Predicting excessive hemorrhage in adolescent idiopathic scoliosis patients undergoing posterior spinal instrumentation and fusion

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.

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.

Risk Factors of Total Blood Loss and Hidden Blood Loss in Patients with Adolescent Idiopathic Scoliosis: A Retrospective Study

Objectives

To investigate the risk factors of total blood loss (TBL) and hidden blood loss (HBL) in adolescent idiopathic scoliosis (AIS) patients undergoing posterior orthopedic surgery.

Methods

The AIS patients who visited department of spine surgery between January 2015 and December 2020 were retrospectively reviewed. Those with a history of posterior orthopedic surgery for AIS were identified, and their clinical data were collected. Gross formula was used to calculate the TBL and HBL. SPSS 20.0 was used for statistical analysis. The potential risk factors of TBL and HBL were assessed by independent t-test or univariate analysis. The risk factors of TBL and HBL were determined by multiple linear regression.

Results

A total of 114 patients were included in this study. Operative time (P < 0.001), postoperative platelets (PLT) (P = 0.001), the number of surgical fixation segments (P < 0.001), implanted screws (P < 0.001), hospital stay (P = 0.006), type of scoliosis (P < 0.001), and correction angle of scoliosis (P = 0.063) were the potential risk factors of TBL. Operative time (P < 0.000), postoperative PLT (P = 0.095), the number of surgical fixation segments (P < 0.001), implanted screws (P < 0.001), type of scoliosis (P < 0.001), correction angle of scoliosis (P = 0.073), and total blood volume (P = 0.098) were the potential risk factors of HBL. Multiple linear regression analysis showed that operative time (P = 0.003) and the number of surgical fixation segments (P = 0.014) were risk factors of TBL, while the number of surgical fixation segments (P = 0.004) was a risk factor of HBL.

Conclusions

In AIS patients undergoing posterior internal fixation surgery, the operative time and the number of surgical fixation segments are risk factors of TBL, and the number of surgical fixation segments is a risk factor of HBL. Surgeons need to consider these factors when making surgical strategies for AIS patients.

Factors Affecting Operation Duration in Posterior Spinal Fusion (PSF) Using Dual Attending Surgeon Strategy Among Lenke 1 and 2 Adolescent Idiopathic Scoliosis (AIS) Patients

STUDY DESIGN

This was a retrospective study.

SUMMARY OF BACKGROUND DATA

Prolonged operation duration in adolescent idiopathic scoliosis (AIS) surgery was associated with increased perioperative complications. However, the factors affecting operation duration in AIS surgery were unknown.

OBJECTIVE

The aim of the study was to investigate the factors affecting operation duration in posterior spinal fusion (PSF) surgery using a dual attending surgeon strategy among Lenke 1 and 2 AIS patients.

METHODS

In all, 260 AIS patients with Lenke 1 and 2 curves who underwent PSF were retrospectively reviewed. Preoperative and intraoperative factors affecting operation duration such as age, sex, height, weight, body mass index, Risser grade, Lenke subtypes, number of fusion level, number of screws, screw density, wound length, upper and lowest instrumented vertebrae level, preoperative Cobb angle, and flexibility of the major curve were assessed using univariate and multivariate linear regression analyses. Independent factors were determined when P-value <0.05.

RESULTS

The mean operation duration was 122.2±28.6 minutes. Significant independent factors affecting operation duration in PSF among Lenke 1 and 2 AIS patients were Lenke 2 subtypes (β=8.86, P=0.008), number of screws (β=7.01, P<0.001), wound length (β=1.14, P=0.009), and flexibility of the major curve (β=-0.25, P=0.005). The overall model fit was R2=0.525. Operation duration can be predicted using the formula: (8.86×Lenke subtypes)+(7.01×number of screws)+(1.14×wound length)-(0.25×flexibility)-0.54, where Lenke 2=1 and Lenke 1=0.

CONCLUSION

The factors affecting operation duration in PSF among Lenke 1 and 2 AIS patients were Lenke 2 curves, number of screws, wound length, and curve flexibility. The knowledge of these factors enables the spinal deformity surgeons to plan and estimate the operation duration before AIS surgery.

Operative time in adolescent idiopathic scoliosis surgery: a need for a standard definition

Our objective is to report and define 'operative time' in adolescent idiopathic scoliosis (AIS) posterior spinal fusion surgeries. Documenting key times during surgery are important to compare operative risks, assess learning curves, and evaluate team efficiency in AIS surgery. 'Operative time' in literature has not been standardized. Systematic review was performed by two reviewers. Keywords included operative time, duration of surgery, and scoliosis. One thousand nine hundred six studies were identified, 1092 duplicates were removed and 670 abstracts were excluded. Of the 144 articles, 67 met inclusion and exclusion criteria. Studies were evaluated for number of patients, operative time, and definition of operative time. Meta-analysis was not performed due to confounders. Of the 67 studies (6678 patients), only 14 (1565 patients) defined operative time, and all specified as incision to closure. From these 14 studies, the median operative time was 248 minutes (range 174-448 minutes). In the 53 studies (5113 patients) without a definition, one study reported time in a non-comparable format, therefore, data were analyzed for 52 studies (5078 patients) with a median operative time of 252 minutes (wider range 139-523 minutes). A clear standardized definition of operative or surgical time in spine surgery does not exist. We believe that operative time should be clearly described for each published study for accurate documentation and be defined from incision time to spine dressing completion time in order to standardize study results. Level of evidence: IV.

