Great Walks gets to the bottom of heat exhaustion after experiencing it first-hand.
“Hydrate, hydrate, hydrate.” That’s what I was told on the first day of my desert hike in the Red Centre. I was with a group of bushwalkers experiencing the Simpson Desert and the on-site doctor didn’t mince his words.
I’d been to this part of Australia many times but never so early into the walking season. It was late April and the daytime temperature would be at least 35°C and only a few degrees cooler in the shade. So I did what I was told: hydrate, hydrate, hydrate. I added electrolytes to my waterbottle and wore a wide brimmed hat. I did everything I could to stay cool and yet I still got heat exhaustion.
Delayed reaction
The strange thing was I didn’t experience it until I was out of the desert and on my way back to Sydney on the plane. We left the Simpson on the sixth day after having a really enjoyable walk and drove back to Alice Springs. I do remember having a headache that night at the hotel but when I woke in the morning to catch my flight home I felt completely fine. I had breakfast and caught a cab to the airport.
The first hour of the flight to Melbourne was fine and I happily read my book. After about 90 minutes I began to feel hot and clammy and my head began to throb. I thought this was pretty strange so I drank water and tried to forget about it. Soon enough this heavy fatigue hit me and I was no longer able to read my book so I tried to snooze, but I just felt worse.
Once the plane landed in Melbourne I had no time to think about what was going on as I had to rush to catch my connecting flight to Sydney. By the time I boarded that flight I felt terrible and heavily fatigued. I could barely stay awake so I closed my eyes and when I woke up the plane had landed in Sydney. I didn’t feel any better and I began to think I didn’t have the strength to get up and collect my baggage from the carousel, but I knew I couldn’t sit there.
I stood up to get my bag from the overhead locker and bang! I hit the floor in a faint. The lady behind me yelled for help and suddenly I was surrounded by members of the crew trying to work out what was wrong with me. At that point in my fog-filled brain I thought this might be heat exhaustion or even heat stroke. I tried to explain this to one of the members of the crew who was checking my pulse but I wasn’t making much sense.
Worse for wear
After some minutes they got me up on a seat so the other passengers could pass and I was given oxygen, which I don’t know if it helped or not. After much discussion I was wheelchaired off the plane and I immediately threw up in the airport lounge. I continued to talk gibberish and someone called an ambulance.
The ambulance officer checked my vitals which were all fine. I got to the hospital and the triage nurse asked me lots of questions that I can’t remember then they put me in the A&E waiting room where my partner Holly was anxiously waiting. I had rung her at the airport but I made no sense over the phone so I handed it to someone who explained the situation as best they could.
The first hour at A&E I could hardly stay awake and was still talking gibberish. My limbs were heavy and I sat crumpled over the chair quietly moaning. However, after another hour I began to come to. After 2.5 hours and still not seeing a doctor I told Holly I felt good enough to go home as our kids were being looked after and they needed to be home.
Once home I went straight to bed and felt slightly better in the morning but I took the day off work. The following day I felt even better and saw a doctor to get the all-clear. The doctor organised some blood tests and they were all fine but she did confirm I had suffered heat exhaustion. And yet I still don’t really know what happened.
I was the only person on the desert trip to get it. So why me and could I have done anything else to prevent it? And why did it take so long for the heat exhaustion to affect me? I decided to speak to a professional to get a better understanding of heat-related illnesses.
Ask the expert
Meet Dr Matt Brearley, a thermal physiologist, and Australia’s pre-eminent occupational heat stress consultant.
GRW: What’s the difference between heat exhaustion and heat stroke?
Matt: “People use the terms interchangeably but they are very different. Heat stroke is clinically diagnosable but with heat exhaustion there are no clinical guidelines for that. It’s more based on an opinion.
“Heat stoke is where you have two diagnosable conditions. Firstly, you have a core temperature above 40°C which is extremely high. Heat stroke is an illness of the motivated. You have to be motivated to reach that core temperature. During this time your body will be giving you all the messaging to slow down, stop, seek shade.
“The second condition is you will have central nervous system impairment which will translate to being incoherent when you are trying to communicate to someone. I’ve seen some really bizarre behaviour. I’ve seen people take off all their clothes in the middle of a worksite. You can have trouble with your gait and picking up objects.
“Heat exhaustion is profound fatigue following exposure to heat. You can have a normal temperature and all your vital signs can be normal. You can also have heat exhaustion sometime after you’ve been exposed to heat. So what happened to you was quite profound. It’s not like you just needed a nap on the plane. It’s nothing to be sneezed at. Your condition was quite serious.”
Heat Hangover
Matt: “I’ve come up with this term the Heat Hangover. Most of my work is in occupational settings like mining where people work deep underground. It’s like a sauna down there. Miners get very hot and sometimes show signs of a bit of a headache, slight nausea but nothing too serious, they might just go to bed early. They show the signs of an alcoholic hangover without drinking any alcohol. What we have tapped into here is that heat doesn’t just affect people during the exposure but sometime afterwards as well. We see some miners have heat hangovers day after day. And I think this is related to what you felt.”
GRW: In the desert I was told to hydrate, hydrate, hydrate. I also tried to stay as cool as possible and seek shade when I could. And yet I still got sick. Why?
Matt: “Staying hydrated is good advice but we can get a bit fixated on it. You should ask ‘what else can I do to cool myself?’ I think where you were you didn’t have a lot of options.
“With heat-related illness we look at two things. We look at hydration and we look at cooling. As soon as you start feeling hydrated you also need to think about cooling. It’s your body temperature that drives those responses either during or following heat exposure. Also you can drink yourself to the point of having an illness called hyponatremia or over drinking (where too much water in the body dilutes the sodium, causing the condition and symptoms to be similar to heat exhaustion).
“We have seen studies from the US military where soldiers have suffered heat stroke even though they were hydrated. In one study over a 22-year period they studied 5200 soldiers who had to be hospitalised due to heat stroke; almost 1000 of those soldiers had severe heat stroke and there were 37 deaths. And of those thousands of soldiers that went to hospital only 17 per cent were dehydrated. So if you were to say dehydration equals heat stroke I’d say no.
“In these hot settings you need to avoid walking in the hottest part of your day and limit your work rate (for example walk slower) to avoid bringing your core body temperature up too much. It’s all about paying attention to your body.”