MONTREAL (FRONTLINE MEDICAL NEWS) – Surgeons, nurses, and anesthesia providers were all pretty bad at estimating surgical blood loss in a small study. And more experience doesn’t improve accuracy, though experienced providers were more confident in their estimates.

These were the findings from a study that simulated operating room scenarios and asked providers to estimate blood loss. “Estimation of blood loss is inaccurate and unreliable,” Dr. Luke Rothermel said at the Central Surgical Association’s annual meeting.

Dr. Rothermel, a resident at Case Western Reserve University, Cleveland, noted that although the Joint Commission requires operative notes to contain estimated blood loss, “no study in the United States has compared the characteristics of operating room personnel or conditions associated with improved accuracy or reliability of blood loss estimation.”

Beyond the required reporting, estimating blood loss (EBL) also provides important guidance in perioperative care. Still, said Dr. Rothermel, previous studies have shown that EBL is typically inaccurate.

To assess providers’ ability to be accurate and reliable in estimating blood loss, Dr. Rothermel and his collaborator, Dr. Jeremy Lipman, assistant residency director at MetroHealth, Cleveland, designed a study to simulate three different operating room scenarios, involving high, medium, and low blood loss volumes. The materials used, such as blood-soaked sponges and suction canisters, were identical to what’s actually used in the operating room (porcine blood was used in the simulations).

Before the study, Dr. Rothermel said that he and Dr. Lipman hypothesized that those providers who had more experience and those who were working at the operating field would be more accurate in estimating blood loss. They also hypothesized that estimations in procedures with lower volumes of blood loss would be more accurate.

The study recruited providers from the surgery, anesthesia, and nursing services at an urban level 1 trauma center. Each scenario included a written description of the procedure performed and the course of surgery, and participants could handle study materials for each scenario under the supervision of study staff.

A total of 60 participants (22 from surgery, 17 from anesthesia, and 21 from nursing) participated; they had an average of 12.8 years of experience. The surgical participants included surgical scrub techs, trainees, and attending physicians. Anesthesia participants included anesthesia assistants, CRNAs, trainees, and attending physicians. Nursing participants were all RNs.

The findings? All over the board: “There was no association between specialty, years of experience, or confidence in ability with the consistency or accuracy of estimated blood loss,” said Dr. Rothermel.

Most participants were far shy of the mark, with just 5% of study participants overall able to come within 25% accuracy in judging EBL in all scenarios. Just over a quarter were consistent in over- or underestimating blood loss.

These findings held true across scenarios, across disciplines, and regardless of the number of years of experience. “Increased years of experience trended toward increased error,” said Dr. Rothermel, though the difference was not statistically significant. However, those with more years of experience tended to be more confident of their judgments.

Dr. Rothermel noted the small study size and single institution studied as limitations. Also, “this model was not a high fidelity representation of the OR experience, “ he said, explaining that during surgery, caregivers continually assess intraoperative blood loss and may form an estimate in a different – and potentially more accurate – manner than occurs when presented with the contrived presentation of a scenario.

The study calls into question the validity of using EBL as a quality indicator in assessing physician performance and patient outcomes, said Dr. Rothermel, who had no financial disclosures.

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