<s>[INST] context: late sign of Hypoxia Cyanosis is a late sign of hypoxia. In a trauma patient one should not wait for cyanosis to identify hypoxia and other signs of hypoxia should be looked for. If cyanosis is seen it means that hypoxia is profound. Reason- Cyanosis is seen when more than 5 g of hemoglobin per 100 mL of blood are desaturated. For a person with a normal hemoglobin concentration of 15 g/100 mL, cyanosis appears only when one-third of the blood is desaturated. Thus cyanosis appears late. Cyanosis may appear even later in a person with anemia. He may have a significant poion of the hemoglobin desaturated without displaying cyanosis. This individual will not appear cyanotic but may be profoundly hypoxic. (e.g. if an anemic person has haemoglobin conc. of 8 gm/100 mL, he will develop cyanosis only when more than 60% of his blood is desaturated.) Conversely, a polycythemic person may develop cyanosis early, sometimes even under otherwise normal condition, as there is great excess of haemoglobin. (For e.g. if his Hb conc. is 20 gm/mL, he needs only 20% of desaturated blood to produce cyanosis.) [/INST] question: Cyanosis in trauma is interpreted as: | options: A: Early sign of hypoxia B: Late sign of Hypoxia C: Absence of cyanosis means adequate tissue ventilation D: Absence of cyanosis means adequate tissue oxygenation | answer: B </s>