Predicting massive transfusion in adolescent idiopathic scoliosis patients undergoing corrective surgery: Association of preoperative radiographic findings

The effect of surgical time on perioperative complications in adolescent idiopathic scoliosis cases. A propensity score analysis

BACKGROUND

Posterior spinal instrumentation and fusion (PSIF) for adolescent idiopathic scoliosis (AIS) can be lengthy and complication-ridden. The aim of this study was to evaluate the effect of surgical time on perioperative complications in this procedure when controlling for confounding variables with propensity score analysis.

METHODS

This was an IRB-approved review of electronic health records from 2010 to 2019 at a single tertiary care children's hospital. Patients undergoing PSIF were grouped into "short" (< 6 h) or "long" (≥ 6 h) surgical time groups. Outcome measures were estimated blood loss (EBL), cell saver transfusions, packed red blood cell (pRBC) transfusions, length of stay (LOS), intraoperative monitoring (IOM) alerts, hematocrit, ICU transfer, neurologic loss, surgical site infection, and 90-day readmissions. We controlled for age, sex, BMI, curve severity, number of segments fused, and surgeon factors.

RESULTS

After propensity score matching there were 113 patients in each group. The short surgical time group had lower EBL (median 715, IQR 550-900 vs median 875, IQR 650-1100 cc; p < 0.001), received less cell saver blood (median 120, IQR 60-168 vs median 160, IQR 97-225 cc; p = 0.001), received less intraoperative pRBCs (median 0, IQR 0-0 vs median 0, IQR 0-320, p = 0.002), had shorter average LOS (4.8 ± 1.7 vs 5.4 ± 2.5 days; p = 0.039), and fewer IOM alerts (4.3% vs 18%, p = 0.003).

CONCLUSIONS

Patients with shorter surgical times had less blood loss, received less transfused blood, had a shorter LOS, and fewer IOM alerts compared to patients with longer surgical times. Surgical times < 6 h may have safety and efficacy advantages over longer times.

LEVEL OF EVIDENCE

III.

Utility of postoperative laboratory testing after posterior spinal fusion for adolescent idiopathic scoliosis

PURPOSE

With advancements to blood management strategies, risk of perioperative transfusion following surgical treatment of adolescent idiopathic scoliosis (AIS) has diminished. We hypothesize that routine laboratory testing on postoperative-day 1 (POD1) and beyond is unnecessary. The purpose of this study is to determine necessity of POD1 labs, particularly hematocrit and hemoglobin levels, following surgical management of AIS.

METHODS

We performed a retrospective cohort study of consecutive AIS patients aged 11-19 who underwent posterior spinal fusion (PSF) at a single institution. Univariable logistic regression was utilized to determine factors associated with hematocrit ≤ 22% on POD1 or a postoperative transfusion. Firth's penalized logistic regression was used for any separation in data. Youden's index was utilized to determine the optimal point on the ROC curve that maximizes both sensitivity and specificity.

RESULTS

527 patients qualified for this study. Among the eight total patients with POD1 hematocrit ≤ 22, none underwent transfusion. These patients had lower last intraoperative hematocrit levels compared to patients with POD1 hematocrit > 22% (24.1% vs 31.5%, p < 0.001), and these groups showed no difference in preoperative hematocrit levels (38.2% vs 39.8%, p = 0.11). Four patients underwent postoperative transfusion. Both preoperative hematocrit levels (34.0% vs 39.9%, p = 0.001) and last intraoperative hematocrit levels (25.1% vs 31.4%, p = 0.002) were lower compared to patients without transfusion. Intraoperative hematocrit < 26.2%, operative time of more than 35.8 min per level fused, or cell salvage > 241 cc were significant risk factors for postoperative transfusion.

CONCLUSION

Transfusion after PSF for AIS is exceedingly rare. POD1 labs should be considered when last intraoperative hematocrit < 26%, operative time per level fused > 35 min, or cell salvage amount > 241 cc. Otherwise, unless symptomatic, patients do not benefit from postoperative laboratory screening.

Determining the factors associated with a prolonged length of stay for adolescent idiopathic scoliosis patients undergoing posterior spinal instrumentation and fusion in a single-payer health care system: are these factors different than those in the United States?

INTRODUCTION

Rapid recovery pathways (RRP) for adolescent idiopathic scoliosis patients undergoing posterior spinal instrumentation and fusion (PSIF) have been shown to be successful in reducing hospital length of stay (LOS). Although the majority of patients are discharged within 3 days, some patients require longer hospital admission. Previous studies in the United States have identified predictors of prolonged LOS for this patient population. The goal of this project was to determine if these predictors are the same for Canadian scoliosis patients and to identify those features which are different under this single-payer system.

