Why hot summers temperatures affect the elderly so much?

A friend recently asked 'why hot summer temperatures affected the elderly so much more than younger people?' This made me realised that while many people accept the elderly are more vulnerable to hotter temperatures they don't understand why or what they should be cautious about. Given the increase in heat alerts we all need to be aware of the impact the elderly and know how to help them. The vulnerability of the elderly can be divided under two categories: physical and social. This blog will focus on the physical aspects and the next on the social. First let us examine how a health person physically copes with a hot day, then we can identify the areas of susceptibilty for older people and how we can help them.

 

Normal physical response to heat

On a hot summers day the temperature (28oc) your outside and feeling a little warm. Your body registers the higher air temperature and knows it needs to keep your body cool. The body has 2 effective ways of keeping you cool:

  1. dilating veins  (vasodilation): allowing heat to be lost through the skin to the air- this is why people look red in the face, arms, legs when they are hot. The heart has to work harder at this time as it needs to push the same amount of blood around a greater area and still keep a good volume of blood going to the lungs, brain and muscles. The blood vessels need to have the elasticity to dilate and not let water leak out of them into the tissues. This is why we can sometimes get swollen fingers and toes when it is hot- some is due to the blood vessel dilation and some to fluid leaking out of the dilated vessels. 
  2. sweating: if vasodilation is not enough your body will activate sweat glands to release water onto the skin which cools the body as it is evapourated. On a humid day the air is moist and the sweat is not evapourated as quickly, this is why we often feel more comfortable on a hotter drier day than a cooler more humid one. As your body sweats it losses fluid, which you need to replace to keep the process going and why you feel thristy on a hot day. 

 

The elderly

  • Physiologically the elderly cannot regulate their body temperature as efficiently or quickly as younger people. The body is older and it does not sense temperature changes as quickly or kick in to play responses to cool down. 
  • Existing cardiovascular disease reduces the ability of the heart to manage the extra workload when veins dilate. This can result in people feeling dizzy, short of breath. It can also increase the risk of other conditions such as stroke, heart attack, heart failure and pulmonary oedema.
  • Cardiovascular disease also increases the permeability of the veins so fluid leaks into the tissues and lungs causing swelling and difficulty breathing.
  • Medications for cardiovasular disease also affect the heart and veins, restricting the ability of the heart to respond to the higher temperatures.
  • Diuretics increase the potential for dehydration as they make the body loose water.
  • Other medications can also reduce the ability to sweat.
  • Many elderly have an ineffective thrist drive and overall do not drink enough. This is a problem as their blood volume is probabaly lower so when the body vasodilates it does not have enough volume to keep a good bloody supply to the brain and they can feel faint.
  • Air pollution (ozone) also increases with increasing temperatures due to a chemical reactio with sunlight. This can increase shortness of breath and difficulty in breathing for those whose conditions are normally under control.

What to do

  • Know which medications will affect the heart, lungs, vasccular system and kidneys and how.
  • Know which medications will reduce/stop sweating.
  • Increase fluid intake.
  • Stay in an airconditioned space.
  • Move slowly from cool to warm spaces to prevent dizziness and fainting. 
  • Reduce execise and outings during the hottest part of the day.