It is bluish discoloration of skin and mucous membrane due to increased deoxyhemoglobin in blood.
Examine the tongue, soft palate, buccal mucosa, lower palpebral conjunctiva and peripheral sites.
It is seen in cyanotic congenital heart diseases like TOF,Truncus arteriosus and respiratory conditions like acute severe asthma,COPD,Cor pulmonale.
Examine tip of nose, ear lobules, outer aspect of lips and nail beds.
It is seen in Congestive heart failure, PVD, Raynaud’s phenomenon, frost bite.
To differentiate central and peripheral cyanosis, massage the ear lobules for 30 seconds,bluish discoloration disappears in peripheral cyanosis whereas it remains the same in central cyanosis.