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..

Accurate Assessment of Blood Loss during Cesarean Delivery Improves Estimation of Postoperative Hemoglobin.

OBJECTIVE: To determine if accurate blood loss determination during cesarean delivery can improve the prediction of postoperative hemoglobin levels. STUDY DESIGN: This is a retrospective cohort study using visually estimated blood loss (traditional, n = 2,025) versus estimates using a mobile application that photographs sponges and canisters and calculates their hemoglobin content (device, n = 756). RESULTS: The correlation between the actual and predicted postoperative day 1 hemoglobin value (PPO1 Hgb) was better in the device group (R 2 = 0.519, correlation = 0.720) than in the traditional group (R 2 = 0.429, correlation = 0.655) (p = 0.005). For patients in the device group where the estimated blood loss was >1,000 mL (n = 53), the PPO1 Hgb was also better correlated with the actual value (R 2 = 0.319, correlation = 0.565) than the predictions using visually estimated blood loss for those patients in the device group whose visual estimation was >1,000 mL (n = 32) (R 2 = 0.035, correlation = 0.187) (p = 0.027). CONCLUSION: Implementation of a device that accurately measures blood loss allows for a better prediction of postoperative day 1 hemoglobin concentration than is possible using visual blood loss estimation. This improvement was seen in the entire patient group and was particularly prominent in patients with blood losses of > 1,000 mL.

How does blood loss relate to the extent of surgical wound excision?

PURPOSE: We investigated a novel system that uses image-processing algorithms to accurately measure the hemoglobin content of discarded surgical sponges to determine how blood loss relates to the excised area when current methods to minimize bleeding are employed. The system was used during 130 procedures in adult patients having wound excisions ≥1% BSA (study group). An historic group of 105 similar cases in whom visually estimated blood was determined was also evaluated. RESULTS: Surgical blood loss was less than previous estimates. The correlation between blood loss and the excised area in the study group was poor (R2=0.3988 for all patients and R2=0.1439 for excisions ≥10% BSA). Moreover, the visual estimates of blood loss in the historic group were more closely related to excised area than the accurate measurements in the study group (R2=0.6017 (historic), R2=0.3988 (study), p<0.001 for both). The mean absolute unstandardized residuals were 140.18±158.52 (historic) vs. 307.99±317.03 (study), p<0.001. CONCLUSIONS: As demonstrated in the historic group, visual estimates of blood loss tend to be more related to the size of excision than the amount of bleeding. The actual blood loss is not well correlated with the extent of excision. Clinicians should not rely on traditional blood loss estimates. Accurate measurement is needed to inform transfusion decisions and guide care.

Clinical Experience with the Implementation of Accurate Measurement of Blood Loss during Cesarean Delivery: Influences on Hemorrhage Recognition and Allogeneic Transfusion.

OBJECTIVE: This article compares hemorrhage recognition and transfusion using accurate, contemporaneous blood loss measurement versus visual estimation during cesarean deliveries. STUDY DESIGN: A retrospective cohort study using visually estimated blood loss (traditional, n = 2,025) versus estimates using a mobile application that photographs sponges and canisters and calculates their hemoglobin content (device, n = 756). RESULTS: Blood loss > 1,000 mL was recognized in 1.9% of traditional visual estimation patients, while measured blood loss of > 1,000 mL occurred in 8.2% of device patients (p < 0.0001). In both groups, this was accompanied by a greater decrease in transfusion-adjusted hemoglobin levels than occurred in patients without hemorrhage (p < 0.0001). Despite similar transfusion rates (1.6% in both groups), fewer red cell units were given to transfused patients in the device group (1.83 ± 0.58 versus 2.56 ± 1.68 units; p = 0.038). None of the patients in the device group received plasma or cryoprecipitate. Seven patients in the traditional group received these products (p = 0.088). Device use was associated with shorter hospital stays (4.0 ± 2.3 versus 4.4 ± 2.9 days; p = 0.0006). CONCLUSION: The device identified hemorrhages more frequently than visual estimation. Device-detected hemorrhages appeared clinically relevant. Blood product transfusion was reduced possibly due to earlier recognition and treatment, although further studies are needed to verify the conclusion.

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.

Use of Thromboelastography (TEG) for Detection of New Oral Anticoagulants.

CONTEXT: The clinical introduction of new oral anticoagulants (NOACs) has stimulated the development of tests to quantify the effects of these drugs and manage complications associated with their use. Until recently, the only treatment choices for the prevention of venous thromboembolism in orthopedic surgical patients, as well as for stroke and systemic embolism in patients with atrial fibrillation, were vitamin K antagonists, antiplatelet drugs, and unfractionated and low-molecular-weight heparins. With the approval of NOACs, treatment options and consequent diagnostic challenges have expanded. OBJECTIVE: To study the utility of thromboelastography (TEG) in monitoring and differentiating between 2 currently approved classes of NOACs, direct thrombin inhibitors (dabigatran) and factor Xa inhibitors (rivaroxaban and apixaban). DESIGN: Blood samples from healthy volunteers were spiked with each NOAC in both the presence and absence of ecarin, and the effects on TEG were evaluated. RESULTS: Both the kaolin test reaction time (R time) and the time to maximum rate of thrombus generation were prolonged versus control samples and demonstrated a dose response for apixaban (R time within the normal range) and dabigatran. The RapidTEG activated clotting time test allowed the creation of a dose-response curve for all 3 NOACs. In the presence of anti-Xa inhibitors, the ecarin test promoted significant shortening of kaolin R times to the hypercoagulable range, while in the presence of the direct thrombin inhibitor only small and dose-proportional R time shortening was observed. CONCLUSIONS: The RapidTEG activated clotting time test and the kaolin test appear to be capable of detecting and monitoring NOACs. The ecarin test may be used to differentiate between Xa inhibitors and direct thrombin inhibitors. Therefore, TEG may be a valuable tool to investigate hemostasis and the effectiveness of reversal strategies for patients receiving NOACs.