METHODS

A RRP for scoliosis surgery was implemented in March 2015 at a single, tertiary referral children's hospital in Canada. Previously identified features, along with numerous other patient factors, were collected. Spearman correlations were used to determine the factors most associated with hospital LOS and those factors were used in a multivariable regression model.

RESULTS

A total of 161 patients were included in the analysis. Of the previously identified patient factors, only receiving a peri-operative transfusion was found to be significant (ρ = 0.24; p = 0.002). None of the other pre-identified variables were found to be significantly correlated with LOS. Variables not previously examined that were found to be significantly correlated with hospital LOS included ASA status (ρ = 0.19, p = 0.046), fusion involving both the thoracic and lumbar spine (ρ = 0.18, p = 0.025), and receiving celecoxib on post-operative day 1 (ρ = - 0.16; p = 0.038). The features that had the greatest association with LOS through multivariable regression was receiving a blood transfusion (B = 0.48; 95%CI 0.096-0.89; p = 0.017).

CONCLUSIONS

In this study, we found that many of the features found to be significantly correlated with prolonged hospital LOS in the United States are not transferable to the Canadian healthcare system. This is important for the Canadian, and other surgeons in a single-payer system, in order to identify pre-operative or immediate post-operative factors that may extend patient LOS following PSIF and plan resources accordingly.

LEVEL OF EVIDENCE

III; therapeutic.

The Incidence and Risk Factors for Allogeneic Blood Transfusions in Pediatric Spine Surgery: National Data

(1) Background: Pediatric spinal surgery is a blood-intensive procedure. In order to introduce a rational blood management program, identifying the risk factors for transfusions is mandatory. (2) Methods: Data from the national database covering the period from January 2015 to July 2017 were analyzed. The available data included the demographics, characteristics of the surgeries performed, length of stay, and in-house mortality. (3) Results: The total number of patients used for the analysis was 2302. The primary diagnosis was a spinal deformity (88.75%). Most fusions were long, with four levels or more (89.57%). A total of 938 patients received a transfusion; thus, the transfusion rate was 40.75%. The present study identified several risk factors; the most significant was a number of levels fused greater than 4 (RR 5.51; CI95% 3.72-8.15; p < 0.0001), followed by the deformity as the main diagnosis (RR 2.69; CI95% 1.98-3.65; p < 0.0001). These were the two most significant factors increasing the odds of a transfusion. Other factors associated with an increased risk of transfusion were elective surgery, the female sex, and an anterior approach. The mean length of stay in days was 11.42 (SD 9.93); this was greater in the transfused group (14.20 vs. 9.50; p < 0.0001). (4) Conclusions: The rate of transfusions in pediatric spinal surgery remains high. A new patient blood management program is necessary to improve this situation.

Development and Validation of a Prediction Model for Need for Massive Transfusion During Surgery Using Intraoperative Hemodynamic Monitoring Data

Importance

Massive transfusion is essential to prevent complications during uncontrolled intraoperative hemorrhage. As massive transfusion requires time for blood product preparation and additional medical personnel for a team-based approach, early prediction of massive transfusion is crucial for appropriate management.

Objective

To evaluate a real-time prediction model for massive transfusion during surgery based on the incorporation of preoperative data and intraoperative hemodynamic monitoring data.

Design, Setting, and Participants

This prognostic study used data sets from patients who underwent surgery with invasive blood pressure monitoring at Seoul National University Hospital (SNUH) from 2016 to 2019 and Boramae Medical Center (BMC) from 2020 to 2021. SNUH represented the development and internal validation data sets (n = 17 986 patients), and BMC represented the external validation data sets (n = 494 patients). Data were analyzed from November 2020 to December 2021.

Exposures

A deep learning-based real-time prediction model for massive transfusion.

Main Outcomes and Measures

Massive transfusion was defined as a transfusion of 3 or more units of red blood cells over an hour. A preoperative prediction model for massive transfusion was developed using preoperative variables. Subsequently, a real-time prediction model using preoperative and intraoperative parameters was constructed to predict massive transfusion 10 minutes in advance. A prediction model, the massive transfusion index, calculated the risk of massive transfusion in real time.

Results

Among 17 986 patients at SNUH (mean [SD] age, 58.65 [14.81] years; 9036 [50.2%] female), 416 patients (2.3%) underwent massive transfusion during the operation (mean [SD] duration of operation, 170.99 [105.03] minutes). The real-time prediction model constructed with the use of preoperative and intraoperative parameters significantly outperformed the preoperative prediction model (area under the receiver characteristic curve [AUROC], 0.972; 95% CI, 0.968-0.976 vs AUROC, 0.824; 95% CI, 0.813-0.834 in the SNUH internal validation data set; P < .001). Patients with the highest massive transfusion index (ie, >90th percentile) had a 47.5-fold increased risk for a massive transfusion compared with those with a lower massive transfusion index (ie, <80th percentile). The real-time prediction model also showed excellent performance in the external validation data set (AUROC of 0.943 [95% CI, 0.919-0.961] in BMC).

