Validity of non-invasive point-of-care hemoglobin estimation in healthy and sick children-a method comparison study

Validation of ToucHb, a non-invasive haemoglobin estimation: Effective for normal ranges, needs improvement for anaemia detection

Non-invasive methods for haemoglobin estimation hold enormous potential for early detection and treatment of anaemia, especially in limited resource settings. We sought to validate the diagnostic accuracy of ToucHb, a non-invasive haemoglobin estimation device available in the Indian market. We prospectively evaluated the diagnostic performance of the ToucHb device using the Automated complete blood count (CBC) method as the gold standard. Persons referred for haemoglobin estimation to the central laboratory of the government medical college hospital in Mysore, southern India were included in the study. Out Of 140 people approached, 127 gave consent; 65% (n = 82) were female with median age of 37 (IQR 28-45). ToucHB reported median haemoglobin value of 14 g/dL compared to 13.3 g/dL for CBC. Within 1 g/dL and 2 g/dL of CBC, 55.2% (70/127) and 74% (94/127) of ToucHb haemoglobin observations fell, respectively. The Bland-Altman plot showed a mean difference of 3 g/dL in haemoglobin between ToucHb and CBC among those with anaemia. The ToucHb device showed 22.2% sensitivity and 94.5% specificity for anaemia detection. In rural resource-limited settings, point of care non-invasive devices such as ToucHb can improve access and acceptance for anaemia screening. However, ToucHb has showed low sensitivity for anaemia detection and low accuracy at lower haemoglobin values. The utility of the instrument is especially limited in detecting anaemia, while it can estimate haemoglobin accurately among those with haemoglobin is in the normal range. Based on these findings, ToucHb and devices that work on the core technology deployed in ToucHb may be better suited to monitor known haemoglobin level rather than in anaemia screening or detection in primary/ secondary care and community settings.

Utility of continuous pulse CO-oximetry for hemoglobin monitoring in pediatric patients with solid organ injuries at level 1 trauma centers: A pilot study

INTRODUCTION

Hemorrhage is a major cause of preventable death in injured children. Monitoring after admission often requires multiple blood draws, which have been shown to be stressful in pediatric patients. The Rainbow-7 device is a continuous pulse CO-oximeter that measures multiple wavelengths of light, permitting continuous estimation of the total hemoglobin (Hb) level. The purpose of this study was to evaluate the utility of the noninvasive Hb measurement for monitoring pediatric trauma patients admitted with solid organ injury.

METHODS

This is a prospective, dual-center, observational trial for patients younger than age 18 years admitted to a Level I pediatric trauma center. Following admission, blood was routinely measured as per current solid organ injury protocols. Noninvasive Hb monitoring was initiated after admission. Time-synced data for Hb levels were compared with that taken using blood draws. Data were evaluated using bivariate correlation, linear regression, and Bland-Altman analysis.

RESULTS

Over a 1-year period, 39 patients were enrolled. The mean ± SD age was 11 ± 3.8 years. Forty-six percent (n = 18) of patients were male. The mean ± SD Injury Severity Score was 19 ± 13. The average change in Hb levels between laboratory measurements was -0.34 ± 0.95 g/dL, and the average change in noninvasive Hb was -0.12 ± 1.0 g/dL per measurement. Noninvasive Hb values were significantly correlated with laboratory measurements ( p < 0.001). Trends in laboratory Hb measurements were highly correlated with changes in noninvasive levels ( p < 0.001). Bland-Altman analysis demonstrated similar deviation from the mean throughout the range of Hb values, but the differences between measurements were increased by anemia, African American race, and elevated shock index, pediatric age-adjusted score and Injury Severity Score.

CONCLUSION

Noninvasive Hb values demonstrated correlation with measured Hb concentration as isolated measurements and trends, although results were affected by skin pigmentation, shock, and injury severity. Given the rapid availability of results and the lack of requirement of venipuncture, noninvasive Hb monitoring may be a valuable adjunct for pediatric solid organ injury protocols. Further study is required to determine its role in management.

