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Verification of the airway securing capacity of a life jacket in a flood disaster

Koichi Imai, MD, Hidenobu Ochiai, MD, PhD, Keisuke Murakami, PhD


Objective: To verify the life jacket's airway-securing capacity to keep the nose and mouth out of the water in a flood disaster.

Design: Physical experiment.

Setting: University of Miyazaki.

Materials and Methods: We experimented with an open channel in which we created a wave and running water. In the channel, we observed a dummy attached to a balloon as a buoyant body. We used 170-, 220-, and 320-ml balloons. Experiment 1, we reproduced a tsunami. We created three sizes of wave. Experiment 2, we reproduced running water. When we installed an obstacle at the channel bottom, the current that submerged the dummy occurred downstream of the obstacle. We measured the submergence time of the dummy.

Results: For the medium-sized wave, the submergence time decreased as the balloon volume increased. For the largest wave, the submergence time was the shortest for a balloon of 220 ml, not 320 ml. Experiment 2, the submergence time decreased as the balloon volume increased. However, a dummy attached to a 320-ml balloon remained downstream of the obstacle.

Conclusions: The biggest drawback is that the parameters of this study are not based on real-world experience. Therefore, if an evacuee with a life jacket is submerged in a flood disaster, we cannot easily decide whether the buoyancy is appropriate because in some situations, buoyancy adversely affected airway security. If we could decide buoyancy based on specific disaster conditions, the airway-securing capacity of a life jacket would improve.


life jacket, airway, tsunami, flood disaster, buoyancy

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