The MAR method versus the visual estimation method in predicting external blood loss: a randomized controlled study

Area of Science:

• Medical Education
• Emergency Medicine
• Clinical Skills Training

Background:

• Accurate blood loss estimation is vital for managing hemorrhagic shock.
• Visual Estimation (VE) is a common but potentially inaccurate method.
• The MAR method offers a standardized approach using fist measurements for external blood estimation.

Purpose of the Study:

• To compare the accuracy and duration of blood loss estimates using the MAR method versus the VE method.
• To evaluate if participants' height, weight, or gender influenced MAR method estimates.

Main Methods:

• A randomized, double-blind study involved 140 medical and paramedic students.
• Participants used either the MAR or VE method to estimate blood loss in simulated scenarios with varying volumes (75 mL, 150 mL, 750 mL).
• Statistical analyses, including non-parametric tests, compared estimation errors and durations between and within groups.

Main Results:

• The MAR method demonstrated statistically significant improvement in blood loss estimation accuracy, reducing errors compared to actual volumes.
• MAR method usage led to fewer outlier estimates but required more time.
• Estimates using the MAR method were not significantly affected by participants' height, weight, or gender.

Conclusions:

• The MAR method shows potential for enhancing the accuracy of external blood loss estimation.
• Integrating the MAR method into clinical skills training could benefit prehospital and hospital management of external bleeding.
• Further research may explore broader clinical applications and refine training protocols.