Accuracy of noninvasive hemoglobin monitoring in patients at risk for hemorrhage

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.

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.

Progressive evaluation in spectroscopic sensors for non-invasive blood haemoglobin analysis - a review

Frequent monitoring of haemoglobin concentration is highly recommended by physicians to diagnose anaemia and polycythemia Vera. Moreover, Some other conditions also demand assessment of haemoglobin, and these conditions are blood loss, before blood donation, during pregnancy, preoperative, perioperative and postoperative conditions. Cyanmethaemoglobin/haemiglobincyanide method, portable haemoglobinometers and haematology analyzers are few standard methods to diagnose mentioned ailments. However, discomfort, delay and risk of infection are typical limitations of traditional measuring solutions. These limitations create the necessity to develop a non-invasive haemoglobin monitoring technique for a better lifestyle. Various methods and products are already developed and popular due to their non-invasiveness; however, invasive solutions are still considered as the reference standard method. Therefore, this review summarizes the attributes of existing non-invasive solutions. These attributes are finalized as brief details, accuracy, optimal benefits, and research challenges for exploring potential gaps, advancements and possibilities to consider as futuristic alternative methodologies. Non-invasive total haemoglobin assessing techniques are mainly based on optical spectroscopy (reflectance/transmittance) or digital photography or spectroscopic imaging in spot check/continuous monitoring mode. In all these techniques, we have noticed that there is a need to consider different light conditions, motion artefacts, melanocytes, other blood constituents, smoking and precise fixing of the sensor from the sensing spot for exact formulation. Moreover, based on careful and critical analysis of outcomes, none of these techniques or products is used independently or intended to replace invasive laboratory testing. Therefore there is a requirement for a more accurate technique that can eliminate the requirement of blood samples and likely end up as a reference standard method.

NIR-based sensing system for non-Invasive detection of Hemoglobin for point-of-care applications

BACKGROUND

Hemoglobin is essential biomolecule for the transportation of oxygen therefore; its assessment is also obligatory very frequently in innumerable clinical practices. Traditional invasive techniques have concomitant shortcomings e.g. time delay, onset of infections and discomfort, which necessitates a non-invasive hemoglobin estimating solution to get rid of these constraints in health informatics. Currently various techniques are underway in allied domain and scanty products are also feasible in the market but due to low satisfaction rate, invasive solutions are still assumed as gold standard. Recently introduced technologies are effectively evolved as optical spectroscopy and digital photographic concepts on different sensing spots e.g. fingertip, palpebral conjunctiva, bulbar conjunctiva and fingernail. Productive sensors utilize more than eight wavelengths to compute hemoglobin concentration and four wavelengths to display only Hb-index (trending of hemoglobin) either in disposable adhesive or reusable clip type sensor's configuration.

OBJECTIVE

This study aims an optimistic optical spectroscopic technique to measure hemoglobin concentration and conditional usability of non-invasive blood parameters' diagnostics at point-of-care.

METHODS

Two distinguishable light emitting sources (810nm & 1300nm) are utilized at isosbestic points with single photodetector (800-1700nm). With this purpose, reusable finger probe assembly is facilitated in transmittance mode based on newly offered sliding mechanism to block ambient light.

RESULTS

Investigation with proposed design presents correlation coefficients between reference hemoglobin and every individual feature, multivariate linear regression model for highly correlated independent features. Moreover, principal component analytical model with multivariate linear regression offers mean bias of 0.036 & -0.316 g/dL, precision of 0.878 & 0.838 and limits of agreement from -1.685 to 1.758 g/dL & -1.790 to 1.474 g/dL for 18 & 21 principle components respectively.

CONCLUSION

The encouraging readouts emphasize favorable precision therefore proposed sensing system is amenable to assess hemoglobin in settings with limited resources and strengthening future routes for point of care applications.

