<prompt> Cyanosis in trauma is interpreted asEarly sign of hypoxiaLate sign of hypoxiaAbsence of cyanosis means adequate tissue ventilationAbsence of cyanosis means adequate tissue oxygenation  <response>: Cyanosis is a bluish discoloration of the skin, mucous membranes, tongue, lips, or nail beds and is due to an increased concentration of reduced hemoglobin Hb in the circulation. Clinically evident cyanosis typically occurs at an oxygen saturation of 85 or less. Mild cyanosis may be difficult to detect Ref: guyton and hall textbook of medical physiology 12 edition 