Intraoperative red blood cell salvage in posterior spinal fusions for idiopathic scoliosis: identifying potential criteria for selective use

STUDY DESIGN

Retrospective.

OBJECTIVES

Evaluate the role and effectiveness of ICS in primary posterior spinal fusion (PSF) for idiopathic scoliosis (IS). Intraoperative cell salvage (ICS) minimizes blood loss and need for allogeneic transfusions. However, it adds substantial charges ($800-1200 US) and may be of less clinical benefit in some PSF for IS.

MATERIALS AND METHODS

This was a single-hospital, retrospective analysis of 178 consecutive IS cases (10-18 years of age) who underwent primary PSF by a single pediatric spine surgeon.

RESULTS

Overall, 41% of cases received a mean 167 cc of ICS blood, after a mean EBL of 528 mL (range 200-1800 mL). No blood was returned in 59% of cases, with a mean EBL of 293 mL (range 75-700 mL). Only 6.5% of the entire cohort received > / = 250 cc via ICS, after a mean EBL of 773 mL. A positive correlation exists between EBL and vertebral levels fused, preoperative major Cobb angle, and length of anesthesia (p < 0.001). ICS may be more efficacious at an inflection point of 12 vertebral fusion levels, preoperative major Cobb angles > / = 55°, anesthesia exposure > / = 6 h, and with use of posterior column osteotomies (PCOs) (p < 0.05). In addition, lack of tranexamic acid use lead to greater EBL (p < 0.0001) and ICS volumes (p = 0.008).

CONCLUSION

The use of ICS in IS patients undergoing PSF resulted in the return of > / = 250 cc of ICS blood (similar volume to one allogeneic unit) in only 6.5% of cases. Charges for ICS set-up and processing of one bowl of ICS is much higher than for one allogeneic unit ($1200 vs. $462 US), hence transfusing lower volumes of autologous ICS blood is not cost-effective for all PSF for IS.

LEVEL OF EVIDENCE

IV; Therapeutic studies.

Low Radiation X-rays: Benefiting People Globally by Reducing Cancer Risks

Modern medical imaging facilitates the diagnosis and treatment of human diseases. However, few people are aware of the cons of radiation exposure from medical imaging. Emerging evidence reveals that cumulative doses of radiation exposure will increase the morbidity and mortality of pertaining cancer. As a special young population, patients with adolescent idiopathic scoliosis (AIS) suffer more radiation harms from repeated diagnostic imaging, most of which can be avoided in clinical practice. Accumulating evidence highlights reduced cancer risks of radiation exposure for AIS patients with low/zero radiation imaging modalities proposed, amongst which easy conversion from anterior-posterior (AP) to posterior-anterior (PA) projection for whole-spine radiographs should be stressed. It can greatly reduce radiation doses without compromising the quality of diagnostic imaging. Tight collimation combined with PA projection can further reduce radiation harms, and need to be spread to benefit people globally.

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.

The incidence and risk factors for perioperative allogeneic blood transfusion in primary idiopathic scoliosis surgery

STUDY DESIGN

Case-control study.

OBJECTIVES

Evaluate the rate and risk factors for perioperative allogeneic blood transfusion (ABT) in primary idiopathic scoliosis surgery at a single institution. Avoiding perioperative ABT is ideal as transfusions are associated with adverse reactions, increased rates of infection, prolonged hospitalization, additional laboratory testing, and increased cost. Risk factors identified in other studies have differed, and to our knowledge, few studies have identified clinical strategies to predict patients at high risk for ABT.

METHODS

We reviewed 402 idiopathic scoliosis patients who underwent primary posterior spinal fusion and instrumentation (PSFI) at a single institution from 2015 to 2017. Medical records and radiographs were reviewed for all patients. Transfused patients were compared to the remaining cohort to find significant differences and identify predictors of higher ABT risk.

RESULTS

ABT occurred in 73 patients (18.2%), with the majority of transfusions occurring intraoperatively (41%) or postoperatively on the day of surgery (25%). The seven surgeons involved varied significantly in incidence of ABT (2.4-35.8%, p = 0.002). Patients who had ABT were younger (13.3 vs. 14.1 years, p < 0.01), had lower BMI (48th vs. 61st percentile, p < 0.001), and lower preoperative hemoglobin (13.1 vs. 13.7 g/dL, p < 0.01). Greater preoperative major Cobb angle (69° vs. 61.5°, p < 0.001), number of fusion levels (11.8 vs. 10.3, p < 0.001), and estimated blood loss (770 vs. 448 mL, p < 0.001) also predicted ABT.

CONCLUSIONS

ABT was associated with several risk factors, five of which are known preoperatively. Surgeons can use knowledge of these risk factors to assess transfusion risk preoperatively and plan surgery, blood management, and laboratory testing accordingly. The development of best practices for ordering ABT is possible given the variation amongst providers.

LEVEL OF EVIDENCE

Level III.

Blood Management and Risk Assessment for Transfusion in Pediatric Spinal Deformity Surgery

Objectives

Evaluate the impact of a Quality and Safety Program (QSP) on the reduction of blood loss and transfusion needs in pediatric spinal deformity surgery, while defining risk factors for transfusion.

