Acute Respiratory Distress Syndrome (ARDS) is an acute, severe injury to most or all of both lungs. Patients with ARDS experience severe shortness of breath and often require mechanical ventilation (life support) because of respiratory failure. ARDS is not a specific disease; instead, it is a type of severe, acute lung dysfunction that is associated with a variety of diseases, such as pneumonia, shock, sepsis (a severe infection in the body) and trauma. ARDS can be confused with congestive heart failure, which is another common condition that can also cause acute respiratory distress.  The term Acute Lung Injury "ALI" is sometimes used in the same setting as ARDS, but also includes less severe instances of generalized, acute lung injury.

To understand ARDS, it is important to review how the lungs work. Air, which contains oxygen, is inhaled through the nose and mouth, and passes into the windpipe (trachea). From the trachea, air flows through tubes called bronchi into microscopic air sacs called alveoli. Very small blood vessels (capillaries) are imbedded in the walls of these air sacs. Oxygen passes through the thin walls of the alveoli into the bloodstream. Carbon dioxide, a waste product of cellular function throughout the body, passes from the bloodstream into the alveoli and then is exhaled.
 

At the onset of ARDS, lung injury may first appear in one lung, but then quickly spreads to affect most of both lungs.  

When alveoli are damaged, some collapse and lose their ability to receive oxygen. With some alveoli collapsed and others filled by fluid, it becomes difficult for the lungs to absorb oxygen and get rid of carbon dioxide.  Within one or two days, progressive interference with gas exchange can bring about respiratory failure requiring mechanical ventilation.

As the injury continues over the next several days, the lungs, fill with inflammatory cells derived from circulating blood and with regenerating lung tissue.  Fibrosis (formation of scar tissue) begins after about 10 days and cam become quite extensive by the third week after onset of injury.  Excessive fibrosis further interferes with the exchange of oxygen and carbon dioxide.  The sequential stages of ARDS are described in further detail below.

The first is a direct physical or toxic injury to the lungs. Examples include inhalation of vomited stomach contents (aspiration), smoke or other toxic fumes, and a severe 'bruising' of the lungs that usually occurs after a severe blow to the chest.

The second mechanism is more common, but less understood. This is an indirect, blood-born injury to the lungs. When a person is very sick or the body is severely injured, some chemical signals are released into the bloodstream. These signals reach the lung, and the lung reacts by becoming inflamed, thus causing lung failure. Examples of this type of indirect lung injury include the presence of severe infection (sepsis) and severe injury (trauma) - the two most common factors in ARDS cases. Other examples are severe bleeding (resulting in massive blood transfusions), severe inflammation of the pancreas (pancreatitis) and some types of drug overdoses.

Not everyone who has these problems, however, develops ARDS, which is fortunate, since all of the above problems are common. There are no easy answers as to why some patients with sepsis or trauma develop ARDS and others do not.

No one can predict with any certainty who will get ARDS and who will escape it. This unpredictable nature makes ARDS a complication of other illnesses that may be serious enough by themselves.

ARDS has generally been characterized into three stages. In full-blown cases, these three stages unfold sequentially over a period of several weeks to several months.

Some experts recognize a fourth phase of ARDS. This is the period longer than six to twelve months after onset, when some patients experience continued health problems caused by the acute illness. These problems may include cough, limited exercise tolerance and fatigue. Others experience anxiety, depression and flashback memories of their critical illness, which are very similar to post-traumatic stress disorder. This fourth phase is incompletely characterized, and is very much in need of research.

Treatment primarily involves supportive care in an intensive care unit (ICU), including use of a mechanical ventilator (vent) and supplemental oxygen. The goal of mechanical ventilation is to support the patient's breathing during the time needed for the patient's lungs to heal. Good progress has been made recently in improving the use of ventilators. For the most recent information regarding lower tidal volumes used in ventilation you will want to discuss with your physician an article titled, "Ventilation with Lower Tidal Volumes as Compared with Traditional Tidal Volumes for Acute Lung Injury and the Acute Respiratory Distress Syndrome" which was provided by the ARDSNetwork. This article was published in the New England Journal of Medicine in the May 4, 2000 issue and you may find this journal in your hospital library. Using this technique has shown a decrease in mortality.

ARDS patients frequently receive medications to reduce anxiety and discomfort and help conserve energy. Sometimes, these medications make patients very sleepy.

The use of paralytic drugs has been substantially reduced in recent years. Only a small percentage of ARDS patients need this treatment. The use of the many adjuncts to ARDS management are tailored to the individuals and depend on severity of illness and other factors.

