ARDS

Overview

Acute respiratory distress syndrome (ARDS) occurs when lung swelling causes fluid to build up in the tiny elastic air sacs in the lungs. These air sacs, called alveoli, have a protective membrane, but lung swelling damages that membrane. The fluid leaking into the air sacs keeps the lungs from filling with enough air. This means less oxygen reaches the bloodstream, so the body's organs don't get the oxygen they need to work properly.

ARDS usually occurs in people who are already critically ill or have major injuries. People usually are severely short of breath — the main symptom of ARDS — within a few hours to a few days after the injury or infection that caused ARDS.

Many people who get ARDS don't survive. The risk of death gets higher with age and how severe the illness is. Of the people who survive ARDS, some fully recover. But others have lasting lung damage.

Symptoms

The seriousness of ARDS symptoms can vary depending on what's causing them and whether there is underlying heart or lung disease. Symptoms include:

• Severe shortness of breath.
• Labored and rapid breathing that is not usual.
• Cough.
• Chest discomfort.
• Fast heart rate.
• Confusion and extreme tiredness.

When to see a doctor

ARDS usually follows a major illness or injury, and most people who have ARDS are already in a hospital. But if you have symptoms of ARDS and are not in a medical facility, go to the nearest emergency department right away or call 911 or your local emergency number for help.

Causes

Causes of ARDS include:

• Sepsis. The most common cause of ARDS is sepsis, a serious and widespread infection of the bloodstream.
• Severe pneumonia. Severe cases of pneumonia usually affect all five lobes of the lungs.
• Coronavirus disease 2019 (COVID-19). People who have severe COVID-19 may get ARDS. Because COVID-19 mainly affects the respiratory system, it can cause lung injury and swelling that can lead to COVID-19-related ARDS.
• Head, chest or other major injury. Accidents, such as falls or car crashes, can damage the lungs or the portion of the brain that controls breathing.
• Breathing in harmful substances. Breathing in a lot of smoke or chemical fumes can lead to ARDS, as can breathing in vomit. Breathing in water in cases of near-drownings also can cause ARDS.
• Other conditions and treatments. Swelling of the pancreas (pancreatitis), massive blood transfusions and severe burns can lead to ARDS.

Risk factors

Most people who get ARDS already are in a hospital for another condition. Many are critically ill. People are especially at risk if they have an infection, such as sepsis or pneumonia. They're also at higher risk if they have COVID-19, especially if they also have metabolic syndrome.

People who have alcohol use disorder or who use recreational drugs or smoke ― lifestyle habits that can harm the lungs ― are at higher risk of getting ARDS. Having a history of alcohol, drug or tobacco use also raises the risk of ARDS.

Complications

ARDS can cause other medical problems while in the hospital, including:

• Blood clots. Lying still in the hospital while you're on a ventilator can make it more likely that you'll get blood clots, particularly in the deep veins in your legs. If a clot forms in your leg, a portion of it can break off and travel to one or both of your lungs, where it can block blood flow. This is called a pulmonary embolism.
• Collapsed lung, also called pneumothorax. In most people with ARDS, a breathing machine called a ventilator brings more oxygen into the body and forces fluid out of the lungs. But the pressure and air volume of the ventilator can force gas to go through a small hole in the very outside of a lung and cause that lung to collapse.
• Infections. A ventilator attaches to a tube inserted in your windpipe. This makes it much easier for germs to infect and injure your lungs.
• Scarred and damaged lungs, known as pulmonary fibrosis. Scarring and thickening of the tissue between the air sacs in the lungs can occur within a few weeks of the start of ARDS. This makes your lungs stiffer, and it's even harder for oxygen to flow from the air sacs into your bloodstream.
• Stress ulcers. Extra acid that your stomach makes because of serious illness or injury can irritate the stomach lining and lead to ulcers.

Thanks to better treatments, more people are surviving ARDS. But many survivors end up with potentially serious and sometimes lasting effects:

• Breathing problems. After having ARDS, many people get most of their lung function back within several months to several years, but others may have breathing problems for the rest of their lives. Even people who do well usually have shortness of breath and fatigue and may need extra oxygen at home for a few months.
• Depression. Most ARDS survivors also report going through a period of depression, which can be treated.
• Problems with memory and thinking clearly. Sedatives and low levels of oxygen in the blood can lead to memory loss and learning problems after ARDS. In some people, the effects may get better over time. But in others, the damage may last for the rest of their lives.
• Tiredness and muscle weakness. Being in the hospital and on a ventilator can cause your muscles to weaken. You also may feel very tired after treatment.