Among orthopedic surgeries, posterior spinal internal fixation and fusion for scoliosis causes the largest amount of trauma. It often requires the transfusion of allogeneic RMCs and plasma to correct anemia. Although the safety of blood products has greatly improved in recent years, blood transfusion-related complications still cannot be completely avoided [2, 10, 11]. More importantly, delays of surgeries due to inadequate blood supply has been an issue noted by Chinese doctors for many years.
As one of the important blood conservation methods, intraoperative autologous blood reinfusion has been widely used in orthopedic spinal surgery for more than 20 years, but its effectiveness and economic efficacy related to conserving blood is still controversial. A study by Owens et al with patients at an average age of 57.2 years showed that a cell saver system could not reduce intraoperative and postoperative blood usage during posterior spinal fusion surgery. A study by Kelly et al  demonstrated that a cell saver system had poor economic efficacy after studying 508 adult patients who underwent posterior spinal fusion. A study by Canan et al showed that the use of a cell saver system in single-segment lumbar decompression and fusion surgery for patients older than 18 years cannot reduce the need for allogeneic blood and is not economically efficient. The work by Akgul et al  showed poor results for the application of a cell saver system for scoliosis patients who were, 17 to 18 years old on average. Weiss et al and Michelet et al studied the application of cell saver systems in posterior spinal fusion for scoliosis in patients who, on average, were 13–14 years old and in 147 patients who were 15 ± 3 years old, respectively, and the results suggested poor effects of cell saver systems. However, other studies reported that cell saver system can reduce blood usage and is cost effective. A study with patients who, were approximately 15–16 years old showed that among patients undergoing posterior spinal fusion for scoliosis, the allogeneic blood transfusion rate could be reduced from 32.7–14.5% and the blood transfusion volume can be decreased from 0.58 U to 0.21 U for each patient through the application of a cell saver system; furthermore, the number of fused segments, preoperative low Hb and the use of a cell saver system predicted the requirement for a blood transfusion . A study with patients who were approximately 14 years old showed that a cell saver system could reduce blood usage in patients with pediatric idiopathic scoliosis, especially when the operation time was longer than 6 h and the blood loss volume was > 30% of the total blood volume .
A meta-analysis published by Cheriyan et al included 15 retrospective and three prospective studies, including a total of 2815 patients undergoing posterior spinal fusion, including patients with scoliosis. The conclusion was that cell saver systems can reduce intraoperative allogeneic RBC demand but cannot reduce the total volume of postoperative and perioperative blood transfusions and the proportion of patients requiring blood transfusion, but the economic efficiency of cell saver systems was difficult to evaluate. A systematic review of the efficacy of autologous blood reinfusions during surgery for scoliosis, which was published by Stone et al in 2017, included seven studies with patients who, on average, were 10–19 years old, and the conclusion was that cell saver systems reduced the blood usage. However, this paper only included one randomized controlled trial (RCT); the other six studies were retrospective, and the final level of evidence was only level 4.
Previously published studies on the application of intraoperative autologous blood reinfusion during the surgical treatment of scoliosis have mostly included adolescent patients who were 13–18 years old [3, 5, 7, 16]. To date, there have been no reports on school-age children between 7–12 years old. The purpose of this study was to investigate whether the application of intraoperative autologous blood reinfusion in school-age children can reduce the need for allogeneic RBCs and plasma and blood transfusion costs. Although this was a retrospective study, post hoc randomization of the control group and the cell saver group was conducted using propensity score matching with matched baseline indicators. Therefore, the results reported in study have increased reliability relative to those in previous studies with inconsistent baseline data[3, 5, 12, 14].
The results of this study suggested that there were no significant difference between the two groups in perioperative parameters, including intraoperative infusion volumes of crystalloid and colloid, urine output, duration of postoperative hospital stay, and Hb level before discharge. The cell saver group required a lower intraoperative allogeneic RBC transfusion volume (P = 0.021). The results of this study suggested that the cell saver system did not reduce the requirement for allogeneic RBCs during the entire perioperative period (P = 0.051). Considering that the test efficacy was a critical value and the included sample size was only 36 patients in each group, different statistical results might be obtained after expanding the sample size. In addition, although the cell saver system did not reduce the plasma infusion volume after surgery (P = 0.276), the allogeneic plasma requirement was reduced during surgery and throughout the perioperative period (P = 0.011, P = 0.018). These results suggest that, in general, the cell saver system did not reduce the allogeneic RBC and plasma infusion volumes at each stage of the perioperative period, did not reduce blood transfusion-related costs, but it reduced the intraoperative allogeneic RBCs requirement. These findings are still of positive significance to clinicians, potentially leading to a reduction in surgical delays due to insufficient blood stocks.
In this study, the mean intraoperative blood loss for pediatric patients was approximately 1344–1409 ml, while in previous studies [3, 5, 7, 12, 14, 16], the volume of intraoperative blood loss ranged from 400 to 800 ml, less than the blood loss observed in this study. This result may be due to the fact that the 306th Hospital of the People's Liberation Army is one of the first hospitals to perform orthopedic surgery for scoliosis in China and admitted some patients who were referred from other hospitals that did not have the technical capabilities to perform the treatment. Therefore, the disease condition was more severe in patients with scoliosis in this study than in other studies, resulting in more surgical trauma and blood loss. Weinstein et al suggested that 90% of scoliosis patients under 12 years of age had a Cobb angle < 40°. The ages of patients were mostly between 13 and 18 years old, and the preoperative average Cobb angle ranged from 55–68° in some previous studies [3, 5, 7]. This study included 72 pediatric patients with an average age of 10.11–10.93 years old and a body weight of approximately 33.69–34.18 kg. However, the average preoperative Cobb angle was approximately 70.58–75.53°, indicating that the age of patients included in this study was younger but the symptoms of scoliosis were more severe. With the increase in blood loss, the effects of autologous blood collection and reinfusion may decrease, which may be one of the reasons for the inconsistent clinical conclusions. However, the exact cause requires further study.
In summary, the results from this study suggested that during pedicle screw placement for posterior spinal fusion for scoliosis in school-age children, the application of autologous blood reinfusion using a cell saver system reduced the intraoperative allogeneic RBC transfusion volume and the requirement for allogeneic plasma during the entire perioperative period. However, the requirement for allogeneic RBCs was not reduced for the entire perioperative period, and the overall economic efficacy was poor. However this was a retrospective study, a well-designed large-sample RCT should be conducted for further investigation.