Does a non-invasive hemoglobin monitor correlate with a venous blood sample in the acutely ill?

Abstract

Non-invasive hemoglobin measuring technology has potential for rapid, portable, and accurate way of providing identification of blood loss or anemia. Our objective is to determine if this technology is reliable in critically ill patients presenting to the Emergency Department. Prospective cross-sectional observational study was done at an urban level-one trauma center, 135 subjects were conveniently sampled, suspected of having active bleeding, sepsis, or other critically ill condition. Non-invasive measurements with Masimo (Irvine, CA, USA) Radical-7 and Rad-57 hemoglobin monitors were compared with the Beckman-Coulter LH-550 (Brea, CA, USA) clinical laboratory blood cell analyzer. The primary outcome was the relationship of the non-invasive device to the clinical laboratory results. Secondary evaluations included the effect of pulse rate, systolic BP, respiratory rate, temperature, capillary refill, skin color, nail condition, extremity movement. The Radical-7 was able to capture reading in 78% (88/113) of subjects, and the Rad-57 in 65% (71/110) of subjects. The correlation (R(2)) of the device Hb was 0.69 and 0.67 (p < 00.01) for the Radical-7 and Rad-57, respectively. The coefficient of variation for the Radical-7 was 18%, and for the Rad57 it was 13%. Univariate analysis shows none of the observed factors is associated with the difference values between the device Hb and laboratory Hb. Our results show that Radical-7 and Rad-57 devices do not report readings in 29% of patients and accuracy is significantly lower than reported by the manufacturer with over 50% of readings falling outside of ± 1 g/dL. We determined that none of the several potential factors examined are associated with the degree of device accuracy.

Reliability of spot‐check transcutaneous hemoglobin measurement in children

“…In non‐invasive measurements, many patient‐ and environment‐related factors can influence the results. According to one study of clinical parameters that can influence the correlation between transcutaneous Hb level and the actual level, heart rate, respiratory rate, body temperature, skin color, movement of extremities, and capillary refill did not affect the correlation between the measurements . In the present study, there was a weak and negative correlation between actual versus measured Hb and bodyweight.…”

“…In many studies, non-invasive measurement has been correlated with actual Hb, 9,10,13,14 but others report poor to moderate correlations. 8,16,16 The most important advantage of continuous measurements is the ability to detect trends in the data obtained. Furthermore, the probability of error is low due to repeated measurement.…”

Methods and analyzers for hemoglobin measurement in clinical laboratories and field settings

“…43,53,104,123,124,126–128 Von Schweinitz et al also analyzed venous blood by the Masimo Radical-57 compared with the reference finding a higher mean Hb concentration (12.0 g/L) by the Masimo Radical-57 (data not shown). 125 When applying the variation in mean difference threshold of ±7% to the studies comparing the Masimo Radical-7 with the reference, nine studies 41,43,53,104,116,124,125,127,128 were within the allowable range of variation and four studies exceeded the ±7% bias range 43,107,123,126 (Fig. 5A).…”

“…5A and C). Eleven studies included 13 comparisons between the reference and the Masimo Radical-7 with the reference among children aged 3 years and 12−17 years and adult males and females aged 18 years and older 41,43,107,116,[123][124][125][126][127][128] (Fig. 5A).…”

Hemoglobin point-of-care testing in rural Gambia: Comparing accuracy of HemoCue and Aptus with an automated hematology analyzer

“…However, such measures require both more time and materials, thereby making them less feasible in LMICs and high-throughput screenings in particular. Alternative non-invasive devices have not yet been shown to be consistently reliable [ 6 , 35 , 36 ], so more advanced PoCD capabilities—such as the MCHC measurement of the Aptus—would improve the value of invasive procedures. This holds for low-resource settings in particular, where full blood count analysis is often unavailable and PoCDs are the modus operandi.…”