Heat waves and the elderly: reducing thermal and cardiovascular consequences

摘要 热浪是致命的，导致老年人死亡的人数与其他任何年龄的人都不成比例 组重要的是要注意，这种死亡主要是心血管疾病，而不是体温过高本身。 尽管如此，我们对实际高温下老化对心血管功能的影响知之甚少。 波浪状的条件。这项工作的中心假设是，老年人表现出受损 在热浪条件下的心血管反应，这可以通过采用低- 能源需求冷却策略。目标1将测试将测试假设，老化损害否则 在长时间暴露于热浪条件下的必要的心血管反应。全面 将在暴露期间评价老年人相对于年轻成人的心血管和热反应 两个长期的热浪条件：炎热和潮湿（复制1995年芝加哥热浪），非常热， 干燥（复制2018年的洛杉矶热浪）。目的2A将检验皮肤润湿是有效的 减轻老年人核心体温升高和伴随的心血管紧张的方法 在热浪中。虽然空调是预防与热有关的疾病的最有效策略， 死亡率，约12%的美国人没有空调，这一比例可能更高， 美国中西部和东北部在热浪期间受伤和死亡人数特别高。此外，委员会认为， 社会经济因素、停电和政府强制的轮流停电等变量威胁着 在最需要的时候，全区域都可以使用空调。这一目标将评估皮肤的功效 仅润湿，仅使用风扇，以及皮肤润湿和风扇使用的组合，以减轻 两种热浪期间老年人的核心体温和相关的心血管应变 在目标1中。目的2B将检验在高温期间体温调节和心血管紧张的假设， 在10天的基于家庭的热适应方案后，老年人的波浪将减轻。热适应是 反复暴露于加热条件下的过程提高了耐受能力，甚至 生存，随后的热应力。这一目标将评估一种易于实施、价格低廉、 新的基于家庭的热适应方案（即，小腿连续10天热水浸泡90 分钟/天），以减轻核心体温的过度升高和相关的心血管紧张， 老年人在目标1中概述的相同热浪条件下。本机构的预期成果 这项工作将重新塑造我们对高温下老化对心血管功能影响的理解。 波，以及确定低能耗冷却模式的潜力，旨在挽救生命，这 易受伤害的人群。

Abstract Heat waves are lethal and cause a disproportionate number of deaths in the elderly relative to any other age group. It is important to note that such deaths are primarily cardiovascular, not hyperthermia itself, in origin. Nevertheless, we know relatively little about the effects of aging on cardiovascular function during actual heat wave-like conditions. The central hypothesis of this work is that the elderly exhibit impaired cardiovascular responses during heat wave conditions, which can be mitigated by employing low- energy demand cooling strategies. Aim 1 will test will test the hypothesis that aging impairs otherwise necessary cardiovascular responses during prolonged exposure to heat wave conditions. Comprehensive cardiovascular and thermal responses in the elderly, relative to younger adults, will be evaluated during exposure to two prolonged heat wave conditions: hot and humid (replicating the 1995 Chicago heat wave), very hot and dry (replicating the 2018 Los Angeles heat wave). Aim 2A will test the hypothesis that skin wetting is an effective modality to attenuate elevations in core body temperature and accompanying cardiovascular strain in the elderly during heat waves. Though air conditioning is the most effective strategy to prevent heat-related morbidity and mortality, ~12% of Americans do not have access to air conditioners, and this percentage is likely higher in the Midwest and Northeast United States where injury and deaths during heat waves are particularly high. Moreover, variables such as socio-economic factors, power outages, and government-imposed rolling blackouts threaten region-wide access to air conditioning at times when it is most needed. This aim will assess the efficacy of skin wetting only, fan use only, and a combination of skin wetting and fan use in mitigating excessive elevations in core body temperature and associated cardiovascular strain in the elderly during both types of heat waves outlined in Aim 1. Aim 2B will test the hypothesis that thermoregulatory and cardiovascular strain during heat waves will be mitigated in the elderly after a 10 day home-based heat acclimation regimen. Heat acclimation is the process by which repeated exposure to heated conditions improves the capacity to tolerate, and even survive, a subsequent heat stress. This aim will evaluate the efficacy of an easily implemented, inexpensive, and novel home-based heat acclimation regimen (i.e., 10 continuous days of lower-leg hot water immersion for 90 min/day) in attenuating excessive elevations in core body temperature and associated cardiovascular strain in elderly adults during the same heat wave conditions outlined in Aim 1. The expected outcomes from this body of work will re-shape our understanding of the consequences of aging on cardiovascular function during heat waves, as well as identify the potential of low-energy cooling modalities directed towards saving the lives of this vulnerable population during heat wave exposure.