Decay in Blood Loss Estimation Skills After Web-Based Didactic Training

[Visual estimation of blood losses : Known high error rate-How can it be improved?]

Every day blood losses are visually estimated by medical personnel (physicians, midwives, paramedics) because an exact quantitative measurement is impossible or impractical. Anesthesiologists are confronted with blood loss in the operating room, in the delivery room, in the emergency room and at the scene of an emergency; however, the literature shows that in all the named areas enormous errors occur in the visual estimation. Errors of 50% and more are not uncommon, which means that, e.g., an estimated blood loss of 2000ml could actually be 3000ml or only 1000ml. General, in all the abovenamed areas blood losses are more likely to be underestimated than overestimated. The ability to make an estimation is not improved by professional experience. The amount of blood loss indicates and "justifies" invasive measures and the administration of blood and cost-intensive blood products. This overview is dedicated to the problems in the estimation of blood loss, demonstrates the sequelae of an incorrectly estimated blood loss, provides tips on how the ability to make an estimation can be improved and describes the considerable potential of further education as well as which digital support options are now available.

Real-time and accurate estimation of surgical hemoglobin loss using deep learning-based medical sponges image analysis

Real-time and accurate estimation of surgical hemoglobin (Hb) loss is essential for fluid resuscitation management and evaluation of surgical techniques. In this study, we aimed to explore a novel surgical Hb loss estimation method using deep learning-based medical sponges image analysis. Whole blood samples of pre-measured Hb concentration were collected, and normal saline was added to simulate varying levels of Hb concentration. These blood samples were distributed across blank medical sponges to generate blood-soaked sponges. Eight hundred fifty-one blood-soaked sponges representing a wide range of blood dilutions were randomly divided 7:3 into a training group (n = 595) and a testing group (n = 256). A deep learning model based on the YOLOv5 network was used as the target region extraction and detection, and the three models (Feature extraction technology, ResNet-50, and SE-ResNet50) were trained to predict surgical Hb loss. Mean absolute error (MAE), mean absolute percentage error (MAPE), coefficient (R2) value, and the Bland-Altman analysis were calculated to evaluate the predictive performance in the testing group. The deep learning model based on SE-ResNet50 could predict surgical Hb loss with the best performance (R2 = 0.99, MAE = 11.09 mg, MAPE = 8.6%) compared with other predictive models, and Bland-Altman analysis also showed a bias of 1.343 mg with narrow limits of agreement (- 29.81 to 32.5 mg) between predictive and actual Hb loss. The interactive interface was also designed to display the real-time prediction of surgical Hb loss more intuitively. Thus, it is feasible for real-time estimation of surgical Hb loss using deep learning-based medical sponges image analysis, which was helpful for clinical decisions and technical evaluation.

Analysis of the estimation of bleeding using several proposed haematometric equations

PURPOSE

Among various methods for estimating blood loss, the gravimetric method is the most accurate; however, its use in routine practice is complicated. Although several equations have been proposed for this purpose, there is no consensus on the most suitable.

METHODS

A cross-sectional study was conducted in seven secondary and tertiary hospitals between March and July 2018 including all patients undergoing total hip arthroplasty or hip prosthesis replacement under general or regional anaesthesia. We compared blood loss estimates obtained using the gravimetric method (weighing gauzes and pads and measuring volumes of blood collected by suction during surgery) and using three different equations, two of which considered intravenous fluids (CRYS 3.5 and 1.5) and a third which did not (the traditional equation). Additionally, intraclass correlation coefficients (ICCs) and Bland-Altman plots were used.

RESULTS

The mean blood loss estimated using the gravimetric method was 513.7 ± 421.7 mL, while estimates calculated using the CRYS 3.5, CRYS 1.5 and traditional equations were 737.2 ± 627.4, 420.8 ± 636.2 and 603.4 ± 386.3 mL, respectively. Comparing these results, we found low levels of agreement (based on ICCs), except when using the traditional equation (ICC: 0.517). The limits of agreement comparing external blood loss with the estimates from the equations ranged from - 1655.6 to 1459.2 in the case of the CRYS 1.5 equation to - 839.6 to 1008.4 in the case of the traditional equation.

CONCLUSIONS

For use in clinical practice, haematological index-based equations, regardless of whether they consider fluids administered, do not show sufficiently strong correlations with gravimetric estimates of intraoperative blood loss.

Oxytocin receptor DNA methylation is associated with exogenous oxytocin needs during parturition and postpartum hemorrhage

BACKGROUND

The oxytocin receptor gene (OXTR) is regulated, in part, by DNA methylation. This mechanism has implications for uterine contractility during labor and for prevention or treatment of postpartum hemorrhage, an important contributor to global maternal morbidity and mortality.

METHODS

We measured and compared the level of OXTR DNA methylation between matched blood and uterine myometrium to evaluate blood as an indicator of uterine methylation status using targeted pyrosequencing and sites from the Illumina EPIC Array. Next, we tested for OXTR DNA methylation differences in blood between individuals who experienced a postpartum hemorrhage arising from uterine atony and matched controls following vaginal birth. Bivariate statistical tests, generalized linear modeling and Poisson regression were used in the analyses.

