A noninvasive hemoglobin monitor in the pediatric intensive care unit

Reducing Blood Draws in Pediatric Patients With Solid Organ Injury Through Protocolized Transcutaneous Hemoglobin Monitoring

BACKGROUND

Management of pediatric solid organ injuries continues to evolve, decreasing the need for serial hemoglobin measurements, repeat imaging, and operative intervention. Transcutaneous continuous hemoglobin monitoring (TCHM) has been shown to effectively monitor hemoglobin levels in children with solid organ trauma.

METHODS

A 6-year, single-center, retrospective chart review was conducted of pediatric solid organ injury patients aged 30 days to <18 years admitted to a quaternary children's hospital following implementation of a highly protocolized TCHM system. A laboratory hemoglobin measurement was obtained at the time of diagnosis and additional measurements were determined based on injury grading. Adverse events were tracked and included: central or arterial line placement, blood product(s) administration, percutaneous embolization procedures, transfer to the pediatric ICU and operative intervention.

RESULTS

A total of 97 patients met the inclusion criteria. Blood draws were significantly reduced following TCHM protocol implementation (3.0 [IQR 2.0-5.5] vs 2.0 [IQR 1.0-4.5], p 0.01) without a significant increase in blood product administration (p = 0.30), central or arterial line placement (p = 1), or operative intervention (p = 0.29). Length of stay was not impacted (p = 0.36). The rate of unplanned ICU transfers and percutaneous embolization procedures were too low for statistical evaluation.

CONCLUSION

TCHM safely reduces the need for serial blood draws in pediatric trauma patients when utilized within a well-defined protocol for solid organ injury. Further studies are needed to evaluate the role of TCHM in shortening or eliminating hospital admission for low-grade solid organ injuries in children.

LEVEL OF EVIDENCE

Level III.

TYPE OF STUDY

Single-center, retrospective chart review cohort study.

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).

Utility of continuous pulse CO-oximetry for hemoglobin monitoring in pediatric patients with solid organ injuries at level 1 trauma centers: A pilot study

INTRODUCTION

Hemorrhage is a major cause of preventable death in injured children. Monitoring after admission often requires multiple blood draws, which have been shown to be stressful in pediatric patients. The Rainbow-7 device is a continuous pulse CO-oximeter that measures multiple wavelengths of light, permitting continuous estimation of the total hemoglobin (Hb) level. The purpose of this study was to evaluate the utility of the noninvasive Hb measurement for monitoring pediatric trauma patients admitted with solid organ injury.

METHODS

This is a prospective, dual-center, observational trial for patients younger than age 18 years admitted to a Level I pediatric trauma center. Following admission, blood was routinely measured as per current solid organ injury protocols. Noninvasive Hb monitoring was initiated after admission. Time-synced data for Hb levels were compared with that taken using blood draws. Data were evaluated using bivariate correlation, linear regression, and Bland-Altman analysis.

RESULTS

Over a 1-year period, 39 patients were enrolled. The mean ± SD age was 11 ± 3.8 years. Forty-six percent (n = 18) of patients were male. The mean ± SD Injury Severity Score was 19 ± 13. The average change in Hb levels between laboratory measurements was -0.34 ± 0.95 g/dL, and the average change in noninvasive Hb was -0.12 ± 1.0 g/dL per measurement. Noninvasive Hb values were significantly correlated with laboratory measurements ( p < 0.001). Trends in laboratory Hb measurements were highly correlated with changes in noninvasive levels ( p < 0.001). Bland-Altman analysis demonstrated similar deviation from the mean throughout the range of Hb values, but the differences between measurements were increased by anemia, African American race, and elevated shock index, pediatric age-adjusted score and Injury Severity Score.

CONCLUSION

Noninvasive Hb values demonstrated correlation with measured Hb concentration as isolated measurements and trends, although results were affected by skin pigmentation, shock, and injury severity. Given the rapid availability of results and the lack of requirement of venipuncture, noninvasive Hb monitoring may be a valuable adjunct for pediatric solid organ injury protocols. Further study is required to determine its role in management.

LEVEL OF EVIDENCE

Dianostic Test or Criteria; Level III.

