Accuracy of Noninvasive and Invasive Point-of-Care Total Blood Hemoglobin Measurement in an Outpatient Setting

Abstract

Objective: The purpose of this study was to determine the accuracy of noninvasive hemoglobin measurement using pulse CO–oximetry (Pronto® SpHb®, Masimo Corp.) and a commonly used, invasive, point–of–care, automated spectrophotometer (HemoCue 201+®, HemoCue, Inc.), in comparison with hemoglobin measurements obtained from a laboratory hematology analyzer (measuring total blood hemoglobin) in the outpatient setting. Methods: Adult patients presenting to an outpatient research clinic were tested for total blood hemoglobin measurement by 3 methods: noninvasive pulse CO–oximetry (SpHb®), finger–stick blood sample on a point–of–care device, and venous sample on a laboratory hematology analyzer (reference device). Bias and standard deviation (SD) of SpHb® and HemoCue 201+® compared with the values obtained with the laboratory hematology analyzer were calculated and Bland–Altman graphs were generated. Results: Samples from 152 subjects were assessed (average age, 46 years; 69% female). The bias ± SD compared with the reference method was −0.5 ± 1.0 g/dL for SpHb® and 0.3 ± 1.0 g/dL for HemoCue 201+®. The Bland–Altman plots assessing agreement of the test methods to the reference method had limits of agreement of +2.5 to 1.5 g/dL for SpHb® and +1.7 to 2.3 g/dL for HemoCue 201+®. A noninvasive measurement could not be obtained in 4 subjects after 2 attempts (2.5% failure rate), whereas the HemoCue 201+® measurements were obtained for all subjects. Conclusion: Noninvasive SpHb® testing had bias and SD similar to those of HemoCue 201+®. Because SpHb® measurement is noninvasive, it may offer additional patient and provider benefits.

Keywords:

• hemoglobin
• anemia
• pulse oximetry
• outpatients
• point-of-care technology
• monitoring
• physiologic