Conclusions and Relevance

The findings of this prognostic study suggest that the real-time prediction model for massive transfusion showed high accuracy of prediction performance, enabling early intervention for high-risk patients. It suggests strong confidence in artificial intelligence-assisted clinical decision support systems in the operating field.

Predictors of perioperative blood loss in primary posterior hemivertebra resection for pediatric patients with congenital scoliosis

Several studies have elucidated the risk factors of intraoperative bleeding. However, the total blood loss (visible and hidden loss) and related risk factors were seldom reported. In this study, we aimed to identify predictors of massive blood loss in posterior hemivertebra resection for pediatric patients. Clinical records were retrospectively reviewed for 108 pediatric patients who underwent primary posterior hemivertebra resection and spinal fusion for congenital scoliosis from June 2017 to June 2019. Intraoperative blood loss was recorded and hidden blood loss was calculated by deducting the intraoperative loss from the total blood loss calculated using specific formula. Perioperative information was collected for multivariable linear regression analysis to determine the independent risk factors of the blood loss. The mean total blood loss was 575.0 ± 318.0 ml during the perioperative period, accounting for 42.1% of the estimated blood volume. The intraoperative and hidden loss were 337.6 ± 179.5 ml and 237.4 ± 204.8 ml, respectively, accounting for 58.7 and 41.3% of the total loss. Multivariable linear regression indicated that age, preoperative Cobb angle, operative time, and number of fused levels were independent risk factors of the total blood loss. Patients with operative time ≥145 minutes, fused levels ≥4, and preoperative Cobb angle ≥40° have an increased risk of massive blood loss. The perioperative blood loss of surgery for congenital scoliosis was considerable, with a high percentage of hidden blood loss. Patients with severe deformity, more fused levels, and longer operative time had higher risk of massive blood loss.

Hidden blood loss in adolescent idiopathic scoliosis surgery

INTRODUCTION

Posterior spinal fusions (PSF) for adolescent idiopathic scoliosis (AIS) have higher blood loss than other pediatric orthopedic surgeries. There is a paucity of literature estimating the hidden blood loss (HBL) in patients with AIS undergoing PSF. The purpose of this study was to compare intraoperative and postoperative estimated blood loss (EBL) in patients undergoing PSF for AIS to determine HBL.

HYPOTHESIS

With contemporary blood loss prevention strategies, HBL will be higher than intraoperative EBL.

MATERIAL AND METHODS

Over a 3-year period, 67 patients with preoperative and postoperative hemoglobin (Hgb) measurements undergoing PSF for AIS were evaluated. Intraoperative EBL was estimated using a volumetric method and recorded by a perfusionist managing a cell saver machine. Total perioperative EBL was estimated using the validated formula: EBL=weight (kg)×age sex factor×(preoperative Hgb - postoperative Hgb)/preoperative Hgb. HBL was calculated as the total perioperative EBL minus the intraoperative EBL.

RESULTS

Calculated total EBL was higher than intraoperative EBL (771±256mL vs. 110±115mL, p<0.001). Mean HBL after wound closure was 660±400mL. Patients 14 years or greater (p=0.03), with a BMI≥25kg/m²(p=0.02) and with surgical times over 3.5hours (p=0.05) had increased HBL. Multivariate analysis determined BMI≥25kg/m² (OR 9.91; CI, 1.01-104.26; p=0.05) was associated with increased HBL. Allogenic blood transfusion was rare (4%) and associated with increased HBL (897±112mL vs. 540±402mL, p=0.05).

DISCUSSION

For patients undergoing PSF for AIS there is more HBL after wound closure than intraoperative blood loss. This HBL is higher in older patients who undergo longer operations and have a BMI≥25kg/m².

LEVEL OF EVIDENCE

IV; retrospective cohort study.

High- versus low-dose tranexamic acid as part of a Patient Blood Management strategy for reducing blood loss in patients undergoing surgery for adolescent idiopathic scoliosis

PURPOSE

The administration of tranexamic acid (TXA) has been shown to be beneficial in reducing blood loss during surgery for adolescent idiopathic scoliosis (AIS), but optimal dosing has yet to be defined. This retrospective study compared high- versus low-dose TXA as part of a Patient Blood Management strategy for reducing blood loss in patients undergoing posterior spine fusion surgery.

METHODS

Clinical records were reviewed for 223 patients with AIS who underwent posterior spinal fusion of five or more levels during a 6-year time period. We compared normalized blood loss, total estimated blood loss (EBL), and the need for transfusion between patients receiving high-dose TXA (loading dose of ≥ 30 mg/kg) versus low-dose TXA (loading dose < 30 mg/kg). Both groups received maintenance TXA infusions of 10 mg/kg/h until skin closure.