Noninvasive Hemoglobin Monitoring for Postoperative Pediatric Orthopaedic Patients: A Preliminary Study

BACKGROUND

Hemoglobin (Hgb) levels are frequently checked through venipuncture [invasive hemoglobin (iHgb)] in pediatric orthopaedic patients after high blood loss procedures. This needlestick may causes further anxiety and fear in hospitalized children. Noninvasive hemoglobin (nHgb) monitoring has been effectively utilized in the adult intensive care and postoperative total joint arthroplasty setting. nHgb monitoring has not yet been validated in children for routine postoperative Hgb assessment in pediatric orthopaedics.

METHODS

In this prospective study, 46 pediatric orthopaedic patients were enrolled who were undergoing surgery and postoperative standard of care iHgb testing. On postoperative day 1, Hgb levels were obtained through venipuncture and nHgb monitor (Pronto-7; Masimo) within a 2-hour period. Patient preferences, iHgb and nHgb values, time to result, and provider preferences were recorded. Cost data were estimated based on the standard Medicare payment rates for lab services versus the cost of nHgb probe.

RESULTS

nHgb results were obtained after 1 attempt in 38 patients (83%), after multiple attempts in 7 patients (15%), and could not be obtained in 1 patient. The mean time to obtain nHgb value was significantly shorter than that to obtain iHgb results (1.3±1.5 vs. 40±18.1 min; P <0.0001). The mean nHgb value was significantly higher than the mean iHgb value (11.7±1.5 vs. 10.6±1.1 g/dL, P <0.0001). nHgb exceeded iHgb by 2 g/dL or more in 12 (26%) patients (2.64±0.9 vs. 0.54±0.84 g/dL; P <0.0001). The concordance correlation coefficient between the 2 Hgb methods was 0.59, indicating moderate agreement. Forty-three (93%) of our patients and 34 (74%) of the care providers preferred nHgb over iHgb if results were equivalent. At our institution, the cost per iHgb monitoring is approximately $28 per blood draw as compared with $5 for nHgb monitoring. Interestingly, no patients required postoperative transfusion during the study period, as asymptomatic patients with no cardiac disease are typically observed unless the Hgb is <6.

CONCLUSIONS

nHgb monitoring in postoperative pediatric patients overestimated Hgb levels compared with the standard of care methods; however, nHgb had high patient and provider satisfaction and had moderate agreement with iHgb. As no patients required transfusion, postoperative Hgb checks could likely be discontinued in some portion of our population.

LEVEL OF EVIDENCE

Level Ib-Diagnostic study.

Noninvasive Hemoglobin Measurement Reduce Invasive Procedures in Thalassemia Patients

This study was conducted to investigate the agreement between laboratory hemoglobin (LabHb) measured in venous blood and noninvasive, spectrophotometric hemoglobin (SpHb) measurement and the usability of SpHb measurement in the transfusion decision-making in patients with thalassemia whose hemoglobin (Hb) was monitored by taking blood samples at frequent intervals and who were transfused. Cardiac pulse, oxygen saturation, Pleth variability index (PVI), and SpHb values were measured in patients who came to the hematology outpatient clinic for a control visit and whose Hb levels were planned to be measured. Venous blood samples were taken for LabHb measurement, which we accept as the gold standard. Cohen's kappa value was calculated for the agreement between SpHb measurements and LabHb values. The relationship and predictability between both measurement methods were evaluated by Pearson correlation analysis, a modified Bland-Altman plot and the linear regression model. In the study conducted with a total of 110 children with thalassemia, a moderate level of agreement between the two measurement methods (kappa = 0.370, p < 0.0001) and a significantly high correlation between the two tests (r = 0.675) were found. The mean bias between the differences was found to be 0.3 g/dL (-1.27 to 1.86 g/dL). The sensitivity and the specificity of SpHb in identifying patients who needed transfusions (Hb <10.0 g/dL) were calculated as 92.2 and 57.1%, respectively. Our results suggest SpHb measurement may be used to screen anemia in hemodynamically stable hemoglobinopathy patients and even for transfusion decision-making with combination clinical findings.

Impact of Blood Sampling on Anemia in the PICU: A Prospective Cohort Study

OBJECTIVES

Fifty percent of children are anemic after a critical illness. Iatrogenic blood testing may be a contributor to this problem. The objectives of this study were to describe blood sampling practice in a PICU, determine patient factors associated with increased sampling, and examine the association among blood sampling volume, anemia at PICU discharge, and change in hemoglobin from PICU entry to PICU discharge.

