Stridor 2009-07-12T02:16:48Z SNOMEDCT_US:70407001 Stridor is different from wheezing by the following reasons. It is louder over the neck than chest wall. Secondly; stridor is mainly inspiratory. If occurs in expiration, it is usually biphasic. On the other hand; wheeze is mainly expiratory and occurs during both phases. It indicates extrathoracic upper-airway obstruction (supraglottic lesions like laryngomalacia, vocal cord lesion) when heard on inspiration. It occurs in expiration if associated with intrathoracic tracheobronchial lesions (tracheomalacia, bronchomalacia, and extrinsic compression). It occurs in both phases if lesion is fixed, for example, stenosis. Stridor is caused by the turbulent flow passing through a narrowed segment of the upper respiratory tract. HP:0010307 SNOMEDCT_US:248573009 Stridor is a high pitched sound resulting from turbulent air flow in the upper airway. Noisy breathing UMLS:C0038450 UMLS:C0237304 Abnormal breath sound