title: Smaller body size increases the percentage of blood volume lost during posterior spinal arthrodesis.
abstract: 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.
authors: c/o Rachel Box, MS, ELS, Senior Editor, Editorial Services, Department of Orthopaedic Surgery, The Johns Hopkins University/Johns Hopkins Bayview Medical Center, 4940 Eastern Avenue, #A665, Baltimore, MD 21224-2780. E-mail address: rbox1@jhmi.edu.
authors: Amit
authors: A
authors: Jain
authors: c/o Rachel Box, MS, ELS, Senior Editor, Editorial Services, Department of Orthopaedic Surgery, The Johns Hopkins University/Johns Hopkins Bayview Medical Center, 4940 Eastern Avenue, #A665, Baltimore, MD 21224-2780. E-mail address: rbox1@jhmi.edu.
authors: Paul D
authors: PD
authors: Sponseller
authors: Department of Orthopedics, Rady Children's Hospital of San Diego, 3020 Children's Way MC 5062, San Diego, CA 92123.
authors: Peter O
authors: PO
authors: Newton
authors: Nemours/Alfred I. duPont Hospital for Children, 1600 Rockland Road, Wilmington, DE 19803.
authors: Suken A
authors: SA
authors: Shah
authors: Department of Orthopaedic Surgery, Shriners Hospitals for Children, Philadelphia, 3551 N. Broad Street, Philadelphia, PA 19140.
authors: Patrick J
authors: PJ
authors: Cahill
authors: c/o Rachel Box, MS, ELS, Senior Editor, Editorial Services, Department of Orthopaedic Surgery, The Johns Hopkins University/Johns Hopkins Bayview Medical Center, 4940 Eastern Avenue, #A665, Baltimore, MD 21224-2780. E-mail address: rbox1@jhmi.edu.
authors: Dolores B
authors: DB
authors: Njoku
authors: Institute for Spine and Scoliosis, 3100 Princeton Pike, Lawrenceville, New Jersey 08648.
authors: Randal R
authors: RR
authors: Betz
authors: Department of Orthopaedic Surgery, Shriners Hospitals for Children, Philadelphia, 3551 N. Broad Street, Philadelphia, PA 19140.
authors: Amer F
authors: AF
authors: Samdani
authors: Department of Orthopedics, Rady Children's Hospital of San Diego, 3020 Children's Way MC 5062, San Diego, CA 92123.
authors: Tracey P
authors: TP
authors: Bastrom
authors: Department of Orthopedics, Rady Children's Hospital of San Diego, 3020 Children's Way MC 5062, San Diego, CA 92123.
authors: Michelle C
authors: MC
authors: Marks
mesh_terms: D000293:Adolescent; D016063:Blood Loss, Surgical; D001810:Blood Volume; D049628:Body Size; D002547:Cerebral Palsy / Q000601:surgery*; D005260:Female; D006801:Humans; D007738:Kyphosis / Q000601:surgery*; D008297:Male; D012189:Retrospective Studies; D012600:Scoliosis / Q000601:surgery*; D013123:Spinal Fusion; D016896:Treatment Outcome