TYK71
What is the MINIMAL level of deoxygenated hemoglobin is required for CLINICAL cyanosis?
A. 0.5 g/dL
B. 1 g/dL
C. 3 g/dL
D. 7 g/dL
E. 9 g/dL
Answer
The answer is C.
It is generally written that you must have a minimum of 3-5 g/dL of deoxygenated hemoglobin to see clinical cyanosis. Ok, so this isn't the most exact question in the world...but it does have clinical significance. If a child comes in with severe chronic anemia (like our iron and folate deficiencies from the past) and has a hemoglobin of 3-5 g/dL a pulse oximetry reading of 60-70% may not give you CLINICAL cyanosis, but you should probably believe the number. BTW, if that happens the child's oxygen delivery has now gone from bad to worse. This is different than methemoglobinemia which usually has clinical signs of cyanosis at a methemoglobin level of 1.5 g/dL.
Notes