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Noninvasive hemoglobin meter readings seen to be unreliable

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – Noninvasive measurements of hemoglobin levels using the Masimo hemoglobin meter are “systematically” underestimated and are not reliable enough to guide decisions about the need for blood transfusions, a French team reports in the Annals of Emergency Medicine online January 20.

The device is approved by the US Food and Drug Administration and is in wide use in the US and Europe, Dr. Etienne Gayat at Hopital Foch in Suresnes, France and colleagues point out. They compared readings obtained with the Masimo meter, version 7.5.0.3, with standard values obtained using an ADVIA 2120 lab analyzer.

For the study, the authors enrolled 300 consecutive emergency department patients. Hemoglobin levels were recorded using the Masimo device at the same time that venous blood samples were obtained and sent to the lab.

Noninvasive readings could not be obtained for 24 of the patients. For the other 276, hemoglobin readings ranged from 4.7 to 18.0 g/dL using the Masimo meter, compared to 4.8 to 21.0 g/dL when measured in the lab, according to the report.

The investigators found that the Masimo meter values were significantly lower than the ADVIA 2120 values, by a mean of 1.59 g/dL. The coefficient of variation for the Masimo meter was 6.8%, which “is not in accordance with the required standard, fixed at 1.4%,” Dr. Gayat and colleagues report.

They also saw that in 13% of instances, discrepancies in the pairs of readings as being below or above 9.0 g/dL, could have led to errors in transfusion decisions.

The authors note that only a few patients in their study had severe anemia and none had hemoglobinopathies, so the results are not generalizable to such patients.

That said, they conclude, “Although the Masimo hemoglobin meter could be a promising tool, providing a totally noninvasive measure of hemoglobin concentration, the studied version seems to underestimate the hemoglobin value and could lead to misestimation of the need for blood transfusion. Thus, it is too early to recommend this device as an accurate spot-check device.”

Reference:

Performance Evaluation of a Noninvasive Hemoglobin Monitoring Device

Ann Emerg Med 2011.