Transforming Hemoglobin Measurement in Trauma Patients: Noninvasive Spot Check Hemoglobin

High-precision non-invasive RBC and HGB detection system based on spectral analysis

Non-invasive blood composition analysis based on dynamic spectrum (DS) theory has gained significant attention due to its non-invasive, simple, and fast performance. However, most of the multi-wavelength photoplethysmography (PPG) detection devices used to obtain DS are composed of halogen light sources and spectrometers and cannot detect effective PPG signals in the visible light short band (400-620 nm), which limits the detection accuracy of blood components with significant absorption spectral differences in that band. Therefore, this paper designs a multi-wavelength spectral acquisition system that can measure high signal-to-noise ratio (SNR > 65 dB) PGG signals at wavelengths of 405, 430, 450, 505, 520, and 570 nm and combines this system with a halogen lamp spectrometer acquisition system for non-invasive blood component detection. Furthermore, this paper collects the DS of 272 subjects with the combined system and establishes a predictive model for DS with the content of red blood cell (RBC) and hemoglobin (HGB) components. The results show that, compared with the halogen lamp spectrometer acquisition system, the correlation coefficient (Rp) of RBC and HGB prediction model established by the combined system has increased by 0.0619 and 0.0489, respectively, and the root mean square error (RMSE) has decreased by 0.08 1e12/L and 0.85 g/L, which confirm the feasibility of the designed multi-wavelength spectrum acquisition system to enhance the accuracy of blood component detection.

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.

Determining the validity of non-invasive spot-check hemoglobin co-oximetry testing to detect anemia in postpartum women at a tertiary care centre, a prospective cohort study

BACKGROUND

Spot-check hemoglobin co-oximetry analyzers measure hemoglobin transcutaneously and offer the benefit of a hemoglobin measurement without phlebotomy. The objective of this study was to determine the validity of non-invasive spot-check hemoglobin co-oximetry testing for the detection of postpartum anemia (hemoglobin < 10 g/dL).

METHODS

Five hundred eighty-four women aged 18 and over were recruited on postpartum day one following a singleton delivery. Two non-invasive spot-check hemoglobin co-oximetry monitors, Masimo Pronto Pulse CO-Oximeter (Pronto) and Masimo Rad-67 Pulse CO-Oximeter (Rad-67), were evaluated and compared to the postpartum phlebotomy hemoglobin value.

RESULTS

Of 584 participants, 31% (181) had postpartum anemia by phlebotomy hemoglobin measurement. Bland-Altman plots determined a bias of + 2.4 (± 1.2) g/dL with the Pronto and + 2.2 (± 1.1) g/dL with the Rad-67. Low sensitivity was observed: 15% for the Pronto and 16% for the Rad-67. Adjusting for the fixed bias, the Pronto demonstrated a sensitivity of 68% and specificity of 84%, while the Rad-67 demonstrated a sensitivity of 78% and specificity of 88%.

CONCLUSION

A consistent overestimation of hemoglobin by the non-invasive spot-check hemoglobin co-oximetry monitors compared to phlebotomy hemoglobin result was observed. Even after adjusting for the fixed bias, the sensitivity for detecting postpartum anemia was low. Detection of postpartum anemia should not be based on these devices alone.

Hemoglobin Determination Using Pulse Co-Oximetry and Reduced-Volume Blood Gas Analysis in the Critically Ill: A Prospective Cohort Study

Hospital-acquired anemia is common in patients hospitalized in the intensive care unit (ICU). A major source of iatrogenic blood loss in the ICU is the withdrawal of blood for laboratory testing. The aim of our study was to analyze the feasibility and accuracy of non-invasive spot-check pulse co-oximetry (SpHb), and a reduced-volume blood gas analysis (ABG Hb) for the determination of Hb concentration in critically ill patients. Comparisons between Hb determined with test devices and the gold standard—complete blood count (CBC)—were performed using Bland−Altman analysis and concordance correlation coefficient (CCC). The limits of agreement between SpHb and CBC Hb were −2.0 [95%CI −2.3−(−1.7)] to 3.6 (95%CI 3.3−3.9) g/dL. The limits of agreement between ABG Hb and CBC Hb were −0.6 [95%CI −0.7−(−0.4)] to 2.0 (95%CI 1.9−2.2) g/dL. Spearman’s coefficient and CCC between ABG Hb and CBC Hb were 0.96 (95%CI 0.95−0.97, p < 0.001) and 0.91 (95%CI 0.88−0.92), respectively. Non-invasive spot-check Hb co-oximetry is not sufficiently accurate for the monitoring of hemoglobin concentration in critically ill patients. Reduced volume arterial blood gas analysis has acceptable accuracy and could replace complete blood count for the monitoring of Hb concentration in critically ill patients, leading to a significant reduction in blood volume lost for anemia diagnostics.

