huànzhě / quēyǎng / shí / zuǐchún / hé / zhǐjiǎchuáng / kěnéng / chūxiàn / fāgàn患者缺氧时,嘴唇和指甲床可能出现发绀。When a patient is deprived of oxygen, cyanosis may appear on the lips and nail beds.