Preoperative plasma fibrinogen concentration, factor XIII activity, perioperative bleeding, and transfusions in elective orthopaedic surgery: A prospective observational study

Abnormal bleeding after lumbar vertebrae surgery because of acquired factor XIII deficiency: A case report and literature review

RATIONALE

Abnormal bleeding due to low fibrinogen (Fib) and coagulation factor XIII (FXIII) levels after lumbar vertebral surgery is exceedingly rare. Excessive bleeding is also associated with secondary hyperfibrinolysis. This report presents a case of abnormal incision bleeding caused by coagulation factor XIII deficiency (FXIIID) and secondary hyperfibrinolysis in a state of low fibrinogen after lumbar vertebral surgery.

PATIENT CONCERNS

A middle-aged woman experienced prolonged incision and excessive bleeding after lumbar vertebral surgery.

DIAGNOSIS

Combined with coagulation factors, coagulation function tests, and thromboelastography, the patient clinical presentation supported the diagnosis of FXIIID and secondary hyperfibrinolysis in a hypofibrinogenemic state.

INTERVENTIONS

Cryoprecipitat, Fresh Frozen Plasma, Fibrinogen Concentrate, Leukocyte-depleted Red Blood Cells, Hemostatic (Carbazochrome Sodium Sulfonate; Hemocoagulase Bothrops Atrox for Injection; Tranexamic Acid).

OUTCOMES

After approximately a month of replacement therapy and symptom treatment, the patient coagulation function significantly improved, and the incision healed without any hemorrhage during follow-up.

LESSONS

Abnormal postoperative bleeding may indicate coagulation and fibrinolysis disorders that require a full set of coagulation tests, particularly coagulation factors. Given the current lack of a comprehensive approach to detect coagulation and fibrinolysis functions, a more comprehensive understanding of hematology is imperative. The current treatment for FXIIID involves replacement therapy, which requires supplementation with both Fib and FXIII to achieve effective hemostasis.

Effect of Prophylactic Fibrinogen Concentrate In Scoliosis Surgery (EFISS): a study protocol of two-arm, randomised trial

INTRODUCTION

Fibrinogen is one of the essential coagulation factors. Preoperative lower plasma fibrinogen level has been associated with higher blood loss. Scoliosis surgery presents a challenge for the anaesthetic team, one of the reasons being blood loss and transfusion management. Recently, the prophylactic fibrinogen administration has been a debated topic in various indications. It has been described for example, in urological or cardiovascular surgery, as well as in paediatrics. This pilot study is focused on verifying the feasibility of potential large randomised trial and verifying the safety of prophylactic fibrinogen administration in paediatric scoliosis surgery.

METHODS AND ANALYSIS

A total of 32 paediatric patients indicated for scoliosis surgery will be recruited. Participants will be randomised into study groups in a 1:1 allocation ratio. Patients in the intervention group will receive prophylactic single dose of fibrinogen, in addition to standard of care. Patients in the control group will receive standard of care without study medication prior to skin incision. The primary aim is to assess the safety of prophylactic fibrinogen administration during scoliosis surgery in children, the incidence of any adverse events (AEs) and reactions will be monitored during participation in the study. The secondary objective is to investigate the additional safety information, feasibility and efficacy of a prophylactic fibrinogen administration. The incidence of AEs and reactions according to selected adverse events of special interest will be monitored. All collected data will be subjected to statistical analysis according to a separate statistical analysis plan.

ETHICS AND DISSEMINATION

This trial follows the applicable legislation and requirements for good clinical practice according to the International Conference on Harmonisation E6(R2). All essential trial documents were approved by the relevant ethics committee and national regulatory authority (State Institute for Drug Control) and their potential amendments will be submitted for approval.

TRIAL REGISTRATION NUMBER

NCT05391412.

Management of severe peri-operative bleeding: Guidelines from the European Society of Anaesthesiology and Intensive Care: Second update 2022

BACKGROUND

Management of peri-operative bleeding is complex and involves multiple assessment tools and strategies to ensure optimal patient care with the goal of reducing morbidity and mortality. These updated guidelines from the European Society of Anaesthesiology and Intensive Care (ESAIC) aim to provide an evidence-based set of recommendations for healthcare professionals to help ensure improved clinical management.

