Hot To Go: A Newsletter on Heat and Health
Your summer guide to heat, health and primary care
Today we will be focusing a little on heat; because it is HOT outside, and OSHA recently released a proposal for heat injury and illness prevention. It’s a bit of a soft ball, designed to be easily digested by our slow-moving summer brains (or is that just me?).
In this newsletter we will cover the basics of how heat affects health and provide guidance on how to council your patients to stay safe throughout the summer.
For PennChart users steal my dot phrases .EHheat, .EHheatforclinicians for other folks, click here to access a handout to put in your after visit summaries during summer months, and a guide for you to remember who is at increased risk, and what medications increase risk of heat related illness.
Clinical scenario:
A young woman brings her grandmother into the office after recently being discharged from the hospital. She was found unresponsive in her home and was diagnosed with heat stroke and an acute kidney injury on top of her previously established chronic kidney disease (stage 3a). Her granddaughter brought her into the office to determine what ways she could prevent similar events in the future. Her grandmother states she feels fine today, although she is behind on some of her utility bills so has not been using her air conditioning often. Her medical history includes depression (stable on Lexapro, and Olanzapine), hypertension (at goal on Olmesartan-hydrochlorothiazide – currently held after her hospitalization) and hypothyroidism (stable on Synthroid). She lives alone, but just down the block from her kids and grandkids. Both the patient and her granddaughter would like to know ways to avoid events like this in the future.
A little bit of ~data~ about heat and heat related illness:
As extreme heat events continue to increase across the globe, record numbers of people are exposed to extreme temperatures; compared to 2000-2004, from 2017-2021 heat related deaths increased 68% (Romanello et al., 2022). In the U.S. alone over 132 million Americans were under some form of heat advisory this past weekend, with 10% of the population experiencing extreme temperatures.
Heat has been linked with multiple adverse health outcomes, including acute kidney injury, adverse pregnancy outcomes, worsening of pre-existing cardiovascular and respiratory conditions, decompensation of mental health and worsened sleep (Romanello et al., 2022).The main mechanisms that lead to heat related morbidity and mortality are decreased blood volume and increased blood viscosity due to fluid loss. Additionally, increased strain is placed on the cardiovascular system due to vasodilation in cutaneous capillaries and splanchnic vasoconstriction (Hifumi et al., 2018; Kovats & Hajat, 2008). Hot air can also directly affect our respiratory system, triggering airway responses that worsen chronic respiratory conditions like asthma (D’Amato et al., 2016).
Who is most at risk?
Patients at increased risk for adverse health events due to heat include those that work outdoors during summer months, those with existing cardiovascular and respiratory conditions, children younger than one, adults over the age of 65, patients with depression, and patients on certain psychotropic medications (Fleischer et al., 2013; Hifumi et al., 2018; Martin-Latry et al., 2007). Classes of psychotropic drugs that affect body temperature regulation and increase risk of health-related hospital visits include anticholinergics, antipsychotics, and anxiolytics (Martin-Latry et al., 2007).
Unsurprisingly, multiple studies suggest that people living in poorer neighborhoods, areas with less greenspace, and those that lack access to air conditioning are more vulnerability to heat. Additionally, non-white and black communities are more vulnerable to heat related adverse health outcomes (Gronlund et al., 2016). Thus, when assessing a patient’s vulnerability to heat it is important to consider their age, chronic health conditions, medications, occupation as well as their access to air conditioning and neighborhood environment.
Back to the patient encounter:
When assessing a patient’s vulnerability to heat related illness, I suggest you think in three big buckets: living and work environment, health status and medical conditions, and medications. Thinking in this way can ensure you are maximizing each of these domains, and not missing any important pieces of history.
Living and Work Environment: Important considerations when discussing living environment include: whether or not the patient has access to AC (and if so, if they have the funds to use it), proximity to close friends and relatives (studies have shown increased community connectivity can decrease mortality during heat waves), ability to ambulate around their home and leave their home, access to transportation, amount of neighborhood greenspace, and proximity to public places with AC (libraries) or local cooling centers. It is also imperative to consider a person’s occupation- if they work outside, in hot environments, or are required to wear lots of protective equipment or semi/non-permeable clothing, they are at increased risk of heat related illness (see NIOSH link below to counsel patients about what they should expect from their employer).
