Predicting lowest hemoglobin level and risk of blood transfusion in spinal fusion surgery for adolescent idiopathic scoliosis

Prophylactic cryoprecipitate transfusion in patients undergoing scoliosis surgery: A randomised-controlled trial

BACKGROUND

Scoliosis surgeries in adults often have a high risk of massive blood loss and significant transfusion of blood products during and after surgery. It is not known whether early cryoprecipitate therapy is useful in reducing blood loss and transfusion requirements. The objective of this randomised, prospective placebo control study was to evaluate whether prophylactic administration of cryoprecipitate would reduce blood loss and transfusion requirements during scoliosis surgery.

METHODS

Eighty adult patients scheduled to undergo elective scoliosis correction were randomly assigned to receive either ten units of cryoprecipitate before incision (cryo group) or an equivalent volume of 0.9% saline (placebo group). Blood loss, transfusion requirements, coagulation parameters and complications were assessed.

RESULTS

No significant differences were found in the volume of transfused blood products, intraoperative estimated blood loss between the intervention and placebo groups. Postoperative blood loss was significantly lower in the cry group when compared to the other group. During adult surgical correction of scoliosis, prophylactic administration of cryoprecipitate did not diminish the amount of transfused blood products or decrease intraoperative blood loss.

CONCLUSION

It could be concluded that the prophylactic administration of cryoprecipitate shows no differences in intraoperative blood loss and transfusion requirements during scoliosis surgery.

Error traps and preventative strategies for adolescent idiopathic scoliosis spinal surgery

Anesthesia for posterior spinal fusion for adolescent idiopathic scoliosis remains one of the most common surgeries performed in adolescents. These procedures have the potential for significant intraprocedural and postoperative complications. The potential for pressure injuries related to prone positioning must be understood and addressed. Additionally, neuromonitoring remains a mainstay for patient care in order to adequately assess patient neurologic integrity and alert the providers to a reversible action. As such, causes of neuromonitoring signal loss must be well understood, and the provider should have a systematic approach to signal loss. Further, anesthetic design must facilitate intraoperative wake-up to allow for a definitive assessment of neurologic function. Perioperative bleeding risk is high in posterior spinal fusion due to the extensive surgical exposure and potentially lengthy operative time, so the provider should undertake strategies to reduce blood loss and avoid coagulopathy. Pain management for adolescents undergoing spinal fusion is also challenging, and inadequate analgesia can delay recovery, impede patient/family satisfaction, increase the risk of chronic postsurgical pain/disability, and lead to prolonged opioid use. Many of the significant complications associated with this procedure, however, can be avoided with intentional and evidence-based approaches covered in this review.

Is routine blood typing and screening necessary for degenerative cervical spine surgery patients in specialty surgical hospitals?

BACKGROUND

Blood loss warranting transfusion is a relatively rare requirement for degenerative cervical spine surgery. Despite this rarity, pretransfusion testing (blood typing, screening, and cross-matching) has become routine in most parts of the world. We sought to determine if such routine testing is necessary for patients who undergo degenerative cervical spine surgery patients in specialty surgical hospitals by (1) measuring the current rate of intraoperative transfusions in degenerative cervical spine surgery and (2) identifying risk factors for transfusions.

STUDY METHODS

Retrospective review was performed on patients who underwent degenerative cervical spine surgery in two institutions. Demographic and baseline clinical and laboratory data were collected and analyzed to identify predictors of transfusion. Bivariate and multivariate logistic regression analysis was performed to identify perioperative transfusion risk factors.

RESULTS

Overall transfusion rate was 1.9% (7/372), with no emergent transfusions. Decreases between preoperative and postoperative hemoglobin and hematocrit were 1.4 (SD 1.1) g/dL and 7.2 (SD 4.1) %, respectively. Multivariate logistic regression identified preoperative Hgb lower than 12 gr/dl (OR 27.62; 95% CI 4.31-176.96; p < 0.001) as significant independent transfusion risk factor. The receiver operating characteristic (ROC) curve for the model showed a very good discriminatory power with an area under the curve of 0.91.

DISCUSSION

Our study suggests that pretransfusion testing for all patients undergoing degenerative cervical spine surgery is unnecessary. We recommend that only patients with preoperative Hgb lower than 12 gr/dl would routinely need pretransfusion testing.

Development and validation of a novel predictive model and web calculator for evaluating transfusion risk after spinal fusion for spinal tuberculosis: a retrospective cohort study

Objectives

The incidence and adverse events of postoperative blood transfusion in spinal tuberculosis (TB) have attracted increasing attention. Our purpose was to develop a prediction model to evaluate blood transfusion risk after spinal fusion (SF) for spinal TB.

