[Preventing Bathing-Related Accidents without Overemphasizing "Heat Shock": toward Prevention Strategies Centered on...

Japan is reported to have the world's highest per-capita drowning mortality among older adults, and most deaths occur in bathtubs, suggesting that Japan-specific bathing practices contribute to this occurrence. Because fatal bath-related accidents increase during the cold seasons and physiological studies simulating bathing have documented marked blood pressure fluctuations, prevention efforts have traditionally focused on preventing rapid blood pressure changes induced by indoor temperature gradients-the so-called "heat shock." However, it has been reported that cases involving organic diseases, such as myocardial infarction or stroke, which may be triggered by blood pressure fluctuations, account for less than half of all fatal bath-related accidents. Furthermore, among individuals rescued after being unable to get out of the bathtub unaided, fewer than 10% were diagnosed as having an organic disease; in the remaining individuals, impaired consciousness, hyperthermia, and tachycardia improved after their rescue and removal from the hot environment. These findings suggest that hyperthermia due to heat exposure-i.e., heat illness-may play a larger role than blood pressure fluctuations alone, indicating the need to prioritize prevention strategies with heat illness in mind.In this article, we re-examine the validity of the conventional heat-shock-centered framework and argue for new prevention strategies focused on preventing hyperthermia and heat illness during bathing. We specifically address two practical questions: how to avoid bathing-related hyperthermia that can lead to heat illness, and how to detect early situations in which hyperthermia causes impaired consciousness and prevents self-evacuation from the bathtub.