RESULTS

Patient demographics, curves, and surgical characteristics were similar in both groups. The high-dose TXA group had a 36% reduction in normalized blood loss (1.8 cc/kg/level fused versus 2.8 cc/kg/level fused, p < 0.001) and a 37.5% reduction in total EBL (1000 cc versus 1600 cc, p < 0.001). Patients in the high-dose group had a 48% reduction in PRBC transfusion, with only 19% receiving a transfusion of PRBC compared to 67% in the low-dose group (p < 0.001).

CONCLUSION

When combined with other proven Patient Blood Management strategies, the use of high-dose TXA compared to low-dose TXA may be beneficial in reducing blood loss for patients with adolescent idiopathic scoliosis undergoing posterior spinal fusion surgery.

LEVEL OF EVIDENCE

Level III, retrospective cohort.

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.

Antifibrinolytic Drugs and Allogeneic Transfusion in Pediatric Multilevel Spine Surgery: A Propensity Score Matched Cohort Study

STUDY DESIGN

Observational cohort study with propensity score matching.

OBJECTIVE

Determine whether antifibrinolytic drug use is associated with decreased allogeneic blood transfusion in multilevel pediatric spine surgery.

SUMMARY OF BACKGROUND DATA

Antifibrinolytic drugs are commonly used in adult multilevel spine surgery to reduce blood loss and allogeneic transfusion; however, only small studies have examined their efficacy in pediatric patients having multilevel spine surgery.

METHODS

Pediatric patients who had posterior multilevel spine surgery between 2016 and 2017 were identified in the national surgery quality improvement program participant use file. Propensity score matching was used to reduce bias from confounding and the rate of intraoperative allogeneic transfusion was compared between patients who received antifibrinolytic drugs and those who did not. Secondary outcomes included intraoperative cell saver volume, postoperative allogeneic transfusion, massive intraoperative transfusion, and adverse events including venous thromboembolism and seizure.

RESULTS

A total of 6904 patients underwent posterior multilevel spine surgery during the study period and 83% received antifibrinolytics. The matched cohort included 604 patients. Antifibrinolytic use had no association with reduced intraoperative allogeneic transfusion: odds ratio (OR) = 0.71 (99% confidence interval [CI] = 0.40-1.26, P = 0.12) or cell saver volume, median volume = 114 mL (0, 250 mL) in antifibrinolytic group versus 100 mL (0, 246 mL) in control group, P = 0.04. There was also no association with reduced postoperative allogeneic transfusion OR = 1.23 (99% CI = 0.54-2.81, P = 0.52) or massive transfusion OR = 1.0 (99% CI = 0.34-2.92, P = 1.0). No patient in the matched cohort had a venous thromboembolism or seizure.

CONCLUSION

Antifibrinolytic drugs are commonly used in pediatric multilevel spine surgery in the United States, but no efficacy was demonstrated in our study. There were no venous thromboembolisms or seizures implying an excellent safety profile in pediatric patients.

LEVEL OF EVIDENCE

3.

Prediction of perioperative transfusions using an artificial neural network

BACKGROUND

Accurate prediction of operative transfusions is essential for resource allocation and identifying patients at risk of postoperative adverse events. This research examines the efficacy of using artificial neural networks (ANNs) to predict transfusions for all inpatient operations.

METHODS

Over 1.6 million surgical cases over a two year period from the NSQIP-PUF database are used. Data from 2014 (750937 records) are used for model development and data from 2015 (885502 records) are used for model validation. ANN and regression models are developed to predict perioperative transfusions for surgical patients.

RESULTS

Various ANN models and logistic regression, using four variable sets, are compared. The best performing ANN models with respect to both sensitivity and area under the receiver operator characteristic curve outperformed all of the regression models (p < .001) and achieved a performance of 70-80% specificity with a corresponding 75-62% sensitivity.

CONCLUSION

ANNs can predict >75% of the patients who will require transfusion and 70% of those who will not. Increasing specificity to 80% still enables a sensitivity of almost 67%. The unique contribution of this research is the utilization of a single ANN model to predict transfusions across a broad range of surgical procedures.

Pediatric Anesthesia Concerns and Management for Orthopedic Procedures

Anesthetic management of pediatric orthopedic patients is uniquely challenging. Approach to the pediatric patient must consider heightened preoperative anxiety and its postoperative behavioral and pain effects. Frequent respiratory infections can complicate timing of surgery and anesthetic care. Perioperative pain management usually involves a multimodal pharmacologic approach with the goal of minimizing opioid requirements. Regional anesthesia is valuable for postoperative pain control. Safety of its use in the pediatric population has been confirmed in recent studies. Included for discussion are fractures, slipped capital femoral epiphysis, club foot, and scoliosis.