Acute Lung Injury (ALI)

Overview

Acute lung injury (ALI) or acute respiratory distress syndrome (ARDS), is a lung condition that leads to low oxygen levels in the blood. ARDS can be life threatening. This is because your body's organs, such as the kidneys and brain, need oxygen-rich blood to work properly.

ARDS usually occurs in people who are very ill with another disease or who have major injuries. Most people are already in the hospital when they develop ARDS.

To understand ARDS, it helps to understand how the lungs work. When you breathe, air passes through your nose and mouth into your windpipe. The air then travels to your lungs' air sacs. These sacs are called alveoli.

Small blood vessels called capillaries run through the walls of the air sacs. Oxygen passes from the air sacs into the capillaries and then into the bloodstream. Blood carries the oxygen to all parts of the body, including the body's organs.

In ARDS, infections, injuries, or other conditions cause the lung's capillaries to leak more fluid than normal into the air sacs. This prevents the lungs from filling with air and moving enough oxygen into the bloodstream.

When this happens, the body's organs don't get the oxygen they need. Without oxygen, the organs may not work properly or may stop working completely.

Most people who develop ARDS are in the hospital for other serious health problems. Rarely, people who aren't hospitalized have health problems that lead to ARDS, such as severe pneumonia.

 

Source: The National Heart, Lung, and Blood Institute (NHLBI)

Symptoms

The first signs and symptoms of ARDS are feeling like you can't get enough air into your lungs, rapid breathing, and low oxygen levels in the blood.

Other signs and symptoms depend on the cause of the ARDS. They may occur before ARDS develops. For example, if pneumonia is causing ARDS, you may have a cough and fever before you feel short of breath.

Sometimes, people who have ARDS develop signs and symptoms such as low blood pressure, confusion, and extreme tiredness. This may mean that the body's organs, such as the kidneys and heart, aren't getting enough oxygen-rich blood.

Most people who develop ARDS are in the hospital for other serious health problems. Rarely, people who aren't hospitalized have health problems that lead to ARDS, such as severe pneumonia.

 

Source: The National Heart, Lung, and Blood Institute (NHLBI)

Causes

ARDS can be caused by any major swelling (inflammation) or injury to the lung. Some common causes include:

• Breathing vomit into the lungs (aspiration)

• Inhaling chemicals

• Pneumonia

• Septic shock

• Trauma

ARDS leads to a buildup of fluid in the air sacs. This fluid prevents enough oxygen from passing into the bloodstream.

The fluid buildup also makes the lungs heavy and stiff, and decreases the lungs' ability to expand. The level of oxygen in the blood can stay dangerously low, even if the person receives oxygen from a breathing machine (mechanical ventilator) through a breathing tube (endotracheal tube).

ARDS often occurs along with the failure of other organ systems, such as the liver or the kidneys. Cigarette smoking and heavy alcohol use may be risk factors.

 

Source: Pubmedhealth

Prevention

People at risk for ARDS have a condition or illness that can directly or indirectly injure their lungs.

Direct Lung Injury

Conditions that can directly injure the lungs include:

• Pneumonia. This is an infection in the lungs.

• Breathing in harmful fumes or smoke.

• Inhaling vomited stomach contents from the mouth.

• Using a ventilator. This is a machine that helps people breathe; rarely, it can injure the lungs.

• Nearly drowning.

Indirect Lung Injury

Conditions that can indirectly injure the lungs include:

• Sepsis. This is a condition in which bacteria infect the bloodstream.

• Severe bleeding caused by an injury to the body or having many blood transfusions.

• An injury to the chest or head, such as a severe blow.

• Pancreatitis. This is a condition in which the pancreas becomes irritated or infected. The pancreas is a gland that releases enzymes and hormones.

• Fat embolism. This is a condition in which fat blocks an artery. A physical injury, like a broken bone, can lead to a fat embolism.

• Drug reaction.

 

Source: The National Heart, Lung, and Blood Institute (NHLBI)

Diagnosis

Your doctor will diagnose ARDS based on your medical history, a physical exam, and results from tests.

Medical History

Your doctor will ask about conditions you may have or have recently had that could lead to ARDS.

Your doctor also will ask whether you have heart problems, such as heart failure, which can cause fluid to build up in your lungs.

Physical Exam

ARDS may cause abnormal breathing sounds, such as crackling. Your doctor will listen to your lungs with a stethoscope to hear these sounds. He or she also will listen to your heart and look for signs of extra fluid in other parts of your body. Extra fluid may mean you have heart or kidney problems.

Your doctor will look for a bluish color on your skin and lips. A bluish color means your blood has a low level of oxygen. This is a possible sign of ARDS.

Diagnostic Tests

Diagnostic tests are used to find the cause of your symptoms. You may have ARDS or another condition that causes similar symptoms.

Initial Tests

The first tests done are:

• An arterial blood gas test. This blood test shows the oxygen level in your blood. A low level of oxygen in the blood may be a sign of ARDS.

• Chest x ray. This test is used to take pictures of the structures in your chest, such as your heart, lungs, and blood vessels. It can show whether you have extra fluid in your lungs.

• Blood tests, such as a complete blood count, blood chemistries, and blood cultures. These tests help find the cause of ARDS, such as an infection.

• Sputum cultures. This test looks at the spit you've coughed up from your lungs. It can help find the cause of an infection.

Other Tests

Other tests used to diagnose ARDS include:

• Chest computed tomography (to-MOG-rah-fee) scan, or chest CT scan. This test uses a computer to create detailed pictures of your lungs. It may show lung problems, such as fluid in the lungs, signs of pneumonia, or a lung tumor.

