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The “air leak” test around the endotracheal tube, as a predictor of postextubation stridor, is age dependent in children

Mhanna, Maroun J. MD; Zamel, Yaacov B. MD; Tichy, Cathleen M. NP; Super, Dennis M. MD, MPH

CLINICAL INVESTIGATIONS
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Objectives The airleak test is measured with a manometer as the pressure necessary to generate an audible airleak around the endotracheal tube. Our objectives were to determine whether the airleak test predicts postextubation stridor in children and if age affects its sensitivity and specificity.

Design A retrospective study.

Setting Pediatric intensive care unit.

Patients We studied all intubated patients admitted to our pediatric intensive care unit between July 1998 and December 1999. Patients were excluded if they had acute viral croup, tracheal surgery, hypotonic airway, or vocal cord paralysis or if they died before extubation.

Interventions Medical records were reviewed for patient demographics, presence of an airleak on the day of extubation, airleak values, presence of postextubation stridor, and extubation failure secondary to upper airway obstruction.

Measurements and Main Results One hundred and five patients met our inclusion criteria and had an airleak test at the time of extubation. In children <7 yrs of age, the incidence of postextubation stridor was similar in patients with or without an airleak at >20 mm Hg (50% vs. 67.7%;p > .05) with a sensitivity of 65.6% (95% confidence interval, 46.9–80.8). In children ≥7 yrs of age, the incidence of postextubation stridor was greater in patients with an airleak at >20 mm Hg (55.5% vs. 5.8%;p = .01) with a sensitivity of 83.3% (95% confidence interval, 36.8–99) in predicting postextubation stridor.

Conclusions Our study suggests that the airleak test has a low sensitivity when used as a screening test to predict postextubation stridor in young children (<7 yrs old), whereas in older children (≥7 yrs old) the airleak test may predict postextubation stridor.

From the Department of Pediatrics, Division of Pediatric Critical Care, MetroHealth Medical Center, Case Western Reserve University, Cleveland, OH.

Supported, in part, by general clinical research center grant MO1 RR00080 from the National Institutes of Health, Bethesda, MD, awarded to Case Western Reserve University, Cleveland, OH.

Address requests for reprints to: Maroun J. Mhanna, MD, Department of Pediatrics, MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland, OH 44109. mmhanna@metrohealth.org

Our study suggests that the air leak test (ALT) has a low sensitivity when used as a screening test to predict postextubation stridor in patients <7 yrs old, whereas in older patients (≥7 yrs old), the ALT may predict postextubation stridor and its severity.

© 2002 by the Society of Critical Care Medicine and Lippincott Williams & Wilkins