RESULTS

Here we show a significant positive correlation between blood and uterine DNA methylation levels at several OXTR loci. Females with higher OXTR DNA methylation in blood had required significantly more exogenous oxytocin during parturition. With higher DNA methylation, those who had oxytocin administered during labor had significantly greater relative risk for postpartum hemorrhage (IRR 2.95, 95% CI 1.53-5.71).

CONCLUSIONS

We provide evidence that epigenetic variability in OXTR is associated with the amount of oxytocin administered during parturition and moderates subsequent postpartum hemorrhage. Methylation can be measured using a peripheral tissue, suggesting potential use in identifying individuals susceptible to postpartum hemorrhage. Future studies are needed to quantify myometrial gene expression in connection with OXTR methylation.

Postpartum hemorrhage: The role of simulation

Postpartum hemorrhage (PPH) persists as a leading cause of maternal death worldwide, and in the United States, most maternal deaths due to hemorrhage are deemed preventable. While essential preparations for hemorrhage include protocols and checklists, implementation science has revealed that it is not enough to merely introduce these tools into units. Simulation affords safe opportunities for practice and produces reliable behavior change, and it does not always need to be highly expensive and resource consuming. We review how simulation can be applied to address a unit's vulnerabilities in identifying, managing, and resolving PPH, as well as considerations for crafting a comprehensive simulation program for your unit.

Oxytocin receptor single nucleotide polymorphism predicts atony-related postpartum hemorrhage

BACKGROUND

Postpartum hemorrhage remains a key contributor to overall maternal morbidity in the United States. Current clinical assessment methods used to predict postpartum hemorrhage are unable to prospectively identify about 40% of hemorrhage cases. Oxytocin is a first-line pharmaceutical for preventing and treating postpartum hemorrhage, which acts through oxytocin receptors on uterine myocytes. Existing research indicates that oxytocin function is subject to variation, influenced in part by differences in the DNA sequence within the oxytocin receptor gene. One variant, rs53576, has been shown to be associated with variable responses to exogenous oxytocin when administered during psychological research studies. How this variant may influence myometrial oxytocin response in the setting of third stage labor has not been studied. We tested for differences in the frequency of the oxytocin receptor genotype at rs53576 in relationship to the severity of blood loss among a sample of individuals who experienced vaginal birth.

METHODS

A case-control prospective design was used to enroll 119 postpartum participants who underwent vaginal birth who were at least 37 weeks of gestation. Cases were defined by either a 1000 mL or greater blood loss or instances of heavier bleeding where parturients were given additional uterotonic treatment due to uterine atony. Controls were matched to cases on primiparity and labor induction status. Genotype was measured from a maternal blood sample obtained during the 2^nd postpartum month from 95 participants. Statistical analysis included bivariate tests and generalized linear and Poisson regression modeling.

RESULTS

The distribution of the genotype across the sample of 95 participants was 40% GG (n = 38), 50.5% AG (n = 48) and 9.5% AA (n = 9). Blood loss of 1000 mL or greater occurred at a rate of 7.9% for GG, 12.5% for AG and 55.6% for AA participants (p = 0.005). Multivariable models demonstrated A-carriers (versus GG) had 275.2 mL higher blood loss (95% CI 96.9-453.4, p < 0.01) controlling for parity, intrapartum oxytocin, self-reported ancestry, active management of third stage or genital tract lacerations. Furthermore, A-carrier individuals had a 79% higher risk for needing at least one second-line treatment (RR = 1.79, 95% CI = 1.08-2.95) controlling for covariates. Interaction models revealed that A-carriers who required no oxytocin for labor stimulation experienced 371.4 mL greater blood loss (95% CI 196.6-546.2 mL).

CONCLUSIONS

We provide evidence of a risk allele in the oxytocin receptor gene that may be involved in the development of postpartum hemorrhage among participants undergoing vaginal birth, particularly among those with fewer risk factors. The findings, if reproducible, could be useful in studying pharmacogenomic strategies for predicting, preventing or treating postpartum hemorrhage.

Measurement of hemorrhage-related severe maternal morbidity with billing versus electronic medical record data

OBJECTIVE

Measurement of obstetric hemorrhage-related morbidity is important for quality assurance purposes but presents logistical challenges in large populations. Billing codes are typically used to track severe maternal morbidity but may be of suboptimal validity. The objective of this study was to evaluate the validity of billing code diagnoses for hemorrhage-related morbidity compared to data obtained from the electronic medical record.

STUDY DESIGN

Deliveries occurring between July 2014 and July 2017 from three hospitals within a single system were analyzed. Three outcomes related to obstetric hemorrhage that are part of the Centers for Disease Control and Prevention definition of severe maternal morbidity (SMM) were evaluated: (i) transfusion, (ii) disseminated intravascular coagulation (DIC), and (iii) acute renal failure (ARF). ICD-9-CM and ICD-10-CM for these conditions were ascertained and compared to blood bank records and laboratory values. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) with 95% confidence intervals (CI) were calculated. Ancillary analyses were performed comparing codes and outcomes between hospitals and comparing ICD-9-CM to ICD-10-CM codes. Comparisons of categorical variables were performed with the chi-squared test. T-tests were used to compare continuous outcomes.

