The Utility of a Noninvasive Hemoglobin Monitoring (SpHb) Device in African Surgical Patients

Anemia is prevalent in approximately 25% of patients in Sub-Saharan Africa, and point-of-care diagnosis is a convenient option. We aimed to assess the accuracy of the Masimo SpHb when compared to the full blood count (FBC) in determining hemoglobin (Hb) levels.

A total of 307 adult surgery patients were enrolled. FBC-Hb and SpHb measurements were performed simultaneously. Correlation coefficients and Bland-Altman plots were used to compare Hb levels, and sensitivity and specificity were derived.

Among the 306 patients analyzed, the median age was 42.5 y (range, 32-57 y), with a male preponderance (n = 196, 64.5%). The mean Hb levels for SpHb and FBC were 12.2 ± 2.8 and 11.1 ± 3.4, respectively, with a correlation coefficient of 0.73 (P = 0.000). Bland-Altman plots revealed the limits of agreement to be -3.74 to 5.26 g/dL, and the mean difference (bias) was 0.76 g/dL (Confidence intervals: 0.48 to 1.03). At an Hb cutoff <7, the sensitivity and specificity of the Masimo device were 71.4% and 90.5%, respectively. At an Hb cutoff of <12, the sensitivity and specificity of the Masimo device were 90.6% and 59.5%, respectively. The area under the receiver operating characteristic curve for Hb <7 is 0.67% and 0.73% at Hb <12.

The Masimo SpHb monitoring device, compared to FBC, shows only moderate overall agreement, with fair performance at higher Hb levels and poor performance at lower Hb levels. Given the high specificity for anemia, noninvasive SpHb has utility in excluding anemia, but SpHb alone should not be used when making transfusion decisions.