Step Duration Effects on Blood Loss in Simulated Designs of Tourniquet Use Procedure


Kragh JF, Aden JK, Dubick MA 20(2). 76 - 82 (Journal Article)

Background: We sought new knowledge by further developing a model of using calculations in the simulation of a first-aid task. The purpose of this study was to develop the model to investigate the performance of tourniquet use in its component steps. Methods: We aimed to design an experiment on a desktop computer by mathematically manipulating simulated data in tourniquet use. A time factor of tourniquet use was ranged widely through time challenges in five degrees from ideal to worst performances. Redesigning the task was assessed by time costs and blood losses. Results: The step of tourniquet application took 17% of the trial time and securing the tourniquet after bleeding control took the longest amount of the trial time, 31%. A minority of the time (48% [17% + 31%] to apply tourniquet plus secure it) was spent after the tourniquet touched the patient, whereas most of the time (52%) was spent before the tourniquet touched the patient. The step of tourniquet application lost 14% of the total blood lost, whereas no blood was lost during securing the tourniquet, because that was the moment of bleeding control despite securing the tourniquet taking much time (31%). Most (86%) of blood lost occurred before the tourniquet touched the patient. But blood losses differed 10-fold, with a maximum of 2,434mL, which, when added to a pretask indication blood loss of 177mL, summed to 2,611mL. Before redesigning the task, costs of donning gloves and calling 9-1-1 included uncontrolled bleeding, but gloving mitigated risk of spreading pathogens among people. By step and person, redesigns of the task altered the risk-benefit profile. Conclusions: The model was useful because it simulated where most of the bleeding occurred before the tourniquet touched the patient. Modeling simulated redesigns of the task, which showed changes in the task's risk-benefit profile by step and among persons. The model generated hypotheses for future research, including the capability to screen candidate ideas among task designs.

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