Heat Stress / Challenge
May be of use, but bear in mind this handout is maritime specific...
Hydration & Heat Injuries
Introduction
Over the last 2 decades there has been quite literally a ‘quantum leap’ in research and with regards to how the human body responds to the challenge of operating within an environment and climate with the potential to cause hyperthermia; “Hyper†meaning HIGH and “Thermia†relating to TEMPERATURE.
The purpose of this handout is to debunk some of the myths and misinformation about how our bodies cope with the heat challenge and also what we can or cannot do to ensure that our ‘coping mechanisms’ are optimised and finally what we can do to mitigate the actual risk of heat related injuries.
If you are currently residing within the UK you will be technically living within an environment that is categorised as being ‘temperate’ i.e. clearly defined seasons of Autumn, Winter, Spring and Summer - with no excessive or prolonged periods of extreme weather / temperature.
To this end, our clothing, diet and even our homes are all geared up to matching the environment that we live in.
Herein lies the problem! You are reading this sat within the air-conditioned confines of a Vessel that operates within both tropical and sub-tropical environments. Even on-board the vessel you will be switching from temperatures of around 17 Celsius (cabin) to 40 Celsius or more whilst on watch.
For our bodies to fully acclimatise (physically adjust) from a temperate to a tropical or sub-tropical environment takes an average adult male 6-8 weeks. Taking the latter into account it’s hardly surprising that many personnel on this contract will at some stage be exposed to the effects of, at the very least, moderate to severe dehydration and / or heat stress.
Risk-Factors to consider:
• First deployment to tropical / sub-tropical environment
• Skill Fade; no longer in possession of current / basic knowledge on prevention of heat stress
• Age > 40 years
• General Fitness (aerobic)
• General Health
• BMI
• Speed of Deployment
• Current Weather / Season in UK i.e. what climate they left when deploying
• Size of Security Team / Watch System
• Task / Mission
• Suitability of Equipment & Clothing
• Physical Nature of Task
How We ‘Cope’ With the Heat
Your body has an internal thermostat located within the brain (this element may be in doubt with certain team members!) which is known as the hypothalamus. In short its job is to regulate the body’s heat control mechanisms in order to maintain an internal, or core temperature of approximately 38.00 Celsius.
This is mainly achieved via the following methodologies:
• Evaporation: Sweat glands on the skin (the single largest organ of the human body) are stimulated and perspiration is produced. As the ‘sweat’ evaporates it also takes with it a percentage of heat from the skin’s surface and the underlying blood vessels
• Radiation: Blood vessels close to the skin’s surface dilate (expand) and literally radiate heat – hence the old caricature of a Brit on holiday resplendent with knotted hanky and a flustered looking red face... The circulatory system is key to you coping mechanisms and even your heart rate will eventually adjust to match the actual climate you are operating within.
• Expiration: A small percentage of the air that you expire will also contain heat and does play a small part in heat regulation.
If the above mechanisms begin to fail, then there will be significant changes in the way that an individual performs and acts whilst on duty. In the most simplest forms possible you must be aware that ANY form of heat stress / dehydration WILL affect the performance of the brain!
Even minor dehydration (for example just an hour on watch in direct sunlight with no fluids) can lead to a 20% drop in your problem solving (a process of constant evaluation where outcomes and scenarios are played out) abilities and capabilities. So in real terms, failure to remain fully hydrated could actually mean that a fleeting glance or sighting of an object on the horizon will be ignored or simply written off as a wave etc.
If you want to consider the effects of dehydration in real terms then imagine this scenario; A team member has had severe D & V (Diarrhoea & Vomiting - not to be confused with David & Victoria Beckham’s Perfume / Aftershave range) for 24 hours. How would you feel about this individual being up to the job of the first night watch whilst drifting within the waters of the Somali Basin?
You’d hardly be happy about their ability to be able to concentrate would you? Would you really trust someone who’s possibly on the verge of hallucinating with a weapon?
If the above is not a scenario to your liking, then you should realise that being on watch and not keeping your own fluid intake in check is exactly the same scenario – you will not be performing at 100%.
Common Misconceptions & Myths Associated With Hydration and Heat Stress
• Tea, Coffee & Coca Cola are all to be avoided in hot climates...
This all stems from the old theory (generally accepted via research carried out in the 50’s and 60’s) that any form of caffeine can have a diuretic effect if taken in high enough quantities. The most recent and credible research (2010/2011) has debunked this a nothing more than an unfounded myth based upon anecdotal findings rather than hard scientific evidence. Tea, Coffee and Cola might not be as easily processed by the body, in the absence of water, but they still replace lost fluids and have a part to play in staying hydrated in climates where continual water consumption actually becomes a chore and monotonous...
By the way, have you ever noticed that sometimes a hot drink like a good old cup of piping hot Tea seems to quench your thirst and perk you up in no time? It’s basically due to the fact that (A) People will sit down in the shade to drink the tea and also rest and (B) That hot fluids are assimilated by the body at virtually twice the rate of cold fluids.... Hence the old trick of providing a casualty (if injuries allow) with tepid rather than cold water...
