Post-Extubation Stridor: Sensitivity and Specificity

Introduction: Laryngeal edema around the ET tube that causes upper airway obstruction when the tube is removed during extubation, thus requiring re-intubation.

Generally it is felt that one should test for an air leak around the ET tube (after deflating the cuff) to indicate that the larynx has not swelled. One can test either by listening with a stethoscope or by looking at the vent monitors.

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Prevalence

Population / Calculator	Prevalence	Comments / Study / Link
Intubated patients	4.6%	Respir Care. 2005 Dec;50(12):1632-8. PMID 16318644
Intubated patients	1.6%	severe enough to require reintubation Respir Care. 2005 Dec;50(12):1632-8. PMID 16318644
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The sensitivity and specificity of findings for Post-Extubation Stridor are listed below. See the left navigation bar to change the display.

Pre-Test Probability (Prevalence): %.	Post-Test Probability (Predictive Value): %.	Switch to display mode.
Note that calculating probabilities from more than one** finding is inherently inaccurate because findings are not independent. (For example, using two positive findings that share a common pathogenesis is likely to overestimate the true probability.)

Poorly Diagnostic Findings
Finding	Result	Sensitivity	Specificity
[ + ] Cuff Leak Test	+ 0 -	50%	84%
defined by an absolute leak volume < or = 110 mL Other studies have given a range of sensitivity from 15-85% and specificity of 72-99%, e.g. PMID 12528025 and PMID 12209275. However, given the relatively low prevalence (5-12% in the studies cited), the positive predictive value would still be poor and the negative predictive value still rather good. Study: Respir Care. 2005 Dec;50(12):1632-8. PMID 16318644