Techniques for blood loss estimation in major non-cardiac surgery: a systematic review and meta-analysis

The Impact of Prior Obesity Surgery on Bleeding after Abdominal Body Contouring Surgery

Background

Body contouring surgery removes excess skin and fat, often after massive weight loss. Some reports suggest that patients who have previously undergone obesity (bariatric) surgery are at excess risk of subsequent bleeding, possibly due to complex nutritional and metabolic sequelae of massive weight loss.

Methods

A retrospective cohort study of intraoperative blood loss and postoperative bleeding indicators were examined for patients who had undergone abdominoplasty. Participants were categorized based on their history of previous obesity surgery, and outcome variables were compared using odds ratio, followed by subgroup comparison between a history of restrictive versus malabsorptive obesity surgery.

Results

The study included 472 patients, of which 171 (36.2 %) had a history of obesity surgery. Mean age was 40.4 years, and 402 (85.1%) participant were women. Fifty-five (11.6%) patients were smokers whereas 65 (13.7%) were hypertensive. Mean body mass index before surgery was 30.2 kg per m2, and average time between obesity and body contouring surgery (if applicable) was 35.8 months. Patients with a history of obesity surgery exhibited greater intraoperative blood loss (162.2 mL versus 132.1 mL; P = 0.001), drainage volume at 24 h (155 mL versus 135 mL; P = 0.001), and total drainage volume (300ml versus 220 mL; P = 0.001). Postoperative hematoma requiring surgical re-exploration was almost three times higher following a history of obesity surgery (4.7% versus 1.7 %; P = 0.05).

Conclusions

History of obesity surgery increases intraoperative blood loss, postoperative serosanguinous drainage volumes, and the risk of postoperative hematoma requiring surgical evacuation after abdominal body contouring procedures.

IN VITRO EVALUATION OF A NOVEL AUTOMATIC INTRAOPERATIVE BLOOD LOSS MONITOR

ABSTRACT

Introduction: Accurate and real-time monitoring of surgical blood loss is essential for ensuring intraoperative safety. However, there is currently no standard way to assess the amount of blood lost in patients during surgery. This study aims to evaluate the accuracy and precision of a new automatic intraoperative blood loss monitor, which can measure both free blood volume and blood content in sponges in real time. Methods: The monitor uses an integrated photoelectric probe to gauge hemoglobin levels in both free blood and blood taken from surgical sponges. These data, combined with initial hemoglobin levels, are processed using specific calculations to determine blood volume. We created 127 diverse free blood samples and 160 blood-containing sponge samples by using fresh pig blood and physiological saline. The monitor then measured these samples. We subsequently compared its measurements with actual values acquired through physical measurements, detecting both agreement and measurement errors. Repeated measurements were performed to calculate the coefficient of variation, thereby evaluating the monitor's precision. Results: The estimated blood loss percentage error of the monitor was 5.2% for free blood, -5.7% for small sponge, -6.3% for medium sponge, and -6.6% for large sponge. The coefficient of variation of free blood with different hemoglobin concentrations measured by the monitor was less than 10%. Bland-Altman analysis showed that the limits of agreement between the monitor and the reference method were all within the acceptable clinical range. Conclusion: The new automatic intraoperative blood loss monitor is an accurate and reliable device for monitoring both free blood and surgical sponge blood, and shows high performance under various clinical simulation conditions.

Role of prophylactic tranexamic acid in reducing blood loss during cesarean section: A double-blind placebo-controlled randomized controlled trial

Background

Postpartum hemorrhage (PPH) is defined by the World Health Organization as blood loss of ≥500 mL within 24 h of delivery. Globally, hemorrhage accounts for 27.1% of maternal deaths, making it the leading direct cause of maternal death. PPH has been identified in more than two-thirds of reported hemorrhage-related deaths, causing 38% of maternal deaths in India. Tranexamic acid, an antifibrinolytic, has been used to control bleeding after PPH is identified.

Materials and Methods

Antenatal women admitted for elective cesarean section were randomized into two arms: the case group (received one gram of tranexamic acid 20 min prior to skin incision) and the control group (received a placebo), each group consisting of 36 participants. Clinical Trials Registry - India (CTRI) registration number - CTRI/2021/02/031579.