• The Body Needs at Least 2 Litres of Water a Day to Function Healthily...
This old chestnut really did the rounds from around the year 2000 onwards and was quoted by many a health guru as being sound scientifically based advice. Unfortunately, as with a lot of these well intentioned edicts, the advice was actually based upon research carried out in the UK during the 1930’s! The methodologies used to come up with this amazing 2 litre figure were way out of line with current findings and (even worse still) were actually presented as part of a study commissioned by a Spring Water Company...
• Salt Tablets are Required to Replace Lost Salts Caused by Excessive Sweating
This one is still popular with some of the ‘old and bold’ on the circuit and stems from them being literally force fed a salt tablet during trips to BATUS or Belize etc.
You will generally gain enough salt replacement from the foods you eat at meal-times and do not have to put additional salt on you food unless you actually feel the urge to!
Taking salt tablets puts a huge strain on the body and kidneys and will increase the risk of dehydration and heat stress. If you want a quick ‘pick me up’ and the opportunity is there to eat them, then eat a couple of bananas; they’re perfect for hot climates and produce a good slow release of energy as well as being packed with replacement potassium.
• I only Need to Drink When I’m Thirsty
In layman’s terms that’s almost based upon the same logic as saying “I only take a sh*t every 4-5 days – I literally wait until I have a turtles-head and am about to sh*t my kecks...!â€
Thirst is a notoriously poor indicator of your hydration status. By the time you are gagging for a drink the damage is already occurring and you are succumbing to the effects of the climate.
The actual ‘gold standard’ in hydration is to take fluids on-board at such regular intervals that you are never truly ‘gagging’ for a drink towards the end of your watch etc.
Top Tips to Stay Hydrated
The following acronym (f*cking hell there’s always an acronym or mnemonic for something isn’t there?) will help you to work in the environment we are currently operating in.
POSTCARD....
PLAN your task: avoid the worst ‘sun-traps’ or areas where exhaust fumes and additional heat are emitted from the engine... work out when it’s best to take a water break e.g. when the vessel is under steam and not whilst the nets are deployed etc....
ONLY expose yourself to direct sun-light when absolutely necessary, and even then minimise your exposure...
SHADE should be utilised at all times, as the vessel moves position then so will the shade, be ready to move your position to maximise the available shade
TEMPERATURE: Be aware of the temperature you are working in, have a good working knowledge of when it will peak and also drop within the area you are working in
CLOTHING: Wear loose fitting cotton clothing and cover your huge ****ing napper with a decent hat! Whenever you are in the shade REMOVE the hat to optimise the cooling process.
AVOID unnecessary physical exertion – no need to expand upon this one in any greater details with this team...
REST in between watches. Sounds simple, but too much time in the sun followed by an hour’s PT is simply too much to ask of your body on a 30 day rotation and will certainly lead to dehydration. You have AC, shade and cold water on tap – make the most of them!
DRINK your water at regular intervals. As a benchmark half a litre an hour should be the minimum based upon a 4 hour watch and within this climate – if you need more then drink more...!
Dehydration & Early Signs of Heat Stress
Within this section we’re going to concentrate upon the EARLY signs rather than a whole list of signs and symptoms associated with every single level of heat stress through to heat cramps and the eventual onset of heat stroke. Just to clarify, if you ever end up being face with a casualty with heat stroke it really is a genuine medical emergency and will often end up producing a casualty that is critically ill.
There is one key sign that virtually ALL of the first aid manuals and books ignore; BEHAVIOUR!
Take a look at the list below and see if you’ve witness any of these old chestnuts whilst on this deployment...
Irritability: A normally patient guy seems to develop a slightly shorter fuse than normal and may appear to ‘fly off the handle’ especially towards the end of his watch..
Inability to Concentrate: A simple task, counting / checking the link for example, seems to take longer than usual and more recounts than a Labour By-Election...
Fatigue: You can generally clock this one or identify this one within yourself or someone else without any help!
Loss of Appetite: This is a classic sign to look out for when the dehydration has progressed onto the early signs and symptoms associated with heat stress. Lack of regular food intake will lead to electrolyte imbalance and subsequently reduce energy levels and even starve the brain of the glucose it requires to function effectively.
Thirst: Too late matey! If you come off watch with a raging thirst then you’re already succumbing to the early stages of dehydration and heat stress...
Disturbed Sleep Patterns: Poor levels of hydrations are now known to be clinically linked to poor sleep quality. Somebody who is suffering from minor to moderate dehydration will generally be able to sleep for a 12 hour stint without any issues – the problem is that whilst they can do a good impression of a corpse, they do not seem to get any benefit from their sleep marathon and wake up without actually feeling refreshed and re-energised.
Urine Output: What goes in must, to a certain degree, come out! If you are taking on board regular fluids then you should also be passing water at regular intervals. Your urine should be clear in colour and you should be passing water for longer than 15-20 second intervals. If you are hardly going for a piss and, when you do, are producing something of a dark sinister and smelly nature then get some water down your neck!
Headaches: Do you really need me to tell you what a headache is lol! Seriously though, you are looking for someone with a strong ‘blinding’ frontal headache of migraine type quality if left unchecked...