• Heart tests that look for signs of heart failure. Heart failure is a condition in which the heart can't pump enough blood to meet the body's needs. This condition can cause fluid to build up in your lungs.

 

Source: The National Heart, Lung, and Blood Institute (NHLBI)

Prognosis

About a third of people with ALI die from the disease. Survivors usually get back normal lung function, but many people have permanent, usually mild, lung damage.

Many people who survive ALI have memory loss or other problems with thinking after they recover. This is due to brain damage that occurred when the lungs weren't working properly and the brain wasn't getting enough oxygen.

 

Source: Pubmedhealth

Treatment

ARDS is treated with oxygen therapy, fluids, and medicines. Treatments are done in a hospital's intensive care unit.

The main goals of treating ARDS include getting oxygen to your lungs and organs (like the brain and kidneys) and treating the underlying condition that's causing ARDS.

Oxygen Therapy

First, your doctor will try to give you extra oxygen. Oxygen is given through a mask that fits over your mouth (or mouth and nose).

If your oxygen level doesn't increase or it's still hard for you to breathe, your doctor will give you oxygen through a breathing tube. The flexible tube will be inserted through your mouth or nose and into your windpipe.

Before inserting the tube, your doctor will squirt or spray a liquid medicine into your throat (and possibly your nose) to make it numb. This helps prevent coughing and gagging when the tube is inserted. Your doctor also will give you medicine through an intravenous (IV) line into your bloodstream to make you sleepy and relaxed.

The breathing tube will be connected to a machine that helps you breathe (a ventilator). The ventilator will fill your lungs with oxygen-rich air.

Your doctor will adjust the ventilator as needed to help your lungs get the right amount of oxygen. This also will help prevent injury to your lungs from the pressure of the ventilator.

The breathing tube and ventilator are used until you can breathe on your own. If you need a ventilator for more than a few days, your doctor may do a tracheotomy.

This procedure involves making a small cut in your neck to create an opening to the windpipe. The opening is called a tracheostomy. Your doctor will place the breathing tube directly into the windpipe. The tube is then connected to the ventilator.

Fluids

Fluids may be given to improve the flow of blood through your body and to provide nutrition. Your doctor will make sure you get the right amount of fluids.

Too much fluid can fill the lungs, making it harder to get the oxygen you need. Not enough fluid can limit blood and oxygen flow to the body's organs. Fluids usually are given through an IV line inserted in one of your blood vessels.

Medicines

Your doctor may give you medicines to prevent and treat infections and to relieve discomfort.

 

Complications from ARDS

If you have ARDS, you can develop other medical problems while in the hospital. The most common are infections, pneumothorax, lung scarring, and blood clots.

• Infections. Being in the hospital and lying down for a long time can make you prone to infections, such as pneumonia. Being on a ventilator also puts you at higher risk for infections. Infections can be treated with antibiotics.

• Pneumothorax (collapsed lung). This is a condition in which air or gas collects in the space around the lungs. This can cause one or both lungs to collapse. The pressure of the air from a ventilator can cause this condition. If you develop pneumothorax, your doctor will put a tube into your chest to remove the air and let your lung(s) expand again.

• Lung scarring. ARDS causes the lungs to become stiff (scarred) and makes it hard for them to expand and fill with air. Being on a ventilator also can cause lung scarring.

• Blood clots. Lying down for long periods can cause blood clots to form in your body. A blood clot that forms in a vein deep in your body is called a deep vein thrombosis. This type of blood clot can break off, travel through the bloodstream to the lungs, and block blood flow. This condition is called pulmonary embolism.

 

Source: The National Heart, Lung, and Blood Institute (NHLBI)

Resources

Living With ARDS

Some people fully recover from ARDS. Others continue to have health problems. After you go home from the hospital, you may have one or more of the following problems:

• Shortness of breath. After treatment, lung function in most people who have ARDS improves within 3 months and is back to normal within 6 months. For others, it may take up to a year or more. Some people have breathing problems for the rest of their lives.

• Tiredness and muscle weakness. Being in the hospital and on a ventilator (a machine that helps you breathe) can cause your muscles to weaken. You also may feel very tired following treatment.

• Depression. Many people who've had ARDS feel depressed for a while after treatment.

• Problems with memory and thinking clearly. Certain medicines and a low oxygen level in your blood can cause these problems.

These health problems may go away within a few weeks, or they may last longer. Talk with your doctor about how to deal with these problems. Also, see the suggestions below.

Getting Help

You can take steps to recover from ARDS and improve your quality of life. For example, ask your family and friends for help with everyday activities.

If you smoke, quit. Smoking can worsen lung problems. Talk to your doctor about programs and products that can help you quit. Also, try to avoid secondhand smoke and other lung irritants, such as harmful fumes.

Go to pulmonary rehabilitation (rehab) if your doctor recommends it. A rehab program can show you how to return to normal activities and stay active. Rehab may include exercise training, education, and counseling.

Your rehab team may include doctors, nurses, and other specialists. They will work with you to create a program that meets your needs.

Emotional Issues and Support

Living with ARDS may cause fear, anxiety, depression, and stress. It's important to talk about how you feel with your health care team. Talking with a professional counselor also can help. If you're very depressed, your doctor may recommend medicines or other treatments that can improve your quality of life.

Joining a patient support group may help you adjust to living with ARDS. You can see how other people who have the same symptoms have coped with them. Talk to your doctor about local support groups or check with an area medical center.

Support from family and friends also can help relieve stress and anxiety. Let your loved ones know how you feel and what they can do to help you.

 

Source: The National Heart, Lung, and Blood Institute (NHLBI)