Results

The mean (±standard deviation [SD]) intraoperative blood loss in the case group was 241.25 (±67.83) mL, and in the control group, it was 344.92 (±146.67) mL (P = 0.001), while postoperative blood loss did not differ significantly between the groups (P = 0.1470). In terms of the difference in hemoglobin, there was a significant difference between the two groups (P = 0.001). No significant maternal or neonatal side effects were found.

Conclusion

Preoperative tranexamic acid, when given in elective cesarean section, significantly reduces intraoperative blood loss.

Oral as compared to intravenous tranexamic acid to limit peri-operative blood loss associated with primary total hip arthroplasty: A randomised noninferiority trial

BACKGROUND

Oral as compared to intravenous tranexamic acid (TXA) is an attractive option, in terms of cost and safety, to reduce blood loss and transfusion in total hip arthroplasty. Exclusion criteria applied in the most recent randomised trials may have limited the generalisability of oral tranexamic acid in this indication. Larger and more inclusive studies are needed to definitively establish oral administration as a credible alternative to intravenous administration.

OBJECTIVES

To assess the noninferiority of oral to intravenous TXA at reducing intra-operative and postoperative total blood loss (TBL) in primary posterolateral approached total hip arthroplasty (PLTHA).

DESIGN

Noninferiority, single centre, randomised, double-blind controlled study.

SETTING

Patients scheduled for primary PLTHA. Data acquisition occurred between May 2021 and November 2022 at the University Hospital of Liège, Belgium.

PATIENTS

Two hundred and twenty-eight patients, randomised in a 1 : 1 ratio from a computer-generated list, completed the trial.

INTERVENTIONS

Administration of 2 g of oral TXA 2 h before total hip arthroplasty and 4 h after incision (Group oral) was compared to the intravenous administration of 1 g of TXA 30 min before surgery and 4 h after incision (Group i.v.).

MAIN OUTCOME MEASURES

TBL (measured intra-operative and drainage blood loss up to 48 h after surgery, primary outcome), decrease in haemoglobin concentration, D-Dimer at day 1 and day 3, transfusion rate (secondary outcomes).

RESULTS

Analyses were performed on 108 out of 114 participants (Group i.v.) and 104 out of 114 participants (Group oral). Group oral was noninferior to Group i.v. with regard to TBL, with a difference between medians (95% CI) of 35 ml (-103.77 to 33.77) within the noninferiority margins. Median [IQR] of estimated TBL was 480 ml [350 to 565] and 445 ml [323 to 558], respectively. No significant interaction between group and time was observed regarding the evolution of TBL and haemoglobin over time.

CONCLUSIONS

TXA as an oral premedication before PLTHA is noninferior to its intravenous administration regarding peri-operative TBL.

TRIAL REGISTRATION

European Clinical Trial Register under EudraCT-number 2020-004167-29 ( https://www.clinicaltrialsregister.eu/ctr-search/trial/2020-004167-29/BE ).

Automated deep learning model for estimating intraoperative blood loss using gauze images

The intraoperative estimated blood loss (EBL), an essential parameter for perioperative management, has been evaluated by manually weighing blood in gauze and suction bottles, a process both time-consuming and labor-intensive. As the novel EBL prediction platform, we developed an automated deep learning EBL prediction model, utilizing the patch-wise crumpled state (P-W CS) of gauze images with texture analysis. The proposed algorithm was developed using animal data obtained from a porcine experiment and validated on human intraoperative data prospectively collected from 102 laparoscopic gastric cancer surgeries. The EBL prediction model involves gauze area detection and subsequent EBL regression based on the detected areas, with each stage optimized through comparative model performance evaluations. The selected gauze detection model demonstrated a sensitivity of 96.5% and a specificity of 98.0%. Based on this detection model, the performance of EBL regression stage models was compared. Comparative evaluations revealed that our P-W CS-based model outperforms others, including one reliant on convolutional neural networks and another analyzing the gauze's overall crumpled state. The P-W CS-based model achieved a mean absolute error (MAE) of 0.25 g and a mean absolute percentage error (MAPE) of 7.26% in EBL regression. Additionally, per-patient assessment yielded an MAE of 0.58 g, indicating errors < 1 g/patient. In conclusion, our algorithm provides an objective standard and streamlined approach for EBL estimation during surgery without the need for perioperative approximation and additional tasks by humans. The robust performance of the model across varied surgical conditions emphasizes its clinical potential for real-world application.

