Circulation Problems

The Circulatory System

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The circulatory system

The circulatory system consists of a closed network of tubes (arteries, veins and capillaries) connected to a pump (the heart).

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Carry blood away from the heart. They have strong, elastic, muscular walls which are able to expand as blood from the heart beating surges through. The largest artery, which connects directly to the heart, is called the ‘aorta’.

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Carry blood away from the heart. They have strong, elastic, muscular walls which are able to expand as blood from the heart beating surges through. The largest artery, which connects directly to the heart, is called the ‘aorta’ and carries blood towards the heart. They have thinner walls than arteries because the blood in them is under less pressure. They have one-way valves, which keeps blood flowing towards the heart. The largest veins, which connect to the heart, are called ‘vena cava’.


Are the tiny blood vessels between the arteries and veins which allow the transfer of oxygen, carbon dioxide and nutrients in and out of the cells of the body.

The Heart

Is a four-chambered pump. The left and right sides of the heart are separate. The left side takes blood from the lungs and pumps it around the body. The right side takes blood from the body and pumps it to the lungs. The two sides of the heart are separated into two chambers called the ‘atria’ and the ‘ventricles’. The atria are the top chambers which collect blood as it returns from the lungs and the body and pump it to the ventricles. The ventricles then pump the blood out of the heart, to the lungs and around the body.

The Blood

60% of the blood consists of a clear yellow fluid called plasma. Suspended within the plasma are red blood cells, white blood cells, platelets and nutrients.

Red Cells Contain haemoglobin, which carries oxygen for lIse by the cells of the body. Red cells give the blood its colour.

White Cells Fight infection.

Platelets Trigger a complicated chemical reaction if a blood vessel is damaged, forming a clot.

Nutrients Are derived from the food by the digestive system. When combined with oxygen in the cells of the body, they provide vital energy, keeping the cell alive.

The blood carries carbon dioxide (the waste gas produced by the cells) mainly in the form of ‘carbonic acid’. Carbonic acid is diluted within the plasma.

The blood also circulates heat (generated mostly by the liver) around the body. Heat is carried to the skin by the blood if the body needs to be cooled.

The Pulse

Every time the heart contracts a pulsation of blood is pumped through the arteries.

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The walls of the arteries are elastic and expand as the blood flows rhythmically through. This expansion can be felt at the points where arteries come close to the skin.

When checking a pulse use the pads of the fingers, not the thumb (which has i ts own pulse). The First Aider should make a note of the following:

Rate Is it fast or slow? How many beats are there per minute?

Rhythm Are the beats regular? Are there any ‘missed’ beats?

Strength Does the pulse feel strong or weak?

The main pulse locations for first aid use are in the neck (carotid pulse), the wrist (radial pulse) and the upper arm (brachial pulse).

Capillary refill

Circulation to the end of an arm or leg can be checked by squeezing the tip of a finger or toe. The skin will become pale when it is squeezed, if the circulation is effective, the colour should return within 2 seconds of releasing it (this may take longer if the hands or feet are cold).

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Angina (angina pectoris) is a condition usually caused by the build up of a cholesterol plaque on the inner lining of a coronary artery. Cholesterol is a fatty chemical which is part of the outer lining of cells in the body. A cholesterol plaque is a hard, thick substance caused by deposits of cholesterol on the artery wall. Over time, the build up of the plaque causes narrowing and hardening of the artery.

During exercise or excitement, the heart requires more oxygen, but the narrowed coronary artery cannot increase the blood supply to meet this demand. As a result an area of the heart will suffer from a lack of oxygen. The patient will feel pain in the chest (amongst other symptoms) as a result.

Typically, an angina attack occurs with exertion, and subsides with rest. If the narrowing of the artery reaches a critical level, angina at rest (called ‘unstable angina’) may result. A patient with angina, especially ‘unstable’ angina has a high risk of suffering a heart attack in the near future.

Heart attack

Heart attack (myocardial infarction) is often caused when the surface of a cholesterol plaque in a coronary artery cracks and has a ‘rough surface’. This can lead to the formation of a blood clot on the plaque, which completely blocks the artery resulting in the death of an area of the heart muscle.

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Unlike angina, the death of the heart muscle from heart attack is permanent and will not be relieved by rest.

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Possible signs and symptoms

It should be remembered that every heart attack is different. Only a few of the signs and symptoms may be present, indeed up to a quarter of heart attacks suffered are ‘silent’ without any chest pain.

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Treatment of angina and heart attack

Sit the casualty down and make them comfortable. Do not allow them to walk around. A half sitting position is often the best.

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  • Allow the casualty to take their own glyceryl tri-nitrate (G. T.N.) medication if they have it.
  • Reassure the casualty.
  • Remove any cause of stress or anxiety if possible.
  • If you suspect heart attack, check the casualty is not allergic to aspirin, older than 16 and not already taking ‘anti-coagulant’ drugs (such as warfarin). If this is the case, allowing them to chew an aspirin tablet slowly may be beneficial. If you are unsure however, wait for the ambulance crew to arrive (see note, below right).
  • NOTE: Aspirin reduces the clotting ability of the blood. Chewing the tablet allows the drug to absorb quickly into the blood through the skin of the mouth, so it works faster. The ideal dose is a 300 mg aspirin, but any strength will do.
  • Monitor the casualty, if a heart attack victim becomes unconscious it is very likely that the heart has stopped altogether, so be prepared to perform CPR!

Dial 999 for an ambulance if:

  • You suspect a heart attack.
  • The casualty has not been diagnosed as having angina.
  • The symptoms are different, or worse than the patients’ normal angina attacks.
  • Angina pain is not relieved by the patients’ medication and rest after 15 minutes.
  • You are in any doubt.

