Noninvasive Hemoglobin Measurement Research Articles

Is noninvasive hemoglobin measurement suitable for children undergoing preoperative anesthesia consultation?

Preoperative anemia in children is a significant clinical concern requiring precise diagnosis. Although traditional blood sample collection is effective, it poses challenges because of children's aversion and technical difficulties. Therefore, this study explores the suitability of noninvasive hemoglobin measurements in children during preoperative anesthesia consultation. Noninvasive hemoglobin measurement (SpHb®; Masimo) in children aged ≤ 17years was performed during preoperative anesthesia consultation and compared with laboratory hemoglobin (labHb) levels. SpHb was measured in 62 children (median age: 6years, standard deviation [SD] ± 5.3) without adverse effects but was unsuccessful in one child. The bias, limits of agreement, and root mean square error between SpHb and labHb were 0.3, -2.26-+2.8, and 1.3g/dl, respectively. LabHb demonstrated a significant regression relationship with R2 of 0.359. LabHb was associated with a negative effect on bias [- 0.443 (CI 95: - 0.591- - 0.153, P < 0.001)], i.e., SpHb tends to underestimate labHb for high labHb values. The retest reliability between two consecutive SpHb measurements was 0.727 (P < 0.001). Double measurement of SpHb, age, weight, sex, heart rate, and perfusion index had no significant effects on accuracy. Using SpHb, a specificity of 96.3% (95% confidence interval [CI 95]: 87.3%-99.5%) and a sensitivity of 57.1% (CI 95: 18.4%-90.1%) were observed. Based on adapted cut-off values for SpHb (age-dependent cut-off values plus 0.8g/dl), a sensitivity of 100% (CI 95: 64.6%-100%) was achieved for the investigated study collective. SpHb measurement in children is a quick procedure. The accuracy of hemoglobin measurement is insufficient for the diagnosis of anemia. Thus, whether the calculated cut-off SpHb values of this study collective can be considered for anemia screening in pediatric patients undergoing preoperative anesthesia consultation should be confirmed. Trial registration number and date of registration: This prospective study was registered at ClinicalTrials.gov (NCT03586141).

Effect of hyperbilirubinemia on the accuracy of continuous non-invasive hemoglobin measurements in liver transplantation recipients

This study evaluated the effect of hyperbilirubinemia on the accuracy of continuous non-invasive hemoglobin (SpHb) measurements in liver transplantation recipients. Overall, 1465 SpHb and laboratory hemoglobin (Hb) measurement pairs (n = 296 patients) were analyzed. Patients were grouped into normal (< 1.2 mg/dL), mild-to-moderate (1.2–3.0 mg/dL), and severe (> 3.0 mg/dL) hyperbilirubinemia groups based on the preoperative serum total bilirubin levels. Bland–Altman analysis showed a bias of 0.20 (95% limit of agreement, LoA: − 2.59 to 3.00) g/dL, 0.98 (95% LoA: − 1.38 to 3.35) g/dL, and 1.23 (95% LoA: − 1.16 to 3.63) g/dL for the normal, mild-to-moderate, and severe groups, respectively. The four-quadrant plot showed reliable trending ability in all groups (concordance rate > 92%). The rates of possible missed transfusion (SpHb > 7.0 g/dL for Hb < 7.0 g/dL) were higher in the hyperbilirubinemia groups (2%, 7%, and 12% for the normal, mild-to-moderate, and severe group, respectively. all P < 0.001). The possible over-transfusion rate was less than 1% in all groups. In conclusion, the use of SpHb in liver transplantation recipients with preoperative hyperbilirubinemia requires caution due to the positive bias and high risk of missed transfusion. However, the reliable trending ability indicated its potential use in clinical settings.

High-precision hemoglobin detection based on hyperspectral reconstruction of RGB images

Hemoglobin concentration is an important indicator for evaluating human health. The concentration value is an important evidence for early diagnosis of anemia and other blood diseases. However, existing optical detection methods usually suffer from low precision, strong noise and tedious operation, makes it difficult to obtain an accurate hemoglobin concentration evaluation. In this work, we propose and demonstrate a method for hemoglobin detection with the hyperspectral reconstruction of RGB images. To be specific, this overall model consists of a SHR-Net (Skin Hyperspectral Reflectance Network) to reconstruct hyperspectral images from RGB images of fingers, a feature selection process to capture full-band reflectance spectra based on the maximum blood perfusion region and an SVR (Support Vector Regression) algorithm to predict the hemoglobin concentration. The experimental results show that the coefficient of determination between the predicted and true values is 0.945. The mean square error of cross-validation is 0.49 g/dL. Therefore, this method provides a new solution for the accurate and noninvasive measurement of hemoglobin.