Preoperative fibrinogen level and blood transfusions in liver transplantation: A systematic review

BACKGROUND

Orthotopic liver transplantation (OLT) is a major surgery often associated with significant bleeding. We conducted a systematic review to explore the association between preoperative fibrinogen level and intraoperative blood products transfusion, blood loss and clinical outcomes in patients undergoing OLT.

METHODS

We included observational studies conducted in patients undergoing an OLT mostly for end-stage liver disease that reported an association between the preoperative fibrinogen level and our outcomes of interest. Our primary outcome was the intraoperative red blood cell (RBC) transfusion requirements. Our secondary outcomes were intraoperative blood loss, intraoperative transfusion of any blood product, postoperative RBC transfusion, postoperative thrombotic or hemorrhagic complications, and mortality. We used a standardized search strategy. We reported our results mostly descriptively but conducted meta-analyses using random-effect models when judged feasible.

RESULTS

We selected 24 cohort studies reporting at least one of our outcomes. We found that a high preoperative fibrinogen level was associated with fewer intraoperative RBC and other blood products transfusions, and lower blood loss. We also found a lower overall survival in patients with a higher fibrinogen level (pooled hazard ratio [95% CI] of 1.50 [1.23 to 1.84]; 5 studies, n = 1012, I2 = 48%). Only one study formally explored a fibrinogen level threshold effect. Overall, reporting was heterogeneous, and risk of bias was variable mostly because of uncontrolled confounding.

CONCLUSION

A higher preoperative fibrinogen level was associated with fewer intraoperative RBC and other blood products transfusions, lower blood loss, and higher mortality. Further studies may help clarify observed associations and inform guidelines.

Perioperative Factors Associated With Intraoperative Transfusion in Patients Undergoing Major Lower Limb Amputation

BACKGROUND

Intraoperative transfusions in vascular patients undergoing major lower limb amputations (LLAs) are associated with worse postoperative outcomes.

METHODS

We conducted a retrospective study from 2015 to 2020 to identify perioperative factors associated with the need for intraoperative transfusion for patients undergoing below knee or above knee amputations secondary to vascular disease.

RESULTS

A total of 65 patients with major LLAs were identified, 39 (60%) with below knee and 26 (40%) with above knee amputations. There were 15 (23%) patients who were transfused intraoperatively and 50 (77%) who were not. Six (15%) of the below knee patients and 9 (34%) of the above knee patients required intraoperative transfusion. Of the variables studied, only preoperative hemoglobin (8.6 ± .4 vs 9.9 ± .2 g/dL, P = .01), change in hemoglobin (-.1 ± .4 vs .8 ± .2 g/dL, P = .01), estimated intraoperative blood loss (416 ± 168 vs 126 ± 14 mL, P = .04), and operative duration (116 ± 19 min. vs 89 ± 6 min, P = .046) were associated with a transfusion requirement with these patients having a longer length of stay (42 [13-76] vs 21 [12-31] days, P = .04) and a higher risk of mortality (33% vs 10%, P = .03).

DISCUSSION

The study is limited by a small sample size from a single institution. However, patients who received an intraoperative transfusion had a lower starting hemoglobin, higher estimated blood loss, required longer hospital stays, and were at a higher risk for post-discharge mortality.

Predictive factors for respiratory failure and in-hospital mortality after surgery for spinal metastasis

PURPOSE

Spinal metastasis surgeries carry substantial risk of complications. PRF is among complications that significantly increase mortality rate and length of hospital stay. The risk factor of PRF after spinal metastasis surgery has not been investigated. This study aims to identify the predictors of postoperative respiratory failure (PRF) and in-hospital death after spinal metastasis surgery.

METHODS

We retrospectively reviewed consecutive patients with spinal metastasis surgically treated between 2008 and 2018. PRF was defined as mechanical ventilator dependence > 48 h postoperatively (MVD) or unplanned postoperative intubation (UPI). Collected data include demographics, laboratory data, radiographic and operative data, and postoperative complications. Stepwise logistic regression analysis was used to determine predictors independently associated with PRFs and in-hospital death.

