No Difference Between Blood Preserving Strategies During Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis

Abstract

Background

There is conflicting evidence on whether normovolemic hemodilution is efficacious in reducing intraoperative blood loss and transfusions, and existing pediatric literature does not evaluate hemodilution in combination with antifibrinolytics. The purpose of our study was to compare patient outcomes with combined use of hemodilution and antifibrinolytics against antifibrinolytics alone in patients undergoing posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS).

Methods

Inclusion criteria were diagnosis of AIS and operative management with PSF. Patients with a history of bleeding disorders were excluded. Blood preservation strategies included antifibrinolytics with and without hemodilution. Descriptive statistics, independent t-tests, and paired t-tests were conducted using SPSS, with an α level of 0.05.

Results

The study included 65 patients (mean age: 14.7 ± 2.8 years, 73.8% female, mean body mass index: 21.7 ± 5.2, Cobb angle: 54.5 ± 14.5). All 65 patients received antifibrinolytics, and 39 of those patients underwent preoperative hemodilution as well. The hemodilution group had a significantly decreased use of cell saver. The hemodilution and antifibrinolytic group had a longer duration of procedure than the antifibrinolytic group. There were no significant differences in estimated blood loss or rate of transfusion. Additionally, there were no significant differences in the perioperative decrease of hemoglobin, hematocrit, or platelets between the two groups. No patients had postoperative infections, one patient required postoperative transfusion, and three patients eventually returned to the operating room.

Conclusions

This study is the first to compare the use of both hemodilution and antifibrinolytics to antifibrinolytics alone in PSF for AIS. Existing literature supports antifibrinolytics in PSF for AIS, but evidence for the addition of hemodilution is only convincing in adults. Our study suggests hemodilution does not provide additional benefit in preserving blood volume for pediatric patients when combined with antifibrinolytics.

Key Concepts

• (1) Evidence supporting addition of hemodilution during posterior spinal fusion (PSF) is only convincing in adults.

• (2) This is the first study to compare the use of both hemodilution and antifibrinolytics to antifibrinolytics alone in PSFs for adolescent idiopathic scoliosis.

• (3) Hemodilution does not provide additional benefit in preserving blood volume for pediatric patients when combined with antifibrinolytics.

Level of Evidence

III: case-control study

Introduction

Adolescent idiopathic scoliosis (AIS) is a common condition defined by an abnormal curvature of the spine in the coronal plane. Surgical stabilization using posterior arthrodesis and segmental instrumentation is indicated when the major curve magnitude approaches 50° [1]. There is a known risk of major blood loss requiring blood transfusion among patients undergoing this surgery [2]. Use of allogeneic or autologous blood transfusions is associated increased medical cost, hospital stay, rate of infection, lung injury, and sepsis [3,4].

Currently, there have been multiple techniques applied both preoperatively and intraoperatively to reduce acute blood loss during spinal fusion surgery which would decrease the need for blood transfusion. These methods are known in the literature and include use of intraoperative cell salvage, perioperative antifibrinolytic agents, and acute normovolemic hemodilution (ANH) [5]. Within orthopaedic surgery, the evaluation of the effects of using antifibrinolytics, specifically tranexamic acid (TXA), on reducing intraoperative blood loss has been well investigated. Multiple studies show that usage of TXA can reduce surgical time, intraoperative blood loss, and blood transfusion in those undergoing corrective surgery for AIS [[6], [7], [8]].

The effectiveness of ANH in combination with TXA in reducing intraoperative blood loss has yet to be studied in the pediatric population needing surgery for AIS correction. The objective of this study is to compare patient outcomes with combined use of hemodilution and TXA against TXA alone in pediatric patients undergoing posterior spinal fusion (PSF) for AIS. We hypothesized that the combined use of TXA and hemodilution would not be an added benefit to prevent intraoperative blood loss and decreased transfusion requirements.

Materials and methods

This study was an institutional review board–approved retrospective study of all pediatric patients who underwent PSF for AIS. Patients were identified using Current Procedural Terminology (CPT) codes 22842, 22843, and 22848 for posterior segmental instrumentation including multiple segments of fusion from 10/1/2015 to 1/1/2024. Inclusion criteria were diagnosis of AIS and an age <18 years. Exclusion criteria were any patient with a history of a bleeding disorder.

