Estimated Blood Loss Underestimates Calculated Blood Loss during Radical Retropubic Prostatectomy

Abstract

Objective: To compare the calculated blood loss for radical retropubic prostatectomy (RRP) with the anesthesiologist’s and operating surgeon’s estimates of operative blood loss. Methods: A retrospective review of 52 consecutive patients undergoing RRP between January 1999 and February 2000 was performed. Patient charts were reviewed for preoperative hemoglobin (Hgb_i), preoperative hematocrit (Hct_i), body weight (Wt), anesthesiologist’s and surgeon’s estimated blood loss (EBL_A and EBL_S), and postoperative day one morning hemoglobin (Hgb_f) and hematocrit (Hct_f). For each patient, the actual blood loss (ABL), i.e., the amount of blood that left the patient’s body, was calculated as the average ABL_n resulting from two computations of the following formula: ABL_n = (EBV × (H_i – H_f)) / ((H_i + H_f)/2) + (500 × T_u) where: (1) estimated blood volume (EBV) is assumed to be 70 cm³/kg; (2) H_i and H_f represent Hgb_iand Hgb_f for one computation and Hct_i and Hct_f for the second computation, and (3) T_u is the sum of autologous whole blood (AWB), packed red blood cells (PRBC), and cell saver (CS) units transfused. For each patient, ABL was compared with EBL_A and EBL_S. Descriptive statistics of the pooled data were calculated. Results: The mean (± SD) age was 60 ± 7.1 years. The mean ABL was 2,774 ± 1,014 cm³. Patients received an average of 1.96 U CS, 0.14 U PRBC, and 0.42 U AWB. Five patients (9.6%) were exposed to homologous blood. The average ABL_net (i.e. ABL reduced by the amount of CS returned) was 1,794 ± 806 cm³. EBL_A and EBL_S were 1,337 ± 676 and 1,300 ± 658 cm³, respectively. Conclusion: During radical retropubic prostatectomy, anesthesiologists and urologists both appear to underestimate blood loss as determined by standard calculation.

Preoperative predictors of blood loss at the time of radical prostatectomy: results from the SEARCH database

“…Others, using different methodologies, have corroborated the finding that EBL varies with, but is typically lower than, actual surgical blood loss. 20 Moreover, there is no reason to suspect EBL should correlate better or worse with actual blood loss for one patient group rather than another (for example, for normal-weight vs overweight men). As such, though EBL may be lower than actual blood loss, the overall trends should hold.…”

A reply

“…USA) technology in humans), they had no basis upon which to estimate the magnitude and variance of the results they were likely to encounter. This is surprising considering that we have previously used the same technology to measure the forces applied to the maxillary incisors by videolaryngoscopes and the Macintosh laryngoscope [2,3]. We found that videolaryngoscopy results in less force applied to the maxillary incisors when compared with direct laryngoscopy, but found no difference between videolaryngoscopes.…”

“…College We cannot agree with his suggestion that the oxygen flush is not meant to increase oxygen concentration in the inspired gas: as long ago as 1968, BS4272 [2] specifically described this feature as the emergency oxygen supply, but we agree that this is not a feature of drawover apparatus.…”

“…Generally, the checklist (p4 of the document) does not apply to drawover systems and associated equipment. For example, the high continuous flows used when checking an oxygen flush are contraindicated in any system with an inflating valve [2][3][4], including drawover apparatus, because they may lead to valve occlusion for as long as the flush button is depressed, risking pulmonary barotrauma. The reservoir bag in a circle system is designed to burst above pressures of 55 cmH 2 O, which mitigates this hazard.…”

Is the Blood Loss Score universally acceptable?

“…This might explain the trend in performance of the EBVLoss method compared with the tool: this was poor intra-operatively (11% vs 77% of variance in measured loss explained) but improved at 24 h and significantly so at 48 h. The finding by this study that the 'estimation by expert' method outperformed the direct calculation method at 24 h is seemingly at odds with that previously reported during radical prostatectomy. A study in 52 patients used the average of pre-operative Hb and day-one postoperative Hb and demonstrated substantial underestimation by expert assessor [5]. This inconsistency might result from the inaccurately large denominator of the present study or from additional factors.…”