RESULTS

This study included 236 patients (average age 57 ± 14 years, 126 males). MVD and UPI occurred in 13 (5.5%) patients and 13 (5.5%) patients, respectively. During admission, 14 (5.9%) patients had died postoperatively. Multivariate logistic regression analysis revealed significant predictors of MVD included intraoperative blood loss > 2000 mL (odds ratio [OR] 12.28, 95% confidence interval [CI] 2.88-52.36), surgery involving cervical spine (OR 9.58, 95% CI 1.94-47.25), and ASA classification ≥ 4 (OR 6.59, 95% CI 1.85-23.42). The predictive factors of UPI included postoperative sepsis (OR 20.48, 95% CI 3.47-120.86), central nervous system (CNS) metastasis (OR 10.21, 95% CI 1.42-73.18), lung metastasis (OR 7.18, 95% CI 1.09-47.4), and postoperative pulmonary complications (OR 6.85, 95% CI 1.44-32.52). The predictive factors of in-hospital death included postoperative sepsis (OR 13.15, 95% CI 2.92-59.26), CNS metastasis (OR 10.55, 95% CI 1.54-72.05), and postoperative pulmonary complications (OR 9.87, 95% CI 2.35-41.45).

CONCLUSION

PRFs and in-hospital death are not uncommon after spinal metastasis surgery. Predictive factors for PRFs included preoperative comorbidities, intraoperative massive blood loss, and postoperative complications. Identification of risk factors may help guide therapeutic decision-making and patient counseling.

Preoperative Fibrinogen Level and Bleeding in Liver Transplantation for End-stage Liver Disease: A Cohort Study

BACKGROUND

Liver transplantation is a high-risk surgery associated with important perioperative bleeding and transfusion needs. Uncertainties remain on the association between preoperative fibrinogen level and bleeding in this population.

METHODS

We conducted a cohort study that included all consecutive adult patients undergoing a liver transplantation for end-stage liver disease in 1 center. We analyzed the association between the preoperative fibrinogen level and bleeding-related outcomes. Our primary outcome was intraoperative blood loss, and our secondary outcomes were estimated perioperative blood loss, intraoperative and perioperative red blood cell transfusions, reinterventions for bleeding and 1-y graft and patient survival. We estimated linear regression models and marginal risk models adjusted for all important potential confounders. We used restricted cubic splines to explore potential nonlinear associations and reported dose-response curves.

RESULTS

We included 613 patients. We observed that a lower fibrinogen level was associated with a higher intraoperative blood loss, a higher estimated perioperative blood loss and a higher risk of intraoperative and perioperative red blood cell transfusions (nonlinear effects). Based on an exploratory analysis of the dose-response curves, these effects were observed below a threshold value of 3 g/L for these outcomes. We did not observe any association between preoperative fibrinogen level and reinterventions, 1-y graft survival or 1-y patient survival.

CONCLUSIONS

This study suggests that a lower fibrinogen level is associated with bleeding in liver transplantation. The present results may help improving the selection of patients for further studies on preoperative fibrinogen administration in liver transplant recipients with end-stage liver disease.

Phlebotomy resulting in controlled hypovolemia to prevent blood loss in major hepatic resections (PRICE-2): study protocol for a phase 3 randomized controlled trial

INTRODUCTION

Blood loss and red blood cell (RBC) transfusion in liver surgery are areas of concern for surgeons, anesthesiologists, and patients alike. While various methods are employed to reduce surgical blood loss, the evidence base surrounding each intervention is limited. Hypovolemic phlebotomy, the removal of whole blood from the patient without volume replacement during liver transection, has been strongly associated with decreased bleeding and RBC transfusion in observational studies. This trial aims to investigate whether hypovolemic phlebotomy is superior to usual care in reducing RBC transfusions in liver resection.