Implementation of a comprehensive blood conservation program can reduce blood use in a community cardiac surgery program.

OBJECTIVE: The study objective was to determine the effects of implementing a blood conservation algorithm on blood product use and outcomes in a community cardiac surgery program. METHODS: A blood management strategy including lower hemoglobin transfusion threshold and algorithm-driven decisions was adopted. Intraoperatively, point-of-care testing was used to avoid inappropriate component transfusion. A low prime perfusion circuit was adopted. Blood was withdrawn from patients before initiating bypass when possible. Patients undergoing coronary and valve procedures were included. Outlier patients receiving more than 10 units packed red blood cells were excluded. Data were collected for 6 months as a baseline group (group I). A 3-month period of program implementation was allotted. Data were subsequently collected for 6 months and comprised the study patients (group II). Prospective data were collected on demographics, blood use, and outcomes. RESULTS: Group I comprised 481 patients, and group II comprised 551 patients. Group II received fewer units of packed red blood cells, fresh-frozen plasma, and cryoprecipitate than group I. There was no difference in platelets transfused. Total blood product use was reduced by 40% in group II (P < .001). The overall 30-day mortality was 1.3%. There were no differences in mortality, reoperation for bleeding, or other postoperative outcomes between the groups. CONCLUSIONS: Implementation of a comprehensive blood conservation algorithm can be rapidly introduced, leading to reductions in blood and component use with no detrimental effect on early outcomes. Point-of-care testing can direct component transfusion in coagulopathic cases, with most coagulopathic patients requiring platelets. Further research will determine the effects of reduced transfusions on long-term outcomes.

The thymus: a comprehensive review.

Since first being described as such by Galen of Pergamum (130-200 ad), the thymus has remained an "organ of mystery" throughout the 2000-year history of medicine. The thymus reaches its maximum weight in puberty and subsequently undergoes involution, and thus is hardly an eye-catching structure on imaging studies performed in healthy adults. However, once there has been involvement of the thymus by a disease process, the gland demonstrates a variety of clinical and radiologic manifestations that require comprehensive understanding of each entity. Furthermore, it is important for radiologists to be familiar with the current World Health Organization histologic classification scheme for thymic epithelial tumors and to understand its clinical-pathologic, radiologic, and prognostic features.

Microdebrider bronchoscopy: a new tool for the interventional bronchoscopist.

PURPOSE: We report our experience with a new airway tool, the microdebrider, in treating central airway obstruction. DESCRIPTION: From April 2002 to April 2004, 23 patients undergoing treatment of central airway obstruction were managed with the microdebrider. All procedures were done under general anesthesia with either a rigid bronchoscope (19 patients) or a suspension laryngoscope (4 patients). The microdebrider was used in an oscillating mode with rotation speeds of 1,000 to 3,000 rpm to resect obstructing tissue. EVALUATION: Fourteen patients (61%) had tracheal granulation tissue from prior intubation or tracheostomy, 6 (26%) had idiopathic subglottic stenosis, and 3 (26%) had malignant disease. Obstructing lesions were rapidly removed in all patients with interventions lasting between 2 and 15 minutes. There were no procedure-related complications. No patients required reoperation for airway obstruction in follow-up ranging from 1 to 24 months. CONCLUSIONS: Microdebrider bronchoscopy is a new technique that allows for precise, rapid, and safe removal of lesions obstructing the central airways. Complications of thermal modalities such as airway injury, tracheoesophageal fistulas, and airway fires can be avoided.

Mediastinal and chest wall limitations to asymmetry of lung inflation.

The extent to which inflation of one lung increases pleural pressure around the contralateral lung could affect ventilatory function, e.g., after pneumonectomy or lung transplantation. The rise in contralateral pleural pressure is limited by mediastinal stiffness and other chest wall properties. To estimate these properties, we determined an elastance of asymmetric expansion (E(Asym)) in 20 supine adults undergoing thoracic surgery requiring endobronchial intubation. Esophageal pressure, measured with a balloon catheter, was used as an estimate of pleural pressure for determining chest wall elastance during symmetric inflation. Pressures measured in the left and right lung airways during sequential asymmetric inflations with known volumes were used to calculate E(Asym) and elastances of left and right lungs by using a four-element mathematical model. Elastances (means +/- SD) were 13.0 +/- 8.7 (E(Asym)), 14.0 +/- 7.0 (left lung), 12.2 +/- 6.1 (right lung), and 6.7 +/- 2.1 cmH(2)O/l (chest wall). E(Asym) was high in three patients with prior cardiac surgery or mediastinal radiation therapy, suggesting that mediastinal stiffening due to scarring and fibrosis reduced pressure transmission between hemithoraxes. Simulations with a previously published model showed that changes in E(Asym) in the range of values observed could substantially affect lung ventilation after single-lung transplantation for emphysema.