, and thoracic and abdominal movements are monitored. The number of obstructed breaths, percentage of decreased airflow, and degree of oxygen desaturation are used to determine whether obstructive apnea or hypopnea is present. Obstructive apnea is defined as >90% decrease in airflow despite respiratory effort. Obstructive hypopnea is defined as >50% decrease in airflow despite respiratory effort and a >3% decrease in oxygen saturation. The apnea-hypopnea index determines the severity of OSA. Severe OSA is defined as an apnea-hypopnea index score >10 and oxygen desaturation nadir <80%. In the absence of a polysomnography study, the parent’s description of the symptoms or home sleep video is used to determine the need for AT.

What should be included in the preoperative evaluation for adenotonsillectomy?

The preoperative evaluation should be directed at assessment of the airway, cardiopulmonary system, and bleeding history ( Box 65-2 ). Tonsillar hypertrophy is classified according to the percentage of pharyngeal airway it occupies, as follows:

  • +1 = <25%

  • +2 = 25–50%

  • +3 = 50–75%

  • +4 = >75%

BOX 65-2

Preoperative Evaluation of Patients with Severe Obstructive Sleep Apnea

  • Airway

    • Tonsillar size

    • Craniofacial abnormalities

  • Pulmonary

    • Arterial blood gas

  • Cardiac

    • Electrocardiogram

    • Echocardiogram

    • Chest x-ray

    • Cardiac consultation

  • Hematology

    • Hemoglobin and hematocrit

  • Bleeding history

    • Coagulation studies

    • Platelet count

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Jul 14, 2019 | Posted by in ANESTHESIA | Comments Off on Adenotonsillectomy
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