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UPPER AIRWAY OBSTRUCTION

AIRWAY PHYSICS

  • Poiseuille's law

    • Q=ΔPπr48ηl; r = Radius of airway

    • Flow (Q) is proportional to the radius to the fourth power; incremental changes in the radius cause exponential decreases in airflow

  • Bernoulli's principle

    • Increased airflow results in a decrease in pressure

    • Narrowed airway → Increased airflow speed → Decreased intraluminal pressure (vacuum) → Further collapse of walls of lumen

  • Stridor – high-speed airflow through collapsed tissues causes vibration and a resonance, resulting in a sound

NOISY BREATHING

  • Physical obstruction of the airway is associated with noise on inspiration or expiration, depending on the site and nature of the lesion

  • Stridor is not only audible, but also visible

    • Examiner should be able to visualize site of obstruction while noise is being made

    • Requires adequate instrumentation techniques of the airway

  • Isolated tachypnea (i.e., without stridor) is not a sign of airway obstruction

SYMPTOMS BY SUBSITE SEE TABLE 20-1

TABLE 20-1

Symptoms by Subsite

LESIONS AND TREATMENTS BY SUBSITE

NASAL OBSTRUCTION

  • Piriform aperture stenosis

    • Bony narrowing of the anterior nasal vestibule in neonates; results in airway-related respiratory distress and feeding problems

    • Diagnosed by computerized tomography (CT) scan showing <8 mm patency between nasal processes of maxillary bone

    • Can be associated with holoprosencephaly (central incisor) or choanal atresia

    • Treatment: sublabial approach to nasal vestibule with high-powered drill reduction of nasal process of maxillary bone

  • Choanal atresia/stenosis

    • Incomplete or uncannulated opening from the nose to the nasopharynx in neonates; results in airway-related respiratory distress

    • CHARGE syndrome (coloboma, heart defects, atresia choanae, growth retardation, genital abnormalities, and ear abnormalities)

    • May go undiagnosed if unilateral

    • Treatment: transnasal or transpalatal resection of posterior obstructive tissues

PHARYNGEAL OBSTRUCTION

  • Adenotonsillar disease

    • Most common cause of obstructive sleep apnea (OSA) in children

    • Diagnosed by direct visualization on exam and attended nocturnal polysomnogram

    • Treatment: adenotonsillectomy adequately treats >80% of patients with pharyngeal airway obstruction

  • Pharyngomalacia

    • Poor pharyngeal muscle tone, results in collapse of tissues and obstruction with stertor

    • Treatment: noninvasive positive pressure ventilation (continuous or bilevel)

  • Glossoptosis/macroglossia (Figure 20-1)

    • Tongue and tongue base obstruction of the airway

    • Pierre-Robin's sequence, Down's syndrome, lingual tonsil hypertrophy, isolated micrognathia, Ludwig's angina (anterior floor of mouth abscess)

    • Treatment: alleviate obstruction by ...

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