DESIGN

Prospective observational cohort study.

SETTING

PICU of Sainte-Justine University Hospital.

PATIENTS

All children consecutively admitted during a 4-month period.

MEASUREMENTS AND MAIN RESULTS

Four hundred twenty-three children were enrolled. Mean blood volume sampled was 3.9 (±19) mL/kg/stay, of which 26% was discarded volume. Children with central venous or arterial access were sampled more than those without access (p < 0.05). Children with sepsis, shock, or cardiac surgery were most sampled, those with a primary respiratory diagnosis; the least (p < 0.001). We detected a strong association between blood sample volume and mechanical ventilation (H, 81.35; p < 0.0001), but no association with severity of illness (Worst Pediatric Logistic Organ Dysfunction score) (R, -0.044; p = 0.43). Multivariate analysis (n = 314) showed a significant association between the volume of blood sampled (as continuous variable) and anemia at discharge (adjusted OR, 1.63; 95% CI, 1.18-2.45; p = 0.003). We lacked power to detect an association between blood sampling and change in hemoglobin from PICU admission to PICU discharge.

CONCLUSIONS

Diagnostic blood sampling in PICU is associated with anemia at discharge. Twenty-five percent of blood losses from sampling is wasted. Volumes are highest for patients with sepsis, shock, or cardiac surgery, and in patients with vascular access or ventilatory support.

Evaluation of the accuracy of a non-invasive hemoglobin-monitoring device in schoolchildren

BACKGROUND

Iron deficiency anemia (IDA) is a public health problem in children and adolescents that is characterized by reduced hemoglobin (Hb) levels. Non-invasive monitoring devices can measure Hb levels continuously without pain or discomfort; however, little is known about their accuracy in children and adolescents. This study estimated the accuracy of a non-invasive Hb monitor in this age group.

METHODS

Participants were outpatients visiting the Tokyo Metropolitan Children's Medical Center for blood tests between January and March 2019. Hb levels were measured using both non-invasive Astrim Fit monitoring devices and invasive blood collection followed by automated analysis. Bland-Altman analysis assessed the agreement between the two measurements.

RESULTS

Overall, 120 schoolchildren (9-15 years old, 51 % female) were enrolled. The non-invasive measuring device recorded Hb levels of 13.5 ± 1.6 g/dL (mean ± standard deviation [SD]), while the mean Hb level obtained from the collected blood was 13.7 ± 1.7 g/dL. Therefore, the mean difference of bias and SD of precision was 0.17 ± 1.95 g/dL. Values of lower and upper limits of agreement were -3.65 and 3.99, respectively. There was no systematic fixed or proportion bias. Fifty-nine participants (49 %) had a relative error of ± 0.10.

CONCLUSION

The Astrim Fit non-invasive Hb monitor can be used to evaluate Hb levels among schoolchildren for health promotion or research purposes because of its extremely low bias (or precision), no systematic biases (including fixed or proportion biases), and positive correlation between non-invasive monitoring and blood drawing. However, it is difficult to assess Hb levels in children and adolescents using the Astrim Fit device for diagnostic purposes.

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.

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.

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.

The patient with anemia

PURPOSE OF REVIEW

Anemia remains a global health issue. This review addresses the recent findings on anemia in surgical patients and its significance in perioperative setting.

RECENT FINDINGS

The prevalence of anemia in surgical populations is high, ranging from one-third of population to nearly 100%. Anemia is an independent, modifiable risk factor for a growing list of unfavorable events, complications and diminished functional outcomes (lasting for months following discharge), as well as a major predisposing factor for allogeneic blood transfusions. Therefore, timely screening and diagnosis of anemia prior to elective surgeries is of great importance. Nonetheless, studies suggest that many opportunities to properly manage anemia in perioperative setting are lost. Patient blood management provides a framework of evidence-based strategies to effectively reduce the risk of occurrence of anemia and treat it with the ultimate goal of improving patient outcomes. Studies on the clinical impact of patient blood management strategies are emerging.

SUMMARY

Active screening for anemia and proper management of it in perioperative setting is essential. Several strategies to prevent anemia - including elimination of unnecessary diagnostic blood draws - are effective and reasonable approaches.