Background

Multimodal plan aiming to minimize transfusion needs has been shown to reduce transfusions and index rates in spinal deformity surgery. Anticipating blood loss and transfusion may help direct resources to patient needs or encourage reconsideration of the surgical plan.

Methods

This is a single-center retrospective study of prospectively collected data. Impact of this multimodal plan was studied on idiopathic deformities (Group A, 109 patients) and scoliosis associated with syndromic, neuromuscular, and muscular dystrophies (Group B, 100 patients), both before and after QSP.

Results

A decrease in total estimated blood loss was observed. In Group A, transfused patients decreased from 83.7% to 28% (p < 0.001, odds: 0.077), and, in Group B, from 98.7% to 66% (p < 0.01, odds: 0.038). Pearson's correlation identified patient body weight (r = 0.245, p=0.001) and Cobb angle (r = 0.175, p=0.017) as factors related to blood loss. A linear regression model to estimate hematic losses revealed that only body weight and transfusion showed predictive power, resulting in a low predictive model (R² = 0.156; F(3,167) = 15.483, p < 0.001). A mediated model to explain blood loss was built based on a set of variables influencing transfusion which is, in turn, related to blood loss.

Conclusion

Transfusion needs in scoliosis surgery can be substantially reduced following a multimodal approach. The success of a program is strongly dependent on team effort, and the introduction of a risk assessment tool for transfusion needs indirectly assesses surgical risk, thus allowing relocation of resources to decrease blood loss.

Coagulative function assessed preoperatively via the clot formation and lysis assay as a prognostic factor for blood loss in adolescents undergoing posterior spinal fusion for idiopathic scoliosis

BACKGROUND

Posterior spinal fusion for adolescent idiopathic scoliosis is a complex surgery often associated with clinically significant blood loss leading to perioperative blood transfusion. Knowledge of risk factors for blood loss and transfusion stems mostly from retrospective studies.

AIM

We sought to prospectively investigate putative prognostic factors for intraoperative blood loss and perioperative blood transfusion in adolescent idiopathic scoliosis patients undergoing posterior spine fusion, including clinical characteristics, surgical factors, and preoperative assessment of overall coagulative and fibrinolytic functions in plasma using the clot formation and lysis (CloFAL) assay.

METHODS

Following Internal Review Board approval, adolescents 10 to <21 years old with idiopathic scoliosis undergoing posterior spine fusion were enrolled preoperatively in a single-institutional prospective cohort and biobanking study. Clinical data were collected on patient characteristics, surgical approach, perioperative management, intraoperative estimated blood loss, and blood transfusion through hospital discharge. Coagulative and fibrinolytic functions in plasma were measured on preoperative samples by CloFAL assay (Coagulation Index and modified Fibrinolytic Index). Univariate linear regression and multivariable linear regression were performed to identify predictors of weight-indexed intraoperative estimated blood loss EBL (EBL/kg).

RESULTS

The final study population included 74 patients. Median age was 14.8 years (SD = 2.2). After adjustment for other putative prognostic factors via multivariable linear regression, coagulative function as determined preoperatively by CloFAL Coagulation Index was an independent predictor of intraoperative (EBL)/kg. Specifically, each 10% increase in CloFAL CI was associated with 3% decrease in the geometric mean of EBL/kg (OR 0.97, 95%CI 0.94-0.99, P = .01).

CONCLUSION

In adolescents undergoing posterior spinal fusion for idiopathic scoliosis, increased coagulative function measured preoperatively using the CloFAL assay is independently associated with decreased intraoperative blood loss. Future studies should expand upon these investigations of plasma coagulative and fibrinolytic capacities in combination with clinical factors, to guide precise preventive strategies against blood loss and blood transfusion in this patient population.

Effect of the Ultrasonic Bone Scalpel on Blood Loss During Pediatric Spinal Deformity Correction Surgery

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

Determine the effect of the ultrasonic bone scalpel (UBS) on intraoperative blood loss and surgical time.

SUMMARY OF BACKGROUND DATA

The UBS has shown beneficial effects in limiting blood loss in spinal surgery, but no study has examined its effect in patients with neuromuscular scoliosis.

METHODS

Clinical records were reviewed for patients aged 9-18 who underwent posterior spinal fusion surgery of five or more levels for scoliosis correction by the senior author from April 2013 until October 2016. Exclusion criteria included: vertebral column resections, previous spinal surgery, cell saver usage, cases complicated by signal loss on monitoring, and incomplete medical records. A total of 84 patients met the criteria and were included in data analysis. The UBS was routinely used for performing osteotomies and facetectomies for all cases operated after March 2015. These cases were compared to a control group who underwent surgery prior to this date in which the UBS was not used. The experimental and control groups were further divided into adolescent idiopathic (AIS) and neuromuscular (NMS) subgroups.

RESULTS

EBL in AIS patients decreased from 1,211 mL in the control group to 771 mL in the UBS group for an average total reduction of 440 mL (95% CI 106, 774, p = .01). In NMS patients, EBL fell from 2,171 mL in controls to 1228 mL in the study group for an average total reduction of 943 mL (95% CI 288, 1598, p < .01). On controlling for weight and number of levels fused, blood loss decreased 26.2% in AIS patients and 46.2% in NMS patients.

CONCLUSIONS

The ultrasonic bone scalpel is effective in reducing blood loss in AIS and NMS deformity correction surgery. Surgical time is not adversely affected by its use.

