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 ≤ 17 years was performed during preoperative anesthesia consultation and compared with laboratory hemoglobin (labHb) levels. SpHb was measured in 62 children (median age: 6 years, 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 1.3 g/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 0.8 g/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).

Noninvasive hemoglobin monitoring for maintaining hemoglobin concentration within the target range during major noncardiac surgery: A randomized controlled trial.

STUDY OBJECTIVE: The effect of noninvasive CO-oximetry hemoglobin (SpHb) monitoring on the clinical outcomes of patients undergoing surgery remains unclear. This trial aimed to evaluate whether SpHb monitoring helps maintain hemoglobin levels within a predefined target range during major noncardiac surgeries with a potential risk of intraoperative hemorrhage. DESIGN: A single-center, prospective, randomized controlled trial. SETTING: University hospital. PATIENTS: One hundred and thirty patients undergoing elective noncardiac surgery with a potential risk of hemorrhage. INTERVENTIONS: Patients were randomly allocated to undergo either SpHb-guided management (SpHb group) or usual care (control group). MEASUREMENTS: The primary outcome was the rate of deviation of the total hemoglobin concentration (determined from laboratory testing) from a pre-specified target range (8-14 g/dL). This was defined as the number of laboratory tests revealing such deviations divided by the total number of laboratory tests performed during the surgery. MAIN RESULTS: The primary outcome occurred significantly less frequently in the SpHb group as compared to that in the control group (15/555 [2.7%]) vs. 68/598 [11.4%]; relative risk, 0.24; 95% confidence interval, 0.13-0.41; P < 0.001). Fewer point-of-care blood tests were performed in the SpHb group than in the control group (median [interquartile range], 2 [1-4] vs. 4 [2-5]; P < 0.001). There were no significant intergroup differences in the number of patients who received red blood cell transfusions during surgery (SpHb vs. control, 33.8% vs. 46.2%; P = 0.201). The incidence of unnecessary red blood cell preparation (>2 units) was lower in the SpHb group than in the control group (3.1% vs. 16.9%; P = 0.024). CONCLUSIONS: Compared with routine care, SpHb-guided management resulted in significantly lower rates of hemoglobin deviation outside the target range intraoperatively in patients undergoing major noncardiac surgeries with a potential risk of hemorrhage. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov (identifier: NCT03816514).

Agreement between Noninvasive Hemoglobin and Laboratory Hemoglobin Measurements in Neonates: A Systematic Review and Meta-Analysis.

BACKGROUND AND OBJECTIVE: The noninvasive hemoglobin (NHb) devices are recently evaluated as an alternative to laboratory hemoglobin (LHb) in neonates. This systematic review explores the diagnostic accuracy of NHb devices for neonatal hemoglobin measurement. METHODS: Literature related to the comparison of NHb device with LHb in neonates was searched from Medline, PubMed Central, PubMed, Web of Science, Google Scholar, and Scopus databases after PROSPERO registration. The quality of included publications was assessed by QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies). The pooled correlation coefficient and bias (precision) in Bland-Altman difference plots were used for summary statistics using MetaXL 5.0 software. RESULTS: A total of 1,477 paired NHb-LHb observations were analyzed from 1,047 neonates in 10 studies. Massimo radical-pulse co-oximetry (8 studies) and Mediscan-2000 (2 studies) were used for NHb estimation. The pooled correlation coefficient between NHb and LHb was r = 0.94 (95% CI: 0.83-0.98, p < 0.001), and the pooled bias (precision) was -0.013 (1.4) gm/dL between NHb and LHb measurements in Bland-Altman analysis. NHb device had better precision in stable neonates (0.91gm/dL) over sick neonates (1.66 gm/dL). CONCLUSIONS: Hemoglobin measurement by NHb is excellently correlated with LHb measurement with a minimal average difference. It may be used as a screening tool for hemoglobin measurement in neonates to avoid frequent phlebotomy.

Continuous hemoglobin measurement during frontal advancement operations can improve patient outcomes.

