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Jumat, 06 Januari 2012

Acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is the sudden inability of the body to sufficiently oxygenate the blood, and usually occurs in critically ill patients.2 ARDS clients have a high mortality rate and should be treated as quickly as possible.

What is acute respiratory down sindrom?

ARDS is a medical emergency in which the lungs—due to direct or indirect injury—fill with fluid.2,3 This results in low arterial oxygen levels. ARDS is known for its rapid onset after the first sign of respiratory distress, usuallywithin 24 to 48 hours of the original disease.
Other names for ARDS are shock lung, stiff lung, wet lung, or white lung. If not treated quickly, death can result in less than 48 hours.
Half to 70% of the people who develop ARDS die.1 For those clients who recover, they have little or no lung damage; some have persistent cough, shortness of breath, and increased sputum.

What causes it and why?

Causes of ARDS include:
  • Anaphylaxis.
  • Aspiration.
  • Burns.
  • Drug overdose.
  • Embolus.
  • Heart surgery.
  • Injury to the chest.
  • Near drowning.
  • Inhalation of toxic gases.
  • Massive blood transfusions.
  • Pneumonia.
  • Sepsis.
  • Shock.
Everything listed above can cause direct or indirect lung injury.
outlines some of the lung changes that occur as a result of this injury.
Why
1. Injury reduces blood flow to the lungs. Hormones are released; platelets aggregate
2. Hormones damage the alveolar capillaries, increasing permeability, causing fluids to shift into interstitial space
3. Proteins and fluids leak out of capillaries, causing pulmonary edema
4. Decreased blood flow to the alveoli decreases surfactant; alveoli collapse; gas exchange is impaired
5. CO2 crosses alveoli and is expired; blood O2 and CO2 levels decrease
6. Pulmonary edema increases; inflammation leads to fibrosis. Lungs become tight and cannot effectively exchange gases

Signs and symptoms

The signs and symptoms of ARDS are very subtle and change as the condition of the patient worsens. Initially, clients may have hyperventilation due to the attempt to compensate for the decrease in oxygenation. The accessory muscles may be used as the client attempts to move more air through the stiff lungs. The client feels short of breath and anxiety and restlessness may occur. The heart rate will increase due to the heart’s effort to deliver more blood to be oxygenated. Chest auscultation reveals crackles resulting from the fluid buildup in the lungs. As the pulmonary edema progresses, the client will change to hypoventilation as the CO2 is retained. Cyanosis may develop due to the inability of the lungs to exchange gases.

the signs, symptoms and associated reasons for ARDS.
Signs and symptoms              Why
Shortness of breath                 Hypoxia
Tachycardia                            Hypoxia
Confusion                               Hypoxia
Lethargy                                 Hypoxia
Mottled skin or cyanosis         Hypoxia
Restlessness, apprehension     Hypoxia
Crackles, wheezing                 Fluid buildup in the lungs
Low O2 level in blood            Poor gas exchange
Retractions                             Increased work of breathing in an effort to expand the stiffened lung
Metabolic acidosis                  Compensatory mechanisms are failing
Respiratory acidosis                Poor gas exchange causes buildup of CO2 in the blood
Multiple organ system failure    Bodily chemicals released during ARDS affect all organs
Pneumonia                              Decreased immune response; can’t fight infection
Cyanosis                                 Decreased gas exchange

Quickie tests and treatments

Tests:
  • ABG analysis. If the client is on room air, the PaO2 is usually less than 60 mm Hg and the PaCO2 is usually less than 35 mm Hg. This is due to the increasing inability of the lungs to exchange gases due to the presence of fluid buildup.
  • Chest x-ray. Shows fluid where air normally appears; early bilateral infiltrates; ground glass appearance; white-outs. Caused by lungs filling with fluid; white-outs of both lungs apparent when hypoxemia is irreversible.3
Treatments:
  • Monitor respiratory status.
  • Assess lung sounds: initially you will not hear adventitious breath sounds as the airways fill with fluid last.
  • Keep condensation out of ventilator tubing; this ensures oxygen is
  • getting to client.
  • Monitor ABGs.
  • Monitor the ventilator when positive-pressure mechanical ventilation (PPMV) is used; worry about pneumothorax anytime positive pressure is being used.
  • Use an in-line suction system to prevent disconnecting the ventilator from the ET tube.
  • Administer sedatives or neuromuscular blocking agents to paralyze the respiratory muscles and improve ventilation.
  • Treat blood gas imbalances.
  • Administer vasopressors to maintain BP, diuretics to reduce pulmonary edema, steroids to stabilize the cell membrane.
  • Administer tube feedings to maintain/improve nutritional status.3 What can harm my client?
  • Pulmonary edema.
  • Respiratory failure.
  • Pneumothorax.
  • Multiple organ system failure.
  • Pulmonary fibrosis.
  • Ventilator associated pneumonia.
  • Cardiac arrest due to ventricular arrhythmia. If I were your teacher I would test you on . . .
  • Causes of ARDS and why it occurs.
  • Signs and symptoms and why of ARDS.
  • Monitoring ABGs.

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