Very rare. Unstable hemoglobin due to a mutation in the ß chain (in position 88) where a leucine is replaced by a proline. This causes instability of hemoglobin with chronic hemolytic anemia (dark urines, splenomegaly) and vesicular lithiasis. In addition, its affinity for oxygen is increased (P50 = 22.5 mmHg in place of 27 mmHg for normal hemoglobin) but its structural modification causes a falsely low  value of saturation (SpO2 < 90% at room air).

Anesthetic implications: 

check hemoglobin level; falsely low values of saturation at room air

References : 

-                 Miyazaki A, Nakanishi T, Kishikawa M, Shimizu A et al.
The first Japanese case of Hb Santa Ana, an unstable abnormal hemoglobin, identified rapidly by electrospray ionization mass spectrometry.
Inter Med 1997; 36: 365-70

-                Robertson A, Rahemtulla A.
Pulse oximetry error in a patient with Santa Ana haemoglobinopathy.
BMJ Case Reports 2016; doi: 10;1136/bcr-2016-216781

Updated: December 2017