Hidden Blood Loss in Posterior Lumbar Fusion Surgery: An Analysis of Risk Factors.

STUDY

DESIGN

Descriptive study.

OBJECTIVES

This study aimed to evaluate the hidden blood loss (HBL) of patients who underwent lumbar fusion surgery for degenerative spine and to analyze its risk factors.

SUMMARY OF BACKGROUND DATA: When planning transfusion strategies, blood loss calculation is important. However, in clinical practice, spine surgeons usually ignore the possibility that a large amount of HBL may occur after lumbar fusion surgery.

MATERIALS AND

METHODS

We studied the patients who underwent posterior lumbar fusion (PLF) surgery for degenerative spine from 2014 to 2015 in one institution. The patient's demographics, comorbid conditions, coagulation panel value, surgical time, number of levels fused, American Society of Anesthesiologists (ASA) classification, cell saver, preoperative hematocrit level, preoperative hemoglobin level, and postoperative complications were collected retrospectively. Pearson correlation analyses were used to find an association between patient characteristics and HBL. Multivariate linear analysis was used to determine independent risk factors of HBL.

RESULTS

We reviewed 169 consecutive patients who underwent PLF surgery for degenerative spine in one institution. The mean amount of HBL was 588 mL, which was 39% of the total blood loss. On the basis of the model of multiple linear regression analysis, the multilevel fusion (P=0.001), surgical time (P=0.034), and fibrinogen level (P=0.027) were independent risk factors that contributed to HBL, but age of 60 years or above (P=0.110), postoperative complications (P=0.278), and cell saver were not (P=0.739).

CONCLUSIONS

We conclude that a large amount of HBL may occur in patients who underwent PLF surgery for degenerative spine. In addition, significant hidden loss may have a correlation with postoperative mortality. Multilevel fused, surgical time, and fibrinogen level should be paid close attention when considering strategies of fluid infusion and blood transfusion.