Methods

Nomogram and machine learning algorithms, support vector machine (SVM), decision tree (DT), multilayer perceptron (MLP), Naive Bayesian (NB), k-nearest neighbors (K-NN) and random forest (RF), were constructed to identified predictors of blood transfusion from all spinal TB cases treated by SF in our department between May 2010 and April 2020. The prediction performance of the models was evaluated by 10-fold cross-validation. We calculated the average AUC and the maximum AUC, then demonstrated the ROC curve with maximum AUC.

Results

The collected cohort ultimately was consisted of 152 patients, where 56 required allogeneic blood transfusions. The predictors were surgical duration, preoperative Hb, preoperative ABL, preoperative MCHC, number of fused vertebrae, IBL, and anticoagulant history. We obtained the average AUC of nomogram (0.75), SVM (0.62), k-NM (0.65), DT (0.56), NB (0.74), MLP (0.56) and RF (0.72). An interactive web calculator based on this model has been provided (https://drwenleli.shinyapps.io/STTapp/).

Conclusions

We confirmed seven independent risk factors affecting blood transfusion and diagramed them with the nomogram and web calculator.

Hidden blood loss in adolescent idiopathic scoliosis patients undergoing posterior spinal fusion surgery: a retrospective study of 765 cases at a single centre

Background

In scoliosis corrective surgery, total blood loss is composed of visible blood loss, including intraoperative haemorrhage and drainage, and hidden blood loss in which blood extravasates into the tissues and accumulates in the surgical field. The purpose of this study was to investigate hidden blood loss (HBL) and its potential risk factors in adolescent idiopathic scoliosis patients undergoing posterior spinal fusion surgery and elucidate the influence of HBL on the necessity for postoperative blood transfusion.

Methods

We retrospectively studied adolescent idiopathic scoliosis patients undergoing posterior spine fusion for adolescent idiopathic scoliosis from January 2014 to December 2018 at our hospital. The patients’ demographics, blood loss-related parameters, surgeries and blood loss data were extracted. The association between patient characteristics and HBL was analyzed by Pearson or Spearman correlation analyses. Multivariate linear regression analysis was used to determine independent risk factors associated with HBL. Binary logistic regression analysis was used to analyze the influence of HBL on the necessity for postoperative blood transfusion.

Results

A total of 765 patients, of whom 128 were male and 637 were female (age range 10–18 years), were included in this study. The mean volume of HBL was 693.5 ± 473.4 ml, accounting for 53.9 % of the total blood loss. The multivariate linear regression analysis revealed that preoperative Hct (p = 0.003) and allogeneic blood transfusion (p < 0.001) were independent risk factors for HBL, while tranexamic acid (p = 0.003) was negatively correlated with HBL. Binary logistic regression analysis showed that HBL > 850 ml (P < 0.001, OR: 8.845, 95 % CI: 5.806–13.290) was an independent risk factor for the necessity for postoperative blood transfusion.

Conclusions

Substantial HBL occurred in adolescent idiopathic scoliosis patients undergoing posterior spinal fusion surgeries. Allogeneic blood transfusion and preoperative Hct were independent risk factors for HBL, while tranexamic acid was negatively related to HBL. HBL and its influencing factors should be considered when planning perioperative transfusion management. Patients with HBL greater than 850 ml should be closely monitored in cases of postoperative anaemia.

Level of evidence

Level III.

Perioperative blood conservation strategies for pediatric scoliosis surgery

PURPOSE

Many pediatric patients with severe scoliosis requiring surgery have baseline anemia. Pediatric scoliosis fusion surgery is associated with perioperative blood loss requiring transfusion. As such, many patients in this surgical population could benefit from a perioperative blood conservation program.

METHODS

Here we present a narrative review of perioperative blood conservation strategies for pediatric scoliosis surgery involving nurses, transfusion medicine physicians, anesthesiologists, surgeons, dieticians, perfusionists and neurophysiologists spanning the pre-, intra- and postoperative phases of care.

RESULTS

The review highlights how perioperative blood conservation strategies, have the potential to minimize exposures to exogenous blood products. Further, we describe a relevant example of blood conservation related to the care of a Jehovah's Witness patient undergoing staged scoliosis repair. Lastly, we outline areas which would benefit from clinical studies to further elucidate perioperative blood conservation interventions and their outcomes relevant to pediatric scoliosis surgery patients.

CONCLUSION

Interdisciplinary communication and meticulous blood conservation strategies are proving to be a means of reducing if not eliminating the need for allogeneic blood products for surgical correction of pediatric scoliosis.

Dual attending surgeon strategy learning curve in single-staged posterior spinal fusion (PSF) surgery for 415 idiopathic scoliosis (IS) cases

BACKGROUND CONTEXT

The implementation of a dual attending surgeon strategy had improved perioperative outcomes of idiopathic scoliosis (IS) patients. Nevertheless, the learning curve of a dual attending surgeon practice in single-staged posterior spinal fusion (PSF) surgery has not been established.

