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).

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 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.

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.