RESULTS

35,518 deliveries were analyzed. 786 women underwent transfusion, 168 had serum creatinine ≥1.2 mg/dL, and 99, 40, and 16 had fibrinogen ≤200, ≤150, and ≤100 mg/dL, respectively. Transfusion codes were 65% sensitive (95% CI 62-69%) with a 91% PPV (89-94%) for blood bank records of transfusion. DIC codes were 22% sensitive (95% CI 15-32%) for a fibrinogen cutoff of ≤200 mg/dL with 15% PPV (95% CI 10-22%). Sensitivity for ARF was 33% (95% CI 26-41%) for a creatinine of 1.2 mg/dL with a PPV of 63% (95% CI 52-73%). Sensitivity of ICD-9-CM for transfusion was significantly higher than ICD-10-CM (81%, 95% CI 76-86% versus 56%, 95% CI 51-60%, p < .01). Evaluating sensitivity of codes by individual hospitals, sensitivity of diagnosis codes for transfusion varied significantly (Hospital A 47%, 95% CI 36-58% versus Hospital B 63%, 95% CI 58-67% versus Hospital C 80%, 95% CI 74-86%, p < .01).

CONCLUSION

Use of administrative billing codes for postpartum hemorrhage complications may be appropriate for measuring trends related to disease burden and resource utilization, particularly in the case of transfusion, but may be suboptimal for measuring clinical outcomes within and between hospitals.

Limitations of Gravimetric Quantitative Blood Loss during Cesarean Delivery

Objective  This study examined the accuracy, sources of error, and limitations of gravimetric quantification of blood loss (QBL) during cesarean delivery. Study Design  Blood loss determined by assays of the hemoglobin content on surgical sponges and in suction canisters was compared with QBL in 50 parturients. Results  QBL was moderately correlated to the actual blood loss ( r  = 0.564; p  < 0.001). Compared with the reference assay, QBL overestimated blood loss for 44 patients (88%). QBL deviated from the assayed blood loss by more than 250 mL in 34 patients (68%) and by more than 500 mL in 16 cases (32%). Assayed blood loss was more than 1,000 mL in four patients. For three of these patients, QBL was more than 1,000 mL (sensitivity = 75%). QBL was more than 1,000 mL in 12 patients. While three of these had an assayed blood loss of more than 1,000 mL, 9 of the 46 patients with blood losses of less than 1,000 mL by the assay (20%) were incorrectly identified as having postpartum hemorrhage by QBL (false positives). The specificity of quantitative QBL for detection of blood loss more than or equal to 1,000 mL was 80.4%. Conclusion  QBL was only moderately correlated with the reference assay. While overestimation was more common than underestimation, both occurred. Moreover, QBL was particularly inaccurate when substantial bleeding occurred. Key Points QBL is inaccurate in cesarean delivery.QBL deviated from the assay result by more than 500 mL in 32% of cases.QBL sensitivity and specificity for hemorrhage is 75.0% (95% confidence interval [CI]: 0.19-0.93) and 80.4% (95% CI: 0.69-0.92), respectively.

Automated Quantification of Blood Loss versus Visual Estimation in 274 Vaginal Deliveries

OBJECTIVE

The aim of the study is to compare quantified blood loss measurement (QBL) using an automated system (Triton QBL, Menlo Park, CA) with visual blood loss estimation (EBL) during vaginal delivery.

STUDY DESIGN

During 274 vaginal deliveries, both QBL and EBL were determined. The automated system batch weighs blood containing sponges, towels, pads, and other supplies and automatically subtracts their dry weights and also the measured amount of amniotic fluid. Each method was performed independently, and clinicians were blinded to the device's results.

RESULTS

Median QBL (339 mL [217-515]) was significantly greater than median EBL (300 mL [200-350]; p < 0.0001). The Pearson's correlation between EBL and QBL was poor (r = 0.520) and the Bland-Altman's limits of agreement were wide (>900 mL). QBL measured blood loss >500 mL occurred in 73 (26.6%) patients compared with 14 (5.1%) patients using visual estimation (p < 0.0001). QBL ≥  1,000 mL was recorded in 11 patients (4.0%), whereas only one patient had an EBL blood loss of 1,000 mL and none had EBL >1,000 mL (p = 0.002).

CONCLUSION

Automated QBL recognizes more patients with excessive blood loss than visual estimation. To realize the value of QBL, clinicians must accept the inadequacy of visual estimation and implement protocols based on QBL values. Further studies of clinical outcomes related to QBL are needed.

KEY POINTS

· QBL detects hemorrhage more frequently than visual estimation.. · Median QBL is significantly greater than median EBL.. · There is poor agreement between QBL and EBL..

Comparison of common perioperative blood loss estimation techniques: a systematic review and meta-analysis