An evaluation of hemoglobin measurement tools and their accuracy and reliability when screening for child anemia in Rwanda: A randomized study

Blood hemoglobin (Hb) is a common indicator for diagnosing anemia and is often determined through laboratory analysis of venous samples. One alternative to laboratory-based methods is the handheld HemoCue® Hb 201+ device, which requires a finger prick and wicking of blood into a pretreated cuvette for analysis. An alternative HemoCue® gravity method is being investigated for improved accuracy. Further, recent developments in noninvasive technologies could provide an accurate, rapid, safe, point-of-care option for hemoglobin estimation while addressing some limitations of current tools, but device performance must be assessed in low-resource settings. This study evaluated the performance of two HemoCue® Hb 201+ blood sampling methods and a noninvasive device (Pronto® with DCI-mini™ sensors) in a Rwandan pediatric clinic. Reference hemoglobin values were determined in 132 children 6 to 59 months of age by using a standard hematology analyzer (Sysmex KN21^TM). Half were tested using the HemoCue® wicking method; half were tested using the HemoCue® gravity method; and 112 had successful hemoglobin readings with Pronto® DCI-mini™. Statistical analysis was used to assess the level of bias generated by each method and the key drivers of bias. The HemoCue® gravity method was the least biased. The HemoCue® wicking and Pronto® methods biases were inversely related to the Sysmex KN21^TM results. Both HemoCue® sampling methods correctly classified patients’ anemic status in 80% or more of instances, whereas the Pronto® device had a correct classification rate of only 69%. The HemoCue® gravity method was more accurate than the traditional HemoCue® wicking method in this study, but its accuracy and operational feasibility should be confirmed by future studies. The Pronto® DCI-mini™ devices showed considerable promise but require further improvements in sensitivity and specificity before wider adoption.

Noninvasive hemoglobin monitoring in critically ill pediatric patients at risk of bleeding

OBJECTIVE

To determine the accuracy and usefulness of noninvasive continuous hemoglobin (Hb) monitoring in critically ill patients at risk of bleeding.

DESIGN

An observational prospective study was made, comparing core laboratory Hb measurement (LabHb) as the gold standard versus transcutaneous hemoglobin monitoring (SpHb).

SETTING

Pediatric Intensive Care Unit of a tertiary University Hospital.

PATIENTS

Patients weighing >3kg at risk of bleeding.

INTERVENTIONS

SpHb was measured using the Radical7 pulse co-oximeter (Masimo Corp., Irvine, CA, USA) each time a blood sample was drawn for core laboratory analysis (Siemens ADVIA 2120i).

VARIABLES

Sociodemographic characteristics, perfusion index (PI), pleth variability index, heart rate, SaO₂, rectal temperature, low signal quality and other events that can interfere with measurement.

RESULTS

A total of 284 measurements were made (80 patients). Mean LabHb was 11.7±2.05g/dl. Mean SpHb was 12.32±2g/dl (Pearson 0.72, R² 0.52). The intra-class correlation coefficient was 0.69 (95%CI 0.55-0.78)(p<0.001). Bland-Altman analysis showed a mean difference of 0.07 ±1.46g/dl. A lower PI and higher temperature independently increased the risk of low signal quality (OR 0.531 [95%CI 0.32-0.88] and 0.529 [95%CI 0.33-0.85], respectively).

CONCLUSIONS

SpHb shows a good overall correlation to LabHb, though with wide limits of agreement. Its main advantage is continuous monitoring of patients at risk of bleeding. The reliability of the method is limited in cases with poor peripheral perfusion.

Validation of noninvasive hemoglobin measurements using co-oximetry in anesthetized dogs

New technology allows noninvasive measurement of total hemoglobin (Hb) in humans through use of multiple wavelength co-oximetry. This monitor is now available to the veterinary market but no studies have been performed to validate its use in animals. This study investigated the use of co-oximetry to measure Hb in anesthetized dogs by comparing "gold standard" Hb measurements from a laboratory (LabHb) with those measured by the co-oximeter (SpHb). Bland-Altman analysis showed that the monitor had a bias of -3.01 (SpHb values were lower than LabHb values) and that 64.5% of measured SpHb values were greater than 20 g/L different from their associated LabHb values. Based on the results of this study, use of co-oximetry to measure Hb in anesthetized dogs is not accurate enough to direct treatment. Further studies are warranted in other animal species and under other clinical conditions.

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.

