Non-invasive measurement of hemoglobin: assessment of two different point-of-care technologies.

BACKGROUND: Measurement of blood hemoglobin (Hb) concentration is a routine procedure. Using a non-invasive point-of-care device reduces pain and discomfort for the patient and allows time saving in patient care. The aims of the present study were to assess the concordance of Hb levels obtained non-invasively with the Pronto-7 monitor (version 2.1.9, Masimo Corporation, Irvine, USA) or with the NBM-200MP monitor (Orsense, Nes Ziona, Israel) and the values obtained from the usual colorimetric method using blood samples and to determine the source of discordance. METHODS AND FINDINGS: We conducted two consecutive prospective open trials enrolling patients presenting in the emergency department of a university hospital. The first was designed to assess Pronto-7™ and the second NBM-200MP™. In each study, the main outcome measure was the agreement between both methods. Independent factors associated with the bias were determined using multiple linear regression. Three hundred patients were prospectively enrolled in each study. For Pronto-7™, the absolute mean difference was 0.56 g.L(-1) (95% confidence interval [CI] 0.41 to 0.69) with an upper agreement limit at 2.94 g.L(-1) (95% CI [2.70;3.19]), a lower agreement limit at -1.84 g.L(-1) (95% CI [-2.08;-1.58]) and an intra-class correlation coefficient at 0.80 (95% CI [0.74;0.84]). The corresponding values for the NBM-200MP™ were 0.21 [0.02;0.39], 3.42 [3.10;3.74], -3.01 [-3.32;-2.69] and 0.69 [0.62;0.75]. Multivariate analysis showed that age and laboratory values of hemoglobin were independently associated with the bias when using Pronto-7™, while perfusion index and laboratory value of hemoglobin were independently associated with the bias when using NBM-200MP™. CONCLUSION: Despite a relatively limited bias in both cases, the large limits of agreement found in both cases render the clinical usefulness of such devices debatable. For both devices, the bias is independently and inversely associated with the true value of hemoglobin. TRIAL REGISTRATION: ClinicalTrials.gov NCT01321580 and NCT01321593.

Performance evaluation of a noninvasive hemoglobin monitoring device.

STUDY OBJECTIVE: Hemoglobin measurement is a routine procedure, and a noninvasive point-of-care device may increase the quality of care. The aim of the present study is to compare hemoglobin concentration values obtained with a portable totally noninvasive device, the Masimo Labs Radical-7 Pulse CO-Oximeter, with the results obtained by the ADVIA 2120 in the laboratory. METHODS: This was a prospective monocentric open trial enrolling patients consulting in the emergency department of a university hospital from June 16 to December 17, 2009. The main outcome measure was the agreement between both methods and evaluation of the percentage of potential decision error for transfusion. RESULTS: Samples from 300 consecutive patients were assessed. Hemoglobin concentration could not be obtained with the new device for 24 patients. In others, the mean bias, the lower and the upper limits of agreement between the 2 methods, was 1.8 g/dL (95% estimated confidence interval [CI] 1.5 to 2.1 g/dL), -3.3 g/dL (95% CI -3.8 to -2.8 g/dL), and 6.9 g/dL (95% CI 6.4 to 7.4 g/dL), respectively. The intraclass correlation coefficient was 0.53 (estimated 95% CI 0.10 to 0.74). The number of potential errors about transfusion decision was 38 (13% of patients). The peripheral oxygen saturation and the true value of hemoglobin concentration were independently associated with the bias. CONCLUSION: Results from this widely available noninvasive point-of-care hemoglobin monitoring device were systematically biased and too unreliable to guide transfusion decisions.