Authors (including presenting author) :
Ng TK Odelia (1)
Affiliation :
(1)Trauma and Emergency Centre, Tuen Mun Hospital
Introduction :
Emergency care providers do not estimate blood loss well in a variety of scenarios. Previous studies have shown both prehospital and in-hospital medical personnels are unable to accurately estimate blood loss in simulated scenarios. Visually estimated blood loss may influence decision making in a prehospital setting. Previous research suggested that visual blood loss estimation is inaccurate for laypeople and medical professionals. Another research study on external blood loss estimation using the MAR method showed that use of the MAR method improves blood volume estimations. The MAR method is developed by a team of researchers in UMDNJ-Robert Wood Johnson Medical School and Robert Wood Johnson University Hospital. They compared the anterior surface of fist to the surface area of blood present and created a formula averaging blood per fist. They determined that a fist covers a surface area of blood that equals roughly 20ml.
Objectives :
This study aims to educate health care providers in the use of MAR method, compare the blood estimation before and after the use of MAR method, and improve the reliability of medical personnels in estimating blood loss in trauma settings.
Methodology :
This is an unblinded crossover trial. Participants serve as their own controls. This study was conducted in the ERTC room in the emergency department and each participant will spend around 15 minutes in the experiment. One volume (680ml) of simulated moulage blood was measured with syringes and poured onto a plastic floor sheet (similar material used in trauma room setting). Participants were asked to estimate the amount of moulage blood of the blood pool before and after learning the MAR method.
Participants were given one minute to observe the blood pool. After the blood pool was visualized, answers will be recorded, and participants were brought out of the room and instructed in the use of the MAR method. A teaching video was shown to the participants in another room. The video included teaching phrases including “This method utilizes your fist to estimate blood volumes. The volume of a blood pool depends on how many fists it would take to cover the pool. One fist equals 20ml of blood. So if it takes three fists to cover a blood pool, you have three fists times 20ml which equal 60ml of blood. The fist should be held at a height of 5cm from the blood surface. The anterior surface of the fist should point towards blood as it will have minimum variation in size from time to time. There should not be any gap between fists while measuring. The metacarpophalangeal joints should not point down while measuring.” Participants were then be brought back into the room with the same blood pool and given a second opportunity of one minute to estimate the volume of blood using the newly learnt MAR method. Responses were again documented. An online evaluation questionnaire was sent to participants after the study. They were asked to evaluate on whether the MAR method was easy to learn, easy to use, whether they feel more confident in estimating blood loss after learning the MAR method, and whether they will apply the method at work in the future if the study results proved that it improves blood volume estimation.
Result & Outcome :
56 out of 87 participants responded to the online evaluation questionnaire.
A scale of 1-5 (with 1 being very easy and 5 being very difficult) was use to rate the level of difficulty of learning and using the MAR method. The level of difficulty for learning the method has a mean of 1.55, confidence interval (95%) of 0.22. The level of difficulty for using the method has a mean of 1.71, confidence interval (95%) of 0.22. 94.6% of the respondents feel more confident in estimating blood loss after learning the MAR method, and 98.2% of the respondents say that they will apply the MAR method at work in the future if the study results proved that it improves blood volume estimation.