Estimating intraoperative blood loss is one of the daily challenges for clinicians. Despite the knowledge of the inaccuracy of visual estimation by anaesthetists and surgeons, this is still the mainstay to estimate surgical blood loss. This review aims at highlighting the strengths and weaknesses of currently used measurement methods. A systematic review of studies on estimation of blood loss was carried out. Studies were included investigating the accuracy of techniques for quantifying blood loss in vivo and in vitro. We excluded nonhuman trials and studies using only monitoring parameters to estimate blood loss. A meta-analysis was performed to evaluate systematic measurement errors of the different methods. Only studies that were compared with a validated reference e.g. Haemoglobin extraction assay were included. 90 studies met the inclusion criteria for systematic review and were analyzed. Six studies were included in the meta-analysis, as only these were conducted with a validated reference. The mixed effect meta-analysis showed the highest correlation to the reference for colorimetric methods (0.93 95% CI 0.91-0.96), followed by gravimetric (0.77 95% CI 0.61-0.93) and finally visual methods (0.61 95% CI 0.40-0.82). The bias for estimated blood loss (ml) was lowest for colorimetric methods (57.59 95% CI 23.88-91.3) compared to the reference, followed by gravimetric (326.36 95% CI 201.65-450.86) and visual methods (456.51 95% CI 395.19-517.83). Of the many studies included, only a few were compared with a validated reference. The majority of the studies chose known imprecise procedures as the method of comparison. Colorimetric methods offer the highest degree of accuracy in blood loss estimation. Systems that use colorimetric techniques have a significant advantage in the real-time assessment of blood loss.

Can measuring blood loss at delivery reduce hemorrhage-related morbidity?

Quantitation of blood loss after vaginal and cesarean delivery has been advocated for the timely detection of postpartum hemorrhage and activation of protocols for resuscitation. Morbidity and mortality from postpartum hemorrhage is considered to be largely preventable and is attributed to delayed recognition with under-resuscitation or inappropriate resuscitation. Optimizing detection of postpartum hemorrhage through refining how blood loss is measured is therefore clinically relevant. In this review on quantitative blood loss for postpartum hemorrhage, recent advances in the methods used to quantitate blood loss will be reviewed, with a comparison of utility and precision for blood loss measurement after vaginal and cesarean delivery. Considerations for the implementation of a quantitative blood loss system on the labor and delivery unit, including its benefits and challenges, will be discussed. The existing evidence for impact of blood loss quantitation in obstetrics on hemorrhage-related morbidity will be delineated, along with knowledge gaps and future research priorities.

A Framework for Improving Characterization of Obstetric Hemorrhage Using Informatics Data

OBJECTIVE

To characterize postpartum hemorrhage trends and outcomes using bioinformatics and electronic health record data.

METHODS

This retrospective analysis included all women who delivered in a four-hospital system from July 2014 to July 2017 during implementation of a postpartum hemorrhage bundle. Data on billing codes, uterotonics, transfusion, intrauterine tamponade device placement, and hysterectomy were analyzed. A framework of four postpartum hemorrhage levels based on hemorrhage interventions was created using this informatics data. Levels were analyzed in relation to hematocrit drop from the highest predelivery to the lowest postpartum level. Changes in treatment patterns were assessed with risk-adjusted regression models with adjusted odds ratios (aOR) and 95% CI as the measures of effect. Postpartum hemorrhage-associated severe maternal morbidities were analyzed with adjusted models.

RESULTS

The cohort included 43,657 deliveries. Four mutually exclusive postpartum hemorrhage levels were created based on informatics and billing criteria. Level 1: receipt of uterotonic other than oxytocin (3.7% of patients); level 2: billing diagnosis code for postpartum hemorrhage (3.0% of patients); level 3: placement of the intrauterine tamponade device, transfusion of 1-3 units red blood cells (RBCs), or both (1.8% of patients); and Level 4: hysterectomy, 4 or more units RBCs, or both (0.6% of patients). Higher postpartum hemorrhage levels were associated with higher hematocrit drops. In postpartum hemorrhage levels 1 through 4, 1.6%, 5.6%, 30.2%, and 30.7% of women had hematocrit drops greater than 40%, compared with 0.4% of women without postpartum hemorrhage. Over the course of the study, hematocrit drops within a given level did not change. Postpartum hemorrhage interventions such as uterotonics increased significantly (aOR 1.16, 95% CI 1.11-1.21, with aOR denoting change in outcome across 1 year). Although severe maternal morbidity did not change significantly, risk of hysterectomy decreased significantly (aOR 0.52, 95% CI 0.40-0.68).

CONCLUSION

Postpartum hemorrhage can be characterized in a granular fashion with informatics data. Informatics data are becoming increasingly available and can provide detailed assessment of postpartum hemorrhage incidence, management, and outcomes to facilitate surveillance and quality improvement.

Blood Products in the Management of Abnormal Placentation

A critical tool in the successful management of patients with abnormal placentation is an established massive transfusion protocol designed to rapidly deliver blood products in obstetrical and surgical hemorrhage. Spurred by trauma research and an understanding of consumptive coagulopathy, the past 2 decades have seen a shift in volume resuscitation from an empiric, crystalloid-based method to balanced, targeted transfusion therapy. The present article reviews patient blood management in abnormal placentation, beginning with optimizing the patient's status in the antenatal period to the laboratory assessment and transfusion strategy for blood products at the time of hemorrhage.

Postpartum hemorrhage: early identification challenges

Postpartum hemorrhage is the leading cause of maternal morbidity and mortality worldwide. The majority of maternal deaths associated with hemorrhage could be preventable. The accurate assessment of blood loss, identification of risk factors and timely recognition of postpartum hemorrhage remain major challenges in obstetrics. It is important to review available modalities for estimation and quantification of peripartum blood loss, the value of risk assessment tools as well as the challenges in early recognition of clinical signs and symptoms of postpartum hemorrhage.