DESIGN

A systematic literature search from 2015 to 2021 of several electronic databases was performed without language restrictions. Grading of Recommendations, Assessment, Development and Evaluation (GRADE) was used to assess the methodological quality of the included studies and to formulate recommendations. A Delphi methodology was used to prepare a clinical practice guideline.

RESULTS

These searches identified 137 999 articles. All articles were assessed, and the existing 2017 guidelines were revised to incorporate new evidence. Sixteen recommendations derived from the systematic literature search, and four clinical guidances retained from previous ESAIC guidelines were formulated. Using the Delphi process on 253 sentences of guidance, strong consensus (>90% agreement) was achieved in 97% and consensus (75 to 90% agreement) in 3%.

DISCUSSION

Peri-operative bleeding management encompasses the patient's journey from the pre-operative state through the postoperative period. Along this journey, many features of the patient's pre-operative coagulation status, underlying comorbidities, general health and the procedures that they are undergoing need to be taken into account. Due to the many important aspects in peri-operative nontrauma bleeding management, guidance as to how best approach and treat each individual patient are key. Understanding which therapeutic approaches are most valuable at each timepoint can only enhance patient care, ensuring the best outcomes by reducing blood loss and, therefore, overall morbidity and mortality.

CONCLUSION

All healthcare professionals involved in the management of patients at risk for surgical bleeding should be aware of the current therapeutic options and approaches that are available to them. These guidelines aim to provide specific guidance for bleeding management in a variety of clinical situations.

Temporal changes and predictors of perioperative blood transfusion in elective spine surgery: a retrospective analysis of a large surgical database

BACKGROUND

Allogeneic blood transfusion used to be common in spine surgery. Patient blood management has been widely adopted, and it is important to reassess transfusion predictors in contemporary practice.

METHODS

A retrospective study of inpatient spine surgery was performed using National Surgical Quality Improvement Program (NSQIP) data from 2011 to 2019. The primary outcome was perioperative transfusion within 72 h of surgery. Multivariable logistic regression and recursive partitioning were used to assess up to 15 variables including patient and surgical data, surgical specialty (orthopaedic surgery vs neurosurgery), and year of surgery.

RESULTS

The study population included 251 971 US surgical patients; 6.9% of these patients received perioperative blood transfusion. Perioperative transfusions declined over time with the steepest decline from 2011 to 2015. The greatest reduction was seen among orthopaedic cases where the transfusion rate declined from 16.0% to 8.7% between 2011 and 2015. Eight variables were predictive factors in a reduced model: operative time, preoperative haemoglobin, vertebral level, number of vertebral levels, older age, surgeon specialty, arthrodesis, and year of surgery (area under the curve [AUC]=0.880; 95% confidence interval [CI], 0.878-0.883). Overall, longer operative time (>144 min) and greater numbers of vertebral levels had greater associations with transfusion than surgical specialty after adjustments. Prevalence of anaemia (15%) has not substantially declined.

CONCLUSIONS

Perioperative blood transfusion rate in spine surgery has declined over the past decade. The extent and duration of surgery and preoperative haemoglobin level remain important factors associated with increased odds for perioperative blood transfusion.

Plasma Fibrinogen as a Predictor of Perioperative-Blood-Component Transfusion in Major-Nontraumatic-Orthopedic-Surgery Patients: A Cohort Study

There is a trend towards increased perioperative bleeding in patients with plasma fibrinogen levels < 200 mg/dL^-1. This study aimed to assess whether there is an association between preoperative fibrinogen levels and perioperative blood-product transfusion up to 48 h after major orthopedic surgery. This cohort study included 195 patients who underwent primary or revision hip arthroplasty for nontraumatic etiologies. Plasma fibrinogen, blood count, coagulation tests, and platelet count were measured preoperatively. A plasma fibrinogen level of 200 mg/dL^-1 was the cutoff value used to predict blood transfusion. The mean (SD) plasma fibrinogen level was 325 (83) mg/dL^-1. Only thirteen patients had levels < 200 mg/dL^-1, and only one of them received a blood transfusion, with an absolute risk of 7.69% (1/13; 95%CI: 1.37-33.31%). Preoperative plasma fibrinogen levels were not associated with the need for blood transfusion (p = 0.745). The sensitivity and the positive predictive value of plasma fibrinogen < 200 mg/dL^-1 as a predictor of blood transfusion were 4.17% (95%CI: 0.11-21.12%) and 7.69% (95%CI: 1.12-37.99%), respectively. Test accuracy was 82.05% (95%CI: 75.93-87.17%), but positive and negative likelihood ratios were poor. Therefore, preoperative plasma fibrinogen level in hip-arthroplasty patients was not associated with the need for blood-product transfusion.