Reliability of a spot check non-invasive hemoglobin monitoring (SpHb) of the Masimo RAD-67™ and the HemoCue® for anemia screening

Background : To test the reliability of the spot check Masimo Rad-67 (Masimo Corp., Irvine, CA, USA) as part of a preoperative anemia screening, hemoglobin measurements were compared to those of the HemoCue® Hb 201+ System (HemoCue AB, Ängelholm, Sweden) and the standard laboratory measurement. Methods : During preoperative evaluation of patients scheduled for elective orthopedic surgery hemoglobin concentration was simultaneously determined by standard laboratory analysis (HbLab), the HemoCue® Hb 201+ System (HbHemocue) and by Pulse Co-Oximetry using the Masimo Rad-67 (SpHb) with the rainbow® DCI®-mini Sensor (Masimo Corp., Irvine, CA, USA). Linear correlation, agreement (Bland-Altman analysis), sensitivity/specificity and positive/negative prediction values (PPV/NPV) for anemic hemoglobin values were determined. P-values less than 0.05 were considered statistically significant. Results : 303 patients were analyzed. Twenty-one patients (12 male and 9 female) had mild or moderate anemia, detected by HbLab. In 20 patients, the HbHemocue, and in 34 patients, the SpHb detected anemia. Linear correlation and mean bias (limits of agreement, LOA) for HbHemocue and HbLab were r = 0.969 and -1.08 (+6.44/-8.60) g/L, and for SpHb and HbLab r = 0.61 and +1.76 (+26.92/-23.4) g/L. Sensitivity/specificity of the HbHemocue to detect anemia in all, male and female patients were 85.0/99.3%, 75.0/100/% and 88.9/98.9/% with a PPV/NPV of 89.5/98.9%, 100/98.0% and 80.0/99.3%, respectively. Sensitivity/specificity of SpHb to detect anemia for all, male and female patients were 71.4%, 93.3%, 75.0/95.2/% and 66.7/91.1%, with a PPV/NPV for all, male and female patients of 44.1/97.8%, 56.3/97.9% and 33.3/97.7%, respectively. Conclusions : HbHemocue and HbLab show a strong linear correlation and a good agreement, while linear correlation of SpHb and HbLab is moderate and agreement poor. For both devices, anemia detection is moderate, but the positive prediction value for anemia is much better with the HbHemocue. Both devices reliably detected non-anemic patients. Glossary : CO = carbon monoxide ; PPV = positive predicted value ; NPV = negative predicted value ; HbLab = hemoglobin determined by the laboratory ; HbHemocue = hemoglobin determined by the HemoCue device ; SpHb = hemoglobin determined by the Masimo-RAD67 device ; LOA = limits of agreement ; LOS = length of stay ; POC = point of care ; SpO2 = arterial hemoglobin ; PR = pulse rate ; PI = perfusion index ; PVI = plethysmography variability index ; SpCO = carboxyhemoglobin ; SpMet = methemoglobin ; LED = Light Emitting Diodes ; HiCN = hemiglobincyanide ; SLS = Sodium Lauryl Sulphate ; BMI = body mass index ; BT = body temperature ; WHO = World Health Organization ; IQR = interquartile range ; MAP = mean arterial pressure ; HF = heart frequency ; SD = standard deviation Key point Summary : – Question : Is Hb measurement of the Masimo Rad-67 and of the HemoCue reliable? – Findings : Non-anemic patients are reliably detected with the Masimo Rad-67. Of the 303 patients examined, HbLab detected twenty-one patients (12 male and 9 female) with mild or moderate anemia. The Hbhemocue showed anemia in 20 patients, while the SpHb identified 34 patients as anemic. HbHemocue and HbLab showed a strong linear correlation and a good agreement, while linear correlation of SpHb and HbLab was moderate and agreement poor. For both devices, anemia detection is moderate, but the positive prediction value for anemia is much better with the HbHemocue. Both devices reliably detected non-anemic patients. – Meaning : With both devices, non-anemic patients are reliably recognized, while anemia detection is moderate. However, the prediction for the presence of anemia is much better with the Hbhemocue.

Noninvasive hemoglobin monitoring in clinical trials: a systematic review and meta-analysis

Background and objectives

The measurement of hemoglobin concentration (Hb) by co-oximetry is an innovative technique that offers efficiency and agility in the processing of information regarding the measurement of Hb obtained through continuous, non-invasive and rapid monitoring. Because of this attribute, it avoids unnecessary exposures of the patient to invasive procedures by allowing a reduction in the number of blood samples for evaluation and other unnecessary therapies. It also helps to make decisions about the need for transfusion and how to handle it. The objective of this study is to compare the performance offered to obtain Hb values between the Masimo Corporation (Irvine, CA, USA) instrument and the standard gold tool (laboratory examination).

