Adrenaline is an example of how the body uses one hormone (and medication) to achieve multiple effects in the body. 

We use adrenaline in everyday dentistry. It’s found in local anaesthetic to help the numbness last longer. Its concentration is 1:100,000. The effect of Adrenaline, when injected in with the local anaesthetic into soft tissue, is to cause the surrounding blood vessel to close down. This prevents the anaesthetic to be carries away by the blood vessels, mainly the veins, from the injection site area. There are micro muscles in the small veins that contract or spasm when they come into contact with this hormone. 

However when Adrenaline comes into miro-arteries there also is a micro muscle that also spasm/contacts and stops blood flow to the area. The skin/gum can white in colour. We sometimes use this property by injecting a small amount into a bleeding gum to stop the blood flow. 

In the mouth we can get away with the effects of changes in blood flow without it causing damage as there are plenty of other (or collateral) blood vessels that can nourish the area. Because of this we NEVER use a local anaesthetic with Adrenaline to numb a finger or toe tip as there is no collateral blood vessels. The hormone shuts all the blood vessel in small local area and starves the site of blood for up to four hours. These tips of the body die and do not recover. 

Another effect of Adrenaline is if it’s injected into a vein. Sometimes this happens in dentistry as vein may be in places where they usually are not present. The anatomy of people can vary greatly in some of us! Adrenaline then travels directly to the heart. Its affect here is to make the heart beat faster. The effect does not last long as the amount is small and fleeting as the blood flow is quicker than in local soft tissue.

Adrenaline also counteracts the effects of histamine that is released by the in a severe irritation causing inflammation.

Here is the amazing property of Adrenaline in a medical emergency. When this hormone reaches the tubes of various sizes in the lungs (called the Bronchus or airways), they actually open up more. The micro muscles in the tube contact to make to tube diameter larger and thereby allowing more oxygen into the lungs. 

These properties of Adrenaline need to be considered when treating Anaphylaxis.

Anaphylaxis is a fast moving condition that needs to be monitored closely. The swelling and inflammatory response to the allergens (range from bee stings, antibiotics, aspirin, latex, and other medications; to all sorts of substances) begins to spread quickly throughout the body.

Anaphylaxis is a serious allergic reaction that is rapid in onset and may cause death. It typically causes more than one of the following: an itchy rash, throat or tongue swelling, shortness of breath, vomiting, light-headedness, and low blood pressure. These symptoms typically come on in minutes.

CALL THE AMBULANCE

Histamine is the substance that is release by mast cells in the body to fight the threat of the allergens. These cells are found throughout the body. Adrenaline counteracts the effects of histamine; however each application only lasts 3-5 minutes. That is why EpiPens are not useful in this situation as it’s a single dose and that’s it.

ADMINISTER ADRENLAINE 1:1000 IM (intra-muscular) IMMEDIATELY 

The red bag emergency kit has glass vials of Adrenaline at 1:1000 (1mg/ml) concentrations. The Adrenaline is drawn out of the vials with a 1ml syringe and injected into the thigh muscle even through clothing. 

• ADULT 0.5ML 
• CHILD  0.25ML

Repeat dose every 3-5 minutes until signs and symptoms clear up.   

Now when we use Adrenaline, we use the thick thigh muscle for an intramuscular injection. This allows the hormone to soak into blood vessels. To ensure this is the case, we draw back on the needle BEFORE we inject, to make we are not in a vein. That means NO BLOOD is drawn up into the needle. Otherwise the Adrenaline will go straight to the heart and make it beat faster and not be a gradual but effective release over the next 3-5minutes. Remember the concertation in dental anaesthetic is 1:100,000. The hormone concentration for Anaphylaxis is 100 times stronger!

So as to not cause damage of the muscle with prolonged use of Adrenaline, we use the other leg to inject the next dose. The go back to the first leg and use a different site on the thigh.

If the Adrenaline it can cause severe stinging or burning in your eyes, wash with saline if possible immediately.