Acute respiratory distress syndrome (ARDS) is an emergency medical condition that causes lung inflammation and fluid buildup in the lungs’ air sacs. ARDS symptoms are often similar to infant respiratory distress syndrome (IRDS), a condition that affects babies born with immature lungs. Infants with infant respiratory distress syndrome lack surfactant, a substance vital for proper lung function.
Causes of Acute Respiratory Distress Syndrome
ARDS can occur at any age. While conditions responsible for the development of acute respiratory distress syndrome vary, some of the common causes of ARDS may include:
- inhalation of toxic chemicals
- inhalation of vomit
- lung inflammation
- lung injury
- physical injury
- septic shock (caused by systemic infections).
Causes of Infant Respiratory Distress Syndrome
In comparison, infant respiratory distress syndrome (IRDS) is typically caused by premature birth. Babies born before the 34th to 36th weeks of pregnancy have not had enough time in utero for their lungs to mature. Specifically, premature babies lack the chemical surfactant.
Surfactant is a foamy substance that covers the inner lining of the air sacs. Surfactant has a dual role in lung function: It prevents the air sacs from collapsing and also helps the inflation of the air sacs.
Besides a lack of surfactant, maternal diabetes can sometimes result in infant respiratory distress syndrome. However, although stressful labor and delivery can trigger IRDS, premature birth and a lack of surfactant are the primary causes of infant respiratory distress syndrome.
Infant respiratory distress syndrome rates are closely linked to the amount of time the child has had to produce surfactant:
- Sixty percent of babies born earlier than the 28th week of pregnancy have IRDS.
- Thirty percent of babies born between the 28th and 34th weeks of pregnancy have infant respiratory distress syndrome.
- Babies delivered during the 34th week of pregnancy usually have sufficient surfactant for lung function. Fewer than 5 percent of such births suffer IRDS symptoms.
Symptoms ARDS and IRDS
Patients suffering from acute respiratory distress syndrome experience breathing difficulties. Similarly, shallow, rapid breathing, as well as shortness of breath, are common symptoms of both ARDS and IRDS.
If oxygen levels in the blood fall significantly as a result of breathing difficulties, patients will experience:
- cyanosis (Causing the skin to turn a bluish tinge, cyanosis results when the body’s organs aren’t receiving enough oxygenated blood.)
- organ damage
- organ failure
While infant respiratory distress syndrome has symptoms similar to ARDS, it can also cause some additional symptoms, including:
- grunting noises while breathing
- occasional gaps in breathing
- chest muscles drawn back when inhaling
- nasal flaring
- puffy or swollen arms and legs
- rapid breathing
- shortness of breath.
Diagnosing Respiratory Distress Syndrome
To diagnose ARDS, a doctor first checks the patient’s lung function by using a stethoscope to listen for abnormal sounds that would indicate fluid buildup in the lungs. Next, he will check blood-oxygen levels. Low readings indicate that there isn’t enough oxygen in the blood, highlighting the fact that the lungs may be malfunctioning.
Chest X-rays, arterial blood gas tests and mucus samples may be required to properly diagnose the respiratory disease.
In the case of premature birth with breathing difficulties, the medical team is prepared for the possibility of IRDS. Typically, a blood gas analysis will reveal low oxygen levels and the presence of acidosis (high blood acidity). Lung function tests can determine the severity of the respiratory distress.
If a chest X-ray is used in IRDS diagnosis, affected lungs will have an unusual appearance on the X-ray, resembling ground glass.
Although a lack of surfactant is the usual cause of IRDS, blood cultures are routinely taken during diagnosis to rule out infection as the cause. If infection is causing IRDS in the patient, the doctor will need to treat the underlying infection as a part of the IRDS treatment.
Treatment for ARDS
Both ARDS and IRDS are medical emergencies. The primary treatments for acute respiratory distress syndrome are high doses of oxygen administered with positive end-expiratory pressure (PEEP) to keep lung pressure up and the airways open.
During oxygen and PEEP treatment, the patient is connected to a ventilator and is usually sedated. Treatment continues until the patient can breathe independently. Additionally, antibiotics and other medications may be used to fight lung infections and reduce inflammation.
Initially, a premature baby with infant respiratory distress syndrome is administered oxygen at high humidity levels to help keep the lung airways open. Severe cases of IRDS may require a ventilator to simultaneously keep oxygen levels high and lung pressure stable. Oxygen and pressure treatments are stopped as soon as possible, as both treatments cause health complications if used excessively.
In some cases, an artificial version of surfactant is used to prevent IRDS or improve treatment outcomes. Artificial surfactant may be given to infants at high risk of infant respiratory distress syndrome at birth. The surfactant is delivered through an endotracheal tube (a tube that goes down the throat), which deposits the fluid directly into the infant’s lungs.
Preventing Infant Respiratory Distress Syndrome
The best way to prevent your newborn from developing IRDS is to go to all lengths to have a healthy, full-term pregnancy. If premature labor starts, every effort is made to stop or slow delivery until testing determines the infant’s lungs are mature.
When premature birth is unavoidable, corticosteroids are sometimes administered to the mother. When taken for two to four days before delivery, corticosteroids appear to help the fetal lungs mature more quickly than normal.
Prognosis and Complications of ARDS and IRDS
The fatality rates for acute respiratory distress syndrome are between 20 percent to 30 thirty percent. While patients who overcome ARDS can regain full lung functioning, they may suffer from a number of ARDS complications, including:
- cognitive difficulties
- memory loss
- organ failure
- permanent lung damage
- pneumonia (linked to ventilator use)
- pulmonary fibrosis (lung scarring)
- ventilator-related lung injuries.
Severe cases of infant respiratory distress syndrome can prove fatal. In 2002, approximately 24,000 infants were born with IRDS, resulting in 1,019 fatalities. Infant respiratory distress syndrome is the sixth leading cause of infant mortality in the United States.
Complications associated with infant respiratory distress syndrome include:
- brain hemorrhage
- lung hemorrhage (sometimes linked to artificial surfactant)
- mental developmental delays
- mental retardation
- ventilator-related lung damage
- vision problems, including blindness.
ARDS Support Center (n.d.). Learn About ARDS. Retrieved September 17, 2007 from the ARDS Support Center Web site: http://ards.org/learnaboutards/.
Medline Plus (updated August 18, 2006). Respiratory distress syndrome (RDS) in infants. Retrieved September 17, 2007 from the U.S. National Library of Medicine Web site: http://www.nlm.nih.gov/medlineplus/ency/article/001563.htm.
National Heart Lung and Blood Institute (March 2006). What is ARDS? Retrieved September 17, 2007 from the NHLBI Web site: http://www.nhlbi.nih.gov/health/dci/Diseases/Ards/Ards_WhatIs.html.