title: Validity of Estimates of Intraoperative Blood Loss in Pediatric Spinal Deformity Surgery.
abstract: BACKGROUND
  Intraoperative blood loss is a significant concern in pediatric spinal deformity surgery, and numerous reports exist in the literature regarding this issue. Multiple interventions are used to minimize intraoperative blood loss and subsequent need for blood product replacement during and after these procedures. However, a basic question remains regarding the overall accuracy of intraoperative blood loss measurements used to generate these studies.
  
  
  METHODS
  We performed an institutional review board-approved study that compared estimated blood loss (EBL) by the anesthesia provider and surgeon after the completion of surgery for pediatric spinal deformity by a single surgeon. We used the estimate by the anesthesia provider that was to be part of the anesthesia record. The surgeon's estimate was generated based on a formula employing the volume of blood products processed by a Cell-Saver device and available for reinfusion.
  
  
  RESULTS
  We collected data from 51 patients. The mean EBL (surgeon) was 795.84 mL and mean EBL (anesthesia) was 669.30 mL. The mean percent estimated blood volume loss (%EBVL) (surgeon) was 22.9% and mean %EBVL (anesthesia) was 19.8%. Student t-test analysis demonstrated statistical significance between both sets of values (EBL, p = .010; %EBVL, p = .010).
  
  
  CONCLUSIONS
  There was a statistically significant difference in EBL values for this patient sample between the anesthesiologist and orthopedic surgeon; the surgeon's estimates were significantly higher. This difference may be important in interpreting existing studies regarding interventions used to minimize surgical blood loss. In addition, this lack of agreement highlights the need for authors to be more accurate and consistent regarding the source of blood loss data in future clinical studies.
authors.affiliation: Department of Orthopaedic Surgery, Medical University of South Carolina, 96 Jonathan Lucas Street, CSB 708, Charleston, SC 29425, USA. Electronic address: mooneyj@musc.edu.
authors.forename: James F
authors.initials: JF
authors.lastname: Mooney
authors.affiliation: Department of Orthopaedic Surgery, Medical University of South Carolina, 96 Jonathan Lucas Street, CSB 708, Charleston, SC 29425, USA; Department of Health and Human Performance, The College of Charleston, Charleston, SC 29424, USA.
authors.forename: William R
authors.initials: WR
authors.lastname: Barfield
keywords: Blood loss measurement; Scoliosis; Surgery