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Background: Among patients brought to the critical care unit after non-cardiac surgery, the incidence of low hematocrit is estimated to be 25.6%. This is associated with major adverse cardiac events, acute renal failure, increased length of hospital stay and mortality. 1 Blood loss estimations done by visual inspection are typically used to guide perioperative management, however, they have been shown to be inaccurate in, for example, obstetrics/gynecology and orthopedics patient populations. 2 Our aim was to study the blood loss estimation practices at our institution for a heterogeneous group of surgeries.

Methods: With IRB approval, retrospective data were collected during a 3-week period (December 2017) on major non-cardiac surgeries with potential for substantial blood loss. Cases were excluded if pre-and postoperative hemoglobin levels were not recorded. In addition to patient demographics and hemoglobin, blood loss estimates by both the anesthesia and surgical teams were documented. For this study, the calculated blood loss was then obtained using the formula Pre Hgb-Post Hgb/Avg Hgb x BV; blood volume (BV) was calculated using Nadler’s equation. Clinicians more typically use a simplified formula to estimate blood loss, multiplying the patient’s weight by 75 for men and multiplying weight by 65 for women. Spearman’s correlation and Bland-Altman plots were used to analyze associations among the surgical blood loss estimate, anesthesia blood loss estimate and calculated blood loss.

Results: The study included 43 patients (34.7% females) with a mean age of 52.3±17.1 years and BMI of 30.9±10.5. The data were not …