Does living at high altitude increase the risk of bleeding events after total knee arthroplasty? A retrospective cohort study

OBJECTIVE

Post-operative bleeding after total knee arthroplasty (TKA) is a frequent cause of post-operative complications. This study compared blood loss and indicators of coagulation and fibrinolysis between TKA patients living at low or high altitudes.

METHODS

We retrospectively analyzed 120 patients at our institution who underwent primary TKA from May 2019 to March 2020, and we divided them into those living in areas about 500 m or > 3000 m above sea level. We compared the primary outcome of total blood loss between them. We also compared them in terms of several secondary outcomes: coagulation and fibrinolysis parameters, platelet count, reduction in hemoglobin, hidden blood loss, intra-operative blood loss, transfusion rate, and incidence of thromboembolic events and other complications.

RESULTS

Total blood loss was significantly higher in the high-altitude group than in the low-altitude group (mean, 748.2 mL [95% CI, 658.5-837.9] vs 556.6 mL [95% CI, 496.0-617.1]; p = 0.001). The high-altitude group also showed significantly longer activated partial thromboplastin time, prothrombin time, and thrombin time before surgery and on post-operative day one, as well as increased levels of fibrinogen/fibrin degradation product on post-operative days one and three. Ecchymosis was significantly more frequent in the high-altitude group (41.7 vs 21.7%; relative risk (RR) = 1.923 [95% CI, 1.091-3.389]; p = 0.019). The two groups showed similar transfusion rates, and none of the patients experienced venous thromboembolism, pulmonary embolism, or infection.

CONCLUSION

High altitude may alter coagulation and fibrinolysis parameters in a way that increases risk of blood loss after TKA. Such patients may benefit from special management to avoid bleeding events.

Tranexamic acid attenuates early post-operative systemic inflammatory response and nutritional loss and avoids reduction of fibrinogen in total hip arthroplasty within an enhanced recovery after surgery pathway

PURPOSE

Total hip arthroplasty (THA) is an intervention with significant inflammatory response. The impact of additional doses of tranexamic acid (TXA) on inflammatory response, trauma and nutrition parameters, and coagulation and fibrinolysis changes has rarely been reported.

METHODS

A prospective double-blind randomized trial was performed on elective primary THA. Ninety-nine adult patients were recruited consecutively from 2019 to 2020. They were randomized to receive single-dose of TXA before incision, another dose of TXA at three hours post-operatively, or another two doses of TXA at three and six hours  post-operatively. The primary outcomes included changes in white blood cell (WBC) counts, creatine kinase (CK), haemoglobin(Hb), and albumin(Alb); the secondary outcomes included coagulation and fibrinolysis parameters.

RESULTS

Compared with single-dose TXA, patients received three dose TXA had significantly reduced WBC counts and fibrinogen/fibrin degradation product (FDP) levels, increased albumin and fibrinogen levels, and prolonged PT on post-operative day (POD) three. Though patients received three dose TXA had a tendency that increased Hb, decreased CK, reduced D-D, and prolonged APTT on POD3, it is not statistically significant. And the other measured outcomes on POD1 and POD2W shared a similar statistical result, except PT. The PT is significantly prolonged on POD2W in three dose group compared with single dose.

CONCLUSION

Three-dose TXA contribute to attenuate early post-operative systemic inflammatory response and nutritional loss, increase fibrinogen, reduce FDP levels, and prolong PT in THA patients within an ERAS pathway, which may associate with reduced early post-operative haemorrhagic tendency, thrombosis risks, and hypercoagulability.

Therapeutic Application of Fibrinogen in Spine Surgery: A Review Article

BACKGROUND

The aim of this review is to investigate current uses of fibrinogen as a tool to reduce operative and postoperative blood loss in different surgical fields especially orthopedic spine surgery. This is a systematic review.

METHODS

MEDLINE (via Ovid 1946 to June 1, 2020) and Embase (via Ovid 1947 to June 1, 2020) were searched using the keywords "fibrinogen", "surgery", and "spine" for relevant studies. The search strategy used text words and relevant indexing to identify articles discussing the use of fibrinogen to control surgical blood loss.

