As the newborns lungs have narrow tracheas and bronchi, and tender larynx, repeated spastic coughs produce more excretion to block the respiratory way and lead to spasm of larynx, thus bringing about obstruction of ventilation, anoxia and suffocation.

• 小儿气管、支气管内径狭窄、喉软骨柔嫩,反复痉咳刺激致使分泌物阻塞,喉头痉挛,继尔发生阻塞性换气不良,缺氧,窒息。