Contents

The study corresponds to a systematic review followed by meta-analysis, which included fully registered full-text clinical trials published from 1990 to 2018. PubMed, Cochrane, Medline, Embase and Web of Science databases were investigated. The mean overall difference found between the non-invasive and invasive methods of hemoglobin monitoring was 0.23 (95% CI −0.16, 0.62), that is, it did not present statistical significance (p = 0.250). The results of the analysis of heterogeneity within and between the studies indicated high levels of inconsistency (Q = 461.63, p < 0.0001, I² = 98%), method for Hb values.

Conclusions

Although the mean difference between noninvasive measurements of Hb and the gold standard method is small, the co-oximeter can be used as a non-invasive “trend” monitor in detecting unexpected responses at Hb levels.

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.

Systematic comparison of four point-of-care methods versus the reference laboratory measurement of hemoglobin in the surgical ICU setting: a cross-sectional method comparison study

Background

Transfusion decision during the perioperative period mostly relies on the point-of-care testing for Hb measurement. This study aimed systematically compared four point-of-care methods with the central laboratory measurement of hemoglobin (LHb) regarding the accuracy, precision, and assay practicality to identify the preferred point-of-care method during the perioperative period.

Methods

This cross-sectional method comparison study was conducted in the surgical intensive care unit at Ramathibodi Hospital, Thailand, from September 2015 to July 2016. Four point-of-care methods, i.e., capillary hematocrit (HctCap), HemoCue Hb201+, iSTAT with CG8+ cartridge, and SpHb from Radical-7 pulse co-oximeter were carried out when LHb was ordered. Pearson correlation and Bland-Altman analyses were performed to assess the accuracy and precision, while the workload, turnaround time, and the unit cost were evaluated for the method practicality.

Results

Thirty-five patients were enrolled, corresponding to 48 blood specimens for analyses, resulting in the measured hemoglobin of 11.2 ± 1.9 g/dL by LHb. Ranking by correlation (r), mean difference (bias) and 95% limit of agreement (LOA) showed the point-of-care methods from the greater to the less performance as followed, iSTAT-LHb pair (r = 0.941; bias 0.15 (95% LOA; − 1.41, 1.12) g/dL), HemoCue-LHb pair (r = 0.922; bias − 0.18 (95% LOA; − 1.63, 1.28) g/dL), SpHb-LHb pair (r = 0.670; bias 0.13 (95% LOA; − 3.12, 3.39) g/dL) and HctCap-LHb pair (r = 0.905; bias 0.46 (95% LOA; − 1.16, 2.08) g/dL). Considering the practicality, all point-of-care methods had less workload and turnaround time than LHb, but only HemoCue and HctCap had lower unit cost.

Conclusion

This study identified HemoCue as the suitable point-of-care method for the sole purpose of Hb measurement in the surgical ICU setting, while iSTAT should be considered when additional data is needed.

A comparison of noninvasive methods for early detection of hemorrhage: Inferior vena cava ultrasonography and spectrophotometric hemoglobin levels

OBJECTIVES

Blood hemoglobin concentration measurements using a spectrophotometric method (SpHb), and inferior vena cava ultrasonography (IVC-US) are noninvasive methods used to follow-up hemorrhages. We compared their efficacy using voluntary blood donation as a model of moderate (approx. 500 mL) blood loss.

METHODS

In this prospective observational study enrolling blood-donor volunteers (BD) and matched controls, we recorded SpHb, IVC diameters, and vital signs. Changes in variables from baseline were compared between BD and controls using the paired t test and Wilcoxon signed rank test.

RESULTS

We included 118 subjects in the BD group and 95 healthy subjects in the control group. Changes in IVC maximum diameter, IVC minimum diameter, pulse rate, mean arterial pressure, pulse pressure, and shock index, but not in other variables, were significantly different in the BD and the control group (P < 0.05). IVCmax ≥1.1 mm yielded a 74% sensitivity and 77% specificity (PPV 79.8%, NPV 70.2%) in detecting early hemorrhage. With these cutoff values, IVCmax or PR reached a 90% sensitivity, while IVCmin and PR reached 98% specificity.