Massive hemorrhage in pediatric cranioplasty operations may necessitate blood transfusion, which may cause many complications. Radical-7 Pulse CO-Oximeter (Massimo Corporation, Irvine, CA) can provide continuous hemoglobin concentration (SpHb) measurements noninvasively. In this study, we aimed to evaluate the effects of SpHb measurement on perioperative transfusion management and postoperative patient outcomes. For this retrospective case-control study, we collected the data of pediatric patients undergoing fronto-orbital advancement surgery for plagiocephaly and trigonocephaly between 2018 and 2021. Perioperative SpHb monitoring was performed for patients in the SpHb Group. Other patients that were managed conventionally were considered as the control group (C Group). The data on patients' demographic and clinical characteristics, intraoperative hemodynamic and laboratory variables such as blood gases, intraoperative blood losses, the amount of the transfused blood products, the length of postoperative intensive care unit (ICU) stay, and the duration of hospital stay were collected. The data of 42 patients were collected, and 29 of these patients were males (69%). In 16 of the patients, SpHb monitoring was performed. The demographic, clinical, and perioperative hemodynamic characteristics of the patients were comparable between the groups. Compared to the C Group, the SpHb Group had significantly lower perioperative packed red blood cell (PRBC) transfusion (136.3 ± 40.1 vs. 181.5 ± 74.8 mL, P = 0.015), less postoperative drainage (125.3 ± 47.7 vs. 185.8 ± 97.6 mL, P = 0.013), and shorter ICU stay (37.1 ± 12.0 vs. 64.8 ± 24.9 h, P < 0.001). There was a positive correlation between the amount of PRBC transfusion and the length of ICU stay (r = 0.459, P = 0.003). Patients with perioperative continuous SpHb measurement have lower intraoperative PRBC transfusion, less postoperative bleeding, and shorter ICU stay. When necessary, SpHb, together with clinical judgment and laboratory confirmation, can be used in decision-making for perioperative PRBC transfusion.

Spectrometry of cord blood and maternal blood for Hb-F and Hb-A and novel technology for non-invasive measurement of hemoglobin in mother and baby.

BACKGROUND: Human hemoglobin (Hb) is a tetrameric metalloporphyrin. Heme part contains iron radicle and porphyrin. The globin part has pairs of amino-acid chains. Healthy adults have "Hemoglobin-A" made of two alpha and two beta chains (α2 ß2) while a newborn baby has "Hemoglobin-A (α2 ß2)" and "Hemoglobin-F (α2 γ2)". There are few reports about absorption spectrometry of Hb in cord blood. We have here compared absorption spectrum of Hb in cord blood and maternal blood samples (adult blood samples) together. OBJECTIVE: This was done in two parts. Part 1 was about studying absorption spectrum of Hb in cord blood and maternal blood. Part 2 was about developing a comprehensive noninvasive technology and using the same for measurement of Hb in mother (adult) and new-born baby. DESIGN: Observational study. MATERIAL AND METHODS: Part 1. After IRB approval, 25 pregnant mothers enrolled for the study. Cord blood/neonatal blood samples were collected from placental end in ethylene diamine tetra-acetic acid (EDTA) tube after the delivery of fetus and placenta (venous blood). Maternal blood was collected by peripheral venepuncture before delivery/labor. Part 2. Using noninvasive technology for measurement of Hb in mother (adult) and new-born baby. After the necessary approval five pairs of mother and new-born were enrolled in the study to measure Hb by noninvasive method using our novel device. The novel device (SH-1) uses electromagnetic radiations of specific wavelengths between 520 and 580 nm. Light was projected on forehead for a few seconds, operating the light sources one by one. Of the projected light, some was reflected by the recipient's skin. This optical signal was collected by photosensors and converted to electrical signals. After amplification, this was then transmitted to processor unit. Later, Hbs values are displayed. The results were then tallied with standard laboratory methods in clinical laboratory. RESULTS: Part 1. As expected in our study; all blood samples showed Soret band of same peak and wavelength. We expected different spikes corresponding to four globin chains namely alpha, beta, gamma, and delta. But interestingly, both neonatal and maternal blood samples had identical peaks. Part 2. The results appear promising. The Hb as measured by noninvasive method matches well with standard laboratory test. SIGNIFICANCE: The energy level of Hb is low in deoxygenated state compared to oxyhemoglobin. In a state of high energy level, alpha and beta and gamma globin chains show obvious different peaks. Since cord blood and maternal sample was obviously venous or in deoxygenated state with low energy level, single peak of absorption was observed for all three globin chains. Since maternal and cord blood showed similar absorption spectra, it was possible to develop a common method for estimation of biomarkers - Hb in adults and new-borns alike.

