The degree of respiratory obstruction is difficult to assess as it may vary from moment to moment. Stridor usually becomes worse if the child cries or becomes agitated. Therefore stridor in a quiet child should be regarded as severe.
- Inspiratory stridor only, without lower chest wall indrawing (recession or retraction) suggests mild airway obstruction. These children usually only have stridor when they are upset or crying. There is no stridor when they are sleeping or at rest.
- The addition of lower chest wall indrawing or stridor during both inspiration and expiration are very important clinical signs as they indicate worsening airways obstruction. Therefore, expiratory stridor is a sign of severe airway obstruction. Stridor at rest in a quiet child also suggests severe stridor.
- The obvious use of chest and abdominal muscles during expiration (active expiration, restlessness or fast breathing (tachypnea) are signs of dangerous airway obstruction obstruction.
Expiratory stridor is a sign of worsening airway obstruction.
Disappearance or weakening of the peripheral pulse on light palpation during inspiration (pulsus paradoxis), marked recession, apathy and cyanosis are signs of severe airway obstruction. Stridor becomes softer with severe obstruction.