Fluid on the lung – causes and treatment

Fluid on the lung sounds serious and it is. If the tiny air sacs inside the lungs become waterlogged, this produces pulmonary oedema, a frightening condition that causes severe breathing difficulties, coughing, anxiety and distress. Fluid accumulation outside air sacs, in the pleural cavity, leads to a different type of fluid on the lung called pleural effusion. Both problems can result from a variety of underlying health conditions and getting the right treatment depends on a detailed and accurate diagnosis.

This article on fluid on the lung is written by Kathryn Senior, a freelance journalist who writes health, medical, biological, and pharmaceutical articles for national and international journals, newsletters and web sites.

Fluid on the lung: pulmonary oedema

When we breathe in, air fills up the air sacs in the lungs and oxygen from that air dissolves in the natural layer of fluid on the lungs. Once in solution, it passes across to the nearby blood vessels and is taken to the heart to be pumped around the body to supply cells and tissues. Waste carbon dioxide also passes out of the blood and into the alveoli, becoming a gas once more to be breathed out.

Maintaining a thin layer of fluid on the lung is therefore necessary but underlying health conditions or infections can cause large amounts of fluid to accumulate, causing pulmonary oedema. This makes it difficult to get enough air into each individual air sac and also makes the transfer of oxygen and carbon dioxide much less efficient. In severe cases, there is so much fluid on the lung that the person affected is literally drowning in their own tissue fluid.

Fluid on the lung: pleural effusion 

The delicate lungs are protected by a pair of membranes – the pleural membranes. One is right up against the outer surface of the alveoli and the other lines the chest wall. Sandwiched between is a very thin layer of fluid that allows the two membranes to slide over each other as the chest wall moves as we breathe in and out. The whole lot is then enclosed by the rib cage, associated muscles and, finally, skin.

Many different health problems cause an excess of fluid to build up between the two pleural membranes. This is an enclosed space and when there is any significant increase in fluid the inner membrane starts to bulge. This causes pressure on the delicate lung tissue, leading to pain and breathlessness, although breathing difficulties tend not to be as severe as in pulmonary oedema.

What causes fluid on the lung? 

The reasons for excess fluid on the lung are different for pulmonary oedema and pleural effusion:

• Pulmonary oedema can be the result of very high blood pressure, heart problems that affect the left side of the heart, such as valve problems or a heart attack, acute kidney failure, acute respiratory problems, altitude sickness, radiation poisoning, obstruction of the upper airways or liver failure.

• Pleural effusion can be due to a severe lung infection, such as pneumonia or tuberculosis, or can arise because of inflammation caused by lung cancer. Other common causes include heart failure, cirrhosis of the liver, rheumatoid arthritis and kidney disease.  

What does fluid on the lung feel like?

When excess fluid on the lung is present inside the lung tissues the person affected finds it very difficult to breath and is usually pale, or even blue. They are usually distressed and very anxious and it is common to also feel sick and be ‘in a cold sweat’. The body reacts to fluid on the lung by trying to cough it out, particularly in the early stages. People with pulmonary oedema often produce characteristic frothy and pink sputum.

Having excess fluid in the pleural cavity causes much less extreme effects. Some people with this form of fluid on the lung don’t have any obvious breathing difficulties or pain but they might have a fever if pneumonia is the root cause. Because pleural effusion is a symptom in itself, the signs of fluid on the lung may be masked by more serious symptoms that affect other organ systems.

Treating fluid on the lung: pulmonary oedema 

Emergency treatment is essential to reduce the fluid on the lung and can be life saving. Oxygen or artificial ventilation, drugs to treat underlying heart failure and improve heart function, diuretics to treat fluid retention and surgery to replace a faulty heart valve, or even the whole heart may be necessary.

In severe cases, this high intensity medical care to help resolve the cause of the excess fluid on the lung may turn into more palliative care to try to make someone as comfortable as possible as they face the end of their life. Around 40% of people with severe pulmonary oedema die in hospital.

Treating fluid on the lung: pleural effusion

Small amounts of fluid on the lung can be monitored but often don’t need specific treatment if the underlying condition is managed successfully. If antibiotics start to clear up a lung infection, or kidney disease is treated by dialysis, for example, this type of fluid on the lung tends to disappear on its own. If there is a lot of fluid and it is causing problems, it can be drained by putting a thin tube through the chest wall and sometimes talcum powder is used to help the pleural membranes stick together again.