Acute Respiratory Distress Syndrome (ARDS)

Acute respiratory distress syndrome (ARDS) occurs when the millions of tiny air sacs in the lungs, called alveoli, fill with excess fluid. This can be the result of any kind of injury to or illness in the lung.

Key Info

  • ARDS occurs when the air sacs in the lungs, the alveoli, fill with fluid. This prevents adequate oxygen transfer into the blood
  • Medical Treatment for ARDS includes supplemental oxygen, mechanical ventilation, or extracorporeal membrane oxygen (ECMO)
  • ECMO functions as an artificial lung, providing blood with oxygen and returning it to the body

In healthy lungs, the alveoli fill with inhaled air, transferring oxygen into the blood carried by small neighboring vessels. The oxygen-rich blood can then travel throughout the body to deliver its cargo to the kidneys, brain, liver, and other organs. 

Certain lung conditions or injuries can cause the body to initiate an inflammatory response, sending excess fluid to the lungs. When fluid accumulates in the alveoli, they can no longer fill with air, and oxygen cannot pass as easily into the blood. This is called acute respiratory distress syndrome, or ARDS.

Soon after the initial injury or illness, blood oxygen levels decline, and breathing becomes fast and difficult as the body tries to compensate. There may also be signs such as confusion or low blood pressure that result from the vital organs not getting enough oxygen. In some cases, the lung may try to heal itself, creating scar tissue that decreases the lung's elasticity and makes it still harder to breathe.

Conditions that can lead to ARDS include:

  • Pneumonia
  • Trauma
  • Sepsis
  • Inhalation of stomach contents
  • Inhalation of smoke

Medical Treatment for ARDS

The first goal in treating ARDS is to increase oxygen levels in the blood so that organs function better. Three main ways to provide more oxygen are:

  • Supplemental oxygen. For milder symptoms or as a temporary measure, oxygen may be delivered through a mask that fits tightly over the nose and mouth.
  • Mechanical ventilation. Most people with ARDS need the help of a machine to breathe. A mechanical ventilator pushes air into the lungs and forces some of the fluid out of the air sacs.
  • Extracorporeal membrane oxygenation. In this process, the blood is removed from the body and oxygenated externally before it is returned.


Extracorporeal membrane oxygenation (ECMO) is a term used to describe a circuit outside the body ("extracorporeal") that directly oxygenates and removes carbon dioxide from the blood. ECMO functions as an artificial lung working in addition to the failing lungs.

When ECMO is used for respiratory failure, a catheter is placed in a central vein, usually near the heart. A mechanical pump draws blood from the vein into the circuit, where the blood passes along a membrane (referred to as an "oxygenator" or "gas exchanger"), providing an interface between the blood and freshly delivered oxygen.

The blood may be warmed or cooled as needed, and is returned either to a central vein ("veno-venous ECMO") or to an artery ("veno-arterial ECMO"). Veno-venous ECMO provides respiratory support alone, while veno-arterial ECMO provides both respiratory and hemodynamic (blood pressure) support. Examples of scenarios where ECMO may benefit include the following:

  • In cases of life-threatening acute respiratory failure with profound gas exchange abnormalities, ECMO may be used as salvage therapy.
  • ECMO may also be used in those with ARDS who would benefit from lung-protective ventilation strategies but who are unable to tolerate such strategies.

In addition to receiving oxygen therapy, people with ARDS are given medication to:

  • Prevent and treat infections
  • Relieve pain and discomfort
  • Prevent clots in the legs and lungs
  • Minimize gastric reflux

Next Steps

If you need help for a lung or chest issue, we’re here for you. Call (212) 305-7771 or request an appointment online to get started today.

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