Clinical trial NCT06855472: The MAR Method Versus the Visual Estimation Method in Predicting External Blood Loss
Official title: Comparison of the MAR Method and the Visual Estimation Method in Predicting External Blood Loss in Health Students
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Blood Loss
Keywords: blood loss
clinical skills
emergency medicine
medical students
paramedics
randomized controlled trial
simulation training
Lead sponsor: Ankara City Hospital Bilkent
Sponsor class: OTHER
Collaborators: name: Baskent University
First posted: 2025-03-03
Enrollment: 237
Sex: ALL
Standard ages: CHILD
ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: PARALLEL
Intervention model description: Our study does not involve treatment, prevention, diagnosis, supportive care, screening, or medical devices. Instead, it is a randomized controlled trial that focuses on clinical skills training for estimating external blood loss in emergency medicine. The study designed a monocenter, double-blind, randomized, parallel-group, and controlled clinical educational study.
Primary purpose: OTHER

Brief summary: The goal of this educational clinical trial is to determine whether the MAR method is more effective than the Visual Estimation method for estimating blood loss. It also aims to assess whether factors such as gender, weight, and height influence blood loss estimates when using the MAR method.

The main research questions it aims to answer are:

* Does the MAR method provide more accurate blood loss estimates than the Visual Estimation method on flat, non-absorbent surfaces?
* Does the MAR method take longer to estimate blood loss compared to the Visual Estimation method?
* Do demographic factors such as gender, height, and weight affect blood loss estimates using the MAR method?
* Do these demographic factors also influence the time required for estimation using the MAR method? Researchers will compare the MAR method with the Visual Estimation method to determine whether the MAR method is a useful tool for accurately estimating external blood loss in clinical skill training.

Participants will:

* Sign an Informed Consent Form at the start of the study
* Receive a 10-minute orientation session
* Receive a 2-minute MAR method training (for the intervention group-)
* Use either the MAR method or the Visual Estimation method for up to 60 seconds at each of the three stations
* Receive a 2-minute MAR method training (for the control group)
* Use the MAR method for up to 60 seconds at each of the three stations (for the control group)

Detailed description: Preliminary Preparation:

For this study, the Professional Skills Laboratories were used as the physical setting. The scenarios were set up at three different stations, each positioned in a separate corner of a large room. Room dividers separated the stations, and each had a designated entrance and exit to prevent participants who had completed their estimations from encountering those who had not yet participated.

Two researchers designed three distinct simulated environments and scenarios for the study. A synthetic blood product was used to enhance the realism of the simulated blood loss cases. In line with the MAR method's design principles, all three stations featured flat, non-absorbent surfaces.

* Station 1: An acrylic (plexiglass) surface with 75 ml of blood.
* Station 2: A flat, varnished wood surface with 150 ml of blood.
* Station 3: A vinyl surface with 750 ml of blood.

Research Staff:

Three faculty researchers were present in the simulation area, overseeing orientation training for investigators and participants and coordinating activities at each station. Additionally, three medical student investigators were assigned to record blood volume estimates and estimation times.

Randomization:

Out of 237 eligible participants, 140 met the inclusion criteria and consented to participate. Since students from both departments had similar academic levels, ages, educational backgrounds, and no prior formal training in external blood loss estimation, the researchers used a non-stratified selection method. Participants were randomly assigned into two equal groups of 70 using a block randomization method (1:1 ratio) via the online service https://researchrandomizer.com/.

To assign participants, group names were written on paper, placed in a bag, and selected blindly.

* Group 1: Control group (Visual Estimation method), (n1:70).
* Group 2: Experimental group (MAR method), (n2:70). Group assignments were revealed to participants only when they arrived at the simulation room. To ensure allocation concealment, an independent researcher conducted both the randomization and group assignment before the trial began. While faculty researchers who prepared the stations knew the actual blood volumes, participants and study investigators who recorded the data were blinded to this information.

Study Description:

Student investigators at the stations received a 20-minute orientation before the study, covering its purpose, workflow, data form usage, and chronometer operation. Investigators recorded data in real-time as estimations were made. Neither participants nor investigators knew the actual blood volumes at the stations (double-blind design). At the start of the study, both groups received a 10-minute briefing, including:

* Signing the consent form
* Explaining the study's purpose
* Introducing the simulation lab and research team

To clearly describe the procedures, the study is presented in two distinct periods. Period I was conducted to obtain the primary outcomes based on the primary objectives of the study. During this period::

* Group 1 (Control): Estimated blood loss using the Visual Estimation (VE) method.
* Group 2 (Experimental): Received 1-2 minutes of MAR method training separately, then estimated blood loss using the MAR method at all three stations.

Investigators at each station recorded blood volume estimates and estimation times for both groups. Researcher analysed data providing intergroup records (Visual estimation method \[n1\] vs MAR method \[n2\]) and intragroup records (Visual method \[n1\] vs MAR method \[n1\])

Period II process was conducted to obtain the secondary outcomes based on the secondary objectives of the study. In this period::

•Group 1 (Previously Control): Received 1-2 minutes of MAR method training separately, then estimated blood loss using the MAR method at all three stations.

Investigators recorded blood volume estimates and estimation times. For secondary outcomes, data from 140 participants (MAR method \[n2\] plus MAR method \[n1\]) were analyzed to determine whether gender, height, and weight influenced blood loss estimates and estimation durations using the MAR method.

Eligibility criteria: Inclusion Criteria:

* Being a second-year paramedic or medical student
* No prior theoretical or practical training in estimating external blood loss
* Willingness to participate in the study

Exclusion Criteria:

* Not being a second-year paramedic or medical student
* Having received theoretical or practical training in estimating external blood loss
* Declining to participate in the study

Primary outcomes:
measure: Blood loss volume estimate
timeFrame: From enrollment to the completion of method application in 20 minutes.
measure: Blood loss estimation time
timeFrame: From enrollment to the completion of method application in 20 minutes.
Secondary outcomes:
measure: Blood loss volume estimate of each participant using the MAR method
timeFrame: From enrollment to the completion of method application in 25 minutes.
measure: Blood loss estimation time of each participant using the MAR method
timeFrame: From enrollment to the completion of method application in 25 minutes.
Other outcomes:
Locations:
city: Ankara
country: Turkey
facility: Baskent University
city: Ankara
country: Turkey
facility: Ankara Yıldırım Beyazıt University, Faculty of Medicine, Ankara Bilkent City Hospital, Department of Emergency Medicine
Study officials:
affiliation: Ankara Yıldırım Beyazıt University, Faculty of Medicine, Ankara Bilkent City Hospital, Department of Emergency Medicine
name: Betul Akbuga Ozel, Asst.Prof.
role: PRINCIPAL_INVESTIGATOR
References:
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citation: Ashburn JC, Harrison T, Ham JJ, Strote J. Emergency physician estimation of blood loss. West J Emerg Med. 2012 Sep;13(4):376-9. doi: 10.5811/westjem.2011.9.6669.
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