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Intraoperative Estimated Blood Loss is Unreliable in Fronto-orbital Advancement for Craniosynostosis
Mitchel Seruya, MD1, Albert K. Oh, MD2, Kevin D. Han, MD3, Michael J. Boyajian, MD2, Robert F. Keating, MD2.
1Georgetown University, Washington, DC, USA, 2Children's National Medical Center, Washington, DC, USA, 3George Washington University, Washington, DC, USA.
Introduction: Intraoperative blood loss represents a significant source of morbidity associated with fronto-orbital advancement (FOA) and its measurement remains a serious challenge. This study analyzed the relationship between estimated blood loss (EBL) and calculated blood loss (CBL) and assessed patient demographics and intraoperative factors as predictors of hemodynamic outcomes during FOA.
Methods: The authors reviewed all infants with craniosynostosis who underwent FOA at a single institution from 1997 - 2009. Patient demographics, operative time, and serial measurements of mean arterial pressure (MAP) were recorded. EBL was based upon anesthesia records, while CBL was determined by pre/post-operative hemoglobin values in concert with intraoperative transfusion volumes. Bland-Altman analysis and simple/multiple linear and logistic regression models were used to evaluate the relationships between these metrics.
Results: 90 infants underwent FOA with mean age and weight at repair of 10.7 months and 9.0 kg, respectively. Mean operative time was 4.2 hrs and average intraoperative MAP was maintained at 56.1 mmHg, 22.6% lower than preoperative baseline. Mean EBL was 42.2% of estimated blood volume (% EBV) and CBL was 39.3% EBV. Bland-Altman analysis revealed that EBL was greater than CBL at lower levels of blood loss and lesser than CBL at higher levels of blood loss (Figure). Younger patients and increased operative time correlated with higher EBL and CBL (p< 0.001 and p < 0.05, respectively). Mean hospital length of stay (LOS) was 3.7 days with greater LOS correlating with CBL (hazard ratio of discharge = 0.988, p < 0.01), total blood transfusion (hazard ratio of discharge = 0.991, p < 0.05), and total intraoperative fluid requirements (hazard ratio of discharge = 0.999, p < 0.05).
Conclusion: During FOA for craniosynostosis, EBL overestimated CBL at lower levels of blood loss and underestimated CBL at higher levels of blood loss. Intraoperative blood loss positively correlated with operative time but negatively trended with surgical age. The results also show the benefit of reduced intraoperative blood loss on shorter hospital LOS. Overall, these findings highlight the need for reliable, real-time monitoring of intraoperative blood loss to accurately guide blood and fluid resuscitation.
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