Development of Optical Sensor Technology for Non-Invasive Hemoglobin Measurement

This research focuses on the development of hardware and software required to implement optical sensor technology. The optical sensor used is the MAX30102, equipped with infrared (IR) and red-light sources along with a receiver. The signals generated by the sensor are processed by NodeMCU and displayed on the OLED. The calibration results indicate the relationship between hemoglobin obtained using the invasive method and the output of the MAX30102 sensor, which is in the form of wavelength. It has the equation with an value of 0.9114. This equation is utilized to program the NodeMCU through the Arduino IDE. Validation and clinical trials have been conducted to evaluate its accuracy and applicability in clinical contexts. The results show that the non-invasive device has an average standard deviation of 0.32, indicating consistent measurement values. The non-invasive device demonstrates an average accuracy of 99.24%, signifying high precision and similarity to invasive methods. This suggests that the device holds potential as an innovative solution for Hemoglobin measurement.

HTRS2023.P3.6 Correlation of non-invasive hemoglobin measurement with bleeding during cesarean delivery: the PPHgb study

HTRS2023.P3.6 Correlation of non-invasive hemoglobin measurement with bleeding during cesarean delivery: the PPHgb study

Research on a Non-Invasive Hemoglobin Measurement System Based on Four-Wavelength Photoplethysmography

Hemoglobin is an essential parameter in human blood. This paper proposes a non-invasive hemoglobin concentration measurement method based on the characteristic parameters of four-wavelength photoplethysmography (PPG) signals combined with machine learning. The DCM08 sensor and NRF52840 chip form a data acquisition system to collect 58 human fingertip photoelectric volumetric pulse wave signals. The 160 four-wavelength PPG signal feature parameters were constructed and extracted. The feature parameters were screened by combining three feature selection methods: reliefF, Chi-square score, and information gain. The top 10, 20, and 30 features screened were used as input to evaluate the prediction performance of different feature sets for hemoglobin. The prediction models used were XGBoost, support vector machines, and logistic regression. The results showed that the optimal performance of the 30 feature sets screened using the Chi-square test was achieved by the XGBoost model with a coefficient of determination (R2) of 0.997, root mean square error (RMSE) of 0.762 g/L, and mean absolute error (MAE) of 0.325 g/L. The study showed that the four-wavelength-based PPG signal feature parameters with the XGBoost algorithm could effectively achieve non-invasive detection of hemoglobin, providing a new measurement method in clinical practice.

Noninvasive Hemoglobin Measurements With Photoplethysmography in Wrist

Noninvasive Hemoglobin Measurements With Photoplethysmography in Wrist

Haemoglobin Measurement from Eye Anterior Ciliary Arteries through Borescope Camera

Nowadays, smartphones are used as self-health monitoring devices for humans. Self-health monitoring devices help clinicians with big data for accurate diagnosis and guidance for treatment through repetitive measurement. Repetitive measurement of haemoglobin requires for pregnant women, pediatric, pulmonary hypertension and obstetric patients. Noninvasive haemoglobin measurement through conjunctiva leads to inaccurate measurement. The inaccuracy is due to a decrease in the density of goblet cells and acinar units in Meibomian glands in the human eye as age increases. Furthermore, conjunctivitis is a disease in the eye due to inflammation or infection at the conjunctiva. Conjunctivitis is in the form of lines in the eyelid and covers the white part of the eyeball. Moreover, small blood vessels in eye regions of conjunctiva inflammations are not visible to the human eye or standard camera. This paper proposes smartphone-based haemoglobin (SBH) measurement through a borescope camera from anterior ciliary arteries of the eye for the above problem. The proposed SBH method acquires images from the anterior ciliary arteries region of the eye through a smartphone attached with a high megapixel borescope camera. The anterior ciliary arteries are projected through transverse dyadic wavelet transform (TDyWT) and applied with delta segmentation to obtain blood cells from the ciliary arteries of the eye. Furthermore, the Gaussian regression algorithm measures haemoglobin (Hb) with more accuracy based on the person, eye arteries, red pixel statistical parameters obtained from the left and right eye, age, and weight. Furthermore, the experimental result of the proposed SBH method has an accuracy of 96% in haemoglobin measurement.

Targeted Bleeding Management Guided by Non-Invasive Haemoglobin Measurement in Surgical Patients.

