Introduction
Adult respiratory distress syndrome is an acute inflammatory condition, which seems to affect the lower lobes of both lungs more often. It is also known as ARDS.
It is associated with serious health conditions such as serious bacterial infections or viral infections with pneumonia, skin burns and septic shock.
Near drowning incidences, fat embolism, inhalation of toxic gases or pancreatitis are other causes of the adult respiratory distress syndrome.
Signs and symptoms
If within 1 to 2 days following any of the above named conditions the patient starts breathing rapidly and in a labored fashion (dyspnea), chances are that ARDS has set in.
The inflammatory substances that circulate in the blood release toxic enzymes that make the capillaries of the lungs leak and secretions appear in the alveoli (thanks to www.geo.arizona.edu for this image) and lead to an imbalance between the area of the lungs that are perfused with blood and that are ventilated by the airways. The end result is that too little oxygen enters the bloodstream through the lungs, which leads to cyanosis (=bluish skin discoloration) and dyspnea.
Diagnostic tests
Using the stethoscope the doctor will hear crackles and wheezes in the lung areas where the problem is located (usually the lower lung lobes).
Arterial blood gases taken at the radial artery will usually show extremely low partial oxygen pressures in the lab. Chest X-rays show alveolar infiltrates (thanks to www.meddean.luc.edu for this image), which are similar, though different from pulmonary edema changes found with congestive heart failure. X-ray changes usually lag several hours behind the clinical condition.
Clinical course
Within 2 to 3 days fluid and inflammatory secretions accumulate in the lung tissue that is affected. This leads to a cellular infiltrate in the affected lung tissue within 2 to 3 weeks, called interstitial fibrosis.
If the patient survives, depending on the severity of this, this infiltrate may resolve completely in time. At the height of the ARDS there is a danger of bacterial superinfection (pneumonia), in which case the patient’s condition tends to deteriorate. Most of these patients are treated in an Intensive Care Unit where all the modern equipment is available. Nevertheless, a high percentage of these very sick patients die as with severe ARDS there is not enough active lung surface where oxygen can be taken up into the blood stream. Without oxygen in the system life cannot be sustained. Unfortunately modern medicine does not have all the answers for these unfortunate patients at this point in time and more research is needed in this area.
Adult Respiratory Distress Syndrome
Treatment
The treatment is directed at improving oxygen uptake and at the same time to prevent the failure of multiple organ systems such as the heart, the brain, the kidneys, the liver, the gut and the bone marrow. As already indicated due to the complexity of the treatment, this is usually administered in an Intensive Care Unit (ICU) setting.
With an unconscious patient the first step usually is intubation and mechanical ventilation with oxygen by positive end expiratory pressure (PEEP). In order to keep the circulation under control a central line is usually inserted to be able to administer fluids and possibly even intravenous nutrition. These patients need around the clock care by highly trained ICU staff, including respiratory technicians, nurses and doctors. In the past almost 100% of patients with severe ARDS died. Now with modern ICU techniques about 60% of patients survive. Most of the patients who survive live a normal life with no further lung complications. A small percentage of patients who have been treated with artificial ventilation for several weeks may develop lung fibrosis.
References:
1. Noble: Textbook of Primary Care Medicine, 3rd ed., Copyright © 2001 Mosby, Inc.
2. National Asthma Education and Prevention Program. Expert Panel Report II. National Heart, Lung and Blood Institute, 1997.
3. Rakel: Conn’s Current Therapy 2002, 54th ed., Copyright © 2002 W. B. Saunders Company
4. Murray & Nadel: Textbook of Respiratory Medicine, 3rd ed., Copyright © 2000 W. B. Saunders Company
5. Behrman: Nelson Textbook of Pediatrics, 16th ed., Copyright © 2000 W. B. Saunders Company
6. Merck Manual: Pulmonary disorders
7. Goldman: Cecil Textbook of Medicine, 21st ed., Copyright © 2000 W. B. Saunders Company
8. Ferri: Ferri’s Clinical Advisor: Instant Diagnosis and Treatment, 2004 ed., Copyright © 2004 Mosby, Inc.
9. Rakel: Conn’s Current Therapy 2004, 56th ed., Copyright © 2004 Elsevier