LEVEL OF EVIDENCE

Dianostic Test or Criteria; Level III.

Evaluation of the use of non-invasive hemoglobin measurement in early childhood

BACKGROUND

Iron deficiency anemia in children affects psychomotor development. We compared the accuracy and trend of a non-invasive transcutaneous spectrophotometric estimation of arterial hemoglobin (Hb) concentration (SpHb) by rainbow pulse CO-oximetry technology to the invasive blood Hb concentration measured by an automated clinical analyzer (Hb-Lab).

METHODS

We measured the SpHb and Hb-Lab in 109 patients aged 1-5 years. Regression analysis was used to evaluate differences between the two methods. The bias, accuracy, precision, and limits of agreement of SpHb compared with Hb-Lab were calculated using the Bland-Altman method.

RESULTS

Of the 109 enrolled subjects, 102 pairs of the SpHb and Hb-Lab datasets were collected. The average value of measured Hb was 12.9 ± 1.03 (standard deviation [SD]) g/dL for Hb-Lab. A significant correlation was observed between SpHb and Hb-Lab measurements (SpHb = 7.002 + 0.4722 Hb-Lab, correlation coefficient r = 0.548, 95% confidence interval = 0.329-0.615). Bland-Altman analysis showed good visual agreement, with a mean bias between SpHb and Hb-Lab of 0.188 ± 0.919 g/dL (mean ± SD).

CONCLUSIONS

We concluded that non-invasive Hb measurement is useful for Hb estimation in children and provides new insights as a screening tool for anemia.

IMPACT

Our results indicated a good correlation between non-invasive transcutaneous spectrophotometric estimation of arterial hemoglobin (Hb) concentration using a finger probe sensor by rainbow pulse CO-oximetry technology and invasive blood Hb concentration. Although previous studies have indicated that in patients with a worse condition, the bias between the two methods was large, this study, which was conducted on children with stable disease, showed a relatively small bias. Further studies using this non-invasive device might help to understand the current status of anemia in Japan and promote iron intake and nutritional management in children.

Noninvasive Hemoglobin Measurement Reduce Invasive Procedures in Thalassemia Patients

This study was conducted to investigate the agreement between laboratory hemoglobin (LabHb) measured in venous blood and noninvasive, spectrophotometric hemoglobin (SpHb) measurement and the usability of SpHb measurement in the transfusion decision-making in patients with thalassemia whose hemoglobin (Hb) was monitored by taking blood samples at frequent intervals and who were transfused. Cardiac pulse, oxygen saturation, Pleth variability index (PVI), and SpHb values were measured in patients who came to the hematology outpatient clinic for a control visit and whose Hb levels were planned to be measured. Venous blood samples were taken for LabHb measurement, which we accept as the gold standard. Cohen's kappa value was calculated for the agreement between SpHb measurements and LabHb values. The relationship and predictability between both measurement methods were evaluated by Pearson correlation analysis, a modified Bland-Altman plot and the linear regression model. In the study conducted with a total of 110 children with thalassemia, a moderate level of agreement between the two measurement methods (kappa = 0.370, p < 0.0001) and a significantly high correlation between the two tests (r = 0.675) were found. The mean bias between the differences was found to be 0.3 g/dL (-1.27 to 1.86 g/dL). The sensitivity and the specificity of SpHb in identifying patients who needed transfusions (Hb <10.0 g/dL) were calculated as 92.2 and 57.1%, respectively. Our results suggest SpHb measurement may be used to screen anemia in hemodynamically stable hemoglobinopathy patients and even for transfusion decision-making with combination clinical findings.

Reliability of transcutaneous hemoglobin measurements in an outpatient pediatric clinic

OBJECTIVE

Our study assessed the reliability of a transcutaneous hemoglobin (tcHgb) measurement as compared to a standard capillary hemoglobin (cHgb) measurement in screening for iron deficiency anemia in a single university-based pediatric outpatient clinic.