To assess blood transfusion decisions in blood losses using a continuous total haemoglobin (SpHb) and non-invasive haemoglobin (Hb) device. Double-blinded randomised controlled trial. Marmara University Hospital, Istanbul, Turkey, from March 2018 to December 2019. One hundred and twenty adult patients scheduled for elective major surgery and expected to experience a blood loss greater than 20% of their total blood volume were divided into two groups. These groups were compared for bleeding management with conventional blood gas sampling (Group Hb, the control group) according to Hb monitoring versus SpHb measurement (Group SpHb, the study group). In the postoperative measurement, there were fewer red blood cells (RBC) in the SpHb group than in the Hb group (p=0.020). There was a greater change in the amount of RBC from the perioperative to the postoperative period in the SpHb group compared to the Hb group (p<0.001). Postoperative Hb levels of patients in the intensive care unit (ICU) were higher in the SpHb group than in the Hb group (p<0.05). SpHb can provide effective patient blood management in cases of major surgery. It does not cause a delay in the decision of blood transfusion during surgery. Haemorrhage, Anaemia, Blood transfusion, General surgery.

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.

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

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

Evaluation of the usefulness of non-invasive serum haemoglobin measurement in a perioperative setting in a prospective observational study

Patient Blood Management (PBM) programmes seek to reduce the number of missed anaemic patients in the run-up to surgery. The aim of this study was to evaluate the usefulness of haemoglobin (Hb) measured non-invasively (SpHb) in preoperative screening for anaemia. We conducted a prospective observational study in a preoperative clinic. Adult patients undergoing examination for surgery who had their Hb measured by laboratory means also had their Hb measured non-invasively by a trained health care provider. 1216 patients were recruited. A total of 109 (9.3%) patients (53 men and 56 women) was found to be anaemic by standard laboratory Hb measurement. Sensitivity for SpHb to detect anaemic patients was 0.50 (95% CI 0.37–0.63) in women and 0.30 (95% CI 0.18–0.43) in men. Specificity was 0.97 (95% CI 0.95–0.98) in men and 0.93 (95% CI 0.84–1.0) in women. The rate of correctly classified patients was 84.7% for men and 89.4% for women. Positive predictive value for SpHb was 0.50 (95% CI 0.35–0.65) in men and 0.40 (95% CI 0.31–0.50) in women; negative predictive value was 0.93 (95% CI 0.92–0.94) in men and 0.95 (95% CI 0.94–0.96) in women. We conclude that due to low sensitivity, SpHb is poorly suitable for detecting preoperative anaemia in both sexes under standard of care conditions.

Improving non-invasive hemoglobin measurement accuracy using nonparametric models

Uncontrolled hemorrhage is a leading cause of preventable death among patients with trauma. Early recognition of hemorrhage can aid in the decision to administer blood transfusion and improve patient outcomes. To provide real-time measurement and continuous monitoring of hemoglobin concentration, the non-invasive and continuous hemoglobin (SpHb) measurement device has drawn extensive attention in clinical practice. However, the accuracy of such a device varies in different scenarios, so the use is not yet widely accepted. This article focuses on using statistical nonparametric models to improve the accuracy of SpHb measurement device by considering measurement bias among instantaneous measurements and individual evolution trends. In the proposed method, the robust locally estimated scatterplot smoothing (LOESS) method and the Kernel regression model are considered to address those issues. Overall performance of the proposed method was evaluated by cross-validation, which showed a substantial improvement in accuracy with an 11.3% reduction of standard deviation, 23.7% reduction of mean absolute error, and 28% reduction of mean absolute percentage error compared to the original measurements. The effects of patient demographics and initial medical condition were analyzed and deemed to not have a significant effect on accuracy. Because of its high accuracy, the proposed method is highly promising to be considered to support transfusion decision-making and continuous monitoring of hemoglobin concentration. The method also has promise for similar advancement of other diagnostic devices in healthcare.

Non-invasive hemoglobin measurement devices require refinement to match diagnostic performance with their high level of usability and acceptability.