CONCLUSIONS

IVC ultrasound may be superior to SpHb in predicting blood loss and may be useful in addition to vital signs for its follow-up.

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.

Noninvasive Continuous Hemoglobin Monitoring in Combat Casualties: A Pilot Study

OBJECTIVE

To describe the accuracy and precision of noninvasive hemoglobin measurement (SpHb) compared with laboratory or point-of-care Hb, and SpHb ability to trend in seriously injured casualties.

METHODS

Observational study in a convenience sample of combat casualties undergoing resuscitation at two US military trauma hospitals in Afghanistan. SpHb was obtained using the Masimo Rainbow SET (Probe Rev E/Radical-7 Pulse CO-Oximeter v 7.6.2.1). Clinically indicated Hb was analyzed with a Coulter or iStat and compared with simultaneous SpHb values.

RESULTS

Twenty-three patients were studied (ISS 20 ± 9.8; age 29 ± 9 years; male 97%; 100% intubated). Primary injury cause: improvised explosive device (67%) or gunshot (17%). There were 49 SpHb-Hb pairs (median 2 per subject). Bias: 0.3 ± 1.6 g/dL (95% LOA -2.4, 3.4 g/dL). The SpHb-Hb difference < ± 1 g/dL in 37% of pairs. Eighty-six percent of pairs changed in a similar direction. Using an absolute change in Hb of >1 g/dL, a concurrent absolute change in SpHb of >1 g/dL had a sensitivity: 61%, specificity 85%, positive predictive value: 80%, and a negative predictive value: 69%. The SpHb signal was present in 4643 of 6137 min monitored (76%).

CONCLUSIONS

This was the first study to describe continuous SpHb in seriously injured combat casualties. Using a threshold of 1 g/dL previously specified in the literature, continuous SpHb is not precise enough to serve as sole transfusion trigger in trauma patients. Further research is needed to determine if it is useful for trending Hb changes or as an early indicator of deterioration in combat casualties.

Measures of Blood Hemoglobin and Hematocrit During Cardiac Surgery: Comparison of Three Point-of-Care Devices

OBJECTIVE

The primary objective was to compare I-Stat, HemoCue, and RapidLab in measurements of the hemoglobin concentration during cardiac surgeries using cardiopulmonary bypass.

DESIGN

Prospective analysis.

SETTING

Single-center, academic, tertiary care cardiovascular center.

PARTICIPANTS

Thirty-four consecutive patients undergoing cardiac surgery requiring cardiopulmonary bypass.

INTERVENTIONS

Blood samples have been collected intraoperatively, and the hemoglobin concentration in each sample was measured, or calculated, simultaneously by the 3 point-of-care devices, HemoCue, RapidLab, and I-Stat.

MEASUREMENTS AND MAIN RESULTS

Correlation coefficients from the regression analysis for HemoCue versus I-Stat, RapidLab versus HemoCue, and RapidLab versus I-Stat were 0.89, 0.96, and 0.88, respectively. Results of the Bland-Altman analysis of the hemoglobin concentration measurements for each device against one another (Fig 1) were as follows: RapidLab versus I-Stat (bias 0.42; 95% confidence interval [CI], -1.05 to 1.89), I-Stat versus HemoCue (bias 0.23; 95% CI, -1.14 to 1.59), and RapidLab versus HemoCue (bias 0.65; 95% CI, -0.17 to 1.47). It appears that I-Stat slightly underestimated the concentration of hemoglobin when compared with both RapidLab and HemoCue. The results of Bland-Altman analysis of each device to a mean Z value (Fig 2) were as follows: RapidLab versus Z (bias 0.36; 95% CI, -0.29 to 1.01), I-Stat versus Z (bias -0.07; CI -0.97 to 0.84), and HemoCue versus Z (bias -0.29; 95% CI, -0.86 to 0.28). Based on the 174 paired samples used for the Pearson moment analysis, the R² values for I-Stat versus HemoCue, I-Stat versus RapidLab, and RapidLab versus HemoCue were 0.79, 0.80, and 0.87, respectively CONCLUSIONS: These data support the interchangeability of these 3 devices for the intermittent intraoperative point-of-care assessment of hemoglobin concentrations in cardiac surgery patients. It is important, however, to consider the possible pitfalls associated with each device when making a clinical decision to transfuse.