LEVEL OF EVIDENCE

Level II, cohort study.

Use of a novel corrective device for correction of deformities in adolescent idiopathic scoliosis

BACKGROUND

Adolescent idiopathic scoliosis (AIS), with an incidence of 3%, is a common deformity. Correction of severe curvature of the deformity has attracted much investigation to achieve safe, reproducible results. We present our experience with a novel device for the correction of deformities across a spectrum of curve types, the rod link reducer. This system allows direct visualization of a mass derotation to achieve deformity correction.

METHODS

Prospective cohort study of patients with severe AIS treated in our institution during 2017 with major TL/L curves. Pre- and postoperative Cobb angles and coronal balance; operative time; and estimated blood loss, fusion levels, and screw density were recorded. Our results were split between those with a Lenke A/B classification and Lenke C, with a goal of correction of curve in the former and achieving good coronal balance with a preservation of distal motion segments in the latter.

RESULTS

There were 31 patients enrolled in our series. Within the Lenke A/B group, there were 18 patients, achieving a mean correction of 56% (SD 10%) and a correction of a mean coronal balance of 14.5 mm (SD 12.5 mm) of C7 from the CSVL to 10.9 mm (SD 10.6 mm). Our screw density was 1.3 screws (SD 0.1) per vertebrae fused. Our operative time was 185 min (SD 38 min). Average recorded blood loss was 721 ml (SD 289). In our Lenke C cohort, preoperative and postoperative mean Cobb angles (SD) were 73.3 (13.4) and 33.8 (11.9), respectively, with an average correction of 54% (SD 11%). The mean (SD) operative time was 03:35 (SD 00:35). Fusion levels were over a mean of 12.1 (SD 1.7) vertebrae, with a screw density of 1.3 (SD 0.1) per level. Mean intraoperative blood loss was 829 ml (SD 355). No patient received an allogenic blood transfusion. There were no adverse neurological events in this patient cohort.

CONCLUSIONS

The link rod system allows for excellent correction of spinal deformity and a short operative time.

Thoracic Lordosis, Especially in Males, Increases Blood Loss in Adolescent Idiopathic Scoliosis

BACKGROUND

Intraoperative blood loss during posterior spinal fusion for adolescent idiopathic scoliosis (AIS) has been reportedly associated with multiple factors. This study aims to investigate the effect of thoracic kyphosis on blood loss in AIS spinal fusion.

METHODS

Patients with AIS who underwent posterior-only procedures for Lenke I and II type curves were identified. All included patients had intraoperative tranexamic acid. Difference in estimated blood loss per blood volume (EBL/BV) was identified between hypokyphotic curves (-), normal curves (N), and hyperkyphotic curves (+) classified based on Lenke sagittal modifier. Regression analysis was then performed with EBL/BV as dependent variable. Independent variables included radiographically measured T5-T12 kyphosis and calculated 3D T5-T12 kyphosis in addition to sex, body mass index (BMI), operative time, number of fused vertebrae, number of Ponte osteotomy levels, and main thoracic coronal curve.

RESULTS

In total, 837 patients were included. For female patients: EBL/BV was significantly higher for (-) (18%) compared with (N) (16%) and (+) (14%). A total of 29 female patients had T5-T12≤0 (-15 to 0 degree). EBL/BV was not significantly higher than patients with T5-T12>0 degree (18%±9% vs. 16%±11%; P=0.212). For male patients: EBL/BV was significantly higher in (-) (23%) compared with (+) (16%). In total, 14 male patients had T5-T12≤0 (-13 to 0) degree. EBL/BV was significantly higher than patients with T5-T12>0 degree (32%±18% vs. 18%±13%; P=0.015). Significant factors in predicting EBL/BV were sex, BMI, number of fused levels, and both 2D and 3D T5-T12 kyphosis. Male sex as well as every fused-level predicted an increase in EBL/BV~2%. Every 10-unit decrease in BMI predicted an increase in EBL/BV of 7%. Every 10-degree decrease in 2D or 3D T5-T12 kyphosis predicted an increase in EBL/BV~1%. The impact of the number of Ponte osteotomy levels was not significant.

CONCLUSIONS

This study supports the role of sagittal thoracic alignment in affecting EBL/BV in AIS surgery. Male patients with severe thoracic lordosis (T5-T12≤0 degree) are the highest risk group for intraoperative bleeding. These findings are helpful in predicting the intraoperative blood loss for patients with AIS undergoing posterior spinal fusion. In addition to sex and number of fused levels, decreased thoracic kyphosis is associated with increased blood loss.

LEVEL OF EVIDENCE

Level III-prognostic study.

COMPARISON OF IMPLANT DENSITY IN THE MANAGEMENT OF LENKE 1B AND 1C ADOLESCENT IDIOPATHIC SCOLIOSIS

Objective:

To compare radiographic and surgical outcomes of Lenke 1B and 1C patterns.

Methods:

One hundred twenty patients with Lenke 1B and 1C scoliosis were grouped according to implant density as follows: low density (LD) of ≤1.4 and high density (HD) of >1.4. Matched subgroups (30 patients each) based on age, curve magnitude, and body mass index (BMI) were analyzed. Radiographic parameters were evaluated before operation, immediately after operation (ipo), and at 2 years’ follow-up. SRS-30 was administered before operation and at 2 years’ follow-up.

