Department of Epidemiology, Nara Medical University School of Medicine.
Department of Psychiatry, Nara Medical University School of Medicine.
Environ Health Prev Med. 2024;29:12. doi: 10.1265/ehpm.23-00320.
Home hot-tub bathing substantially increases drowning mortality rates among older adults in Japan. Previous laboratory studies on hemodynamic responses during hot-tub bathing have been inconsistent depending on the thermal conditions. Furthermore, real-world hemodynamic changes that occur during bathing remain poorly understood. This study investigated the association between individual thermal states and hemodynamic parameters during hot-tub bathing among community-dwelling older adults.
In this cross-sectional study conducted between January 2016 and April 2019, which involved 1,479 older adults (median [range] age, 68 [40-90] years), skin temperature on the abdominal surface was measured every minute. Ambulatory blood pressure and pulse rate were recorded at 15-min intervals for 24 h. Participants underwent simultaneous living room temperature measurements in their homes, and the time and methods of bathing were recorded. Associations between skin temperature and hemodynamic parameters during bathing and between the pre-bath living room temperature and in-bath maximum proximal skin temperature were evaluated using mixed-effects and linear regression models, respectively.
A 1 °C increase in skin temperature was significantly associated with a 2.41 mmHg (95% confidence interval [CI]: 2.03-2.79) increase in systolic blood pressure and a 2.99 bpm (95% CI: 2.66-3.32) increase in pulse rate, after adjusting for potential confounders, including age, sex, body mass index, antihypertensive medication use, dyslipidemia, diabetes, and living room and outdoor temperatures. Significant interactions were not observed between sex and skin temperature in relation to systolic blood pressure and pulse rate (P = 0.088 and 0.490, respectively). One standard deviation lower living room temperature before bathing was significantly associated with a 0.41 °C (95% CI: 0.35-0.47) higher maximum skin temperature during bathing.
Our findings suggest that pre-bath cold exposure may increase the skin temperature during hot-tub bathing, possibly resulting in excessive hemodynamic changes. This provides a framework for future interventions that utilize pre-bath thermal conditions and bathing environments to prevent bath-related deaths.
在家中泡热水澡会大大增加日本老年人的溺水死亡率。以前关于泡热水澡时血液动力学反应的实验室研究结果因热条件而异。此外，实际洗澡过程中发生的血液动力学变化仍知之甚少。本研究调查了社区居住的老年人在泡热水澡时个人热状态与血液动力学参数之间的关系。
在这项于 2016 年 1 月至 2019 年 4 月进行的横断面研究中，涉及 1479 名老年人（中位[范围]年龄，68 [40-90] 岁），每 1 分钟测量一次腹部表面皮肤温度。24 小时内每 15 分钟记录一次动态血压和脉搏率。同时在家中测量客厅温度，并记录洗澡时间和方法。使用混合效应和线性回归模型分别评估洗澡期间皮肤温度与血液动力学参数之间以及洗澡前客厅温度与洗澡时近端最大皮肤温度之间的关系。
在调整了潜在混杂因素（包括年龄、性别、体重指数、使用抗高血压药物、血脂异常、糖尿病以及客厅和室外温度）后，皮肤温度每升高 1°C，收缩压升高 2.41mmHg（95%置信区间[CI]：2.03-2.79），脉搏率升高 2.99bpm（95%CI：2.66-3.32）。未观察到性别与皮肤温度对收缩压和脉搏率的交互作用（P = 0.088 和 0.490）。洗澡前客厅温度每降低 1 摄氏度，洗澡期间最大皮肤温度就会升高 0.41°C（95%CI：0.35-0.47）。
我们的研究结果表明，洗澡前的寒冷暴露可能会导致热水澡期间皮肤温度升高，从而导致过度的血液动力学变化。这为未来利用洗澡前的热条件和洗澡环境来预防与洗澡相关的死亡的干预措施提供了框架。