Patient demographics such as age, sex, body mass index (BMI), and race were all collected. The major curve magnitude and the number of fused spinal segments were also recorded. The initial preoperative and postoperative hematologic labs were collected which included hemoglobin, hematocrit, platelets, prothrombin time, international normalized ratio, and activated partial thromboplastin time. Intraoperative values such as the estimated blood loss (EBL), duration of procedure, cell saver amount, and amount of blood transfusion (if needed) were collected. EBL was measured based on surgeon estimates, and only returned cell saver values were collected. Complication rates of infection and any return to ORs were collected. Patients were split into cohorts of either receiving just antifibrinolytics or receiving both antifibrinolytics and hemodilution as a blood preserving strategy. Patients were allocated to treatment cohorts based on surgeon preference regarding utilization of antifibrinolytics. There was no formal institutional protocol that assigned patients to specific cohorts during this study period. Hemodilution technique was standardized to take place after induction and before incision. 1 to 2 units of blood based on the patient’s weight was removed and replaced with crystalloid. The units were then returned after closure of fascia. Continuous variables were reported as a mean with a standard deviation, while categorical variables were reported as a number with a percentage. Descriptive statistics, independent t-tests, and paired t-tests were conducted using SPSS, with an α level of 0.05.

Results

This study included 65 patients (mean age: 14.7 ± 2.8 years, 73.8% female, mean BMI: 21.7 ± 5.2, Cobb angle: 54.5 ± 14.5). All 65 patients received antifibrinolytics, and 39 of those patients underwent preoperative hemodilution as well.

The hemodilution and antifibrinolytic group had significantly decreased use of cell saver (230.2 mL vs 328.4 mL, P = .026) (see Table 1). The hemodilution and antifibrinolytic group had a longer duration of procedure than the antifibrinolytic group (445.1 min vs 394.8 min, P = .043). There were no significant differences in EBL or intraoperative transfusion amount (P = .169, P = .902). Additionally, there were no significant differences in the perioperative decrease of hemoglobin, hematocrit, or platelets between the two groups (P = .100, P = .061, P = .271). No patients had postoperative infections, one patient required postoperative transfusion, and three patients eventually returned to operating room (Table 2).

Table 1.

Demographic and adolescent idiopathic scoliosis information.

	Total (n = 65)	Antifibrinolytics (n = 26)	Hemodilution and antifibrinolytics (n = 39)	P value
Age (years)	14.7 (2.8)	15.2 (3.2)	14.3 (2.3)	.214
Sex	73.8% F	65.4% F	79.5% F	.205
BMI	21.7 (5.2)	20.7 (4.1)	22.5 (5.9)	.182
Race	70.8% W	65.4% W	25.6% W	.066
Fused segments	11.4 (2.1)	10.9 (2.0)	11.7 (1.9)	.071
Cobb angle	54.5 (14.5)	56.0 (14.4)	53.6 (14.4)	.466

BMI, body mass index.

Table 2.

Postoperative hematologic changes and complications.

	Total	Antifibrinolytics	Hemodilution and antifibrinolytics	P value
	(n = 65)	(n = 26)	(n = 39)
Initial labs
Hb	10.7 (2.0)	11.2 (2.2)	10.4 (1.9)	.100
Hct	31.8 (6.4)	33.6 (6.5)	30.6 (6.2)	.061
Platelets	224.1 (67.6)	212.5 (52.7)	231.8 (75.3)	.271
PT	12.2 (1.1)	12.2 (0.9)	12.2 (1.2)	.892
INR	1.1 (0.1)	1.1 (0.1)	1.1 (0.1)	.649
aPTT	32.5 (3.3)	32.8 (3.8)	32.4 (3.1)	.664
Intraoperative labs
EBL		577.6 (397.7)	471.3 (216.7)	.169
Transfusion amount		410.9 (228.1)	445.1 (1643.4)	.902
Cell saver (mL)		328.4 (156.4)	230.2 (128.0)	.026∗
Duration of procedure (mins)		394.8 (93.0)	445.1 (98.7)	.043∗
Change of labs postoperatively
Hb		−1.5 (1.8)	−0.8 (1.5)	.131
Hct		−4.7 (5.8)	−1.7 (6.3)	.071
Platelets		−40.6 (45.9)	−23.3 (51.3)	.206
Postoperative complications
Infections		0	0
Transfusions		0%	0.1% (450 cc)
Return to operating room		0.04%	0.05%

P values are less than 0.05 and are significant.

aPTT, activated partial thromboplastin time; EBL, estimated blood loss; INR, international normalized ratio; PT, prothrombin time.

Discussion

AIS is a common condition among the pediatric orthopaedic population and when severe, necessitates surgical intervention to correct for spinal deformity. Blood loss during these major procedures may be significant enough to require transfusion, which carries risks including sepsis, immunologic cross reactions, blood borne infection, and increased hospital stay [9]. Many techniques such as antifibrinolytics, ANH, and intraoperative cell salvage are used in an effort to minimize blood loss [10].