Noninvasive Hemoglobin Level Prediction in a Mobile Phone Environment: State of the Art Review and Recommendations.

BACKGROUND: There is worldwide demand for an affordable hemoglobin measurement solution, which is a particularly urgent need in developing countries. The smartphone, which is the most penetrated device in both rich and resource-constrained areas, would be a suitable choice to build this solution. Consideration of a smartphone-based hemoglobin measurement tool is compelling because of the possibilities for an affordable, portable, and reliable point-of-care tool by leveraging the camera capacity, computing power, and lighting sources of the smartphone. However, several smartphone-based hemoglobin measurement techniques have encountered significant challenges with respect to data collection methods, sensor selection, signal analysis processes, and machine-learning algorithms. Therefore, a comprehensive analysis of invasive, minimally invasive, and noninvasive methods is required to recommend a hemoglobin measurement process using a smartphone device. OBJECTIVE: In this study, we analyzed existing invasive, minimally invasive, and noninvasive approaches for blood hemoglobin level measurement with the goal of recommending data collection techniques, signal extraction processes, feature calculation strategies, theoretical foundation, and machine-learning algorithms for developing a noninvasive hemoglobin level estimation point-of-care tool using a smartphone. METHODS: We explored research papers related to invasive, minimally invasive, and noninvasive hemoglobin level measurement processes. We investigated the challenges and opportunities of each technique. We compared the variation in data collection sites, biosignal processing techniques, theoretical foundations, photoplethysmogram (PPG) signal and features extraction process, machine-learning algorithms, and prediction models to calculate hemoglobin levels. This analysis was then used to recommend realistic approaches to build a smartphone-based point-of-care tool for hemoglobin measurement in a noninvasive manner. RESULTS: The fingertip area is one of the best data collection sites from the body, followed by the lower eye conjunctival area. Near-infrared (NIR) light-emitting diode (LED) light with wavelengths of 850 nm, 940 nm, and 1070 nm were identified as potential light sources to receive a hemoglobin response from living tissue. PPG signals from fingertip videos, captured under various light sources, can provide critical physiological clues. The features of PPG signals captured under 1070 nm and 850 nm NIR LED are considered to be the best signal combinations following a dual-wavelength theoretical foundation. For error metrics presentation, we recommend the mean absolute percentage error, mean squared error, correlation coefficient, and Bland-Altman plot. CONCLUSIONS: We addressed the challenges of developing an affordable, portable, and reliable point-of-care tool for hemoglobin measurement using a smartphone. Leveraging the smartphone's camera capacity, computing power, and lighting sources, we define specific recommendations for practical point-of-care solution development. We further provide recommendations to resolve several long-standing research questions, including how to capture a signal using a smartphone camera, select the best body site for signal collection, and overcome noise issues in the smartphone-captured signal. We also describe the process of extracting a signal's features after capturing the signal based on fundamental theory. The list of machine-learning algorithms provided will be useful for processing PPG features. These recommendations should be valuable for future investigators seeking to build a reliable and affordable hemoglobin prediction model using a smartphone.

Evaluation of noninvasive hemoglobin monitoring in children with congenital heart diseases.