RESULTS

The original literature search yielded 407 articles from which 68 duplications were removed. Three hundred thirty-nine abstracts and titles were screened. Results were separated by surgical specialties.

CONCLUSIONS

Multiple studies have looked at the role of fibrinogen for acute bleeding in the operative setting. The current evidence regarding the use of fibrinogen concentrate in spine surgery is promising but limited, even though this is a field with the potential for severe hemorrhage. Further trials are required to understand the utility of fibrinogen concentrate as a first-line therapy in spine surgery and to understand the importance of target fibrinogen levels and subsequent dosing and administration to allow recommendations to be made in this field.

Nonimmune-acquired factor XIII deficiency: a cause of high volume and delayed postoperative hemorrhage

: Factor XIII (FXIII) levels may decrease because of surgical consumption. Acquired FXIII deficiency could be a cause of postoperative hemorrhage usually underdiagnosed in clinical practice. To determine the diagnosis confirmation rate of acquired FXIII deficiency in postsurgical patients with clinical suspicion and to compare the characteristics and evolution of patients with or without FXIII deficiency. We performed a retrospective cohort study, which included 49 inpatients who were attended at our university hospital from 2014 to 2018 with suspicion of acquired FXIII deficiency because of disproportionate postoperative hemorrhage. FXIIIA levels less than 50% was considered a deficiency. Persistence of bleeding for more than 48 h, drop in hematocrit points, red blood cells transfused units, hemoglobin levels 12-36 h after bleeding, and time elapsed from the procedure to the bleeding were assessed as outcome variables. Logistic regression was employed for both univariate and multivariate analyses. Of the 49 patients included, 27(55%) had FXIII deficiency, with a median level of 34% [interquartile range (IQR) 19-42]. Abdominal surgery was the most common [n = 21 (43%)]. All patients had routine coagulation tests within the hemostatic range. FXIII deficiency was associated with a drop of more than 4 points in hematocrit [OR 59.69 (95% CI 4.71-755.30)], red blood transfused units >2 [OR 45.38 (95% CI 3.48-590.65)], and delayed bleeding >36 h after surgery [OR 100.90 (95% CI 3.78-2695.40)]. Plasma-derived FXIII concentrate was administered to eight patients with life-threatening bleeding with resolution within 24 h. Only one deficient patient died from bleeding. FXIII levels were measured 15 days after diagnosis or more in 20 out of 27 deficient patients, with normal results. Acquired FXIII deficiency may be a frequent underdiagnosed entity that should be considered when high-volume and delayed postoperative hemorrhage is present in patients with hemostatic routine coagulation test results.

Relationship Between Preoperative Plasma Fibrinogen Concentration, Perioperative Bleeding, and Transfusions in Elective Adult Spinal Deformity Correction

STUDY DESIGN

Retrospective analysis.

OBJECTIVE

This study sought to investigate the relationship between preoperative (preop) fibrinogen, bleeding, and transfusion requirements in adult spinal deformity corrections.

SUMMARY OF BACKGROUND DATA

Blood loss after major spinal reconstruction increases the risks and costs of surgery. Preoperative fibrinogen levels may predict intra- and postoperative blood loss.

METHODS

Data were collected from clinic charts and hospital medical records of all 142 of a single surgeon's consecutive adult spine patients undergoing 7 or more levels deformity correction surgeries from January 2011 to December 2014. t tests were used to compare perioperative variables between patients with total blood loss in the upper quartile (≥1,000 mL) and the remaining patients. Similarly, patients receiving >2 units of packed red cells (PRCs) were compared with others. Analysis of variance was used to compare the blood loss between the patients' groups (quartiles) based on their preoperative fibrinogen concentration.

RESULTS

Mean total blood loss was 847.9 (±543.6) mL. Overall, mean preoperative fibrinogen concentration was 254.8 (±82.9) mg/dL. Patients with lower fibrinogen concentration (<193 mg/dL) experienced significantly higher blood loss than those with higher concentrations (p < .05). Patients with transfusion >2 units PRC had significantly greater number of spinal levels treated, higher mean operative time, total blood loss and lower mean preoperative fibrinogen than those transfused 2 or fewer units PRC (p < .05). Total blood loss correlated significantly with preoperative fibrinogen concentration (r = -0.51, p < .05). All the thromboelastography (TEG) variables (G, K, and Angle) correlated significantly with preoperative fibrinogen (p < .05).