In Vitro Evaluation of a Novel Image Processing Device to Estimate Surgical Blood Loss in Suction Canisters

BACKGROUND

Clinicians are tasked with monitoring surgical blood loss. Unfortunately, there is no reliable method available to assure an accurate result. Most blood lost during surgery ends up on surgical sponges and within suction canisters. A novel Food and Drug Administration-cleared device (Triton system; Gauss Surgical, Inc, Los Altos, CA) to measure the amount of blood present on sponges using computer image analysis has been previously described. This study reports on performance of a complementary Food and Drug Administration-cleared device (Triton Canister System; Gauss Surgical, Inc, Los Altos, CA) that uses similar image analysis to measure the amount of blood in suction canisters.

METHODS

Known quantities of expired donated whole blood, packed red blood cells, and plasma, in conjunction with various amounts of normal saline, were used to create 207 samples representing a wide range of blood dilutions commonly seen in suction canisters. Each sample was measured by the Triton device under 3 operating room lighting conditions (bright, medium, and dark) meant to represent a reasonable range, resulting in a total of 621 measurements. Using the Bland-Altman method, the measured hemoglobin (Hb) mass in each sample was compared to the results obtained using a standard laboratory assay as a reference value. The analysis was performed separately for samples measured under each lighting condition. It was expected that under each separate lighting condition, the device would measure the various samples within a prespecified clinically significant Hb mass range (±30 g per canister).

RESULTS

The limits of agreement (LOA) between the device and the reference method for dark (bias: 4.7 g [95% confidence interval {CI}, 3.8-5.6 g]; LOA: -8.1 g [95% CI, -9.7 to -6.6 g] to 17.6 g [95% CI, 16.0-19.1 g]), medium (bias: 3.4 g [95% CI, 2.6-4.1 g]; LOA: -7.4 g [95% CI, -8.7 to -6.1 g] to 14.2 g [95% CI, 12.9-15.5 g]), and bright lighting conditions (bias: 4.1 g [95% CI, 3.2-4.9 g]; LOA: -7.6 g [95% CI, -9.0 to -6.2 g] to 15.7 g [95% CI, 14.3-17.1 g]) fell well within the predetermined clinically significant limits of ±30 g. Repeated measurements of the samples under the various lighting conditions were highly correlated with intraclass correlation coefficient of 0.995 (95% CI, 0.993-0.996; P < .001), showing that lighting conditions did not have a significant impact on measurements. Hb mass bias was significantly associated with hemolysis level (Spearman ρ correlation coefficient, -0.137; P = .001) and total canister volume (Spearman ρ correlation coefficient, 0.135; P = .001), but not ambient illuminance.

CONCLUSIONS

The Triton Canister System was able to measure the Hb mass reliably with clinically acceptable accuracy in reconstituted blood samples representing a wide range of Hb concentrations, dilutions, hemolysis, and ambient lighting settings.

Estimated versus measured blood loss during dilation and evacuation: an observational study

OBJECTIVE

To compare estimated versus measured blood loss at the time of dilation and evacuation (D&E).

STUDY DESIGN

We measured blood loss for all D&E procedures between 16 and 24 weeks at one abortion clinic over 9 months. We weighed all blood-containing items and measured blood captured in the D&E tray. Providers recorded estimated blood loss before weighing or measuring blood. We compared median measured blood loss (MBL) and estimated blood loss (EBL) for each gestational week.

RESULTS

We measured blood loss in 371 of the 534 D&Es in the study period; we excluded 163 procedures because of failure to measure blood loss or contamination with amniotic fluid. Included and excluded procedures had similar median EBLs. Median EBL differed significantly from MBL for each week gestation from 16 to 24 weeks (p≤.001 for all comparisons); MBL was approximately twice as high as EBL for each gestational week. EBL and MBL increased with increasing gestation, as did the difference between EBL and MBL.

CONCLUSION

Providers consistently and significantly underestimate blood loss at the time of D&E. D&E providers may want to consider using a new heuristic for estimating blood loss.

IMPLICATIONS

Providers significantly underestimate blood loss at the time of D&E. Future research should confirm these findings (particularly at 22-24 weeks gestation), evaluate the efficacy of interventions to improve estimations of blood loss, and determine best practices for decreasing blood loss.

Improvement of blood loss volume estimation by paramedics using a pictorial nomogram: A developmental study

INTRODUCTION

To propose and evaluate a nomogram to assist paramedics to visually estimate the external blood loss on a non-absorbent surface and to identify whether the nomogram improves visual estimation.

METHODS

The study was a prospective, paired-control design (pre-training control group & post-training group), utilizing Emergency Medical Assistant (EMA) I and II trainees from the Hong Kong Fire Services Ambulance Command Training School. A nomogram (blood loss volume to area on a non-absorbent surface) was prepared to aid blood loss estimation. All participants estimated four scenarios of blood pools twice (A: 180mL; B: 470mL;C: 940mL; D: 1550mL) before and after using the nomogram. Every participant received two-minute training on how to use the nomogram correctly. The difference between the estimations and the actual volume in each scenario was calculated. The absolute percentage errors were used for direct comparison and identification of improvement between visual estimation and the use of the nomogram.

RESULTS

Sixty-one participants with an average of 3-year paramedic field experience were recruited by convenience sampling. In combining all scenarios, the median of absolute percentage error of 61 participants was 43% (95%CI 38.0-50.9%) in visual estimation, while it was 23% (95%CI 17.4-27.0%) when using the nomogram. There was a significant reduction in absolute percentage error between visual estimation and the use of the nomogram (p<0.0001).

