<prompt> Cyanosis cannot occur in severe anaemia becauseAnaemic blood has a higher O2 carrying capacity per gram of HbIt requires a critical concentration of reduced Hb in bloodPatient improves his alveolar oxygen as a compensation for anaemiaThere is an increased blood flow through the skin  <response>: Cyanosis seen when deoxygenated hb 4 gm. so in severe anemia where HB less than 4 gm we cannot see cyanosis. 