BACKGROUND: Noninvasive measurement of blood hemoglobin could save time and decrease the risk of anemia and infection. The accuracy of CO-oximetry-derived noninvasive hemoglobin (Sp-Hb) had been evaluated in pediatric population; however, its accuracy in children with congenital heart disease has not been studied till date. We evaluated the accuracy of Sp-Hb in relation to laboratory-measured hemoglobin (Lab-Hb) in children with congenital heart disease. METHODS: This prospective observational study included children with congenital heart disease undergoing procedural intervention. Sp-Hb measurements were obtained using Radical-7 Masimo pulse CO-oximeter and were compared against simultaneous Lab-Hb measurements obtained from the arterial line. Children were divided in cyanotic and acyanotic, and separate analysis was performed for each group. The values of both measurements were analyzed using Spearman's correlation coefficient and Bland-Altman analysis. Correlation was performed between Sp-Hb and Lab-Hb bias and each of arterial oxygen saturation and perfusion index. RESULTS: One-hundred and eleven pairs of readings were obtained from 65 children. The median (quartiles) age and weight of the children were 1 (1.2-4) years and 11 (8-17) kg, respectively. There was moderate correlation between Lab-Hb and Sp-Hb with a correlation coefficient (95% confidence interval [CI]) of 0.75 (0.63-0.83) in acyanotic children and 0.62 (0.37-0.79) in cyanotic children. The mean bias (95% limits of agreements) was -0.4 g/dL (-2.4 to 1.6 g/dL) and 1 g/dL (-2.7 to 4.6 g/dL) in acyanotic and cyanotic children, respectively. The mean bias between Sp-Hb and Lab-Hb showed a weak negative correlation with oxygen saturation (r [95% CI]): (-0.36 [-0.51--0.18]), and a weak positive correlation with the perfusion index (r [95% CI]): (0.19 [0.01-0.37]). CONCLUSION: The large bias and the wide limits of agreement between Sp-Hb and Lab-Hb denote that Masimo-derived Sp-Hb is not accurate in children with congenital heart disease especially in the cyanotic group; the error in Sp-Hb increases when oxygen saturation decreases.

Noninvasive Continuous Hemoglobin Monitoring: Role in Cardiovascular Surgery.

Blood transfusions in the operating room are associated with increased morbidity and mortality as well as increased cost. The technology exists for continuous noninvasive hemoglobin monitoring (SpHb), which could allow for the rapid diagnosis and treatment of acute blood loss anemia secondary to surgical bleeding. However, the accuracy of this technology has been called into question. SpHb in the operating room could reduce cost by decreasing lab draws, unnecessary transfusions, and the morbidity associated with blood transfusions. This review examines the accuracy of noninvasive hemoglobin monitoring as well as the role it may play in the operating room.

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.

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.

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.

Comparison between continuous noninvasive hemoglobin monitoring and venous blood hemoglobin monitoring in children with kidney disease / 北京大学学报(医学版)