CONCLUSION

The nomogram significantly improved the estimation of external blood loss volume.

Real-time evaluation of an image analysis system for monitoring surgical hemoglobin loss

Monitoring blood loss is important for management of surgical patients. This study reviews a device (Triton) that uses computer analysis of a photograph to estimate hemoglobin (Hb) mass present on surgical sponges. The device essentially does what a clinician does when trying to make a visual estimation of blood loss by looking at a sponge, albeit with less subjective variation. The performance of the Triton system is reported upon in during real-time use in surgical procedures. The cumulative Hb losses estimated using the Triton system for 50 enrolled patients were compared with reference Hb measurements during the first quarter, half, three-quarters and full duration of the surgery. Additionally, the estimated blood loss (EBL) was calculated using the Triton measured Hb loss and compared with values obtained from both visual estimation and gravimetric measurements. Hb loss measured by Triton correlated with the reference method across the four measurement intervals. Bias remained low and increased from 0.1 g in the first quarter to 3.7 g at case completion. The limits of agreement remained narrow and increased proportionally from the beginning to the end of the cases, reaching a maximum range of -15.3 to 22.7 g. The median (IQR) difference of EBL derived from the Triton system, gravimetric method and visual estimation versus the reference value were 13 (74), 389 (287), and 4 (230) mL, respectively. Use of the Triton system to measure Hb loss in real-time during surgery is feasible and accurate.

Accuracy of Blood Loss Measurement during Cesarean Delivery

Objective This study aims to compare the accuracy of visual, quantitative gravimetric, and colorimetric methods used to determine blood loss during cesarean delivery procedures employing a hemoglobin extraction assay as the reference standard. Study Design In 50 patients having cesarean deliveries blood loss determined by assays of hemoglobin content on surgical sponges and in suction canisters was compared with obstetricians' visual estimates, a quantitative gravimetric method, and the blood loss determined by a novel colorimetric system. Agreement between the reference assay and other measures was evaluated by the Bland-Altman method. Results Compared with the blood loss measured by the reference assay (470 ± 296 mL), the colorimetric system (572 ± 334 mL) was more accurate than either visual estimation (928 ± 261 mL) or gravimetric measurement (822 ± 489 mL). The correlation between the assay method and the colorimetric system was more predictive (standardized coefficient = 0.951, adjusted R2 = 0.902) than either visual estimation (standardized coefficient = 0.700, adjusted R2 = 00.479) or the gravimetric determination (standardized coefficient = 0.564, adjusted R2 = 0.304). Conclusion During cesarean delivery, measuring blood loss using colorimetric image analysis is superior to visual estimation and a gravimetric method. Implementation of colorimetric analysis may enhance the ability of management protocols to improve clinical outcomes.

Obstetric hemorrhage: A global review

Postpartum hemorrhage remains the number one cause of maternal death globally despite the fact that it is largely a preventable and most often a treatable condition. While the global problem is appreciated, some may not realize that in the United States postpartum hemorrhage is a leading cause of mortality and unfortunately, the incidence is on the rise. In New York, obstetric hemorrhage is the second leading cause of maternal mortality in the state. National data suggests that hemorrhage is disproportionally overrepresented as a contributor to severe maternal morbidity and we suspect as we explore further this will be true in New York State as well. Given the persistent and significant contribution to maternal mortality, it may be useful to analyze the persistence of this largely preventable cause of death within the framework of the historic "Three Delays" model of maternal mortality. The ongoing national and statewide problem with postpartum hemorrhage will be reviewed in this context of delays in an effort to inform potential solutions.

Improving Patient Safety through Simulation Training in Anesthesiology: Where Are We?

There have been colossal technological advances in the use of simulation in anesthesiology in the past 2 decades. Over the years, the use of simulation has gone from low fidelity to high fidelity models that mimic human responses in a startlingly realistic manner, extremely life-like mannequin that breathes, generates E.K.G, and has pulses, heart sounds, and an airway that can be programmed for different degrees of obstruction. Simulation in anesthesiology is no longer a research fascination but an integral part of resident education and one of ACGME requirements for resident graduation. Simulation training has been objectively shown to increase the skill-set of anesthesiologists. Anesthesiology is leading the movement in patient safety. It is rational to assume a relationship between simulation training and patient safety. Nevertheless there has not been a demonstrable improvement in patient outcomes with simulation training. Larger prospective studies that evaluate the improvement in patient outcomes are needed to justify the integration of simulation training in resident education but ample number of studies in the past 5 years do show a definite benefit of using simulation in anesthesiology training. This paper gives a brief overview of the history and evolution of use of simulation in anesthesiology and highlights some of the more recent studies that have advanced simulation-based training.

Is accurate and reliable blood loss estimation the 'crucial step' in early detection of postpartum haemorrhage: an integrative review of the literature

BACKGROUND

Postpartum haemorrhage (PPH) is the leading cause of maternal mortality in low-income countries and severe maternal morbidity in many high-income countries. Poor outcomes following PPH are often attributed to delays in the recognition and treatment of PPH. Experts have suggested that improving the accuracy and reliability of blood loss estimation is the crucial step in preventing death and morbidity from PPH. However, there is little guidance on how this can be achieved. The aim of this integrative review was to evaluate the various methods of assessing maternal blood loss during childbirth.

