Estimation of external blood loss by paramedics: is there any point?

There are many patient assessment challenges in the prehospital setting, especially the estimation of external blood loss. Previous studies of experienced paramedics have demonstrated that external blood loss estimation is highly inaccurate. The objective of this study was to determine if undergraduate paramedic students could accurately estimate external blood loss on four surfaces commonly found in the prehospital environment.

This prospective, observational, blinded study used a convenience sample of undergraduate students studying at Monash University during 2006. Students were provided with four clinical vignettes using four different surfaces and varying simulated blood amounts.

Accurate estimation occurred with the vinyl simulation (100 ml), with a mean value of the estimations of 98 ml (95% Confidence Interval (CI) 84-113 ml). Carpet and concrete surfaces were both associated with large under-estimations. The carpet simulation (1,000 ml) had a mean value for the estimations of 347 ml (95% CI 320-429 ml). The concrete simulation (1,500 ml) had a mean value for the estimations of 885ml (95% CI 771-999 ml). Conversely, the clothing simulation (500 ml) emphasized over-estimation, with a mean value for the estimations of 1,253 ml (95% CI 1,093-1,414 ml). There was no relationship between increased accuracy and clinical experience, exposure, educational qualifications, or age of students.

External blood loss estimation by undergraduate paramedic students generally is too inaccurate to be of any clinical benefit. Particularly, absorbent and impermeable surfaces precipitated inaccuracies by undergraduate paramedic students.