Anemia remains an important global health problem. Inexpensive, accurate, and noninvasive solutions are needed to monitor and evaluate anemia in resource-limited settings. We evaluated the performance of multiple point-of-care hemoglobin devices, including a novel noninvasive smartphone application tested on Apple® and Android® cell phones, Masimo Pronto®, and HemoCue® Hb-301 and Hb-801, against a gold-standard hematology analyzer (reference hemoglobin) using venous blood. We examined correlations between hemoglobin devices and reference hemoglobin, device accuracy (average bias, Bland-Altman plots, clinical performance) and classification bias (sensitivity, specificity) among 299 refugees (10mo-65y) in Atlanta, GA. Semi-structured interviews (n = 19) with participants and staff assessed usability and acceptability. Mean reference hemoglobin was 13.7 g/dL (SD:1.8) with 12.5% anemia. Noninvasive hemoglobin devices were not well correlated with reference hemoglobin (Apple® R2 = 0.08, Android® R2 = 0.11, Masimo Pronto® R2 = 0.29), but stronger correlations were reported with HemoCue® Hb-301 (R2 = 0.87) and Hb-801 (R2 = 0.88). Bias (SD) varied across each device: Apple®: -1.6 g/dL (2.0), Android®: -0.7 g/dL (2.0), Masimo Pronto®: -0.4 g/dL (1.6), HemoCue® Hb-301: +0.4 g/dL (0.7) and HemoCue® Hb-801: +0.2 g/dL (0.6). Clinically acceptable performance (within ± 1 g/dL of reference hemoglobin) was higher for the invasive devices (HemoCue® Hb-301: 90.3%; HemoCue® Hb-801: 93.4%) compared to noninvasive devices (Apple®: 31.5%; Android®: 34.6%; Masimo Pronto®: 49.5%). Sensitivity and specificity were 63.9% and 48.2% for Apple®, 36.1% and 67.6% for Android®, 45.7% and 85.3% for Masimo Pronto®, 54.3% and 97.6% for HemoCue® Hb-301, and 66.7% and 97.6% for HemoCue® Hb-801. Noninvasive devices were considered easy to use and were the preferred method by participants. Among the only studies to compare multiple point-of-care approaches to hemoglobin testing, the diagnostic ability of HemoCue® was comparable to reference hemoglobin, while noninvasive devices had high user acceptability but considerable biases. Improvements in noninvasive device performance and further testing in anemic populations are recommended before broader use.

Evaluation of Noninvasive Hemoglobin Measurements in Trauma Patients: A Repeat Study

Reliable, accurate, and non-invasive hemoglobin measurements would be useful in the trauma setting. The aim of this study was to re-examine the ability of the Masimo Radical 7 in this setting after recent hardware and software improvements. Level 1 Trauma patients were prospectively enrolled in the study over a 9-mo period with the goal of obtaining 3 paired data points from 150 patients admitted to the ICU or IMU. Hospital laboratory hemoglobin values were compared with cyanomethemoglobin (HiCN) and Masimo device hemoglobin (SpHb) values using comparison plots and Bland-Altman analysis. A total of 380 patients were enrolled in the study with 150 of those being admitted to the ICU or IMU. Comparison of hospital lab hemoglobin and HiCN (n=494) found a correlation of R2=0.92. Comparison of hospital lab hemoglobin and Masimo device hemoglobin (n=218) found a correlation of R2=0.27. Bland-Altman analysis of the 218of the comparable hospital hemoglobin and Masimo device hemoglobin values had a bias of 0.505 g/dL with 95% of values within the limits of agreement of 4.06 g/dL to -3.60 g/dL. The Masimo Radical 7 device has the potential to provide timely, useful clinical information, but it is not currently able to serve as an initial noninvasive diagnostic tool for trauma patients. There was poor correlation between clinical Hgb and SpHb, and because of that, SpHb should not be used to evaluate hemoglobin levels in trauma patients.

Can perioperative hemodilution be monitored with non-invasive measurement of blood hemoglobin?

BackgroundTrends in non-invasive measurements of blood hemoglobin (Hb) may be useful for identifying the need for transfusion in the perioperative period.MethodsCrystalloid fluid (5–20 mL/kg) was administered intravenously or by mouth to 30 volunteers and 33 surgical patients in five non-randomized clinical studies where Hb was measured on 915 occasions by non-invasive (Radical-7™) and invasive methodology. The hemodilution curves were compared by volume kinetic analysis and linear regression, with the slope and scattering of the data as key outcome measures.ResultsThe slope was 1.0, indicating unity between the two modes of measuring Hb when crystalloid fluid was infused in volunteers; however, only 40–45% of the variability in the non-invasive Hb could be explained by the invasive Hb. Patients undergoing major surgery, who showed the most pronounced hemodilution (median 24 g/L); non-invasive Hb explained 72% of the variability but indicated only half the magnitude of the invasive Hb changes (slope 0.48, P < 0.001 versus the volunteers). Simulations based on volume kinetic parameters from the volunteers showed 25% less plasma volume expansion after infusion when based on non-invasive as compared to invasive Hb, while no difference was found during infusion.ConclusionsIn volunteers the non-invasive Hb had good accuracy (low bias) but poor precision. In surgical patients the non-invasive Hb had good precision but systematically underestimated the hemodilution. Despite severe limitations, the non-invasive technology can be used to follow Hb trends during surgery if supported by occasional invasive measurements to assure acceptable quality of the hemodilution curve.Trial registrationsControlledTrials.gov NCT01195025, NCT01062776, NCT01458678, NCT03848507, and NCT01360333 on September 3, 2010, February 4, 2010, October 25, 2011, February 20, 2019, and May 25, 2011, respectively.

