Abstract
Visual estimation of blood loss is the most common form of evaluating intraoperative hemorrhage, and is also the most inaccurate. This study investigated the visual estimation accuracy of a global population of anesthesia staff and students as an initial estimation and also with the assistance of a pictorial guide. A voluntary, two-part, online, anonymous survey was distributed to members of two email databases with an interest in anesthesia, including students, nurses, interns, residents, general practitioners, and specialists. The survey consisted of visual and brief descriptive depictions of blood loss scenarios involving small animals, principally including images of common surgical items and receptacles containing a blood-like substance. Each participant estimated the blood volume (in mL) for each scenario twice, initially (Pre-Guide [PGD]) and then with the aid of a pictorial guide (With-Guide [WGD]). The pictorial guide used similar images labeled with corresponding volumes. Data was analyzed for normality with the Shapiro-Wilks test, corrected to absolute error and compared for statistical significance using the Wilcoxon signed-ranks test or the Kruskal-Wallis test as appropriate. The overall raw PGD phase median estimation error was−27 mL (range −99 to 248 mL). The PGD raw median error increased with scenario complexity. There were no differences between role, gender, experience, or country of origin. The overall median raw estimation error for the WGD phase was 13 mL (range −80 ml to 143 mL) (p = 0.0128). Visual blood loss estimation is inaccurate amongst veterinary anesthetists and associated staff, showing decreasing accuracy with increasing complexity. A pictorial guide improves the accuracy generally, and specifically for more complex scenarios which are likely to reflect the clinical situation.
Highlights
Acute hemorrhage impairs oxygen delivery and rapid management improves outcomes [1, 2]
Research has been focused around obstetrics, where hemorrhage is common
Recent medical studies have focused on development of pictorial guides to aid in the estimation of blood loss, generally with findings of improved accuracy [9,10,11]
Summary
Acute hemorrhage impairs oxygen delivery and rapid management improves outcomes [1, 2]. Recent medical studies have focused on development of pictorial guides to aid in the estimation of blood loss, generally with findings of improved accuracy [9,10,11]. Colorimetric methods, where spectrophotometrically-measured hemoglobin concentration is used to estimate blood volume, have been positively correlated with direct-measurement in two studies [12, 13]. These methods are both time consuming and technically challenging. Our objective in this study was to investigate the visual estimation accuracy of a global population of veterinarians, associated staff and veterinary students with an interest in anesthesia, and evaluate the utility of a pictorial guide for the improvement of visual estimation. We hypothesized that more complex estimation requirements would result in more inaccuracy
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