OBJECTIVE

To evaluate the surgical learning curve of a dual attending surgeon strategy in IS patients.

STUDY DESIGN

Retrospective study.

PATIENT SAMPLE

415 IS patients (Cobb angle <90°) who underwent PSF using a dual attending surgeon strategy OUTCOME MEASURES: Primary outcomes included operative time, total blood loss, allogenic blood transfusion requirement, length of hospital stay and perioperative complication rate.

METHODS

Regression analysis using Locally Weighted Scatterplot Smoothing (LOWESS) method was applied to create the best-fit-curve between case number versus operative time and total blood loss in identifying cut-off points for the learning curve.

RESULTS

The mean Cobb angle was 60.8±10.8°. Mean operative time was 134.4±32.1 minutes and mean total blood loss was 886.0±450.6 mL. The mean length of hospital stay was 3.0±1.6 days. The learning curves of a dual attending surgeon strategy in this study were established at the 115th case (operative time) and 196th case (total blood loss) respectively (p<.001). In comparison of cases before and after the cut-off points, mean operative time reduced significantly from 147.2±36.5 minutes to 129.5±28.9 minutes and mean total blood loss reduced significantly from 1015.1±506.6 mL to 770.4±357.3 mL (p<.001). No allogenic blood transfusion was required and there were 7 perioperative complications (n=7/415, 1.7%) recorded.

CONCLUSION

The learning curve of a dual surgeon strategy in single-staged PSF surgery based on operative time and total blood loss were established at 115th case and 196th case respectively (p<.001).

Ultrasonic Bone Scalpel (USBS) Does Not Reduce Blood Loss During Posterior Spinal Fusion (PSF) in Patients with Adolescent Idiopathic Scoliosis (AIS): Randomized Clinical Trial

STUDY DESIGN

Randomized Clinical Trial.

OBJECTIVE

The aim of this study was to compare the efficacy of USBS with standard-of-care surgical instruments during posterior spinal fusion (PSF) in patients with adolescent idiopathic scoliosis (AIS) by evaluating the difference in estimated blood loss per level fused (EBL/level).

SUMMARY OF BACKGROUND DATA

PSF surgery for AIS is often associated with high blood loss. Use of an ultrasonic bone scalpel (USBS) has been proposed to reduce blood loss during scoliosis surgery.

METHODS

This was a single-blinded (patient-blinded), randomized, controlled superiority trial. We randomized 66 patients with AIS undergoing PSF to the control group (osteotome) or the experimental group (USBS). The primary outcome was intraoperative EBL/level obtained from red blood cell salvage reports. One-year follow-up was available for 57 of 62 (92%) of patients.

RESULTS

EBL/level averaged 35 and 39 mL/level in the experimental and control groups, respectively [adjusted mean difference USBS - osteotome -8 mL/level, 95% CI: -16.4 to 0.3 mL/level, P = 0.0575]. There was no difference in curve correction [adjusted mean difference: -1.7%, 95% CI: -7.0 to 3.6%, P = 0.5321] or operative time [adjusted mean difference: -3.55 minutes, 95% CI: -22.45 to 15.46 min, P = 0.7089] between groups. Complications requiring change in routine postoperative care were noted in eight patients: two occurred in patients assigned to the experimental group and six occurred in patients assigned to the control group.

CONCLUSION

There was no clinically significant difference in total blood loss, EBL/level, or complications between the two groups. In contrast to reports from other centers, at our high-volume spine center, USBS did not lead to reduced blood loss during PSF for AIS. These results may not be generalizable to centers with longer baseline operative times or higher baseline average blood loss during PSF for AIS.Level of Evidence: 1.

Risk factors for blood transfusion in adolescent patients with scoliosis undergoing scoliosis surgery: a study of 722 cases in a single center

Background

To assess the risk factors for blood transfusion in a great number of adolescent cases with different types of scoliosis who received scoliosis surgery.

Methods

Data of patients who were diagnosed as scoliosis and received one-stage posterior correction and spinal fusion from January 2014 to December 2017 were prospectively collected and retrospectively analyzed. Patients’ demographic characteristics, segments of spinal fusion, Cobb angle of the major curve,osteotomy pattern, preoperative and postoperative levels of hemoglobin, and allogeneic blood transfusion (ABT) were recorded and analyzed.

