Perioperative factors associated with hidden blood loss in intertrochanteric fracture patients

The actual total blood loss after a hip fracture has been found to be considerably larger than that observed during surgery and collected in drainage postoperatively. However, no previous studies have offered reasonable explanations for the deficit between a large hemoglobin drop and a small intraoperative blood loss. The aim was to quantify blood loss associated with hip injuries and surgery, and to identify the relative risk factors for perioperative hidden blood loss.

Eighty-nine patients with a femoral intertrochanteric fracture were operated on between August 2012 and October 2013. The patients were accepted to undergo DHS (AO/ASIF) surgery or PFN-a (AO/ASIF) surgery and were randomly assigned to one of the two groups according to whether they had a wound drain or not. Admission information collected included: age, gender, body mass index (BMI), the American Society of Anesthetists system (ASA grading), plasma albumin (ALB), specific gravity of urine (SGU), fracture type (FT), surgery type (ST), and time from admission to surgery in hours (TAS). Blood samples for HB (hemoglobin) analysis were obtained upon admission, at 1 h preoperatively, and at successive postoperation days. The hidden blood loss was calculated by deducting the observed perioperative blood loss from the calculated total blood loss based on the hematocrit changes.

A total of 82 patients with a mean admission lapse time of 4 h after injury remained for the final analysis. One-way analysis of variance (ANOVA) of HBL shows the significant difference was observed in BMI subgroups, ALB subgroups, SGU subgroups, and ST subgroups, but no difference was observed in other subgroups. A multivariate linear regression investigating the relationship between HBL and all factors show that decreased albumin at admission and PFN-a surgery were variables associated with increased HBL.

Several readily available preoperative factors in the form of non-drainage, BMI < 25 kg/m², admission specific gravity of urine >1.020, surgery type PFN-a, and admission albumin <30 g/L were associated with a greater likelihood of more HBL. In addition, the latter two are independent risk factors for greater HBL in patients with intertrochanteric fractures.