Evaluation of a Non-Invasive Hematocrit Determination Device.

Background: Non-Invasive Hematocrit (Hct) measurement devices have many potential advantages in primary and secondary medical situations. Primarily, these devices prevent the pain, the potential transmission of infectious diseases, and the need for trained technicians. However, truly non-invasive techniques have not been proven to be accurate enough to eliminate the need for blood sampling. A new, non-invasive clinical device, the NBM-100, was tested for accuracy.

Aims: To examine the accuracy of Hct measurements obtained by a non-invasive clinical device as compared to values determined using venous samples.

Methods: Clinical trials using the NBM–100 device were conducted in a blood donation center (USA) and a hematology clinic (Israel). The device utilizes a finger sensor with Occlusion Red/Near-InfraRed spectroscopy (O-RNIRS) technology to non-invasively measure hemoglobin and Hct levels. Studies were carried out on a group of 304 subjects (155 Female, 149 Male), ages 18–96 (average age 54.9). All study volunteers were tested non-invasively with the NBM-100 device, and invasively, using a venous sample evaluated on a Cell-Dyn (Abbott) blood analyzer. At the blood bank center, the NBM-100 measurements were performed before donation and the venous blood sample was taken after donation. To neutralize the decrease in Hct occurring during blood donation, as described in published clinical trials, a value of 2.2% was added to the reference venous values obtained from the blood bank center.

Results: The venous Hct measurements ranged from 15 to 51%. The mean NBM-100 Hct (36%) was the same as the mean venous result. The standard deviation of the difference between the invasive and noninvasive Hct readings was found to be 3.34% and the bias was 0.40%. The mean absolute error (MAE) of their difference was 2.66%. The relative absolute error (RAE) was 7.9%. The operating staff at all centers found the NBM-100 easy to use and appreciated by subjects.

Conclusions: This study indicates the potential use of the NBM-100 device as a useful and accurate non-invasive method for measuring a wide range of Hct in both a hospital (e.g. surgery and blood transfusions) and ambulatory setting (e.g. blood banks). Good agreement was found between the non-invasive NBM-100 and the invasive Cell-Dyn Hct measurements. The non-invasive system was found to be environmentally- and user-friendly by operating staff.