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 (146g.l-1 for women and 152g.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 (138g.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 152g.l-1 in female and 162g.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 28g.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 (132g.l-1 ) could be more clinically appropriate in women.

Non-invasive hemoglobin measurement using embedded platform

This paper is based on the design and development of an in-house algorithm system to Estimate Total Hemoglobin in human blood using the Arduino based Embedded system. In our present society, monitoring Hemoglobin of subjects is very important in hospitals to keep track of low/high hemoglobin count during operations, delivery, dialysis, blood donations, perform stress test, monitoring patients in intensive care units, etc. is often done using invasive methods. In our approach, we have designed a finger probe using five LEDs on a multi-chip having wavelengths 670 nm/770 nm/810 nm/850 nm and 950 nm, and a single silicon photo detector with an inbuilt trans-impedance amplifier to acquire the signals through the finger using the Photoplethysmography (PPG) principle. The non-invasive method can be replaced in hospitals and homes to monitor the total hemoglobin level which is in real-time, painless, and infection-free from needles. We have tested our system on 8 subjects for three and five wavelengths and the values were compared to the hemoglobin measured using invasive methods in the pathology laboratory. The result demonstrates that the five wavelengths PPG method significantly improves the measurement accuracy of total hemoglobin, reducing the mean absolute error between the reference and the estimated hemoglobin values from 1.3778 g/dL for three wavelengths PPG to 0.3499 g/dL for five wavelengths PPG. The five wavelengths PPG system designed showed good linearity to estimate hemoglobin with the Regression Coefficient (R2 = 0.964) compared to three wavelengths PPG system with the Regression Coefficient (R2 = 0.688).

The usefulness of non-invasive co-oximetry haemoglobin measurement for screening pre-operative anaemia.

Pre-operative anaemia (haemoglobin<13.0g.dl-1 ) is a modifiable peri-operative risk-factor. This is screened for using formal laboratory testing. A non-invasive finger-probe sensor that can accurately measure haemoglobin is a possible alternative. This study considers the accuracy of non-invasive haemoglobin measurement using the Rad-67™ Rainbow (Masimo Corp., Irvine, CA, USA) compared with formal laboratory testing and its usefulness in detecting pre-operative anaemia. A total of 392 patients had measurements taken for non-invasive haemoglobin and perfusion index values using the Rad-67 Rainbow, alongside further peri-operative parameters and a formal laboratory haemoglobin test. Bland-Altman and sensitivity analysis showed that the limits of agreement between non-invasive and formal laboratory haemoglobin testing were between -1.95g.dl-1 and 2.23g.dl-1 (p<0.001). The overall performance of non-invasive haemoglobin measurement was better in men than women (ROC 91.1% vs. 78.2%) and less biased in men, mean -0.08 (SD 1.09, 95%Cl -0.23-0.07) compared with women (mean 0.38 (SD 0.99, 95%CI 0.24-0.52)). Pre-operative anaemia was more prevalent in women than men (50.3% vs. 14.4%). The sensitivity of non-invasive anaemia detection (haemoglobin<13g.dl-1 ) was 66% for women and 52% for men. A non-invasive haemoglobin value of 14.0g.dl-1 had an overall 91% sensitivity for detecting pre-operative anaemia (82% in men and 93% in women). The Rad-67 Rainbow is inadequate for the estimation of formal laboratory haemoglobin and lacks sensitivity for detecting pre-operative anaemia, especially in women. Further advancement in technology and accuracy is needed before it can be recommended as a routine pre-operative screening test.

Transcutaneous Hemoglobin Screening in an Adult Orthopaedic Trauma Population.

To evaluate a noninvasive hemoglobin measurement device in an orthopaedic trauma population. Prospective. Level 1 trauma center. One hundred five patients consecutively admitted to the orthopaedic trauma service after surgical treatment of fracture. Transcutaneous hemoglobin (TcHgb) monitoring using the Masimo Pronto Pulse CO-Oximeter model with Rainbow SET Technology for spot TcHgb measurement. TcHgb measurements and standard venipuncture hemoglobin (vHgb) were obtained. Patient preferences for each were recorded. 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). 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. Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.