Results:

The major curves of the LD (n = 82) and HD groups (n=38) were respectively 59.1° and 65.6° before operation (p <.001), 26.3° and 22.9° ipo (p =.05), and 29.9° and 19.8° at 2 years’ follow-up (p <.001). No significant differences in postoperative trunk shift and coronal balance were found (p =.69 and p =.74, respectively). The HD group had higher blood loss (p =.02), number of implants (p <.001), levels fused (p =.002), and surgical time (p <.001). The HD group had a higher prevalence of hypokyphosis from before operation to follow-up (p <.001). No significant differences were observed in the SRS-30 scores before operation and at 2 years’ follow-up. The matched groups had similar preoperative major curves (p =.56), ages (p =.75), and BMIs (p =.61). Significantly longer surgical time (p =.009), higher density (p <.001), and better correction (p =.0001) were found in the HD group at 2 years’ follow-up. No significant differences were found in the SRS-30 scores before operation and at 2 years’ follow-up.

Conclusion:

LD constructs included fewer segments fused, lower intraoperative estimated surgical blood loss, and shorter operation time, and potentially decreasing complication risks due to fewer implants. Level of evidence III, Retrospective Cohort Study.

Preoperative Mechanical Bowel Evacuation Reduces Intraoperative Bleeding and Operation Time in Spinal Surgery

Study Design

Randomized clinical trial.

Purpose

In this study, we evaluated the effect of mechanical evacuation of the bowels prior to operation on intraoperative bleeding.

Overview of Literature

Bleeding is the most significant complication in patients undergoing spinal surgery.

Methods

We randomly divided 108 individuals planned to undergo spinal surgery into two age-, sex-, and co-morbidity (especially preoperative hemoglobin [Hb])-matched groups of 54. The treatment group was administered polyethylene glycol (PEG) before the operation, whereas the control group was not. The exact amount (mL) of bleeding during operation, operative time, and approximate amount of blood transfused were recorded. The volume of bleeding and Hb level were also recorded 24 and 48 hours postoperatively.

Results

T-tests revealed that intraoperative bleeding, the volume of transfusion, and operative time were significantly lower in the treatment group than in the control group. Statistically significant correlations of intraoperative bleeding with age, body mass index (BMI), preoperative Hb levels, operative time, the volume of transfusion, hospitalization time, and 24- and 48-hour postoperative bleeding were observed (p =0.001, all). Repeated measures analysis of covariance after adjusting the covariate variables revealed that the volume of bleeding showed a near-significant trend in the treatment group compared with that in the control group (p =0.056). Diabetic females had the highest bleeding amount between the groups (p =0.03). Bleeding was higher in patients with higher BMI (p =0.02) and was related to operative time (p =0.001) in both the groups.

Conclusions

Preoperative gastrointestinal tract evacuation by PEG administration can decrease intraoperative bleeding in spinal surgeries; however, more research is imperative regarding PEG administration in surgical procedures for this purpose.

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

Corrective surgery with a posterior approach for adolescent idiopathic scoliosis (AIS) is often accompanied by considerable bleeding. Massive transfusion after excessive hemorrhage is associated with complications such as hypothermia, coagulopathy, and acid-base imbalance. Therefore, prediction and prevention of massive transfusion are necessary to improve the clinical outcome of AIS patients. We aimed to identify the factors associated with massive transfusion in AIS patients undergoing corrective surgery. We also evaluated the clinical outcomes after massive transfusion.We included and analyzed AIS patients who underwent corrective surgery with a posterior approach from January 2008 to February 2015. We retrospectively reviewed the electronic medical records of 765 consecutive patients. We performed multivariable logistic regression analysis to assess the factors related to massive transfusion. Furthermore, we compared the effects of massive transfusion on clinical outcomes, including postoperative morbidity and hospital stay.Of 765 patients, 74 (9.7%) received massive transfusion. Body mass index (odds ratio [OR] 0.782, 95% confidence interval [CI] 0.691-0.885, P < .001) and the number of fused vertebrae (OR 1.322, 95% CI 1.027-1.703, P = .03) were associated with massive transfusion. In the comparison among the different Lenke curve types, Lenke type 4 showed the highest prevalence of massive transfusion. Patients in the massive transfusion group showed a higher incidence rate of postoperative morbidity and prolonged hospital stay.Massive transfusion was required in 9.7% of AIS patients who underwent corrective surgery with a posterior approach. A lower body mass index and higher number of fused vertebrae were associated with massive transfusion. Massive transfusion is related to poor clinical outcomes in AIS patients.

Acute Kidney Injury Secondary to Cell Saver in Posterior Spinal Fusion

BACKGROUND

Autologous blood transfusion, commonly referred to as cell saver, is frequently used in spinal fusion to salvage red blood cells because of the risk of significant intraoperative blood loss. This case report describes a case of acute kidney injury (AKI) secondary to cell saver use. Our objective is to increase the knowledge about the process of red blood cell salvage and this exceedingly rare complication.

METHODS

Chart and renal biopsy results for a single case were reviewed and reported in this retrospective study.

RESULTS

A healthy 18-year-old male patient underwent posterior spinal instrumentation and fusion for adolescent idiopathic scoliosis with utilization of intraoperative autologous blood transfusion. The patient subsequently developed hematuria and AKI with a peak creatinine of 13.9 mg/dL. An extensive clinical workup, including autoimmune serology, excluded any identifying causes. A renal biopsy showed pigment-induced acute tubular necrosis.

