This prospective study aimed to compare the simultaneous measurements of noninvasive hemoglobin level (SpHb) and capillary hemoglobin (cHb) with venous hemoglobin (vHb, gold standard) in 33 critically ill patients with severe gastrointestinal hemorrhage. The primary endpoint was the percentage of inaccurate measurements of SpHb. After multiple comparisons, the authors documented that SpHb was highly inaccurate when compared to vHb (rate of inaccurate measurements was 56%, with a poor correlation coefficient r2 = 0.3). This article demonstrates the uncertain value of noninvasive measures in assessing hemoglobin levels. Therefore, red blood cells transfusions in bleeding patients with severe anemia should not be guided by noninvasive hemoglobin determinations.

– Santiago Ramón Leal-Noval