The increased CO2 levels in the blood can get so bad that some people develop cyanosis, which is a blue discoloration of the skin, and this is why patients with chronic bronchitis are sometimes referred to as blue bloaters.

血中二氧化碳含量升高可能引起发绀，即患者的皮肤会变蓝，这就是为什么慢支患者又被比做蓝鲱鱼。