Results

In this study, 722 cases with adolescent scoliosis were included, of whom 32.8% (237/722) received ABT. Risk factors included diagnosis: neurofibromatosis (OR = 5.592), syndromic (OR = 3.029),osteotomy: Ponte osteotomy (OR = 5.997), hemivertebrae resection (OR = 29.171), pedicle subtraction osteotomy (PSO)(OR = 8.712), vertebral column resection (VCR)(OR = 32.265);fusion segments (OR = 1.224) and intraoperative blood loss (OR = 1.004). In the subgroup analysis of cases with idiopathic scoliosis, Ponte osteotomy (OR = 6.086), length of segments of spinal fusion (OR = 1.293), and intraoperative blood loss (OR = 1.001) were found as risk factors for ABT. Results of receiver operating characteristic (ROC) curve analysis revealed that length of segments of spinal fusion equal to 11.5 vertebrae was the best cutoff value for cases with idiopathic scoliosis who did not receive osteotomy in both ABT group and non-ABT group. In the subgroup analysis of congenital scoliosis, Ponte osteotomy (OR = 5.087), hemivertebra resection (OR = 5.457), PSO (OR = 4.055), VCR (OR = 6.940), and intraoperative blood loss (OR = 1.004) were risk factors for ABT.

Conclusions

Method of diagnosis, osteotomy pattern, segments of spinal fusion, and intraoperative blood loss were risk factors for ABT in cases with adolescent scoliosis. In cases with idiopathic scoliosis, Ponte osteotomy and segments of spinal fusion longer than 11.5 vertebrae were risk factors for ABT. In cases with congenital scoliosis, osteotomy pattern was the main risk factor for ABT.

Level of evidence

Level III.

A novel predictive model of intraoperative blood loss in patients undergoing elective lumbar surgery for degenerative pathologies

BACKGROUND CONTEXT

Intraoperative blood loss (IOBL) is unavoidable during surgery; however, high IOBL is associated with increased morbidity and increased risk for requiring allogenic blood transfusion, itself associated with poorer outcomes.

PURPOSE

Here we sought to develop and validate a predictive calculator for IOBL that could be used by surgeons to estimate likely blood loss.

STUDY DESIGN/SETTING

Retrospective cohort.

PATIENT SAMPLE

Series of consecutive patients who underwent elective lumbar spine surgery for degenerative pathologies over a 27-month period at a single tertiary care center.

OUTCOME MEASURES

Primary outcome was IOBL. Secondary outcome was the occurrence of "major intraoperative bleeding," defined as IOBL exceeding 1 L.

METHODS

Charts of included patients were reviewed for medical comorbidities, preoperative laboratory data, surgical plan, and anesthesia records. Univariate linear regressions were performed to find significant predictors of IOBL, which were then subjected to a multivariate analysis to identify the final model. Model training was performed using 70% of the included cohort and external validation was performed using 30% of the cohort. Results of the model were deployed as a freely available online calculator.

RESULTS

We identified 1,281 patients who met inclusion/exclusion criteria. Mean age was 60±15 years, mean Charlson Comorbidity score was 1.1±1.6, and 51.8% were male. There were no significant differences between the training and validation cohorts with regard to any of the demographic variables or intraoperative variables; tranexamic acid use and surgical invasiveness were also similar in both cohorts. Multivariate analysis identified body mass index (βₙ=7.14; 95% confidence interval [3.15, 11.13]; p<.001), surgical invasiveness (βₙ=29.18; [24.62, 33.74]; p<.001), tranexamic acid use (βₙ=-0.093; [-0.171, -0.014]; p=.02), and surgical duration (βₙ=2.13; [1.75, 2.51]; p<.001) as significant predictors of IOBL. The model had an overall fit of r=0.693 in the validation cohort. Construction of a receiver-operating curve for predicting major IOBL showed a C-statistic of 0.895 within the validation cohort.

CONCLUSION

Here we identify and validate a model for predicting IOBL in patients undergoing lumbar spine surgery. The model was a moderately strong predictor of absolute IOBL and was demonstrated to predict the occurrence of major IOBL with a high degree of accuracy. We propose it may have future utility when counseling patients about surgical morbidity and the probability of requiring transfusion.

Surgical treatment of adolescent idiopathic scoliosis: Complications

Despite the fact that spinal surgeries for adolescent idiopathic scoliosis (AIS) result in good outcomes for most patients, they are not without complications either medically or surgically. Neurologic injury represents the most severe complication and is, as such, the most feared. Further complications include dural tears, peripheral neuropathy, surgical-site infections, implant-related issues, thromboembolic events, visual loss, pseudarthrosis, Crankshaft phenomenon, flatback phenomenon, proximal junctional kyphosis, and mortality. It is vital that all spine surgeons to be fully conversant with the possible complications and the proper responses for each of them.

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Surgeons should know how to manage complications of surgery for AIS.

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Patients should know about potential complications prior to surgery.

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Neurologic injury represents the most severe complication.