METHODS

This study is a double-blind multicenter randomized controlled trial. Adult patients undergoing major hepatic resections for any indication will be randomly allocated in a 1:1 ratio to either hypovolemic phlebotomy and usual care or usual care alone. Exclusion criteria will be minor resections, preoperative hemoglobin <100g/L, renal insufficiency, and other contraindication to hypovolemic phlebotomy. The primary outcome will be the proportion of patients receiving at least one allogeneic RBC transfusion unit within 30 days of the onset of surgery. Secondary outcomes will include transfusion of other allogeneic blood products, blood loss, morbidity, mortality, and intraoperative physiologic parameters. The surgical team will be blinded to the intervention. Randomization will occur on the morning of surgery. The sample size will comprise 440 patients. Enrolment will occur at four Canadian academic liver surgery centers over a 4-year period. Ethics approval will be obtained at participating sites before enrolment.

DISCUSSION

The results of this randomized control trial will provide high-quality evidence regarding the use of hypovolemic phlebotomy in major liver resection and its effects on RBC transfusion. If proven to be effective, this intervention could become standard of care in liver operations internationally and become incorporated within perioperative patient blood management programs.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03651154 . Registered on August 29 2018.

Postoperative mortality risk prediction that incorporates intraoperative vital signs: development and internal validation in a historical cohort

PURPOSE

Accurate risk reassessment after surgery is crucial for postoperative planning for monitoring and disposition. Existing postoperative mortality risk prediction models using preoperative features do not incorporate intraoperative hemodynamic derangements that may alter risk stratification. Intraoperative vital signs may provide an objective and readily available prognostic resource. Our primary objective was to derive and internally validate a logistic regression (LR) model by adding intraoperative features to established preoperative predictors to predict 30-day postoperative mortality.

METHODS

Following Research Ethics Board approval, we analyzed a historical cohort that included patients aged ≥ 45 undergoing noncardiac surgery with an overnight stay at two tertiary hospitals (2013 to 2017). Features included intraoperative vital signs (blood pressure, heart rate, end-tidal carbon dioxide partial pressure, oxygen saturation, and temperature) by threshold and duration of exposure, as well as patient, surgical, and anesthetic factors. The cohort was divided temporally 75:25 into derivation and validation sets. We constructed a multivariable LR model with 30-day all-cause mortality as the outcome and evaluated performance metrics.

RESULTS

There were 30,619 patients in the cohort (mean [standard deviation] age, 66 [11] yr; 50.2% female; 2.0% mortality). In the validation set, the primary LR model showed a c-statistic of 0.893 (99% confidence interval [CI], 0.853 to 0.927), a Nagelkerke R-squared of 0.269, a scaled Brier score of 0.082, and an area under precision-recall curve of 0.158 (baseline 0.017 for an uninformative model). The addition of intraoperative vital signs to preoperative factors minimally improved discrimination and calibration.

CONCLUSION

We derived and internally validated a model that incorporated vital signs to improve risk stratification after surgery. Preoperative factors were strongly predictive of mortality risk, and intraoperative predictors only minimally improved discrimination. External and prospective validations are needed.

STUDY REGISTRATION

www.

CLINICALTRIALS

gov (NCT04014010); registered on 10 July 2019.

A Closed-Loop Audit for Orthopedic Trauma Operation Notes Comparing Typed Electronic Notes With Handwritten Notes

Introduction

Operation notes are important documents for ensuring patient safety, effective communication between clinicians, and for medicolegal purposes. It is essential that they are clear and accurate. We audited the quality of our operation notes against the Royal College of Surgeons (RCS) of England's Good Surgical Practice Guidelines.

Methods

This was a prospective audit of 99 orthopedic trauma operation notes. In the first cycle, we audited 58 operation notes for orthopedic trauma surgical procedures. We audited 17 parameters per note. We presented our findings, implemented changes including the use of a typed operation note template, and performed a re-audit using 41 operation notes.

Results

Our documentation for 3/17 parameters was up to standard in both cycles. Post-intervention, there was an improvement in documentation for 12/17 of the parameters with marked improvements in indication for surgery (45% vs 75%), tourniquet time (20% vs 45%), antibiotic prophylaxis (71% vs 89%), closure technique (62% vs 86%) and detailed postoperative instruction (40% vs 92%). Other parameters, particularly estimated blood loss (7% vs 8%) remained unchanged. In the second cycle, we noted that 25% of the typed notes had 100% compliance with the standards, whereas no handwritten note achieved this. However, there was no statistically significant difference in the mean number of correctly documented parameters between the typed and handwritten notes (p < 0.05).