Non-invasive Hemoglobin Measurement Predictive Analytics with Missing Data and Accuracy Improvement Using Gaussian Process and Functional Regression Model

Recent use of noninvasive and continuous hemoglobin (SpHb) concentration monitor has emerged as an alternative to invasive laboratory-based hematological analysis. Unlike delayed laboratory based measures of hemoglobin (HgB), SpHb monitors can provide real-time information about the HgB levels. Real-time SpHb measurements will offer healthcare providers with warnings and early detections of abnormal health status, e.g., hemorrhagic shock, anemia, and thus support therapeutic decision-making, as well as help save lives. However, the finger-worn CO-Oximeter sensors used in SpHb monitors often get detached or have to be removed, which causes missing data in the continuous SpHb measurements. Missing data among SpHb measurements reduce the trust in the accuracy of the device, influence the effectiveness of hemorrhage interventions and future HgB predictions. A model with imputation and prediction method is investigated to deal with missing values and improve prediction accuracy. The Gaussian process and functional regression methods are proposed to impute missing SpHb data and make predictions on laboratory-based HgB measurements. Within the proposed method, multiple choices of sub-models are considered. The proposed method shows a significant improvement in accuracy based on a real-data study. Proposed method shows superior performance with the real data, within the proposed framework, different choices of sub-models are discussed and the usage recommendation is provided accordingly. The modeling framework can be extended to other application scenarios with missing values.

Non-invasive haemoglobin measurement as an index test to detect pre-operative anaemia in elective surgery patients - a prospective study

Non-invasive haemoglobin measurement using absolute values lacks the precision to be the sole basis for the treatment of pre-operative anaemia. However, it can possibly serve as a screening test, indexing 'anaemia' with high sensitivity when values remain under prespecified cut-off values. Based on previous data, non-invasive haemoglobin cut-off values (146 g.l^-1 for women and 152 g.l^-1 for men) detect true anaemia with 99% sensitivity. An index test with these prespecified cut-off values was verified by prospective measurement of non-invasive and invasive haemoglobin pre-operatively in elective surgical patients. In 809 patients, this showed an estimated sensitivity (95%CI) of 98.9% (94.1-99.9%) in women and 96.4% (91.0-99.0%) in men. This saved invasive blood tests in 9% of female and 28% of male patients. In female patients, a lower non-invasive haemoglobin cut-off value (138 g.l^-1 ) would save 28% of invasive blood tests with a sensitivity of 95%. The target 99% sensitivity would be reached by non-invasive haemoglobin cut-off values of 152 g.l^-1 in female and 162 g.l^-1 in male patients, saving 3% and 9% of invasive blood tests, respectively. Bias and limits of agreement between non-invasive and laboratory haemoglobin levels were 2 and - 25 to 28 g.l^-1 , respectively. Patient and measurement characteristics did not influence the agreement between non-invasive and laboratory haemoglobin levels. Although sensitivity was very high, the index test using prespecified cut-off values just failed to reach the target sensitivity to detect true anaemia. Nevertheless, with respect to blood-sparing effects, the use of the index test in men may be clinically useful, while an index test with a lower cut-off (132 g.l^-1 ) could be more clinically appropriate in women.

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.

Evaluation of Noninvasive Hemoglobin Monitoring in Trauma Patients with Low Hemoglobin Levels

OBJECTIVE

Bleeding is a leading cause of death among trauma patients. Delayed assessment of blood hemoglobin level might result in either unnecessary blood transfusion in nonindicated patients or delayed blood transfusion in critically bleeding patients. In this study, we evaluate the precision of noninvasive hemoglobin monitoring in trauma patients with low hemoglobin levels.

METHODS

We included trauma patients with low hemoglobin levels (less than 8 g/dL) scheduled for surgical intervention. Blood samples were obtained on admission and after each blood unit with concomitant measurement of serum hemoglobin using radical-7 Masimo device. The change in blood hemoglobin after every transfused blood unit was also assessed by both methods (change in noninvasive Masimo hemoglobin [Delta-Sp-Hb] and change in laboratory hemoglobin [Delta-Lab-Hb]). The precision of Masimo hemoglobin level (Sp-Hb) compared with Laboratory hemoglobin level (Lab-Hb) was determined using both Bland-Altman and Pearson correlation analyses.

