Abstract 2447: The Optimal Relationship between Oxygen Saturation and Hemoglobin in Adult Patients with Cyanotic Congenital Heart Disease can be Determined and Correlates with Exercise Capacity.
Background: Erythrocytosis in cyanotic heart disease is affected by many factors that alter oxygen saturation (O2sat) or hemoglobin (Hb) and disrupt their expected relationship. We sought to determine the optimal Hb for a given O2sat.
Methods: Adults with cyanotic heart disease were studied prospectively with blood tests and exercise. Non-optimal Hb was defined as any evidence of inadequate erythropoiesis; namely iron, folate, or B12 deficiency, raised erythropoietin, reticulocytosis, or right-shifted oxygen-Hb curve. For patients with optimal Hb, a plot of Hb vs.O2sat was used to mathematically predict optimal Hb for all patients, and calculate the difference between measured and predicted (Hbdiff).
Results: Of 61 patients studied, 17 met all criteria for optimal Hb. For all patients there was no correlation between O2sat and Hb (r=−0.19), whereas there was a strong linear correlation for those with optimal Hb (r=−0.86, p<0.001). There was a negative correlation between Hbdiff and exercise capcity. Those with optimal Hb had better treadmill exercise duration (6.9±2.6 vs. 5.1±2.0 min, p=0.018) and 6-min walk distance (429±88 vs. 336±107 m, p=0.005).
Conclusions: A strong relationship between O2sat and Hb can be shown in those defined to have optimal Hb. Optimal Hb patients have better exercise capacity. This relationship may be useful in defining anemia or excess viscosity in this group.