Rajat Verma

The pattern of blood loss in adolescent idiopathic scoliosis

BACKGROUND CONTEXT Previous studies have shown that modern intraoperative blood-saving techniques dramatically reduce the allogeneic transfusion requirements in surgery for adolescent idiopathic scoliosis (AIS). No studies have looked at the pattern of postoperative hemoglobin (Hb) in AIS patients undergoing corrective spinal surgery and correlated this with the timing of allogeneic transfusion. PURPOSE To describe the pattern of perioperative blood loss in instrumented surgery for AIS. We look at the recommendations regarding an ideal preoperative Hb, the need for preoperative cross-matching, and the timing of postoperative Hb analysis. STUDY DESIGN This was a retrospective case series. Surgeries were performed by one of four substantive pediatric spinal surgeons within a single regional center over a 3-year period. PATIENT SAMPLE A consecutive series of 86 patients who underwent posterior instrumented fusion for AIS were included: 10 males and 76 females. Mean age was 14 years (range 10-17 years). All patients had posterior instrumented fusion using various blood-saving techniques (eg, cell-saver). All patients were cross-matched preoperatively, and our transfusion trigger value (TTV) was 7 g/dL. OUTCOME MEASURES Hemoglobin level was the outcome measure. Hemoglobin readings were obtained preoperatively, within 2 hours of surgery, and daily up to 5 days after surgery. This physiologic measure was assessed using routine blood sampling techniques and standardized laboratory processing. METHODS Patient predictor variables (demographic and surgical) were assessed for association with Hb levels in a hierarchical model, with repeated Hb readings at the lower level being clustered within an individual patient at the upper level of the structure. The variation of Hb levels within individuals was compared with mean levels in different individuals via the variance partition coefficient of the model structure. RESULTS No patients required intraoperative allogeneic transfusion. Only four patients (4.65%) received allogeneic transfusion, all within 2 days of surgery. A clinically important drop in Hb occurred within the first 2 postoperative days, rising thereafter. The average postoperative drop in Hb was 4.1 g/dL. Young males had lower postoperative Hb values. Neither the preoperative curve magnitude (Cobb angle of major curve) nor the number of vertebrae/levels fused significantly affected the blood loss. CONCLUSIONS We recommend setting a minimum preoperative Hb value that is 5 g/dL higher than your TTV. Because no patients required an intraoperative transfusion when using modern blood-saving techniques, preoperative cross-matching is unnecessary and potentially wasteful of blood reserves. Hemoglobin analysis beyond the second postoperative day is unnecessary unless clinically indicated.

The safety, efficacy and cost-effectiveness of intraoperative cell-salvage in metastatic spine tumour surgery

BACKGROUND CONTEXT Metastatic spine tumor surgery (MSTS) is associated with substantial blood loss, therefore leading to high morbidity and mortality. Although intraoperative cell salvage with leukocyte depletion filter (IOCS-LDF) has been studied as an effective means of reducing blood loss in other surgical settings, including the spine, no study has yet analyzed the efficacy of reinfusion of salvaged blood in reducing the need for allogenic blood transfusion in patients who have had surgery for MSTS. PURPOSE This study aimed to analyze the efficacy, safety, and cost-effectiveness of using IOCS-LDF in MSTS. STUDY DESIGN This is a retrospective controlled study. PATIENT SAMPLE A total of 176 patients undergoing MSTS were included in the study. METHODS All patients undergoing MSTS at a single center between February 2010 and December 2014 were included in the study. The primary outcome measure was the use of autologous blood transfusion. Secondary outcome measures included hospital stay, survival time, complications, and procedural costs. The key predictor variable was whether IOCS-LDF was used during surgery. Logistic and linear regression analyses were conducted by controlling variables such as tumor type, number of diseased vertebrae, approach, number and site of stabilized segments, operation time, preoperative anemia, American Society of Anesthesiologists (ASA) grade, age, gender, and body mass index (BMI). No funding was obtained and there are no conflicts of interest to be declared. RESULTS Data included 63 cases (IOCS-LDF) and 113 controls (non-IOCS-LDF). Intraoperative cell salvage with LDF utilization was substantively and significantly associated with a lower likelihood of allogenic blood transfusion (OR=0.407, p=.03). Intraoperative cell salvage with LDF was cost neutral (p=.88). Average hospital stay was 3.76 days shorter among IOCS-LDF patients (p=.03). Patient survival and complication rates were comparable in both groups. CONCLUSIONS We have demonstrated that the use of IOCS-LDF in MSTS reduces the need for postoperative allogenic blood transfusion while maintaining satisfactory postoperative hemoglobin. We recommend routine use of IOCS-LDF in MSTS for its safety, efficacy, and potential cost benefit.

Change in spinal height following correction of adolescent idiopathic scoliosis

BACKGROUND CONTEXT Corrective surgery for adolescent idiopathic scoliosis (AIS) leads to vertical growth arrest of the instrumented spine. This might be offset by the immediate gain in spinal height (SH) as a result of correction of the curvature. PURPOSE This study aimed to identify predictors of gain in SH following corrective surgery for AIS. We present a unique model to predict postoperative height prior to intervention, which could contribute to the preoperative counseling and consenting process. STUDY DESIGN This was a retrospective case series. All surgeries were performed by one of four substantive pediatric spinal surgeons within a single regional center over a 3.5-year period. PATIENT SAMPLE There were 104 patients who had instrumented posterior spinal fusion for AIS included. There were 93 females, and the age range was from 11 to 17 years. All patients had posterior instrumented fusion using rods and anchors (pedicle screws±hooks). OUTCOME MEASURES Postoperative SH was the primary outcome measure. The SH (C7-L5) and Cobb angles were measured from a pre- and postoperative standing X-ray of each patient. METHODS Variables associated with patients (demographic and radiological) and the surgical constructs were analyzed for predictability of height gain. A model was derived including only significant predictors of substantive importance using hierarchical regression methods. Cross-validation procedures verified the adequacy of the model fit. Analysis was performed using IBM SPSS Statistics for Windows version 20.0 (IBM Corp. Armonk, NY, USA). RESULTS The major curve was thoracic in 90% of cases. The number of vertebrae fused ranged from 5 to 15. The average preoperative Cobb angle was 66°, with an average correction of 45°. The average change in SH was 4.66 cm (SD 2.13 cm). The model presented included preoperative height, preoperative Cobb angle, and number of vertebrae within the construct, with coefficients of 1.00 (95% CI: 0.90, 1.09), 0.067 (95% CI: 0.039, 0.095), and 0.26 (95% CI: 0.11, 0.41), respectively. This model had an adjusted-R(2) value of 0.83 and a R(2) for prediction of 0.79, and can be shown to have similar predictive capability as a model comprising a wider range of predictors. CONCLUSION The greatest postoperative height values following posterior spinal fusion for AIS could be expected from a patient with greater preoperative height and Cobb angle, and whose construct spans a large number of vertebrae.