CONCLUSIONS

This case, to our knowledge, is the first and only case report of AKI secondary to cell saver demonstrated by renal biopsy. The literature has shown both the benefit of cell saver by decreasing the need for allogeneic transfusion and the risk of transient hematuria. However, this case demonstrates the importance of monitoring patients for potential complications.

When Does Intraoperative Blood Loss Occur During Pediatric Scoliosis Correction?

BACKGROUND

The purpose of our study was to assess the relationship between amount of blood loss and surgical stage in pediatric patients undergoing posterior spinal fusion for deformity correction to determine: (1) when the highest rate of blood loss occurred; (2) what percentage of total blood loss occurred during deformity correction and closure; and (3) how to predict remaining blood loss during a procedure. Blood loss following exposure and placement of the final pedicle screw is often underestimated, which may result in lack of sufficient blood product availability. Knowledge of the rate of blood loss plays an important role in intraoperative decision making, facilitating communication with the anesthesia team, and improving patient safety.

METHODS

Clinical records were reviewed for all patients 9 to 18 years of age who underwent index spinal fusion surgery with pedicle screw constructs for deformity correction of greater than 4 levels by a single surgeon from April 2013 to July 2015. All patients received tranexamic acid prophylactically. Exclusion criteria included vertebral column resections, cell saver use, cases complicated by signal loss on monitoring, and incomplete records. Sixty-two of 99 patients met criteria and were included in data analysis. The surgery was divided into four stages: exposure, screw/anchor placement, corrective procedures (reduction, osteotomies), and closure. Normalized blood loss (NBL) was calculated by adjusting actual blood loss for patient weight and number of levels fused. Demographic factors of age, sex, weight/BMI, diagnosis, preoperative Cobb angle, and number of levels fused were accounted for and autoregressive moving average was used to assess whether NBL varied significantly at different stages of the procedure.

RESULTS

NBL during reduction and closure (1.69) was significantly greater than NBL during exposure and screw placement (1.49) (p < .040). The rate of blood loss was also highest during reduction/deformity correction procedures than exposure (p < .001), anchor placement (p = .010), and closure (p < .010). At the time of placement of the final pedicle screw, 47% of the total blood loss for the case had occurred.

CONCLUSIONS

Rate of blood loss varies during pediatric posterior spinal deformity correction surgery, with the highest rates occurring during the reduction portion of the operation. Just over half of the total EBL occurs during the reduction and closure stages of surgery requiring the surgical team to plan accordingly. Additional studies investigating modifiable factors affecting blood loss during the later stages of scoliosis surgery are warranted.

The efficacy and safety of using a bipolar sealer to prevent blood loss in spine surgery: A meta-analysis

OBJECTIVE

The purpose of this systematic review and meta-analysis of randomized controlled trials (RCTs) and non-RCTs was to evaluate the effect of using a bipolar sealer to prevent surgical bleeding in spine surgery.

METHODS

In June 2017, the PubMed, Embase, Cochrane controlled trials register, Web of Science, Google, and Chinese Wanfang databases were used to identify RCTs and non-RCTs comparing the effects of intraoperative placement of a bipolar sealer versus standard electrocautery with regard to blood loss and blood transfusion. Stata 12.0 software was used to perform the meta-analysis. Weighted mean differences with 95% confidential intervals (CIs) were used for continuous outcomes, and relative risks with 95% CIs were used for discontinuous outcomes. After testing for publication bias and heterogeneity across studies, the data were aggregated and assessed with a random effects model when necessary.

RESULTS

In total, 6 clinical trials with 560 patients were included in this meta-analysis. The pooled results indicated that the use of a bipolar sealer decreased the estimated blood loss (MD = -165.06, 95% CI -236.73 to -93.40, P < 0.001), the need for a blood transfusion (RR = 0.46, 95% CI 0.31 to 0.68, P < 0.001), the transfusion units used (MD = -0.41, 95% CI -0.60 to -0.21, P < 0.001), the operative time (MD = -12.98, 95% CI -21.82 to -4.15, P = 0.004) and the length of hospital stay (MD = -2.77, 95% CI -5.45 to -0.10, P = 0.042). No significant difference was observed for the occurrence of infection (RR = 0.52, 95% CI 0.19 to 1.39, P = 0.192).

CONCLUSION

Based on the current meta-analysis, the use of a bipolar sealer is superior to standard electrocautery for reducing intraoperative blood loss and is therefore recommend for use during spine surgery.