RESULTS

One hundred eighty-four time-matched samples were available for final analysis. Bland-Altman analysis showed excellent accuracy of Sp-Hb compared with Lab-Hb with mean bias of 0.12 g/dL and limits of agreement between -0.56 g/dL and 0.79 g/dL. Excellent correlation was reported between both measures with Pearson correlation coefficient of 0.872. Excellent agreement was also reported between both Delta-Sp-Hb and Delta-Lab-Hb with mean bias of -0.05 and limits of agreement from -0.62 to 0.51 CONCLUSIONS:: Sp-Hb showed accurate precision in both absolute values and trend values compared with Lab-Hb measurement in trauma patients with low hemoglobin levels.

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.

Improving Accuracy of Noninvasive Hemoglobin Monitors: A Functional Regression Model for Streaming SpHb Data

OBJECTIVE

The purpose of this paper is to develop a method for improving the accuracy of SpHb monitors, which are noninvasive hemoglobin monitoring tools, leading to better critical care protocols in trauma care.

METHODS

The proposed method is based on fitting smooth spline functions to SpHb measurements collected over a time window and then using a functional regression model to predict the true HgB value for the end of the time window.

RESULTS

The accuracy of the proposed method is compared to traditional methods. The mean absolute error between the raw SpHb measurements and the gold standard hemoglobin measurements was 1.26 g/Dl. The proposed method reduced the mean absolute error to 1.08 g/Dl. [1] Conclusion: Fitting a smooth function to SpHb measurements improves the accuracy of Hgb predictions.

SIGNIFICANCE

Accurate prediction of current and future HgB levels can lead to sophisticated decision models that determine the optimal timing and amount of blood product transfusions.

Noninvasive hematocrit assessment for cardiovascular magnetic resonance extracellular volume quantification using a point-of-care device and synthetic derivation

BACKGROUND

Calculation of cardiovascular magnetic resonance (CMR) extracellular volume (ECV) requires input of hematocrit, which may not be readily available. The purpose of this study was to evaluate the diagnostic accuracy of ECV calculated using various noninvasive measures of hematocrit compared to ECV calculated with input of laboratory hematocrit as the reference standard.

METHODS

One hundred twenty three subjects (47.7 ± 14.1 years; 42% male) were prospectively recruited for CMR T1 mapping between August 2016 and April 2017. Laboratory hematocrit was assessed by venipuncture. Noninvasive hematocrit was assessed with a point-of-care (POC) device (Pronto-7® Pulse CO-Oximeter®, Masimo Personal Health, Irvine, California, USA) and by synthetic derivation based on the relationship with blood pool T1 values. Left ventricular ECV was calculated with input of laboratory hematocrit (Lab-ECV), POC hematocrit (POC-ECV), and synthetic hematocrit (synthetic-ECV), respectively. Statistical analysis included Wilcoxon signed-rank test, Bland-Altman analysis, receiver-operating curve analysis and intra-class correlation (ICC).

RESULTS

There was no significant difference between Lab-ECV and POC-ECV (27.1 ± 4.7% vs. 27.3 ± 4.8%, p = 0.106), with minimal bias and modest precision (bias - 0.18%, 95%CI [- 2.85, 2.49]). There was no significant difference between Lab-ECV and synthetic-ECV (26.7 ± 4.4% vs. 26.5 ± 4.3%, p = 0.084) in subjects imaged at 1.5 T, although bias was slightly higher and limits of agreement were wider (bias 0.23%, 95%CI [- 2.82, 3.27]). For discrimination of abnormal Lab-ECV ≥30%, POC-ECV had good diagnostic performance (sensitivity 85%, specificity 96%, accuracy 94%, and AUC 0.902) and synthetic-ECV had moderate diagnostic performance (sensitivity 71%, specificity 98%, accuracy 93%, and AUC 0.849). POC-ECV had excellent test-retest (ICC 0.994, 95%CI[0.987, 0.997]) and inter-observer agreement (ICC 0.974, 95%CI[0.929, 0.991]).

CONCLUSIONS

Myocardial ECV can be accurately and reproducibly calculated with input of hematocrit measured using a noninvasive POC device, potentially overcoming an important barrier to implementation of ECV. Further evaluation of synthetic ECV is required prior to clinical implementation.

Ideal hemoglobin transfusion target for resuscitation of massive-transfusion patients

BACKGROUND

Overtransfusion of packed red blood cells is known to increase the risk of death in stable patients. With the delineation of minimum transfusion ratios in hemorrhaging patients complete, attention must be turned to the other end of the massive transfusion spectrum-that of defining the maximum transfusion of packed red blood cells. We aimed to define the ideal hemoglobin range 24 hours after anatomic hemostasis associated with the lowest mortality.