Evaluation of Noninvasive Hemoglobin Monitoring in Surgical Critical Care Patients

OBJECTIVE

To assess the clinical utility of noninvasive hemoglobin monitoring based on pulse cooximetry in the ICU setting.

DESIGN AND SETTING

A total of 358 surgical patients from a large urban, academic hospital had the noninvasive hemoglobin monitoring pulse cooximeter placed at admission to the ICU. Core and stat laboratory hemoglobin measurements were taken at the discretion of the clinicians, who were blinded to noninvasive hemoglobin monitoring values.

MEASUREMENT AND MAIN RESULTS

There was a poor correlation between the 2,465 time-matched noninvasive hemoglobin monitoring and laboratory hemoglobin measurements (r = 0.29). Bland-Altman analysis showed a positive bias of 1.0 g/dL and limits of agreement of -2.5 to 4.6 g/dL. Accuracy was best at laboratory values of 10.5-14.5 g/dL and least at laboratory values of 6.5-8 g/dL. At hemoglobin values that would ordinarily identify a patient as requiring a transfusion (< 8 g/dL), noninvasive hemoglobin monitoring consistently overestimated the patient's true hemoglobin. When sequential laboratory values declined below 8 g/dL (n = 102) and 7 g/dL (n = 13), the sensitivity and specificity of noninvasive hemoglobin monitoring at identifying these events were 27% and 7%, respectively. At a threshold of 8 g/dL, continuous noninvasive hemoglobin monitoring values reached the threshold before the labs in 45 of 102 instances (44%) and at 7 g/dL, noninvasive hemoglobin monitoring did so in three of 13 instances (23%). Noninvasive hemoglobin monitoring minus laboratory hemoglobin differences showed an intraclass correlation coefficient of 0.47 within individual patients. Longer length of stay and higher All Patient Refined Diagnostic-Related Groups severity of illness were associated with poor noninvasive hemoglobin monitoring accuracy.

CONCLUSIONS

Although noninvasive hemoglobin monitoring technology holds promise, it is not yet an acceptable substitute for laboratory hemoglobin measurements. Noninvasive hemoglobin monitoring performs most poorly in the lower hemoglobin ranges that include commonly used transfusion trigger thresholds and is not consistent within individual patients. Further refinement of the signal acquisition and analysis algorithms and clinical reevaluation are needed.

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.

Hepatocellular carcinoma and liver metastases: clinical data on a new dual-lumen catheter kit for surgical sealant infusion to prevent perihepatic bleeding and dissemination of cancer cells following biopsy and loco-regional treatments

Background

RFA is a safe and effective procedure for treating unresectable primary or secondary liver malignancies, but it is not without complications. The most common reported complications include abdominal hemorrhage, bile leakage, biloma formation, hepatic abscesses, and neoplastic seeding.

The aim of this study is to evaluate the feasibility of percutaneous use of surgical sealant with a new coaxial bilumen catheter, to prevent the perihepatic bleeding and dissemination of cancer cells through the needle-electrode (neoplastic seeding) or along the needle track.

Methods

We designed a novel dual-lumen catheter to facilitate the optimal application of fibrin sealant after diagnostic and therapeutic percutaneous procedures. Percutaneous RFA has been performed using mask ventilation or neuroleptanalgesia. The main aims of this study, after the ablation procedure, in the treatment of unresectable liver cancer were to prevent major adverse events: a) the perihepatic bleeding; b) dissemination of cancer cells through the needle-electrode and or needle track.

Results

A total of 181 patients were evaluated for this study at National Cancer Institute of Naples from January 2012 to January 2014. The association of blood loss (≤1 g/dl; ≥1 g/dl) with age, gender, histological diagnosis were analyzed. No statistical significance was observed between bleeding and age (p = 0.840), gender (p = 0.607) and histological diagnosis (p = 0,571), respectively.

Conclusions

This study demonstrated that fibrin sealant or other surgical sealant injection, after any locoregional procedure such as biopsy or ablation, could make adverse events even more rare.