METHODS

A systematic, integrative review of published research studies was conducted. All types of studies were included if they developed, tested, or aimed to improve methods and skills in quantifying blood loss during childbirth, or explored experiences of those involved in the process.

RESULTS

Thirty-six studies were included that evaluated the accuracy of visual estimation; tested methods to improve skills in measurement; examined their effect on PPH diagnosis and treatment, and / or explored additional factors associated with blood loss evaluation. The review found that health professionals were highly inaccurate at estimating blood loss as a volume. Training resulted in short term improvements in skills but these were not retained and did not improve clinical outcomes. Multi-faceted interventions changed some clinical practices but did not reduce the incidence of severe PPH or the timing of responses to excessive bleeding. Blood collection bags improved the accuracy of estimation but did not prevent delays or progression to severe PPH. Practitioners commonly used the nature and speed of blood flow, and the condition of the woman to indicate that the blood loss was abnormal.

CONCLUSIONS

Early diagnosis of PPH should improve maternal outcomes, but there is little evidence that this can be achieved through improving the accuracy of blood loss volume measurements. The diagnosis may rely on factors other than volume, such as speed of blood flow and nature of loss. A change in direction of future research is required to explore these in more detail.

National Partnership for Maternal Safety Consensus Bundle on Obstetric Hemorrhage

Hemorrhage is the most frequent cause of severe maternal morbidity and preventable maternal mortality and therefore is an ideal topic for the initial national maternity patient safety bundle. These safety bundles outline critical clinical practices that should be implemented in every maternity unit. They are developed by multidisciplinary work groups of the National Partnership for Maternal Safety under the guidance of the Council on Patient Safety in Women's Health Care. The safety bundle is organized into 4 domains: Readiness, Recognition and Prevention, Response, and Reporting and Systems Learning. Although the bundle components may be adapted to meet the resources available in individual facilities, standardization within an institution is strongly encouraged. References contain sample resources and "Potential Best Practices" to assist with implementation.

How I treat postpartum hemorrhage

Worldwide, ∼800 women die every day from preventable causes related to pregnancy or childbirth. The single most common cause is severe bleeding, which can kill a healthy woman within hours if care is substandard or delayed. Improved antenatal practices have led to the early identification of at-risk women and modern technology and new techniques have enabled effective management strategies so that now, in the western world, most of the morbidity and mortality arises from those cases which occur unexpectedly and could not have been predicted. Prompt and effective management and multidisciplinary involvement is paramount to save the lives of these women. We use a case report to illustrate and discuss the main elements of management of this condition.

Use of a novel visual aid to improve estimation of obstetric blood loss

OBJECTIVE

Visual estimation of blood loss is often inaccurate and imprecise. Obstetric bleeding requires expedient identification and intervention to prevent maternal morbidity and mortality. We aimed to create a visual aid to improve accuracy of estimated obstetric blood loss.

METHODS

We designed a pocket card containing images of blood on common obstetric materials to serve as a visual aid. We created six stations with known volumes of artificial blood using materials from standard delivery kits. Obstetric providers recorded visually estimated blood loss across a variety of volumes and materials before and after receiving our visual aid. We assessed the effects of blood volume, clinical role, and years of experience on accuracy of estimation.

RESULTS

One hundred fifty-one participants assessed six stations. We categorized participants by percent error of estimated blood loss before and after receiving our visual aid. We found a significant improvement in accurate assessments for all provider types after intervention across four of the six volumes (P<.001). In a posttest survey, 90% of participants (n=136) reported subjective improvement in estimation ability. Provider type affected accuracy before intervention in two of six stations (P=.01 and P=.03). This difference persisted in one station after intervention (P<.01). Years of experience did not correlate with accuracy of blood volume estimation in five of six stations (P>.05).

CONCLUSION

A visual aid depicting known volumes of blood on obstetric materials can improve accuracy of blood volume estimation among obstetric providers of varying types and with varying years of experience.

LEVEL OF EVIDENCE

II.

In vitro evaluation of a novel system for monitoring surgical hemoglobin loss

BACKGROUND

Accurate measurement of intraoperative blood loss is an important clinical variable in managing fluid resuscitation and avoiding unnecessary transfusion of blood products. In this study, we measured surgical blood loss using a tablet computer programmed with a unique algorithm modeled after facial recognition technology. The aim of the study was to assess the accuracy and performance of the system on surgical laparotomy sponges in vitro.

METHODS

Whole blood samples of premeasured hemoglobin (Hb) and volume were reconstituted from units of human packed red blood cells and plasma and distributed across surgical laparotomy sponges. Normal saline was added to simulate the presence of varying levels of hemodilution and/or irrigation use. Soaked sponges from 4 different manufacturers were scanned using the Triton System with Feature Extraction Technology (Gauss Surgical, Inc., Palo Alto, CA) under 3 different ambient light conditions in an operating room. Accuracy of Hb loss measurement was evaluated relative to the premeasured values using linear regression and Bland-Altman analysis. Correlations between studied variables and measurement bias were analyzed using nonparametric tests.