Tranexamic acid (TXA) is a synthetic lysine-analog antifibrinolytic that inhibits activation of plasminogen, which effectively inhibits the degradation of fibrin clots [11]. In recent years, the use of TXA as a pharmacological approach to decrease intraoperative blood loss has been supported. It has been shown to help control blood loss in trauma surgery, total knee arthroplasties, spinal surgeries, and scoliosis correction surgery [[12], [13], [14], [15]]. In a systematic review and meta-analysis study, Alajmi et al. [16] showed that use of TXA significantly lowered blood loss and rates of transfusion in pediatric patients undergoing spinal fusion for idiopathic scoliosis surgery. In another systematic review and meta-analysis study, Yuan et al. [8] showed that high-dose TXA (>20 mg/kg) can decrease the total blood loss and intraoperative blood loss during scoliosis surgery.

ANH is a blood conservation technique that involves removing a predetermined amount of a patient’s blood prior to procedure, replacing it with fluid, and reinfusing the blood after surgery; by reducing the patient’s red cell mass immediately prior to surgery, ANH effectively reduces red cells lost during the procedure [17]. The addition of ANH to TXA as an effective method to control blood loss in recent studies has been only convincing in adult studies. In a retrospective observational study, Li et al. [18]. found that a combination of TXA and ANH may be the better choice to reduce blood loss for adult patients undergoing lumbar fusion surgery In a prospective cohort study by Batista et al. [19] that included adults and pediatric patients undergoing a variety of spine deformity surgery, there was no significant difference between TXA combined with ANH group and TXA-only group in terms of intraoperative bleeding and need for blood transfusion. Contrary to efficacy of TXA, the efficacy of using ANH alongside TXA in the pediatric population to reduce intraoperative blood loss during spinal fusion surgery for AIS remains to be fully characterized [20].

This study is the first of its kind to investigate the difference in patient outcomes between combined use of hemodilution and antifibrinolytics and antifibrinolytics alone in the pediatric population undergoing PSF for AIS specifically. Based on our results, hemodilution may not have any additional benefit during PSF compared to using TXA alone as a method for reducing blood loss. Cell saver amount returned was significantly lower in the antifibrinolytic and hemodilution group; this result is plausible as hemodilution reduces intraoperative red blood cell loss and therefore decreased reinfusion need. Although operative time was longer in the autologous hemodilution group, there is no clear mechanistic explanation for this finding as ANH is performed prior to incision and should not meaningfully prolong surgical duration. This difference in our study is likely attributable to case variability or unmeasured differences in surgical complexity that were difficult to interpret due to the retrospective nature of the study. The findings of our study should be used during the initial surgical planning phase when approaching different available options to consider for controlling blood loss during surgery for AIS.

Our study has several limitations. First, due to the single-center nature of this study, the sample size of this study is relatively small. Thus, the operative times and perioperative workflows of this institution may differ from other hospitals participating in national registries such as National Surgical Quality Improvement Program (NSQIP). While this may limit how generalizable the results are to other surgery centers, the internal comparison between groups within the same institution may prove meaningful. Further prospective studies done at various other institutions could be beneficial for future research. Second, this study was limited due to its retrospective nature. The information and data that were collected were limited to that being recorded for clinical purposes only. Third, hemodilution was only favored by one single orthopaedic surgeon at this single center facility, so it is difficult to assess if technique may have affected blood loss and operative time. We were unable to evaluate dissection and electrocautery protocols for blood loss. Numerous surgeon-specific factors including technical practices and performance are potential confounding factors that could have influenced our results. Additionally, variation in anesthesia technique could also contribute to the confounding factors that bias our results. Lastly, the selection process for cohort placement of each patient was surgeon preference and selection, which could result in significant selection bias. The modest sample size of our study and surgeon preference–based cohort may also limit the generalizability of the findings and highlight the need for larger multicenter studies. Regardless of these limitations, this is the first study to investigate if utilizing ANH alongside TXA in the pediatric population undergoing spinal fusion for AIS affects patient outcomes.

Conclusion

This study is the first to compare the use of both hemodilution and antifibrinolytics to antifibrinolytics alone in PSF for AIS. Existing literature supports antifibrinolytics in PSF for AIS, but evidence for the addition of hemodilution is only convincing in adults. Our study suggests hemodilution does not provide additional benefit in preserving blood volume for pediatric patients when combined with antifibrinolytics.

Additional links

• •AAOS Quality & Practice Resources: Intraoperative Blood Management Techniques
• •Journal of Postgraduate Medicine, Education and Research: Blood Conservation in Scoliosis Surgery
• •POSNAcademy: Posterior Spinal Instrumentation and Fusion for Treatment of Adolescent Idiopathic Scoliosis

Author contributions

Akshitha Adhiyaman: Writing – original draft, Data curation. Dorian Cohen: Methodology, Conceptualization. Elizabeth Wang: Writing – review & editing, Writing – original draft. James Barsi: Supervision, Conceptualization.

Ethics approval and consent

The author(s) declare that no patient consent was necessary as no images or identifying information are included in the article. IRB approval was obtained for retrospective collection of the data included in this manuscript.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Declaration of competing interests

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.