METHODS

Study participants included all pediatric patients requiring a hemoglobin (Hgb) assessment from July 2019 to June 2020. A tcHgb measurement was attempted on all children who received a cHgb measurement. Additional variables evaluated were age, visit type, gender, insurance type, weight, BMI percentile and presence of comorbid conditions.

RESULTS

Of 777 attempts, both cHgb and tcHgb were obtained in 196 children aged 9 months to 21 years. Attempts were most successful in children > 2 years of age due to finger size and ability to remain still for one to two minutes. The mean cHgb was 12.5 ± 1.5 g/dL, mean tcHgb value 13.1 ± 2.1 g/dL, and the mean difference was 0.6 ± 2.1 g/dL (tcHgb-cHgb). An intraclass correlation coefficient was 0.29. There were no differences with regards to age, visit type, gender, insurance type, weight, BMI percentile and presence of comorbid conditions. Bland-Altman analysis displayed a lack of agreement between the tcHgb and cHgb measurements and tcHgb tended to over-estimate Hgb values when the cHgb was low.

CONCLUSIONS

The measurement of a transcutaneous Hgb is less invasive for pediatric patients but has significant limitations. Smaller children (probe specifications) and movement limited the ability to obtain a tcHgb measurement in ~75% of children tested. Falsely normal tcHgb values occurred due to overestimation of hemoglobin when compared to the traditional cHgb device. The suboptimal sensitivity of the tcHgb device may cause providers to miss a diagnosis of anemia. Future research should compare both methods of Hgb assessment to the gold standard laboratory-analyzed complete blood count and use a smaller probe for children under 2, once available.

Diagnostic accuracy of point-of-care devices for detection of anemia in community settings in India

Background

Accurate diagnosis of anemia by community workers using a point-of-care device is a challenge. The objective of the study was to establish the diagnostic accuracy of point-of-care devices for detecting anemia in community settings.

Methods

It was diagnostic accuracy study with cross-sectional design on adult patients attending the outpatient department of rural/ urban health centres of Medical colleges from India. The index tests were HemoCue, TrueHb, Massimo’s device and spectroscopic device, compared against autoanalyzer (gold standard). Accuracy was expressed by sensitivity, specificity, likelihood ratios, predictive values, area under the curve (AUC) and levels of agreement. For the diagnostic accuracy component, 1407 participants were recruited with a minimum of 600 for each device. An additional 200 participants were considered to elucidate the performance of devices in different weather conditions.

Results

HemoCue and TrueHb performed better than Massimo and spectroscopic devices. Detection of anemia by technicians was similar between TrueHb and HemoCue (AUC 0.92 v/s 0.90, p > 0.05). Community workers performed better with Hemocue for detecting anemia compared to TrueHb (AUC 0.92 v/s 0.90, p < 0.05). For detection of severe anemia, accuracy of TrueHb was significantly better with technicians (AUC 0.91 v/s 0.70; p < 0.05) and community workers (AUC 0.91 v/s 0.73; p < 0.05).

HemoCue showed a bias or mean difference (95%CI) of 0.47 g/dl (0.42, 0.52) for all values, and 0.92 g/dl (0.82, 1.03) for severe anemia. For TrueHb, it was − 0.28 g/dl (− 0.37, − 0.20) for all readings, and 0.06 g/dl (− 0.52, 0.63) for severe anemia. TrueHb appeared to be more consistent across different weather conditions, although it overestimated Hb in extreme cold weather conditions.

Conclusion

For detection of anemia, True Hb and HemoCue were comparable. For severe anemia, True Hb seemed to be a better and feasible point-of-care device for detecting anemia in the community settings.

Transcutaneous Hemoglobin Screening in an Adult Orthopaedic Trauma Population

OBJECTIVES

To evaluate a noninvasive hemoglobin measurement device in an orthopaedic trauma population.

DESIGN

Prospective.

SETTING

Level 1 trauma center.

PATIENTS/PARTICIPANTS

One hundred five patients consecutively admitted to the orthopaedic trauma service after surgical treatment of fracture.