CONCLUSIONS

In our cohort undergoing correction of adult spinal deformity, patients with preoperative fibrinogen level lower than 193 mg/dL had significantly higher bleeding than their counterparts. Perioperative transfusion requirements correlated moderately both with the blood loss and preoperative fibrinogen concentration. Incorporation of preoperative fibrinogen allows better prediction of total perioperative blood loss and may therefore guide the treatment team in use of ameliorating therapies.

LEVEL OF EVIDENCE

Level IV.

Effects of storage over a 36-month period on coagulation factors in a canine plasma product obtained by use of plasmapheresis

OBJECTIVE

To evaluate stability of coagulation factors in canine plasma obtained by use of plasmapheresis and stored over a 36-month period.

SAMPLE

Canine plasma obtained by use of plasmapheresis acquired from a commercial blood bank.

PROCEDURES

Coagulation testing for fibrinogen concentration and activity of factors II, V, VII, VIII, and IX and von Willebrand factor was performed on canine plasma obtained by use of plasmapheresis. Samples were obtained for testing at 6-month intervals from plasma stored for up to 36 months.

RESULTS

A simple mixed linear regression model was created for each analysis. Median value for the fibrinogen concentration was > 150 mg/dL for all time points, except at 467, 650, and 1,015 days of storage. Median value for factor VIII was > 70% only at 650 days. Median value for factor V was > 50% through 650 days. Median value for factors VII and X was > 50% through 833 days, and median value for factors II and VII was > 50% through 1,015 days. Median value for von Willebrand factor was > 50% for the entire study (1,198 days). Median value for factor X was always < 50%.

CONCLUSIONS AND CLINICAL RELEVANCE

Coagulation factors degraded over time at variable rates, and all labile factors remained at > 50% activity for longer than 1 year. Plasma collected by plasmapheresis potentially offers prolonged life span of some clotting factors. Plasmapheresis is an acceptable form of canine plasma collection for transfusion purposes, and further studies should be performed to determine all of its benefits.

Tocilizumab treatment in patients with rheumatoid arthritis is associated with reduced fibrinogen levels and increased blood loss after total knee arthroplasty

OBJECTIVE

Since IL-6 has been associated with activation of the coagulation cascade and upregulation of fibrinogen transcription, we retrospectively tested the hypothesis that patients with rheumatoid arthritis (RA) treated with tocilizumab (TCZ) may lose more blood when undergoing total knee arthroplasty (TKA).

METHODS

This study included 115 RA patients who underwent primary TKA and were preoperatively tested for fibrinogen levels. The blood volume of each patient was calculated using the Nadler formula, and estimated blood loss after TKA was calculated as the change between pre-operative and post-operative hematocrits. If salvaged blood was reinfused, the volume was measured and added to the volume of the estimated blood loss.

RESULTS

We observed that patients treated with TCZ had significantly lower pre-operative fibrinogen levels than those not treated with TCZ (190.0 mg/dL versus 347.0 mg/dL, respectively; p = .00018). We also observed a statistically significant increase in mean total volume of estimated blood loss after TKA in RA patients who had been treated with TCZ compared with those not treated with TCZ (797.1 mL versus 511.4 mL, respectively; p = .0039).

CONCLUSION

TCZ treatment in patients with RA may increase the risk of blood loss after TKA because of decreased fibrinogen levels.

Red Blood Cell Transfusion Need for Elective Primary Posterior Lumbar Fusion in A High-Volume Center for Spine Surgery

(1) Background: This study evaluated the perioperative red blood cell (RBC) transfusion need and determined predictors for transfusion in patients undergoing elective primary lumbar posterior spine fusion in a high-volume center for spine surgery. (2) Methods: Data from all patients undergoing spine surgery between 1 January 2014 and 31 December 2016 were reviewed. Patients’ demographics and comorbidities, perioperative laboratory results, and operative time were analyzed in relation to RBC transfusion. Multivariate logistic regression analysis was performed to identify the predictors of transfusion. (3) Results: A total of 874 elective surgeries for primary spine fusion were performed over the three years. Only 54 cases (6%) required RBC transfusion. Compared to the non-transfused patients, transfused patients were mainly female (p = 0.0008), significantly older, with a higher ASA grade (p = 0.0002), and with lower pre-surgery hemoglobin (HB) level and hematocrit (p < 0.0001). In the multivariate logistic regression, a lower pre-surgery HB (OR (95% CI) 2.84 (2.11–3.82)), a higher ASA class (1.77 (1.03–3.05)) and a longer operative time (1.02 (1.01–1.02)) were independently associated with RBC transfusion. (4) Conclusions: In the instance of elective surgery for primary posterior lumbar fusion in a high-volume center for spine surgery, the need for RBC transfusion is low. Factors anticipating transfusion should be taken into consideration in the patient’s pre-surgery preparation.