Medications are used to reverse the underlying condition if possible, to prevent and treat complications of critical illness, and to alleviate patient distress, such as pain, air hunger, anxiety and severe confusional states. Antibiotics are commonly used to treat confirmed or suspected infections. Vasopressors (“pressors”) such as dopamine or Neosynephrine may be needed to maintain adequate blood pressure. Pain relievers such as morphine and fentanyl and anti-anxiety drugs such as Ativan or Versed are usually required to improve patient tolerance of mechanical ventilation. Other medications may be used to prevent bleeding from the stomach or to reduce the risk of blood clot formation in the veins of the legs or arms. After the first 2 or 3 days, patient nutrition is resumed, if possible. Until the patient can eat again by mouth, food is given in liquid form into a central vein (total parenteral nutrition “TPN”) or into the stomach or intestine through a feeding tube (total enteral nutrition “TEN”) If liquid feeding is required for longer than one or two weeks, a surgical procedure may be performed to place a tube through the abdominal wall directly into the stomach or intestine (“G-tube”, “J-tube”, or “PEG”).

MORE ABOUT VENTILATORS:

A mechanical ventilator delivers breaths of oxygen-enriched air to the body and removes breaths of carbon dioxide produced by the body, to help the body maintain enough oxygen in the bloodstream while patients recover from ARDS and their other injury(ies) or illness(es). A ventilator can breathe completely for a patient or assist a patient's own breathing. The 'vent' delivers breaths through an artificial airway or endotracheal tube. Since it passes between the vocal cords, the tube interferes with the patient's ability to speak. Positive end expiratory pressure (PEEP) is a special setting on the ventilator that keeps the lungs expanded to help get oxygen from the lungs into the bloodstream. Another important setting is tidal volume control, which measures the amount of air used for inflating the lungs. Usually the tube is inserted through the mouth or nose. Sometimes, tracheostomy is performed (an opening is cut through the neck into the trachea and the ventilation tube is inserted through this opening), ensuring a safe airway. Many patients get tracheostomies to avoid tracheal injury from an orotracheal or nasotracheal tube. Although the timing and necessity of tracheostomy for this purpose are controversial, oftentimes it is the practice to undergo tracheostomy after several weeks on the vent if it appears that the patient will require long-term ventilation.

A decision to proceed with a tracheostomy is not an indication of a worsening of the patient's condition, but rather that mechanical ventilation is not being optimized by other means. A tracheostomy might afford the patient a better pattern of breathing, hence a better possibility of surviving ARDS.

The seriousness and unpredictability of ARDS can emotionally devastate patients, family, friends, as well as doctors and nurses, especially since very few cases of ARDS are alike. Some patients get better quickly within several days, and others take weeks or months to improve. Some patients have no complications and others seem to develop every possible complication of ARDS. Finally, some victims die quickly, while others die after a long and trying illness.

While ARDS is a very serious syndrome, people can and do survive! It is important family and friends of the patient remain hopeful, and seek guidance from others, including ARDS survivors, families and friends of survivors.

The course of events after ARDS has developed is determined, in part, by the degree of abnormality in lung function and by the illness or injury that led to the development of ARDS. If the underlying medical condition(s) stabilize(s) and no new complications develop, the lungs may begin to heal, allowing the patient to breathe more on his/her own. In about one third of ARDS cases, the ventilator may be removed within a week. In another third of ARDS cases, the underlying conditions are so severe that even treatment is unable to reverse the abnormalities. Such patients may have or develop, progressive or irreversible damage to other vital organs. Sometimes the healing process is further compromised by chronic illnesses or advanced age. Although intensive medical care is sometimes able to prolong survival by a few days, such patients often die within the first week. Those who survive the first week, but whose ARDS has not yet improved, usually remain on the 'vent' for an average of 2-4 weeks, though it could be significantly longer. Even upon satisfactory response to treatment of the underlying conditions, a small number of patients have persistent inflammation in the lung(s) and seem unable to begin the healing process. The outcome of patients who enter this chronic stage is dependent on reversing the inflammation and preventing or treating complications, especially infection. In any case, unusual or experimental treatments may be considered. About one half of patients with extreme cases of ARDS get better and leave the hospital, but recovery is slow and may be incomplete.

Bacterial infections are a common complication of ARDS and contribute to continued lung injury. Lung infection or pneumonia may be difficult to diagnose in a patient with ARDS because the chest X-ray is already very abnormal.