INTERVENTION

Transcutaneous hemoglobin (TcHgb) monitoring using the Masimo Pronto Pulse CO-Oximeter model with Rainbow SET Technology for spot TcHgb measurement.

MAIN OUTCOME MEASUREMENTS

TcHgb measurements and standard venipuncture hemoglobin (vHgb) were obtained. Patient preferences for each were recorded.

RESULTS

TcHgb measurements were obtained in 100 patients and compared with their corresponding vHgb measurements. The mean vHgb and TcHgb were 10.2 ± 1.9 g/dL and 11.2 ± 2.1 g/dL, respectively, and the mean difference was 1.1 ± 1.6 g/dL, which was statistically different from 0 (P < 0.001). In 76% of cases, the TcHgb device overestimated vHgb. In a subgroup of patients undergoing procedures with minimal expected blood loss (external fixators of knee or ankle, irrigation and debridement, or open reduction and internal fixation of ankle or calcaneal fractures), the mean difference between vHgb and TcHgb was 0.68 ± 1.6 g/dL (P = 0.06).

CONCLUSIONS

A preliminary study of TcHgb monitoring with the tested device as a potential screening mechanism to limit unnecessary blood draws showed statistical difference from vHgb; however, the mean bias 1.1 g/dL of hemoglobin was notably small. In a subgroup of patients undergoing procedures with minimal expected blood loss, the device may have merit. Larger studies are required to determine the clinical relevance of differences in measurements between the 2 methods.

LEVEL OF EVIDENCE

Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Intraoperative continuous noninvasive hemoglobin monitoring in patients with placenta previa undergoing cesarean section: a prospective observational study

Background

Obstetric patients with placenta previa are at risk for sever peripartum hemorrhage. Early detection of anemia and proper transfusion strategy are important for the management of obstetric hemorrhage. In this study, we assessed the utility and accuracy of noninvasive hemoglobin (SpHb) monitoring in patients with placenta previa during cesarean section.

Methods

Parturients diagnosed with placenta previa and scheduled for cesarean section under spinal anesthesia were enrolled. SpHb and laboratory Hb (Lab-Hb) were measured during surgery as primary outcomes.

Results

Seventy-four pairs of SpHb and Lab-Hb were collected from 39 patients. The correlation coefficient was 0.877 between SpHb and Lab-Hb (P < 0.001). The Bland–Altman plot showed a mean difference ± SD of 0.3 ± 0.8 g/dl between noninvasive Hb and Lab-Hb, and the limits of agreement were −1.2 to 1.8 g/dl. The magnitude of the difference between SpHb and Lab-Hb was < 0.5 g/dl in 64.9%; however, it was > 1.5 g/dl in 10.8%.

Conclusions

SpHb monitoring had a good correlation with Lab-Hb. A small mean difference between SpHb and lab-Hb might not be clinically significant; however, the limits of agreements were not narrow. In particular, SpHb could be overestimated in the anemic population. Based on our results, further studies investigating the accuracy and precision of SpHb monitoring should be performed in parturients presenting Hb below 10 g/dl.

Continuous hemoglobin monitoring in pediatric trauma patients with solid organ injury

BACKGROUND/PURPOSE

Hemoglobin monitoring is required in pediatric trauma patients with solid organ injury. We hypothesized that noninvasive hemodynamic monitoring (NIHM) represents an effective, safe alternative to laboratory hemoglobin (LabHb) monitoring in clinically stable patients.

METHODS

A retrospective cohort study was conducted regarding pediatric trauma patients (<18 years old) with blunt solid organ injury over six consecutive months. Continuous NIHM was initiated at the time of admission, and LabHb measurements were obtained per institutional guidelines. Measurements were correlated within two hours of assessment and patient outcomes were analyzed.