Clinical influence of preoperative factor XIII activity in patients undergoing pancreatoduodenectomy

BACKGROUND

The influence of decreased factor XIII (FXIII) activity on perioperative bleeding has been reported in some surgical procedures. The purposes of this study were to investigate the perioperative dynamics of FXIII in patients undergoing pancreatoduodenectomy and to clarify the effects of low preoperative FXIII activity on intraoperative bleeding and postoperative complications.

METHODS

Total of 43 patients who underwent a pancreatoduodenectomy were enrolled. The perioperative FXIII activities were measured, and their associations with intraoperative bleeding and postoperative outcomes were analyzed.

RESULTS

Fifteen patients (35%) had low FXIII activities (<70%, lower than the institutional normal range). The patients with preoperative FXIII activities <70% experienced significantly greater blood loss (median, 1309 mL) during surgery compared to those with FXIII levels of ≥70% (median, 710 mL) (p = 0.001). The postoperative morbidity rates, including pancreatic fistula, were comparable between the patients with FXIII activities <70% and those with FXIII activities ≥70%. The FXIII levels substantially decreased on postoperative day 1 and remained at low levels until postoperative day 7.

CONCLUSION

Unexpectedly high proportions of patients undergoing pancreatoduodenectomy had low preoperative FXIII activities. Preoperative FXIII deficiency may increase intraoperative bleeding but had no influence on the postoperative outcomes.

Massive blood loss in elective spinal and orthopedic surgery: Retrospective review of intraoperative transfusion strategy

OBJECTIVE

To evaluate the perioperative dynamics of hematologic changes and transfusion ratio in patients undergoing a major spinal surgery accompanied with massive bleeding defined as blood loss >5 liters.

DESIGN

Retrospective cohort study.

SETTING

Operating room of a university-affiliated hospital.

PATIENTS

Adult patients who underwent elective neurosurgical, orthopedic, or combined spinal surgical procedure between 2008 and 2012.

METHODS

Patients who underwent a major spinal or orthopedic surgery and who experienced major bleeding (>5 L) during surgery were identified and selected for final analysis. The following information was analyzed: demographics, clinical diagnoses, hematologic parameters, estimated intraoperative blood loss, blood product transfusions, and survival 1 year after surgery.

RESULTS

During the study period, 25 patients, who underwent 28 spinal procedures, experienced intraoperative blood loss >5 L. Mean patient age was 50.5 years and 56.4% were males. The majority of patients underwent procedures to manage spinal metastases. Median estimated intraoperative blood loss was 11.25 L (IQR 6.35-22 L) and median number of units (U) transfused was 24.5 U (IQR 14.0-32.5 U) of packed red blood cells (RBCs), 24.5 U (IQR 14.0-34.0 U) of fresh frozen plasma (FFP), and 4.5 U (IQR 3.0-11.5 U) of platelets (PLTs). The blood product transfusion ratio was 1 and 4 for RBC:FFP, and RBC:PLT, respectively. Hematocrit, hemoglobin, PLTs, partial thromboplastin, prothrombin time, INR, and, fibrinogen varied significantly throughout the procedures. However, acid-base status did not change significantly during surgery. Patients' survival at 1 year was 79.17%.

CONCLUSION

Our results indicate that a 1:1 RBC:FFP and 4:1 RBC:PLT transfusion ratio was associated with significant intraoperative variations in coagulation variables but stable intraoperative acid-base parameters. This transfusion ratio helped clinicians to achieve postoperative coagulation parameters not significantly different to those at baseline. Future studies should assess if more liberal transfusion strategies or point of care monitoring might be warranted in patients undergoing spinal surgery at risk of major blood loss.