title: Blood loss estimation during fronto-orbital advancement:  implications for blood transfusion practice and hospital length of stay.
abstract: BACKGROUND
  Reliable measurement of intraoperative blood loss remains a serious challenge during correction of craniosynostosis. This study analyzed the relationship between estimated blood loss (EBL) and calculated blood loss (CBL) in fronto-orbital advancement and its implications on blood transfusion practice and hospital length of stay (LOS).
  
  
  METHODS
  The authors reviewed infants who underwent primary fronto-orbital advancement for craniosynostosis (1997-2009). Estimated blood loss was based on anesthesia records and CBL by preoperative/postoperative hemoglobin. Perioperative red blood cell transfusion (RCT) and hospital LOS were recorded.
  
  
  RESULTS
  Ninety infants were included. Mean EBL was 42.2% of estimated blood volume (% EBV), and CBL was 39.3% EBV, without significant difference (P = 0.23). Bland-Altman analysis revealed that EBL was greater than CBL at lower levels of blood loss (≤47.0% EBV) and less than CBL at higher levels (>47.0% EBV). Mean intraoperative RCT was 45.8% EBV; overtransfusion was more frequent at lower levels of bleeding, and undertransfusion at higher levels. Postoperative RCT occurred more frequently with greater blood loss. Mean LOS was 3.7 days, increasing with CBL (hazard ratio of discharge, HR(discharge) = 0.988, P < 0.01), postoperative RCT (HR(discharge) = 0.96, P < 0.05), total RCT (HR(discharge) = 0.991, P < 0.05), and total intraoperative fluid (HR(discharge) = 0.999, P < 0.05).
  
  
  CONCLUSIONS
  Estimated blood loss is a less accurate marker for CBL at the extremes of blood loss during fronto-orbital advancement. The tendency to overestimate blood loss with less intravascular volume loss can result in unnecessary transfusion, whereas underestimation with greater actual blood loss can lead to delay in resuscitation and longer hospitalization.
authors.affiliation: Department of Plastic Surgery at Georgetown University Hospital, Washington, District of Columbia, USA.
authors.forename: Mitchel
authors.initials: M
authors.lastname: Seruya
authors.forename: Albert K
authors.initials: AK
authors.lastname: Oh
authors.forename: Gary F
authors.initials: GF
authors.lastname: Rogers
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Han
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Boyajian
authors.forename: John S
authors.initials: JS
authors.lastname: Myseros
authors.forename: Amanda L
authors.initials: AL
authors.lastname: Yaun
authors.forename: Robert F
authors.initials: RF
authors.lastname: Keating
mesh_terms: D016063:Blood Loss, Surgical / Q000706:statistics & numerical data*; D016009:Chi-Square Distribution; D003398:Craniosynostoses / Q000601:surgery*; D017707:Erythrocyte Transfusion / Q000706:statistics & numerical data; D005260:Female; D005624:Frontal Bone / Q000601:surgery; D006439:Hemodynamics; D006801:Humans; D007223:Infant; D007902:Length of Stay / Q000706:statistics & numerical data; D016014:Linear Models; D008297:Male; D009915:Orbit / Q000601:surgery; D010027:Osteotomy / Q000379:methods; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D013577:Syndrome; D016896:Treatment Outcome