Incidence, influencing factors, and prognostic impact of intraoperative massive blood loss in adolescents with neuromuscular scoliosis: A STROBE-compliant retrospective observational analysis

Factors influencing massive blood loss for neuromuscular scoliosis (NMS) patients.Despite advances in surgical and anesthetic techniques, scoliosis surgery is still associated with intraoperative massive blood loss, which can result in postoperative mortality and morbidity. The aim of this study was to assess the incidence, influencing factors, and prognostic impact of intraoperative massive blood loss in adolescents with NMS.A retrospective review of adolescents who underwent posterior spinal instrumentation and fusion for NMS was performed. Perioperative variables and data were recorded. Massive blood loss was defined as an estimated blood loss that exceeds 30% of total blood volume.We obtained data for 114 patients, of whom 63 (55%) had intraoperative massive blood loss. Compared with those without, patients with massive blood loss were more likely to be older, have lower body mass indexes (BMIs), larger Cobb angles, more fused levels, more osteotomy procedures, and prolonged duration of operation. Logistic regression analysis identified the number of fused levels to be more than 12 (P = 0.003, odds ratio = 6.614, 95% confidence interval [CI]: 1.891-23.131), BMI lower than 16.8 kg/m (P = 0.025, odds ratio = 3.293, 95% CI: 1.159-9.357), age greater than 15 years (P = 0.014, odds ratio = 3.505, 95% CI: 1.259-9.761), and duration of operation longer than 4.4 hours (P = 0.016, odds ratio = 3.746, 95% CI: 1.428-9.822) as influencing factors. Patients with massive blood loss are associated with more intraoperative colloids infusion and blood transfusions (red blood cell and fresh frozen plasma), as well as postoperative drainage volume.In adolescents with NMS who underwent posterior spinal instrumentation and fusion operations, intraoperative massive blood loss is common. The number of fused levels, BMI, age, and duration of operation are factors influencing intraoperative massive blood loss.

Does a dual attending surgeon strategy confer additional benefit for posterior selective thoracic fusion in Lenke 1 and 2 adolescent idiopathic scoliosis (AIS)? A prospective propensity matching score analysis

BACKGROUND CONTEXT

With an increased cost of adolescent idiopathic scoliosis (AIS) surgery over the past 10 years, improvement of patient safety and optimization of the surgical management of AIS has become an important need. A dual attending surgeon strategy resulted in reduction of blood loss and complication rate.

PURPOSE

This study aimed to investigate the perioperative outcome of posterior selective thoracic fusion in Lenke 1 and 2 AIS patients comparing a single versus a dual attending surgeon strategy.

STUDY DESIGN

A prospective cohort study was carried out.

PATIENT SAMPLE

The study sample comprised 60 patients OUTCOME MEASURE: Operative duration, blood loss, postoperative hemoglobin, need for transfusion, morphine usage, and duration of hospital stay were the outcome measures.

METHODS

A total of 116 patients who underwent posterior selective thoracic fusion from two centers were prospectively recruited. The patients were grouped into Group 1 (single surgeon) and Group 2 (two surgeons). One-to-one matching analysis using "propensity score-matched cohort patient sampling method" was done for age, gender, height, weight, preoperative Cobb angle, number of fusion level, and Lenke classification. The outcome measures included operative duration, blood loss, postoperative hemoglobin, need for transfusion, morphine usage, and duration of hospital stay. This study was self-funded with no conflict of interest.

RESULTS

From 86 patients who were operated by the two surgeons (Group 2), 30 patients were matched with 30 patients who were operated by a single surgeon (Group 1). Group 2 (164.0±25.7 min) has a significantly shorter operation duration (p=.000) compared with Group 1 (257.3±51.4 min). The total blood loss was significantly more (p=.009) in Group 1 (1254.7±521.5 mL) compared with Group 2 (893.7±518.4 mL). There were seven patients (23.3%) in Group 1 who received allogenic blood transfusion (p<.05). The morphine usage and average hospital stay were significantly lower in Group 2, 22.4±10.7 mg and 3.4±0.7 days, respectively (p<.05). In Group 1, there was one patient who developed a superficial wound infection. No other major complications were noted.

CONCLUSIONS

A dual attending surgeon strategy was superior to a single surgeon strategy in posterior selective thoracic fusion in Lenke 1 and 2 AIS patients and will lead to a faster operation, reduced intraoperative blood loss, reduced risk of allogenic transfusion, reduced morphine requirement, and shorter hospital stay.

One-step (standard) versus two-step surgical approach in adolescent idiopathic scoliosis posterior spinal fusion: Which is better?

STUDY DESIGN

A retrospective cohort study with IRB approval.

INTRODUCTION

Significant blood loss remains an important concern in terms of the performance of the posterior spinal fusion in adolescent idiopathic scoliosis. Several strategies have been reported to minimize blood loss during surgery. In order to address the need to minimize blood loss without sacrificing the quality of the fusion, in our hospital, we adopted a two-step surgical approach. This surgical approach consist of the exposure and instrumentation of the lumbar region prior to and followed by an extension of the surgical incision to the thoracic region for its subsequent instrumentation. The main purpose of this study was to compare a two-step surgical approach with the one-step (standard) approach.

METHODS

This study was a review of all the data on consecutive posterior spinal fusion surgeries performed by a specific two-surgeon team during 2004-2013. Demographics, surgical variables, radiographic findings, and outcomes regarding blood loss, morbidity, and the duration of the procedure were evaluated.

RESULTS

Eighty-five patients underwent the standard surgical exposure, and 41 patients underwent the two-step surgical technique. With the exception of BMI, neither group showed any statistically preoperative variable significant differences. None of the postoperative outcome variables were statistically significant between both surgical approaches.

CONCLUSIONS

No differences were detected in terms of using a two-step surgical approach versus the one-step standard surgical approach regarding perioperative blood loss, surgical time, or complications.

LEVEL OF EVIDENCE

Level of evidence III.