Objective:To assess the correlation and consistency between continuous noninvasive hemo globin detection and venous blood hemoglobin detection in children with kidney disease,and try to analyze the affecting factors.Try to provide a reference for the monitoring of hemoglobin in children with kid ney disease by continuous noninvasive hemoglobin detection technique.Methods:Eighty-five inpatient children with kidney disease,50 boys (58.8％) and 35 girls (41.2％),aged from 3 years old to 18 years old (9.35 ± 4.29) were included finally.Noninvasive hemoglobin monitoring by spectrophotometry (SpHb) was stably read by PRONTO-7,selecting the ring finger of the non handedness as the detection site.And then the venous blood hemoglobin of the same patient was collected in 5 minutes as the true hemoglobin (tHb) by Beckman coulter DXH-800.The data of SpHb and tHb were compared and analyzed using SPSS 17.0 and MedCalc.Results:Correlation analysis showed data of SpHb and tHb were with significant correlation,the correlation coefficient between SpHb and tHb was 0.85 (P ＜ 0.05).BlandAltman plot points suggested that the mean of differences between SpHb and tHb was-1.3 g/dL.The 95％ CI of agreement of SpHb-tHb was-4.2-1.5 g/dL,suggesting that the average measurement re sult of SpHb was lower than that of tHb.The mean of differences as percent between SpHb and tHb was -9.8％,95％ CI of agreement was (-35.9％,16.2％) exceeding the acceptable range of true value ± 6％.The consistent rate of non-invasive hemoglobin detection and venous blood hemoglobin detection was 31.8％,the 95％ CI of consistent rate was (21.7％,41.9％).The chi square test of the fourfold table showed that the diagnosis of anemia with SpHb was of high sensitivity,but the specificity was low,the false positive rate was high,and the difference was statistically significant (P =0.000).Conclusion:There was a significant correlation between SpHb and tHb in the children with kidney disease.Noninvasive hemoglobin measurement can be used for monitoring of changes of hemoglobin in children with kidney diseases.But the consistency between SpHb and tHb needs to be improved.Noninvasive hemoglobin measurement could not replace the venous hemoglobin measurement.It could not be used for the diagnosis of anemia,and the accuracy of hemoglobin concentration measurement in children with kidney disease should be further explored.

A mini volume loading test (mVLT) using 2.5-mLkg-1 boluses of crystalloid for indication of perioperative changes in hydration status.

BACKGROUND AND OBJECTIVE: A mini volume loading test (mVLT) evaluating hemodilution during step-wise crystalloid infusion has established that the arterio-capillary plasma dilution difference is inversely correlated to the body hydration level of subjects. This observational study aimed to test whether this can be replicated in a perioperative setting using a 2.5-mLkg-1 boluses. MATERIALS AND METHODS: The mVLT was performed before induction of regional anesthesia and 24h later. Step-wise infusion implied six mini fluid challenges. These consisted of 2.5-mLkg-1 boluses of Ringer's acetate infused during 2-3min and followed by 5-min periods with no fluids. Invasive (arterial) and noninvasive (capillary) measurements of hemoglobin were performed before and after each mini fluid challenge, as well as after a 20-min period without fluid following the last bolus. Hemoglobins were used to calculate the arterio-capillary plasma dilution difference which is used as an indication of changes in body hydration level. The 24-h fluid balance was calculated. RESULTS: Subjects were 69.5 (6.0) years old, their height was 1.62m (1.56-1.65), weight was 87.0kg (75.5-97.5) and body mass index (BMI) was 33.5kg/m2 (31.0-35.1). Preoperative arterio-capillary plasma dilution difference was significantly higher than postoperative (0.085 [0.012-0.141] vs. 0.006 [-0.059 to 0.101], P=0.000). The perioperative 24-h fluid balance was 1976mL (870-2545). CONCLUSIONS: The mVLT using 2.5-mLkg-1 boluses of crystalloid was able to detect the higher postoperative body hydration level in total knee arthroplasty patients.

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.

A mini volume loading test for indication of preoperative dehydration in surgical patients.

BACKGROUND AND OBJECTIVE: Previously, a mini volume loading test (mVLT) detected signs of dehydration in healthy volunteers after an overnight fast. Our objective was to investigate whether mVLT could indicate preoperative dehydration in patients after an overnight fast. MATERIALS AND METHODS: The mVLT was performed in 36 elective primary total knee arthroplasty patients. Each subject received three fluid challenges before anesthesia induction. These consisted of 5 mL/kg boluses of Ringer's acetate infused over 3-5 min and followed by a 5-min period without fluids. Invasive (arterial, venous) and noninvasive (capillary) measurements of hemoglobin concentration were performed before and after each fluid challenge, as well as after a 20-min period without fluids which followed the last bolus. Arterial, venous and capillary plasma dilutions were calculated in every data point. Dilution values were used to calculate the plasma dilution efficacy of each fluid challenge. RESULTS: Venous dilution was higher than capillary after the first fluid challenge (P=0.030), but lower than capillary after 20 min period following the last bolus (P=0.009). Arterial dilution was lower than capillary (P=0.005) after 20 min following the last bolus. Veno-capillary and arterio-capillary plasma dilution efficacy differences decreased (P=0.004 and P=0.033, respectively) from positive to negative during mVLT. These are signs of re-hydration from pre-existing dehydration according to a transcapillary reflux model. CONCLUSIONS: Signs of dehydration were observed during mVLT in patients after pre-operative overnight fast. A revised transcapillary reflux model was proposed to explain the results.

