Noninvasive Hemoglobin Measurement Reduce Invasive Procedures in Thalassemia Patients

Evaluation of Non-Invasive Hemoglobin Monitoring in Perioperative Patients: A Retrospective Study of the Rad-67TM (Masimo)

Background: Hemoglobin (Hb) is a crucial parameter in perioperative care due to its essential role for oxygen transport and tissue oxygenation. Accurate Hb monitoring allows for timely interventions to address perioperative anemia and, thus, prevent morbidity and mortality. Traditional Hb measurements rely on invasive blood sampling, which significantly contributes to iatrogenic anemia and poses discomfort and increased infection risks. The advent of non-invasive devices like Masimo's Rad-67™, which measures Hb using pulse CO-oximetry (SpHb), offers a promising alternative. This study evaluates the accuracy of SpHb compared to clinical standard blood gas analysis (BGA) in perioperative patients. Methods: This retrospective study analyzed 335 paired Hb measurements with an interval <15 min between SpHb and BGA in the operating theater and post-anesthesia care unit of a university hospital. Patients experiencing hemodynamic instability, acute bleeding, or critical care were excluded. Statistical analysis included Bland-Altman plots and Pearson correlation coefficients (PCCs) to assess the agreement between SpHb and BGA. Potential confounders, e.g., patient age, skin temperature, sex, perfusion index (PI), and atrial fibrillation, were also analyzed. Results: The bias of the SpHb compared to BGA according to Bland-Altman was 0.00 g/dL, with limits of agreement ranging from -2.70 to 2.45 g/dL. A strong correlation was observed (r = 0.79). Overall, 57.6% of the paired measurements showed a deviation between the two methods of ≤±1 g/dL; however, this applied to only 33.3% of the anemic patients. Modified Clark's Error Grid analysis showed 85.4% of values fell within clinically acceptable limits. Sex was found to have a statistically significant, but not clinically relevant, effect on accuracy (p = 0.02). Conclusions: The Rad-67TM demonstrates reasonable accuracy for non-invasive SpHb, but exhibits significant discrepancies in anemic patients with overestimating low values. While it offers potential for reducing iatrogenic blood loss, SpHb so far should not replace BGA in critical clinical decision-making.

Accuracy of noninvasive total haemoglobin measurement for detecting anaemia in infants: a cross-sectional study in a well-child care clinic, Khon Kaen, Thailand

OBJECTIVE

Infants are at a high risk of developing anaemia, which can arise from various causes, including inappropriate feeding practices. However, few infants attend anaemia screening programmes due to poor cooperation and being time-consuming. This study evaluated the accuracy of noninvasive total haemoglobin (Hb) spot-check monitoring as part of anaemia screening in healthy infants, compared with the conventional laboratory method.

DESIGN

A cross-sectional study was conducted using a consecutive sampling technique.

SETTING

The study was carried out at the Well-Child Clinic, Khon Kaen University, Thailand.

PARTICIPANTS

Healthy, full-term infants aged 6-12 months who were scheduled for vaccination. Spectrophotometric haemoglobin (SpHb) was measured using Masimo Rad-67 with Rainbow DCI-mini Sensor. These values were compared with conventional laboratory analysis (HbLab) performed on the same day.

PRIMARY AND SECONDARY OUTCOME

Differences between Hb values using the two methods were analysed using the Bland-Altman method. Sensitivity, specificity and positive and negative predictive values (PPV and NPV) for detecting anaemia were determined. Anaemia was defined as HbLab of <11.0 g/dL.

RESULTS

A total of 104 infants, with a median age of 9.6 (IQR 9.3, 10.9) months, were included. The prevalence of anaemia, defined by HbLab, was 38.46%. The mean SpHb was 12.20±1.10 g/dL, while the mean HbLab was 11.19±1.21 g/dL. A moderate positive correlation was observed (r=0.575, p<0.001). Bland-Altman analysis of SpHb vs HbLab showed an estimated bias of 1.007 g/dL with a 95% limit of agreement ranging from -1.091 to 3.104 g/dL. The mean bias was 1.635 g/dL (-0.617 to 3.887) in the anaemic group and 0.614 g/dL (-0.964 to 2.192) in the nonanaemic group. Using the SpHb cut-off point of <13.0 g/dL, the sensitivity and specificity of SpHb to detect anaemia were 95.0% and 35.9%, with PPV and NPV of 48.1% and 92.0%, respectively.

CONCLUSION

A noninvasive tool for measuring Hb, with moderate sensitivity and NPV, may provide utility for initial screening to reduce unnecessary venipuncture in infants. However, its limited specificity and PPV necessitate confirmatory testing through conventional laboratory methods for accurate diagnosis. Depending on the context and available resources, it has potential to complement existing diagnostic processes, particularly in settings where rapid and noninvasive screening is prioritised.

TRIAL REGISTRATION NUMBER

Thai Clinical Trials Registry (TCTR20210816002).

Comparing Non-Invasive Spectrophotometry to Hematology Analysis for Hemoglobin Measurements in Sickle Cell Disease Patients

Patients with sickle cell disease (SCD) require repeated blood sampling for hemoglobin (Hb) concentration measurements. The primary aim of this study was to compare non-invasive spectrophotometric hemoglobin (SpHb, g/dL) measurements to those taken via an automated hematology analyzer (Hb, g/dL) in patients with SCD visiting outpatient clinics and to investigate the correlations and agreements between both measurement techniques. Secondarily, we aimed to identify the SpHb cut-off concentration for the diagnosis of anemia and to monitor the effects of the pleth variability index (PVI, %) and perfusion index (PI) on SpHb measurements. The results gained from the examination of one hundred and fifty-eight patients indicated that the SpHb measurements overestimated the lab Hb concentrations, with a mean (SpHb-Hb) bias of 0.82 g/dL (SD 1.29). The SpHb measurements were positively correlated with the Hb measurements (Kendall's tau correlation (τ), n = 158, τ = 0.68, p < 0.001), with an intra-class correlation (ICC) of 0.67 and a 95% CI from 0.57 to 0.74 (p = 0.000). The SpHb cut-off concentration to diagnose anemia was 11.4 and 11.7 g/dL for males and females, respectively. SpHb sensitivity was low for males and females at 64.4% and 57.1%; however, the specificity was higher at 90.9% and 75%, with positive predictive values (PPVs) of 95.6 and 85.7, respectively. No correlation existed between SpHb measurements and the PVI (%) in contrast with a moderate correlation with the PI (r = 0.049, p = 0.54, and r = 0.36, p < 0.001, respectively). The mean PI was low at 2.52 ± 1.7. In conclusion, the SpHb measurements were consistently higher than the lab Hb concentrations, with a positive correlation. The sensitivity and precision of the SpHb measurements were lower than expected. However, the SpHb specificity and its positive predictive values (PPVs) indicated that it is less likely for a patient with a positive SpHb test result for anemia to be non-anemic. These results will allow SpHb measurement to play a role in excluding the presence of anemia. In light of the low PI values determined, the SpHb measurements were challenging to take and, thus, require further technological improvements.