Assessing the Rates, Predictors, and Complications of Blood Transfusion Volume in Posterior Arthrodesis for Adolescent Idiopathic Scoliosis

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To determine predictors of and 30-day complications associated with blood transfusion volume after posterior spinal fusion for adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

Posterior arthrodesis is a common procedure performed for AIS, and patients frequently require perioperative blood transfusions. Few studies, however, have examined the rates and potential complications associated with blood transfusion volume.

METHODS

Patients undergoing posterior arthrodesis for AIS were selected from the National Surgical Quality Improvement Program pediatric database from 2012 to 2013. Patients were stratified on the basis of blood transfusion volume and patient demographics and comorbidities, operative characteristics, and 30-day complications were recorded. Multivariate analyses were performed to determine predictors of transfusion as well as the effect of transfusion volume on 30-day complication rates.

RESULTS

A total of 1691 patients were included. Male sex (P = 0.010), esophageal or gastrointestinal disease (P = 0.016), cardiac risk factors (P = 0.037), preoperative inotrope requirement (P = 0.031), total operative time of 300 minutes or more (P < 0.001), and posterior arthrodesis of 13 or more vertebral segments (P < 0.001) were independent risk factors for requiring blood transfusion. Total transfusion volume of 20 mL/kg or more was the minimum volume independently associated with increased rates of total complications (P = 0.018), with a complication rate of 5.9%.

CONCLUSION

We present the first large, comprehensive analysis of complications related to blood transfusion events and transfusion volume on short-term postoperative complications after posterior arthrodesis for AIS. Although transfusion in general is not associated with 30-day adverse events, a volume of 20 mL/kg was associated with higher complication rates.

LEVEL OF EVIDENCE

4.

Smaller body size increases the percentage of blood volume lost during posterior spinal arthrodesis

BACKGROUND

Our goal was to analyze the relationship between patient size and the proportion of blood volume lost during spinal arthrodesis in patients with a diagnosis of adolescent idiopathic scoliosis, Scheuermann kyphosis, or cerebral palsy. We hypothesized that smaller patients (those with less blood volume) lose a greater proportion of circulating total blood volume during surgery.

METHODS

We reviewed a large, multicenter database, identifying patients with adolescent idiopathic scoliosis (1832), Scheuermann kyphosis (106), or cerebral palsy (196) who had undergone posterior spinal arthrodesis for spinal deformity. Blood volume (estimated from body weight) was used as a measure of patient size. Our primary outcome was the proportion of total circulating blood volume lost (intraoperative blood loss/blood volume, expressed as a percentage).

RESULTS

On multivariate analysis, there was a negative relationship between intraoperative blood loss/blood volume and blood volume in patients with adolescent idiopathic scoliosis (coefficient, -5.8; p < 0.001), Scheuermann kyphosis (coefficient, -2.5; p < 0.001), or cerebral palsy (coefficient, -20.3; p < 0.001), indicating that, despite adjustment for all other factors, smaller patients lost a greater proportion of their blood volume. In patients with adolescent idiopathic scoliosis or Scheuermann kyphosis, multivariate analysis showed that intraoperative blood loss/blood volume also increased significantly when the patient was male and with a greater number of levels fused.

CONCLUSIONS

There is an inverse relationship between the proportion of blood volume lost during deformity correction surgery and size in patients with adolescent idiopathic scoliosis, cerebral palsy, or Scheuermann kyphosis.

Blood Loss Reduction During Surgical Correction of Adolescent Idiopathic Scoliosis Utilizing an Ultrasonic Bone Scalpel

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVES

To evaluate blood loss associated with posterior spinal fusion in adolescent idiopathic scoliosis patients performed with and without the use of an ultrasonic bone scalpel (UBS).

SUMMARY OF BACKGROUND INFORMATION

After using an ultrasonic-powered bone-cutting device with recent Food and Drug Administration approval for use in the spine, the authors perceived a reduction in bone bleeding associated with the cut boney surfaces.

METHODS

The first 20 patients with adolescent idiopathic scoliosis who underwent posterior spinal fusion using the UBS by a single surgeon were compared with 2 control groups: 1) the 20 most recent prior cases of the same surgeon before beginning use of the bone scalpel; and 2) 20 cases of the same surgeon before using the bone scalpel matched based on Cobb angle magnitudes. Both cases and controls had Ponte-type posterior apical releases; none had an anterior procedure. Patient demographic and surgical data were analyzed using analysis of variance (p < .05).

RESULTS

Preoperatively, the UBS group was similar to both control groups in terms of primary and secondary curve magnitudes, number of levels fused, number of levels with Ponte release, antifibrinolytic use, and patient age (p > .05). The UBS group had significantly less estimated blood loss (EBL) (550 ± 359 mL), Cell Saver blood transfused (94 ± 146 mL), and EBL per level fused (48 ± 30 mL) than the most recent controls (EBL: 799 ± 376 mL; Cell Saver: 184 ± 122 mL; EBL/level fused: 72 ± 28 mL) and Cobb-matched controls (EBL: 886 ± 383 mL; Cell Saver: 198 ± 115 mL; EBL/level fused: 78 ± 30 mL) (p < .05). Surgical times were equivalent and there were no dural tears in any group.

CONCLUSIONS

The use of an ultrasonic bone scalpel to perform the bone cuts associated with facetectomies and apical Ponte-type posterior releases resulted in significantly less bleeding compared with cuts made with standard osteotomes and rongeurs, limiting overall blood loss by 30% to 40%.