RESULTS

Twenty-one patients met inclusion criteria and had evaluable data. Blunt trauma was the exclusive mechanism of injury, and mean injury severity score was 16.6 for the cohort. Bland Altman analysis showed an average deviation of 0.80 g/dL between NIHM and LabHb values for all data pairs. Measurement trends were highly correlated in patients with stable hemoglobin levels and those requiring blood transfusion.

CONCLUSIONS

NIHM demonstrated clinically acceptable accuracy when following hemoglobin trends in the defined pediatric trauma patient population. Slight variances between NIHM and LabHb values were occasionally noted, but did not affect clinical management. Continuous NIHM represents a potentially valuable adjunct to traditional laboratory hemoglobin monitoring.

LEVEL OF EVIDENCE RATING

IV.

An evaluation of hemoglobin measurement tools and their accuracy and reliability when screening for child anemia in Rwanda: A randomized study

Blood hemoglobin (Hb) is a common indicator for diagnosing anemia and is often determined through laboratory analysis of venous samples. One alternative to laboratory-based methods is the handheld HemoCue® Hb 201+ device, which requires a finger prick and wicking of blood into a pretreated cuvette for analysis. An alternative HemoCue® gravity method is being investigated for improved accuracy. Further, recent developments in noninvasive technologies could provide an accurate, rapid, safe, point-of-care option for hemoglobin estimation while addressing some limitations of current tools, but device performance must be assessed in low-resource settings. This study evaluated the performance of two HemoCue® Hb 201+ blood sampling methods and a noninvasive device (Pronto® with DCI-mini™ sensors) in a Rwandan pediatric clinic. Reference hemoglobin values were determined in 132 children 6 to 59 months of age by using a standard hematology analyzer (Sysmex KN21^TM). Half were tested using the HemoCue® wicking method; half were tested using the HemoCue® gravity method; and 112 had successful hemoglobin readings with Pronto® DCI-mini™. Statistical analysis was used to assess the level of bias generated by each method and the key drivers of bias. The HemoCue® gravity method was the least biased. The HemoCue® wicking and Pronto® methods biases were inversely related to the Sysmex KN21^TM results. Both HemoCue® sampling methods correctly classified patients’ anemic status in 80% or more of instances, whereas the Pronto® device had a correct classification rate of only 69%. The HemoCue® gravity method was more accurate than the traditional HemoCue® wicking method in this study, but its accuracy and operational feasibility should be confirmed by future studies. The Pronto® DCI-mini™ devices showed considerable promise but require further improvements in sensitivity and specificity before wider adoption.

Noninvasively Measured Hemoglobin Concentration Reflects Arterial Hemoglobin Concentration Before but Not After Cardiopulmonary Bypass in Patients Undergoing Coronary Artery or Valve Surgery

OBJECTIVE

This study compared noninvasively measured hemoglobin and arterial hemoglobin before and after cardiopulmonary bypass in patients undergoing coronary artery or valve surgery.

DESIGN

Observational study with retrospective data analysis.

SETTING

Veterans Affairs hospital.

PARTICIPANTS

Thirty-five men.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Hemoglobin values were measured noninvasively by co-oximetry to corresponding arterial hemoglobin concentrations taken at clinically relevant time points chosen at the discretion of the cardiac anesthesiologist. Thirty-five and 27 pooled pairs of data were obtained before and after cardiopulmonary bypass, respectively. Arterial hemoglobin concentration was analyzed using i-STAT CG8+test cartridges routinely used in the authors' operating rooms and those of other institutions. Linear regression and Bland-Altman analysis revealed a significant positive bias, wide limits of agreement, and low correlation coefficients between the noninvasive and arterial hemoglobin measurements. These findings were especially notable after compared with before cardiopulmonary bypass.

CONCLUSIONS

The results suggested that noninvasive measurement of hemoglobin overestimates arterial hemoglobin by almost 1 g/dL when compared to iSTAT. A lack of precision also was observed with noninvasive measurement of hemoglobin, especially after cardiopulmonary bypass. These findings supported the contention that sole reliance on noninvasive measurement of hemoglobin for transfusion decisions in cardiac surgery patients may be inappropriate.