METHODS

Massive-transfusion patients (≥10 units packed red blood cells within 24 hours) were reviewed from 2010-2013. The hemoglobin 24 ± 6 hours after anatomic hemostasis was used to stratify patients into undertransfusion (<8.0 g/dL), hemoglobin transfusion target (8.0-11.9 g/dL), and overtransfusion (>12.0 g/dL) groups; patients not surviving to 24 hours were excluded.

RESULTS

We identified 418 patients (351 [84%] in the hemoglobin transfusion target group, 38 [9%] in the undertransfusion group, and 29 [7%] in the overtransfusion group) with an overall mortality of 18%. Undertransfusion patients had the greatest risk of death (odds ratio 3.3; 95% confidence interval 1.6-6.7) followed by overtransfusion patients (odds ratio 2.5; 95% confidence interval 1.1-5.6). Though pretransfusion hemoglobin was similar (9.5 ± 2.2 g/dL vs 9.5 ± 2.3 g/dL), overtransfusion patients had greater hemoglobin values during massive transfusion (8.3 ± 3.0 g/dL vs 6.9 ± 1.4 g/dL), persisting until hospital dismissal/death (11.4 ± 2.3 g/dL vs 9.6 ± 1.1 g/dL). In total, 657.4 excess packed red blood cell units were transfused (1.9 ± 1.5 per patient).

CONCLUSION

Overtransfusion patients had increased mortality, comparable to undertransfusion patients, despite younger age and fewer comorbidities. Shorter massive transfusion durations foster a scenario in which patients are at greater risk of overtransfusion.

Admission hematocrit predicts the need for transfusion secondary to hemorrhage in pediatric blunt trauma patients

BACKGROUND

Pediatric trauma uses a substantial amount of resources. Quick and cost-effective measures that can be used to identify children with clinically relevant injuries are essential to resource allocation and optimization of patient care. Admission hematocrit is rapid and inexpensive, causes minimal harm, and can potentially aid in critical decision making. We hypothesize that admission hematocrit predicts the need for transfusion in pediatric blunt trauma patients.

METHODS

Records of trauma patients age 0 year to 17 years (2005-2013) who presented to a pediatric Level 1 trauma center were retrospectively reviewed. Data collected include demographics, computed tomographic scan findings, need for an intervention secondary to bleeding (blood transfusion, angioembolization, or operation), and admission hematocrit.

RESULTS

We found a significant decrease in admission hematocrit between patients requiring a transfusion and patients who did not (27% vs. 36%, p < 0.01). We evaluated a subset of patients who had an abdominal computed tomographic scan and found a significant decrease in admission hemocrit between those who required a transfusion for an intra-abdominal injury and those who did not (29% vs 37%, p < 0.01). In this subset, serial hematocrit values remained significantly lower in the patients requiring a transfusion up to 67 hours after admission (p = 0.04). A cutoff admission hematocrit of 35% or less has a sensitivity of 94% and a negative predictive value of 99.9% in identifying children who need a transfusion after blunt trauma.

CONCLUSION

An admission hematocrit of 35% or less provides a reliable screening test because of its low false negative rate and high specificity for identifying patients at an increased risk of bleeding after injury. Admission hematocrit could be widely implemented to identify patients who may need a transfusion with low expense and minimal harm for our pediatric patients and may be able to alter the entire course of their trauma resuscitation.

LEVEL OF EVIDENCE

Epidemiologic/prognostic study, level III.

Assessing serum hemoglobin levels without venipuncture: accuracy and reliability of Pronto-7 noninvasive spot-check device

BACKGROUND

Hemoglobin is a frequently obtained test in hospital settings. We analyzed accuracy of a noninvasive device compared to standard laboratory analyzers in a variety of settings.

METHODS

A noninvasive hemoglobin monitoring device was analyzed for reliability, correlation, precision, and bias. Hemoglobin levels were obtained from standard laboratory and point-of-care hemoglobin analyzers and compared to noninvasive hemoglobin in inpatient and military field environments.

RESULTS

Ninety-seven patients were enrolled. Overall, the noninvasive hemoglobin device had high correlation compared to invasive laboratory values. Stratified by location, the device had high correlation in hospital and low correlation in austere environment. The highest variation in accuracy was seen in the austere environment.

CONCLUSIONS

Overall, the noninvasive spot-check hemoglobin device is reliable and highly correlates to standard hemoglobin analysis. Use in an austere setting requires further study.