Fluctuating Pulse Oximetry Readings in an Adolescent With Hemoglobin Bibba: A Case Report.

Hemoglobinopathies caused by unstable hemoglobins represent a wide group of diseases that include hemoglobin Bibba. Hemoglobin instability may cause chronic hemolytic anemia and conformational changes in hemoglobin that affect affinity for oxygen and absorption of wavelengths of light used in pulse oximetry devices. We report the case of an adolescent with hemoglobin Bibba and α-thalassemia. SpO2 was unexpectedly low despite stable vital signs when his hemoglobin was closer to 10 g/dL and normal when his hemoglobin was lower, presumably when there was less unstable hemoglobin because of hemolysis.