Noninvasive Hemoglobin Monitoring: A Rapid, Reliable, and Cost-Effective Method Following Total Joint Replacement

BACKGROUND

Noninvasive hemoglobin (nHgb) monitoring was initially introduced in the intensive care setting as a means of rapidly assessing Hgb values without performing a blood draw. We conducted a prospective analysis to compare reliability, cost, and patient preference between nHgb monitoring and invasive Hgb (iHgb) monitoring performed via a traditional blood draw.

METHODS

We enrolled 100 consecutive patients undergoing primary or revision total hip or total knee arthroplasty. On postoperative day 1, nHgb and iHgb values were obtained within thirty minutes of one another. iHgb and nHgb values, cost, patient satisfaction, and the duration of time required to obtain each reading were recorded. The concordance correlation coefficient (CCC) was utilized to evaluate the agreement of the two Hgb measurement methods. Paired t tests and Wilcoxon signed-rank tests were utilized to compare mean Hgb values, time, and pain for all readings.

RESULTS

The mean Hgb values did not differ significantly between the two measurement methods: the mean iHgb value (and standard deviation) was 11.3 ± 1.4 g/dL (range, 8.2 to 14.3 g/dL), and the mean nHgb value was 11.5 ± 1.8 g/dL (range, 7.0 to 16.0 g/dL) (p = 0.11). The CCC between the two Hgb methods was 0.69. One hundred percent of the patients with an nHgb value of ≥ 10.5 g/dL had an iHgb value of >8.0 g/dL. The mean time to obtain an Hgb value was 0.9 minute for the nHgb method and 51.1 minutes for the iHgb method (p < 0.001). At our institution, the cost of iHgb monitoring is approximately $28 per blood draw compared with $2 for each nHgb measurement, resulting in a savings of $26 per Hgb assessment when the noninvasive method is used.

CONCLUSIONS

Noninvasive Hgb monitoring was found to be more efficient, less expensive, and preferred by patients compared with iHgb monitoring. Providers could consider screening total joint arthroplasty patients with nHgb monitoring and only order iHgb measurement if the nHgb value is <10.5 g/dL. If this protocol had been applied to the first blood draw in our 100 patients, approximately $2000 would have been saved. Extrapolated to the U.S. total joint arthroplasty practice, approximately $20 million could be saved annually.

Validity of non-invasive point-of-care hemoglobin estimation in healthy and sick children-a method comparison study

This study was conducted at a tertiary care center in northern India to evaluate the validity of non-invasive transcutaneous hemoglobin estimation in healthy and sick children in comparison to hemoglobin estimation by traditional lab method. A method comparison study was conducted including 150 subjects. Enrolled patients included 80 neonates with average age of 3.9 ± 2.1 days, and 70 children with average age of 5.8 ± 2 years. Each population (newborn and children) comprised of almost equal numbers of healthy and critically ill patients with shock. Hemoglobin (Hb) was estimated on enrolment by transcutaneous spectrophotometry (SpHb) and traditional automated lab analyzer (Hb-Lab). Difference between Hb levels by the two methods (called bias) was measured and analyzed using Bland-Altman method. Out of 148 data pairs analyzed, bias between SpHb and Hb-Lab was -1.52 ± 1.91 g/dl (mean ± SD). SpHb showed excellent positive correlation with Hb-Lab (r = 0.94 (p < 0.001)) and good visual agreement on Bland-Altman plots. Bias was higher in sick subjects with shock as compared to healthy ones in both neonatal and pediatric population (-2.31 ± 2.21 g/dl versus -0.77 ± 1.2 g/dl, respectively).

CONCLUSIONS

SpHb showed good accuracy and correlated well with lab estimated Hb levels in healthy children. However, in children with impaired peripheral perfusion, its diagnostic accuracy was inadequate to justify routine use for quantification of severity of anemia and making transfusion decisions solely on non-invasive estimation of hemoglobin.

WHAT IS KNOWN

Non-invasive hemoglobin estimation is a relatively new and novel method which has given mixed results regarding its potential efficacy in adults. There is limited data regarding usefulness and accuracy of non-invasive Hb estimation by SpHb in sick neonates and children.

WHAT IS NEW

Non-invasive Hb estimation by SpHb monitor is reasonably accurate in healthy neonates and children. It can be used in critically ill children and neonates, but in conjunction with lab confirmation of Hb values.