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.

Hematology testing in urgent care and resource-poor settings: an overview of point of care and satellite testing.

The combination of requirements for decreased turnaround time for hematology laboratory results and advances in technology have driven testing closer to the point of patient contact. This article provides an overview of the technologies available to measure hemoglobin, white blood cell counts, differentials, and CD4+ T cells at the patient's bedside and in satellite laboratories. Comparison with traditional laboratory testing, regulatory requirements, and operational considerations are also discussed, where appropriate.

Factor XI deficiency and orthognathic surgery: a case report on anesthesia management.

Factor XI deficiency (Hemophilia C) is a very rare autosomal recessive bleeding disorder. Patients with factor XI deficiency do not typically show any spontaneous bleeding or specific symptoms. Sometimes those who have this disorder are identified during special situations such as trauma or surgery. Orthognathic surgery is particularly associated with a high bleeding risk. Therefore, great care must be taken when treating patients with bleeding disorders such as factor XI deficiency. There are a few reports that address the management of patients with bleeding disorders during orthognathic surgery. The current report describes a patient with factor XI deficiency who underwent Le Fort I osteotomy together with bilateral sagittal split osteotomy. The patient's condition was assessed using both rotation thromboelastometry (ROTEM™) and noninvasive measurements of total hemoglobin (SpHb) using Masimo Radical 7 (Masimo Co. CA, USA).

Factor XI deficiency and orthognathic surgery: a case report on anesthesia management

Factor XI deficiency (Hemophilia C) is a very rare autosomal recessive bleeding disorder. Patients with factor XI deficiency do not typically show any spontaneous bleeding or specific symptoms. Sometimes those who have this disorder are identified during special situations such as trauma or surgery. Orthognathic surgery is particularly associated with a high bleeding risk. Therefore, great care must be taken when treating patients with bleeding disorders such as factor XI deficiency. There are a few reports that address the management of patients with bleeding disorders during orthognathic surgery. The current report describes a patient with factor XI deficiency who underwent Le Fort I osteotomy together with bilateral sagittal split osteotomy. The patient's condition was assessed using both rotation thromboelastometry (ROTEM™) and noninvasive measurements of total hemoglobin (SpHb) using Masimo Radical 7 (Masimo Co. CA, USA).

Evaluation of hydration status calculated from differences in venous and capillary plasma dilution during stepwise crystalloid infusions: A randomized crossover study in healthy volunteers.

BACKGROUND AND OBJECTIVE: A mini volume loading test (mVLT) was proposed for estimating hydration status and interstitial fluid accumulation during stepwise infusion of crystalloids. The method is based on both the transcapillary reflux model and the hypothesis that when subjects are dehydrated, venous plasma dilution induced by a fluid challenge is higher than in the capillaries, and that difference is diminished when the fluid challenge is given to more hydrated individuals. Our objective was to test that hypothesis by evaluating the veno-capillary dilution difference during mVLT in subjects with different hydration status. MATERIALS AND METHODS: In a prospective randomized crossover study, three mini fluid challenges were given to 12 healthy volunteers on two occasions. The subjects were either dehydrated or hydrated before the experiments. RESULTS: In dehydrated subjects only, capillary plasma dilution was significantly lower than venous (P=0.015, 0.005 and 0.006) after each mini fluid challenge. CONCLUSIONS: Veno-capillary dilution difference during mVLT depends on the hydration status. The mVLT method could possibly discriminate between the different states of hydration.