Question

(25) A 3-month-old baby girl is diagnosed with grade Ill subglottic stenosis with 80% obstruction of the subglottis. The patient is taken to the operating room, where she is sedated and undergoes balloon dilation. After the procedure, the stenosis is classified as grade Il with 55% obstruction. In cases of severe obstruction, upper airway resistance can be described by the Bernoulli Obstruction Theory, which predicts that the relationship between inhalation rate (Q) and airspace cross-sectional area at the trachea (A) is Q = A CD 2 Ap 11 - B4 where CD is a constant, Ap is the pressure drop from nostrils to trachea, p is the air density and B is the ratio of the airway diameter at the constriction to the airway diameter downstream of the constriction. Estimate the percentage increase in the inhalation rate ( after the balloon dilation for a constant pressure drop Ap. Assume that the ratio B is small, so that B -0. Figure: Subglottic stenosis is a congenital or acquired narrowing of the subglottic airway. It can present as a life- threatening airway emergency due to airflow limitation The figure shows an endoscopic view of a grade III subglottic stenosis in a child

Answer 1

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