The Lungs

Your lungs sit behind a protective ribcage on the right and left of your chest. These soft lobe-structured organs receive air as you breathe, absorbing vital oxygen and transferring it to the rest of your body. Your lungs also defend your body from unwanted materials and remove carbon dioxide from your blood - a waste product exhaled by you.

Lung transplant facts

The first lung transplant in 1963 was a single-lung transplantation peformed on a convicted murderer.
It is possible to have a single or double lung transplant, or a simultaneous heart and lung transplant.
Rarely, a living donor can donate a section (or lobe) of their lung - this type of transplant is usually done in children.
A heart-lung transplant is a rare form of lung transplantation. It is difficult to find three perfect organs from one donor and this surgery is only performed roughly six times a year in the UK.
After lung transplants you must take special drugs called immunosuppressants. These suppress the body's immune system and help to prevent rejection of the new organs.

Common reasons for transplantation

A lung transplant can become necessary for a variety of reasons, the most common of which are:

  • Chronic obstructive pulmonary disease (COPD) - the name given to a number of diseases which damage the lungs, often caused by smoking
  • Idiopathic pulmonary fibrosis - scarring of the lungs, casued by reasons not fully understood
  • Cystic fibrosis - a genetic condition in which the lungs and digestive system get clogged with mucus, making it hard to breathe and digest food
  • Pulmonary hypertension - raised blood pressure within the pulmonary arteries - the vessels that carry blood from the heart to the lungs

How they work

When you take a breath, air travels through your windpipe (trachea) and is divided through two smaller tubes (bronchi) - one to the left lung and one to the right. This airway then divides repeatedly into smaller parts leading to millions of miniature air sacs (alveoli).

These alveoli look like tiny bunches of grapes covered in a fine mesh of blood vessels, called capillaries. The thin walls of these capillaries transfer oxygen from the alveoli to your blood - transporting this vital oxygen-rich blood around the body. Your alveoli are so numerous that your body does not need to use them all to breathe efficiently, meaning that the lung has spare resources if it becomes damaged.

Behind the trachea is a second tube (the esophagus) that transports food. To control the path of food and air, the tubes have a control gateway (the epiglottis) which prevents food or liquid from entering the trachea. If your epiglottis fails to do its job and allows food into your windpipe, it causes you to cough or choke.

Below your lungs is a muscle called the diaphragm - a major part of the breathing mechanism. The diaphragm and the intercostal muscles between your ribs work together to provide a space into which your lungs can expand, drawing air through your nose or mouth in the process.

Your lungs other parts

The airways leading to your lungs are specially designed to keep air passages moist and aid in intercepting dust and bacteria. Tiny hairs, called cilia, line the bronchi and the nose helping to waft unwanted materials up to the mouth in the form of mucus.

Each lung is made up of 'lobe' sections which are like balloons filled with sponge-like tissue. There are three lobes on the right and two on the left, because the left lung shares some space with the heart and is slightly smaller than the right.

Cells in the lungs contain enzymes that are crucial for maintaining the tissues of the lung in a healthy state.

Lung transplants

A lung transplant involves the replacement of one or both diseased lungs with the healthy lungs of a donor. People may receive a single lung, double lung or complete heart-lung transplant depending on the reasons for transplantation.

The demand for lung transplants exceeds the supply of available organs. For this reason transplants are only carried out in selected people where there is a relatively good chance of success.

Depending on the complexity of the surgey, a lung transplant normally takes between 4 to 12 hours. During this time, under a general anaesthetic, the patient has a breathing tube placed down their throat to ventilate the lungs. A chest incision is made to open the area through which surgeons will work to remove the diseased lung or lungs. Removal of the old lungs, particularly if there is a lot of scarring related to infection, is one of the most difficult parts of the operation. During this time, the blood is oxygenated by a special machine to keep the rest of the body healthy.

Once the new lung is sewn into place and the transplant team are happy that it is working well, the chest is closed and the patient is moved to an intensive care unit - although tubes are left for several days to drain the chest of any blood and fluid.

Making more lungs available

Most donations are taken from people who have died but whose heart is kept beating using life-support equipment - often these are people who have died after a long illness. These are known as donors after brain death.

There are innovations being implemented that mean more lungs become available for those who need them.

Lungs may also be used from donors who have died and their heart has stopped (donation after circulatory death) The lungs have to be assessed and removed rapidly.

Ex vivo lung perfusion - this involves pumping blood, nutrients and protein into retrieved lungs using a special piece of equipment called a 'perfusion rig'. Lungs may get damaged when the brain dies, meaning that the majority are not then suitable for donation.This new process effectively 'reconditions' the lungs, reversing much of the pre-existing injury.If this new 'perfusion rig' technique proves successful, it will mean more lungs may be available for those waiting on the transplant list.

Living donors

A donor is usually a person who has died, but in some very rare cases, a living donor (or donors) may be used who is compatible in size with the recipient and has a matching blood group.

There are often two donors for this type of lung transplant, each donating a lobe to the recipient. The lower lobe of the right lung is removed from one donor and the lower lobe of the left lung is removed from the other donor. Both lungs are then removed from the recipient and are replaced by the lung implants from the donors in a single operation.

Most people who receive lung transplants from living donors have cystic fibrosis and most donors are close relatives of the recipients. It is usually considered only when patients are too critically ill to survive the waiting list but because of the risks to the donor, this procedure is very rarely done in the UK and other countries.

Mini Glossary

  • Alveoli:
    Gas-exchanging air sacs that cluster at the end of the respiratory airways
  • Bronchi/bronchioles:
    The tubes that carry air in and out of your lungs - bronchi are larger than bronchioles.
  • Capillaries:
    The smallest of the body's blood vessels
  • Cilia:
    Tiny hair-like structures with a wave-like motion that move mucus along the airways
  • Diaphragm:
    The large dome-shaped muscle beneath your lungs
  • Epiglottis:
    A flap attached to the entrance of the larynx that regulates the path of food, liquid and air
  • Esophagus:
    The food pipe
  • Immunosupressants:
    Drugs that inhibit the activity of the body's immune system
  • Pulmonary:
    Of, or about, the lungs
  • Trachea:
    The windpipe

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