Abnormal organ function may involve the liver, kidney(s), brain, blood or immune system. Organ dysfunction may be related to the underlying illness, to treatment, or may occur through the same inflammatory process which injured the lungs. If kidney failure occurs, the patient is given dialysis (treatment to remove waste products from the blood by circulating the blood through a special machine). Liver failure is a difficult problem to treat, since there is no replacement for the many functions the liver performs. Ongoing infections, despite appropriate antibiotic therapy, may be due to dysfunction of the immune system. Patients may become unconscious or confused when they previously have been alert and oriented due to dysfunction of the brain or central nervous system.

Blood transfusions or replacement of certain elements of the blood, such as platelets, which are needed for clotting of the blood, may be required.

Delirium (also sometimes known as “ICU psychosis”). The process that injures the lungs in ARDS also often affects brain function. Many medications, including pain relievers and anti-anxiety drugs, also adversely affect thought and behavior. As a consequence, many victims of ARDS become agitated and confused or disoriented after several days, especially as they reawaken. Severe episodes are called delerium. In this condition, memory and concentrating ability are impaired and awareness of time and place may be lost. Many patients experience visual or auditory hallucinations. Consciousness and confusion typically fluctuate over the course of the day. For unknown reasons many patients are most agitated and confused in the evening. Physical restraints and certain medications such as Haldol are used to protect patients from themselves during periods of severe agitation. Delirium generally resolves after several days as a patient continues to recover from ARDS.

Thousands and thousands of Americans suffer from ARDS each year. Many more suffer throughout the world. Until the recent past, this devastating condition was uniformly fatal. However, since ARDS was first described in 1967, steady progress has been made in reducing mortality. Today, as many as 60% of ARDS victims recover to leave the hospital. More than ever before, survivors are returning to productive and rewarding lives. Medical doctors and scientists still have more work to do to further improve mortality and functional independence after recovery.

Do They Know We're Here? Always gain permission from doctors and nurses before attempting to interact with an ARDS patient. Many ARDS survivors attest that even though they were on a 'vent', in a sleep-induced state, they were, on some level, aware of the people and events around them. Many family members and practitioners find that triggering the patient's senses plays an important role in his/her recovery (i.e., talking, bringing in pictures, playing soothing music, aroma therapy - if conducive to environment, and touch; such as rubbing lotion on the patient's body).

Dreams: Many ARDS survivors recall vivid dreams, while in the sleep-induced state. By stimulating the senses the dreams may be based on reality, which might be helpful. Some dreams can be calming and others frightening. Talk to your loved one about fun things you did together, laugh with your loved one about silly things you did. Request that nurses explain to the patient exactly what they are doing and why, when they clean the 'vent' and perform other procedures.

Ban Negativity! It is vitally important that family and friends remain positive in the patient's presence - leave fears and worries at the door. Conduct all consults with the doctors/nurses away from the patient's hospital room since patients may sense and be affected by stress dispersed in their presence. Keep your faith and your hope strong, making sure that everybody is encouraging and hopeful while with your loved one.
However, it is also important to be realistic. The mortality rate of ARDS has been reduced in recent years but a significant number of ARDS patients succumb to the syndrome.

Prepare to Tell Them. Start a journal. ARDS survivors have a great need to know every detail of what happened while they were asleep. All family members can contribute. A separate journal of 'good things' that are happening in each person's life can also be used to read back to the patient when he/she shows signs of alertness.

Prepare Yourself Daily. Prepare yourself for setbacks. ARDS is a roller coaster ride. Like the patient, it is normal for family and friends to have both good and bad days. Concentrate on the steps taken forward and view the steps backwards as hurdles that can be overcome. 

Take care of yourself. While a family member or close friend requires intensive care, be sure to get enough sleep. Eat well. Attend to the basic and emotional needs of others in the family. Preserve yourself for a prolonged period of recovery when your critically ill love one will especially need your strength and support.

The ARDS Support brochure was revised on October 3, 2001 to reflect the latest scientific research provided by doctors/researchers who serve on the ARDS Support Center Board of Medical Consultants. The consultants who assisted with the revision are:

Dr. John Hansen-Flaschen
Dr. Jason Christie
Dr. William Shull, Jr.
Hospital of the University of Pennsylvania

Dr. Roy Brower
Johns Hopkins University Hospital

Dr. Art Wheeler
Vanderbilt University Hospital

Also reviewed by:

Dr. Kenneth Steinberg
Dr. Leonard Hudson
Harborview Medical Center/University of Washington