First aid is the initial assistance given to a person who has taken ill suddenly or has been injured in an accident.

The aims and objectives of first aid may be summarised as preserving life, preventing further harm and promoting recovery.

In any first aid situation, the priority in terms of the casualty is always to ensure they have a clear airway and are able to breathe. However, the rescuer first needs to make sure the environment is safe.

Having a basic understanding of how the body works will enable the first aider to understand what is happening to the casualty and why the actions they take actually assist the casualty.

Oxygen is required by all the cells in the body. Without it, we die. In first aid, efforts are made to ensure oxygen continues to reach vital organs.

Oxygen is breathed in, and is then circulated around the body in the blood by the pumping action of the heart. If breathing or circulation is affected by illness or injury, this will result in body tissue being deprived of oxygen and it will be permanently damaged or even die. Brain cells start to die off after a few minutes. Without oxygen, the heart stops working.

Blood vessels that carry the oxygenated blood to the tissues are called arteries. When an artery is cut the blood spurts out with each heartbeat and, because it contains oxygen, it is bright red. Blood vessels that take blood back to the heart are called veins. When these are cut the blood is not under such great pressure and does not contain oxygen, so it is a darker red and does not spurt, but flows or gushes out. Capillaries are the smallest blood vessels and when they are damaged they ooze blood.

When a casualty is bleeding it is important to recognise which type of bleeding is happening, as this will dictate the speed of action taken.

The musculoskeletal system is made up of bones, muscles, tendons and ligaments. The skeleton provides a framework to support and move the body and also gives some protection to internal structures. Muscles move the skeleton and are attached to bones by tendons. Ligaments bind bone ends together in joints and also support internal organs.

A first aider does not need to know the individual names of these different structures. When describing an injury it is best to use simple terminology such as “thigh” or “upper arm”.

At any first aid incident, the rescuer will follow a plan of action. This will take place in any setting, either afloat or ashore. The situation and casualty will be assessed, help sought, the casualty treated and any aftermath dealt with. The time it takes, and the methods used, may change according to the circumstances and the severity of the situation, but this process will always be carried out.

Assessing the situation	Check that there is no danger to self or the casualty, and if there is, make it safe. Remember that the danger may not be obvious. Think hygiene and personal safety. Think about the immediate space around your casualty (e.g. spillages on deck, trip hazards, broken glass, wood splinters). Think about the dangers peculiar to your own environment (e.g. swinging boom, open hatches, loose ropes, rough seas). Look for clues to work out what has happened.
Assessing the casualty	The initial assessment of your casualty is called the primary survey. This is the priority in any first aid situation. Does the casualty have an airway? Is the casualty breathing? Remember that if the casualty is able to speak or make sounds, they are breathing. What injuries are there? Can you see any obvious bleeding or broken bones? What can the casualty tell you?
Getting help	Shout for help so others on board are alerted. Ensure everyone on board knows how to summon help on the radio in an emergency. When calling for help, the information required will be the identity of the yacht and your location, what has happened and what help is required, how many casualties there may be and what their injuries are.
Treating the casualty	Constantly be aware of any danger to you and your casualty while treating them. Remember: the priorities of first aid are AIRWAY and BREATHING. This book shows how to recognise and carry out basic treatments for a number of injuries and illnesses.
Dealing with the aftermath	This includes the completion of reports in log books, restocking first aid kits, and cleaning up body fluid spillages in a safe manner. As well as dealing with practical issues, consideration needs to be given to emotional needs. If a major incident has been dealt with, this can be very traumatic for all involved. Though you may react well and deal with the situation at the time, afterwards it is important not to be afraid to talk about how you feel.

After assessing and treating any obvious injuries a casualty may have, it is important to check them over physically in case they have sustained other injuries.

The secondary survey establishes what other injuries the casualty may have that were not identified initially. The casualty may be able to tell you but you may have to search for them. The secondary survey is also called the “top to toe” or “head to toe” survey because it describes what the first aider does.

The first aider should work down the body from the head, feeling for lumps and bumps and looking for wounds. Note if it is tender to touch anywhere. Ideally, this should be done wearing gloves to protect the rescuer from contact with blood or other body fluids.

As well as looking for other injuries, the survey may help to establish the reason why someone has become ill or is unconscious. The first aider becomes a detective. Items found in the casualty’s pockets or smells on the casualty’s breath may help identify the problem.

If a casualty is unconscious they should be placed in the recovery position before the secondary survey is carried out.

While waiting for help to arrive, you will need to monitor the condition of the casualty. You may need to write down what you find, or get someone else to do it for you. The frequency will depend on the condition of the casualty but usually most observations will be done every ten minutes. Breathing checks will be more frequent than this. Your checks will include the following.