Left Ventricular Failure

Left ventricular failure (LVF) is a condition where the left ventricle of the heart is not powerful enough to empty itself. The right chamber of the heart is still working properly and pumping blood into the lungs. This results in a ‘back pressure’ of blood in the pulmonary veins and arteries of the lungs. Fluid from this back pressure of blood seeps into the alveoli causing severe difficulty in breathing.

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The condition can be caused by heart attack, chronic heart failure or high blood pressure. Patients with chronic heart failure often suffer attacks during the night.

Possible signs and symptoms

  • Severe difficulty in breathing.
  • Crackly, often wheezy breathing (fluid on in the lungs).
  • Pale sweaty skin.
  • Cyanosis (blue grey tinges to skin and lips).
  • Coughing frothy, blood stained sputum.
  • Possibility of the signs and symptoms of heart attack.
  • The patient needs to sit up to breathe.
  • Anxiety, confusion, dizziness.


  • Sit the patient up, feet dangling.
  • Dial 999 for an ambulance.
    Allow the patient to take their own glyceryl tri-nitrate (G. T.N.) medication if they have it.
  • Be prepared to resuscitate – the condition can quickly deteriorate.


To most people the word shock means an unpleasant surprise, an earthquake, or what happens if you mess about with the electrics!

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The medical term shock is defined as ‘inadequate tissue perfusion, caused by a fall in blood pressure or blood volume.

‘Inadequate tissue perfusion’ means an inadequate supply of oxygenated blood to the tissues of the body.

Now that you understand what shock is, you can understand why it can quickly result in death if not treated.

The more common causes of ‘life threatening’ shock are:

  • Hypovolaemic Shock
  • Cardiogenic Shock
  • Anaphylactic Shock

Hypovolaemic shock

Hypo means low                vol means volume               aemic means blood

This type of shock is caused by loss of body fluids, which results in a low volume of blood.

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Typical causes of hypovolaemic shock are:

  • External bleeding.
  • Internal bleeding.
  • Burns.
  • Vomiting and diarrhoea (loss of body fluids).
  • Excessive sweating.

Possible signs and symptoms

The first response is release of adrenaline, this will cause:

  • A rise in pulse rate.
  • Pale, clammy skin (for dark skinned casualties
    look at the colour of skin inside the lips).

As the condition worsens

  • Fast, shallow breathing.
  • Nausea or vomiting.
  • Rapid, weak pulse.
  • Dizziness and weakness.
  • Cyanosis (grey blue tinges to skin and lips).
  • Sweating.

As the brain suffers a lack of oxygen

  • Deep, sighing breathing (air hunger).
  • Unconsciousness.
  • Confusion, anxiety, even aggression.


  • Treat the cause of the shock (e.g. external bleeding).
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    Lay the casualty down and raise their legs in the air, returning blood to the vital organs (take core if you suspect a fracture).
  • Dial 999 for an ambulance.
  • Keep the casualty warm.
  • Place a coat or blanket under the patient if they are on a cold surface, but take care not to overheat them (as that would dilate blood vessels, causing the blood pressure to fall even more).
  • Do not allow the patient to eat, drink or smoke.
  • Loosen tight clothing around the neck, chest or waist.
  • Monitor breathing, pulse and levels of response.
  • Be prepared to resuscitate.

Cardiogenic shock

This is a fall in the blood pressure, caused by the heart not pumping effectively. This is the most common type of shock.

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Typical causes of cardiogenic shock are

  • Heart attack.
  • Cardiac failure.
  • Heart valve disease.
  • Tension pneumothorax.
  • Cardiac arrest.

Possible signs, symptoms and treatment

See ‘Heart Conditions’ above.

Anaphylactic shock

Anaphylaxis is an extremely dangerous allergic reaction caused by a massive over-reactionof the body’s immune system (see page 1 8).

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An anaphylactic reaction can cause shock because the large quantity of histamine released in the body makes

  • Blood vessels dilate (causing a fall in blood pressure).
  • Blood capillary walls become ‘Ieaky’ (causing a fall in blood volume).
  • The strength of the heart’s contractions weaker (causing a fall in blood pressure).

Possible signs, symptoms and treatment

See Anaphylaxis.


Fainting is caused by poor nervous control of the blood vessels and heart.

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When a casualty faints, the blood vessels in the lower body dilate and the heart becomes slow. This results in the blood pressure falling and the patient has a temporary reduction in blood supply to the brain.

Typical causes of fainting are

  • Pain or fright.
  • Lack of food.
  • Emotional stress.
  • Long periods of inactivity (such as standing or sitting).
  • Heat exhaustion.

Possible signs and symptoms

  • Temporary loss of consciousness,
    falling to the floor.
  • Slow pulse.
  • Pale, clammy skin.
  • Before the faint the casualty may have suffered nausea, stomach ache, blurred vision or dizziness.
  • Quick recovery.

Treatment of fainting

Lay the casualty down and raise their legs in the air, returning blood to the vital organs.

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  • Check Airway and Breathing.
  • Remove causes of stress, crowds of people and allow plenty of fresh air.
  • Reassure the casualty as they recover. Do not allow the to sit up suddenly.
  • If they feel faint again, repeat the treatment.
  • Look for an underlying cause.

If the casualty does not recover quickly or you are unsure, check airway and breathing again, place them in the recovery position and dial 999 for an ambulance.

Book Your First Aid Training

These lessons and information do not replace actual attendance on a first aid course, getting hands on practice with your first aid skills is the best way to ensure you are a competant and capable first aider.

If you would like to book a first aid course or if you have a question for us please call 0191 7166601, email or complete our online enquiry form and a member of the team will get back to you shortly.

We provide workplace onsite training for Emergency First Aid, First Aid at Work and Paediatric First Aid but a range of other First Aid Courses across the North East, our first aid training centre is based in South Shields

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