For this patient, her lack of reliable AC is her main risk factor for heat stress from an environmental perspective. I would refer her to resources for utility debt support, as well as programs that help homeowners make renovations to make their home more energy efficient (FOR FREE- see links below).
Resources:
Hydration Guide from the National Institute for Health and Safety
Current CDC / NIOSH Recommendations to decrease risk of occupational heat stress
Philadelphia Utility Debt Support
Health Status and Medical Conditions: Important considerations when discussing health status and medical conditions include: age (increased risk if older or very young), cardiovascular conditions, respiratory conditions, conditions that limit mobility or ability to access help when needed.
For this patient, her age and hypertension put her at increased risk for heat related illness. At the very least, I would want to discuss the dangers of heat, ensure she has access to local cooling centers, and discuss hydration. After ensuring her chronic conditions are well controlled and not over treated, I would do a full mobility and frailty assessment and consider ways to maximize the patient’s functional status. This could help ensure she is mobile enough to make it out of her home on hot days as well as increase her cardiovascular capacity and thus her heat tolerance. I would also talk to the granddaughter about setting up a schedule to come check in on her grandmother during heat advisories, as well as refer her to programs to help with utility debt and home energy efficiency repairs (see resources for Environment above). Finally, its important to talk with the patient about their intentions. Just because they can walk or they have air conditioning, does not mean they will act on these resources. Ask about barriers to going to a cooling center or a library and how to sparingly use air conditioning when there are consecutive days over 90 degrees.
Medications: See graphic above for important medications to discuss and the comprehensive CDC page below for more information. Broad categories of medications that interact with heat include antidepressants, antihypertensives, antipsychotics and anticholinergics. The way I think about it is that any medicine that alters the autonomic nervous system or affects the way the body handles electrolytes or water are medications that can increase risk of heat stress and illness.
For this patient her Synthroid and Lexapro can both lead to excess sweating, putting her at increased risk of hypovolemia. Her Olanzapine could lead to impaired sweating, but also would impair her thermoregulation. Her ARB-Diuretic combo may lead to hypotension (obviously increasing her AKI risk) as well as decreased thirst. Moving forward we have options of how best to manage her medications. The first option would be to resume all medications (pending restoration of kidney function), and counsel the patient to drink lots of water (any patient could benefit from the Hydration Guide listed above). Tell her that her medication interferes with her ability to feel thirsty. Alternatively, you could consider discontinuing the hydrochlorothiazide and using only Olmesartan or an Olmesartan-Amlodipine combination pill instead. While calcium channel blockers do have similar risk to other antihypertensives as far as heat is concerned, they would not lead to hypovolemia that we could see with diuretic use. As in all patients, especially the elderly, considering which medications are necessary would highly benefit this patient – that may include consulting with her psychiatrist to determine if she could safely decrease doses of either psychotropic medications, and ensuring her hypothyroidism is not being over treated. This would also be a great time to check and see if your patient is taking Aspirin for no reason, as antiplatelet agents can impair superficial vasodilation, which is important for heat regulation.
Resources:
CDC Heat and Medications- Guide for Clinicians
General Guidance on how to decrease heat related illness:
Stay well hydrated (drink before you’re thirsty, keep your urine clear to light yellow)
Wear light and loose clothing
Plan errands and doctor’s visits for the am when it may be cooler.
Take cool showers and baths as necessary
Go to local cooling centers (usually found via local health departments- info for Philly here)
Avoid alcohol and excessive caffeine
Eat lighter meals
Use sunscreen and avoid sunburn (affect the way our bodies regulate temperature)
Get in the AC whenever possible, fans often will not provide enough cooling during heat waves
Make sure to check in on your friends and neighbors.
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Reviewer: Marilyn V. Howarth, MD, FACOEM, Center of Excellence in Environmental Toxicology
Supported by the National Institute of Environmental Health Sciences (Grant number: P 30 ES013508)