Conclusion

The use of operation note templates (preferably typed) can improve appropriate documentation in orthopedic trauma operation notes. These templates should be made easily accessible to all surgeons. We will recommend orthopedic trauma units to apply similar non-rigid templates that can be tailored to suit different categories of trauma surgery.

Intraoperative phlebotomies and bleeding in liver transplantation: a historical cohort study and causal analysis

BACKGROUND

Liver transplantation is associated with major bleeding and red blood cell (RBC) transfusions. No well-designed causal analysis on interventions used to reduce transfusions, such as an intraoperative phlebotomy, has been conducted in this population.

METHODS

We conducted a historical cohort study among liver transplantations performed from July 2008 to January 2021 in a Canadian centre. The exposure was intraoperative phlebotomy. The outcomes were blood loss, perioperative RBC transfusions (intraoperative and up to 48 hr after surgery), intraoperative RBC transfusions, and one-year survival. We estimated marginal multiplicative factors (MFs), risk differences (RDs), and hazard ratios by inverse probability of treatment weighting both among treated patients and the whole population. Estimates are reported with 95% confidence intervals (CIs).

RESULTS

We included 679 patients undergoing liver transplantations of which 365 (54%) received an intraoperative phlebotomy. A phlebotomy did not reduce bleeding, transfusion risks, or mortality when estimated among the treated but reduced bleeding and transfusion risks when estimated among the whole population (MF, 0.85; 95% CI, 0.72 to 0.99; perioperative RD, -15.2%; 95% CI, -26.1 to -0.8; intraoperative RD, -14.7%; 95% CI, -23.2 to -2.8). In a subgroup analysis on 584 patients with end-stage liver disease, slightly larger effects were observed on both transfusion risks when estimated among the whole population while beneficial effects were observed on the intraoperative transfusion risk when estimated among the treated population.

CONCLUSION

The use of intraoperative phlebotomy was not consistently associated with better outcomes in all targets of inference but may improve outcomes among the whole population.

STUDY REGISTRATION

www.

CLINICALTRIALS

gov (NCT04826666); registered 1 April 2021.

Effect of Two Different Tranexamic Acid Doses on Blood Loss in Head and Neck Cancer Surgery: A Randomized, Double-Blind, Controlled Study

Background and aim

Head and neck cancer is frequent, and surgeries pose more significant morbidity and mortality due to multitudinal causes; heavy blood loss and transfusion are among them. Tranexamic acid (TXA) is known to stabilize the micro clots hence controlling excessive blood loss. The present study aimed to compare perioperative blood loss with two different doses of TXA and placebo to find the effectiveness and optimal dose.

Methods

With ethical approvals and informed consent, the present prospective, randomized, double-blind, controlled study was conducted in a teaching institute from May 31, 2018, to Dec 28, 2019. Patients undergoing elective head and neck cancer (HNC) surgeries were included. Preoperative Hb < 7 gm% or > 16 gm%, known coagulopathy, anticoagulant therapy, contraindications to TXA, intraoperative torrential or blood loss due to arterial injury were excluded. Group T-1 received TXA 10mg/kg, T-II received 15 mg/kg, while the control group (Gr-C) received equal volume normal saline. Data about demography, surgical time, intraoperative and postoperative blood loss, and transfusion were collected and compared. SPSS software was used for analysis; p-value <0.05 was considered significant.

Results

Ninety patients were screened, 84 completed the study. All three groups were similar in demographics. The median blood loss with 25^th -75^th percentile in group C, T-I, and T-II groups were 762.5 (513.5-1193), 541.5 (296.5-787), and 536.0 (180.5 - 879) mL, respectively; p: 0.025. There was a significant difference between the control group and T-I (p-value: 0.0153), and control and T-II (p-value: 0.0248), but an insignificant difference between T-I and T-II (p-value: 0.706). 5 (17.85%) in each of T-I and T-II required transfusion, whereas 14 (50%) in the control group required it; p < 0.011). No major clinically significant related to study drugs were noted.

Conclusion

Compared to placebo (normal saline), preoperative administration of TXA in bolus significantly reduced perioperative blood losses and transfusion requirement in patients undergoing HNC surgery as estimated using the Hb-based method. A bolus dose of doses of 10mg/kg and 15 mg/kg is equally effective.