Adrenaline is a natural substance that occurs in the bodies of all humans, and it is also made as a medicine. Its official name was recently changed to ‘Epinephrine’ but many Doctors and other health care professionals still refer to it as ‘adrenaline’.
Everything in medicine has a benefit, and also a risk. The same applies to adrenaline. It can be very useful, and life-saving, but used in the wrong way, it can be extremely harmful, even lethal.
Adrenaline is used in many different ways in medicine. Outside hospital, such as on boats, adrenaline is used as an emergency treatment for two conditions: cardiopulmonary arrest (cardiac arrest) and anaphylaxis (extreme allergic reactions). This article concerns mostly the use of adrenaline in treating anaphylaxis.
How to give adrenaline – the types of Injecting device
Adrenaline can be given using an ‘auto-injector’ (the general name for injectors such as ‘Epipens’ or ‘Emerades’), as an injection directly in to a muscle (intra-muscular). This type of injection is usually concentrated adrenaline, so is a small volume (about one millilitre or less).
An alternative to auto-injectors is to draw up a dose of adrenaline from a glass vial (ampoule) using a syringe and needle – an easy thing to do, but it does need at a bit of familiarity with the process. This type of injection is usually also concentrated adrenaline (so a small volume of about one millilitre or less) and is usually given intra-muscularly.
The other type of injection of adrenaline is from a larger 10ml pre-filled syringe, often used in states of cardiac arrest by doctors in hospital, and by paramedics. This injection is given directly in to a vein (intra-venous). This more dilute mixture is useful when smaller doses of adrenaline are being used.
The routes to give adrenaline – intramuscular and intravenous injections
This is important. Intramuscular injections cause a slow rise of adrenaline in the circulation, whereas an intravenous injection causes a very rapid rise in adrenaline levels in the circulation.
If an intramuscular injection is given in to a vein by accident, it can prove fatal to the patient. All the adrenaline will arrive at the heart in one go, potentially causing it to stop.
The other problem is that if an intramuscular injection is given in to the fat layer below the skin, it will just stay there and not go in to the general circulation. Therefore it will not do the job its supposed to do, and the patient will not get the benefit.
On a boat, the most likely problem to be treated with adrenaline is anaphylaxis, and the route used would be intramuscular.
To avoid injecting in to the fat layer rather than the underlying muscle, it’s important the auto-injector has a long needle, and there is evidence to suggest that shorter needles are more likely to be ineffective in injecting adrenaline to where it is needed.
Which muscle to inject in to may also be important. Certainly the gluteus muscle (the bottom!) has a significant amount of fat covering it, as may the thigh muscles. However, the upper shoulder may not have such a substantial fat layer, and also provides quite easy access. So the upper shoulder may be quicker to access, and also prove to be more effective in making sure the adrenaline reaches the central circulation.
How much adrenaline to give
In anaphylaxis, the amount of adrenaline to give is related to the size of the patient.
- For children under 20kg body mass (under 6 years old), the dose is 0.15 milligrams.
- For children between a body mass of 20kg and 30kg (6 – 12 years old), the dose is 0.3 milligrams.
- For larger children and adults with a greater body mass that 30kg (over 12 years old), the dose is 0.5 milligrams.
Some makes of auto-injector include all three amounts of adrenaline and this is a distinct advantage.
Repeat injections may be required every ten to fifteen minutes if there is no improvement or symptoms persist. So more adrenaline injections may be required.
Auto-injectors vs manual draw-up adrenaline.
There are advantages and disadvantages to both auto-injectors, and the manual draw-up of adrenaline in to a syringe from a glass vial. Here is a brief summary:
- Relatively easy to use and quick
- Dose is in the syringe ready to go – reduces the risk of mistakes in drawing up
- Once used, it cannot be used again for repeat dosing
- Very expensive
- Short shelf-life – so needs to be replaced often as they go out of date
- Manual draw-up
- Much more adrenaline can be carried in a compact space, so repeat dosing can be achieved if necessary
- Cheaper than auto-injectors
- Generally longer shelf-life than auto-injectors
- Requires more training to use reliably
- More potential for mistakes in dosing than auto-injectors
First of all, prevention is better than cure.
Find out if any of the crew or guests have a medical history of anaphylaxis, and make sure they stay clear of known triggers.
Be prepared – if anyone does have a history of anaphylaxis, make sure there is adrenaline in the medical kit, and that you know how to use it.
Consider carrying a selection of auto-injectors, covering the three doses mentioned above, especially if there are children on-board.
Also carry a back-up supply of adrenaline in glass vials (ampoules) for manual draw-up in case it is required.
Make sure the auto-injectors have long needles so that injections do not end up in fat but go in to muscle, where the adrenaline may do some good.
Keep your training up to date.
Dr Briggs October 2017
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