Acute Respiratory Distress Syndrome: An update and Review

Acute respiratory distress syndrome (ARDS) is a life-threatening, acute, diffuse, inflammatory form of lung damage characterized by low oxygenation, pulmonary infiltrates, and acuity of onset. ARDS is defined as an acute illness that manifests as bilateral lung infiltrates and severe progressive hypoxemia in the absence of cardiogenic pulmonary edema within 7 days after the initial event.

Patients with ARDS typically have various degrees of pulmonary artery vasoconstriction and may eventually develop pulmonary hypertension. ARDS has a significant fatality rate, and there are few effective therapeutic options available to combat it.

ETIOLOGY

There are numerous risk factors for ARDS. Extra-pulmonary causes include sepsis, trauma, major transfusion, drowning, drug overdose, fat embolism, inhalation of toxic gases, and pancreatitis, in addition to pulmonary infection or aspiration. These extra-thoracic infections and/or injuries set off an inflammatory cascade that leads to pulmonary damage.

The lung injury prevention score aids in the identification of low-risk patients, although a high score is less useful.

EPIDEMIOLOGY

The prevalence of ARDS in the United States is estimated to be 64.2 to 78.9 cases per 100,000 people. 25% of ARDS cases are primarily classed as mild, whereas 75% are classified as moderate or severe. However, one-third of mild cases advance to moderate to severe disease.

 An analysis of the literature indicated a 1.1% annual decrease in mortality from 1994 to 2006. The overall pooled death rate for all studies reviewed, however, was 43%. ARDS mortality is proportional to illness severity; it is 27%, 32%, and 45% for mild, moderate, and severe diseases, respectively.

SYMPTOMS

The severity of ARDS symptoms depends on the etiology and severity of the condition. They include -

• Significant shortness of breath
• Breathing is strenuous and unusually fast.
• Hypotension
• Confusion and excessive exhaustion

DIAGNOSIS

The physical exam, chest X-ray, and oxygen levels are used to make the diagnosis. It's also critical to rule out other diseases and ailments that can cause similar symptoms, such as certain cardiac problems. These include -

Imaging

• Chest X-ray - A chest X-ray can identify which sections of your lungs have fluid in them, how much of your lungs have fluid in them, and also whether your heart is inflated.
• Computerized tomography (CT) - CT scans can provide extensive information on the anatomy of the heart and lungs.

Lab Tests

Your oxygen level can be measured using blood drawn from an artery in your wrist. If your doctor suspects you have a lung infection, secretions from your airway may be analyzed to discover the cause.

Heart Tests 

• Electrocardiogram
• Echocardiogram

TREATMENT

Treatment for ARDS typically focuses on improving blood oxygen levels, giving breathing assistance, and addressing the disease's underlying cause.

Oxygen

• Supplemental oxygen – is delivered through a mask
• Mechanical ventilation – pushes air into the lungs and forces fluid out of air sacs

Medication

ARDS medication work by -

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

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