We present 2 cases of dynamic airway obstruction with respiratory failure leading to cardiac arrest. Both have significant aetiology of cystic thyroid mass with sudden haemorrhagic changes leading to airway obstruction. We discuss the plausible pathophysiology leading to cardiopulmonary compromise where tracheobronchomalacia (TBM) and excessive dynamic airway collapse (EDAC) play a significant role. We note that this is under recognised and can be present as a life-threatening event. Recognition of these pathophysiology process facilitate surgical management of thyroid obstructive airway disease.