RESULTS

The overall mean percent error for measure of Hb loss for the Triton System was 12.3% (95% confidence interval [CI], 8.2%-16.4%). A strong positive linear correlation between the premeasured and actual Hb masses was noted across the full range of intraoperative lighting conditions, including (A) high (r = 0.95 [95% CI, 0.93-0.96]), (B) medium (r = 0.94 [95% CI, 0.93-0.96]), and (C) low (r = 0.90 [95% CI, 0.87-0.93]) mean ambient light intensity. Bland-Altman analysis revealed a bias of 0.01 g [95% CI, -0.03 to 0.06 g] of Hb per sponge between the 2 measures. The corresponding lower and upper limits of agreement were -1.16 g (95% CI, -1.21 to -1.12 g) per sponge and 1.19 g (95% CI, 1.15-1.24 g) per sponge, respectively. Measurement bias of estimated blood loss and Hb mass using the new system were not associated with the volume of saline used to reconstitute the samples (P = 0.506 and P = 0.469, respectively), suggesting that the system is robust under a wide range of sponge saturation conditions.

CONCLUSIONS

Mobile blood loss monitoring using the Triton system is accurate in assessing Hb mass on surgical sponges across a range of ambient light conditions, sponge saturation, saline contamination, and initial blood Hb. Utilization of this tool could significantly improve the accuracy of blood loss estimates.

Clinical evaluation of a novel system for monitoring surgical hemoglobin loss

BACKGROUND

Accurate measurement of intraoperative blood loss is an important clinical variable in managing fluid resuscitation and avoiding unnecessary transfusion of blood products. In this study, blood lost onto laparotomy sponges during surgical cases was measured using a tablet computer programmed with a unique algorithm modeled after facial recognition technology. In this study, we assessed the accuracy and performance of the system in surgical cases.

METHODS

In this prospective, multicenter study, 46 patients undergoing surgery with anticipated significant blood loss contributed laparotomy sponges for hemoglobin (Hb) loss measurement using the Triton System with Feature Extraction Technology (Gauss Surgical, Inc., Los Altos, CA). The Hb loss measured by the new system was compared with that measured by manual rinsing of the sponges. Accuracy was evaluated using linear regression and Bland-Altman analysis. In addition, the new system's calculation of blood volume loss was compared with the gravimetric method of estimating blood loss from intraoperative sponge weights.

RESULTS

A significant positive linear correlation was noted between the new system's measurements and the rinsed Hb mass (r = 0.93, P < 0.0001). Bland-Altman analysis revealed a bias of 9.0 g and narrow limits of agreement (-7.5 to 25.5 g) between the new system's measures and the rinsed Hb mass. These limits were within the clinically relevant difference of ±30 g, which is approximately half of the Hb content of a unit of allogeneic whole blood. Bland-Altman analysis of the estimated blood loss on sponges using the gravimetric method demonstrated a bias of 466 mL (overestimation) with limits of agreement of -171 and 1103 mL, due to the presence of contaminants other than blood on the laparotomy sponges.

CONCLUSIONS

The novel mobile monitoring system provides an accurate measurement of Hb mass on surgical sponges as compared with that of manual rinsing measurements and is significantly more accurate than the gravimetric method. Further study is warranted to assess the clinical use of the technology.

Interdisciplinary collaboration to maintain a culture of safety in a labor and delivery setting

A culture of safety is a growing movement in obstetrical healthcare quality and management. Patient-centered and safe care is a primary priority for all healthcare workers, with communication and teamwork central to achieving optimal maternal health outcomes. A mandatory educational program was developed and implemented by physicians and nurses to sustain awareness and compliance to current protocols within a large university-based hospital. A didactic portion reviewing shoulder dystocia, operative vaginal delivery, obstetric hemorrhage, and fetal monitoring escalation was combined with a simulation session. The simulation was a fetal bradycardia activating the decision to perform an operative vaginal delivery complicated by a shoulder dystocia. More than 370 members of the healthcare team participated including obstetricians, midwives, the anesthesia team, and nurses. Success of the program was measured by an evaluation tool and comparing results from a prior safety questionnaire. Ninety-seven percent rated the program as excellent, and the response to a question on perception of overall grade on patient safety measured by the Agency for Healthcare Research and Quality safety survey demonstrated a significant improvement in the score (P = .003) following the program.

Recent trends in simulation for obstetric anesthesia

PURPOSE OF REVIEW

The use of simulation in medicine has grown significantly over the past 2 decades. Simulation in obstetric anesthesia can be divided into four broad uses: technical skills, nontechnical or teamwork skills, individual clinical competence, and the safety of the clinical environment. This review will describe recent trends in the use of simulation in several of these categories.

RECENT FINDINGS

Simulation continues to be an important part of skills (technical and cognitive) and teamwork training in obstetric anesthesia. The acquisition of simple and complex technical skills appears to be improved with the use of simulation. However, the assessment of these skills is currently done in the simulated environment. Simulation is also important in assessing and enhancing the safety of a labor unit. Two simulation trends have recently evolved. Instructional articles describing how to best perform simulation have begun to appear. In addition, several review articles have been published that demonstrate the maturation of the body of research in this field.

SUMMARY

As the use of simulation continues to grow, research should concentrate on whether anesthesia or teamwork skills learned in the simulated environment change behavior and improve outcomes in the clinical setting. More instructional publications would also facilitate the growth into more clinical environments.