What is acute respiratory distress syndrome?
Acute respiratory distress syndrome is a medical emergency characterized by severe shortness of breath due to filling up of air sacs in the lungs by fluid. The fluid build-up occupies the space where the air exchange takes place, hence, disrupting the oxygen concentration in the blood and increase of carbon dioxide. When the blood is deficient of oxygen, vital organs like kidney, brain can get damaged resulting in life-threatening situation. The fluid is released by blood vessels at the time of the major injury, infections, anaphylaxis, etc.
Acute respiratory distress syndrome is generally diagnosed in critically ill-patients or those of old age. Symptoms of ARDS begins within 2-3 days and if not diagnosed, it may lead to potentially life-threatening situation.
The partial pressure of oxygen in ARDS is below 200 mm/Hg.
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Causes of Acute respiratory distress syndrome (ARDS):
Causes can be divided into two categories, i.e. direct causes, and indirect causes.
Direct causes of ARDS are,
· Anaphylaxis (due to drugs, wasp, bee sting)
· Burns
· Drug overdose (heroine, barbiturates)
· Smoke inhalation
· Pancreatitis (inflammation of pancreas)
· Amniotic fluid embolism
· Fat embolism
· Near-Drowning
· Cardiopulmonary bypass
· Non-cardiogenic pulmonary oedema
Indirect causes of ARDS are,
· Sepsis (very common, 20-40%)
· COVID-19 (severe case)
· Aspiration of gastric contents
· Shock of any cause
· Infection
· Lung contusion
· Severe trauma
· Multiple bone fractures
· Multiple blood transfusions
Pathogenesis of ARDS:
Inflammatory cells collect in the lungs because of direct or indirect lung injury. Cytokines are released from inflammatory cells which cause damage to the capillary endothelial cells and alveolar epithelial cells. Damage to these cells causes increased vascular permeability and decreased production of surfactants which result in interstitial and alveolar pulmonary oedema, alveolar collapse and hypoxemia.
Three stages have been ascribed in the evolution of ARDS:
Exudative stage: this stage is characterized by alveolar oedema, neutrophil-rich leukocytic infiltration and hyaline membrane formation.
Proliferative stage: this phase occurs within seven days and is characterized by interstitial inflammation & early fibrotic changes. Some patients enter the fibrotic phase approximately 3 weeks after the initial lung injury.
Fibrotic stage: it is characterized by substantial fibrosis and bullae formation.
Symptoms of ARDS:
· Rapid onset of profound difficulty in breathing.
· Laboured breathing
· Tachypnea (increased heart rate)
· Mental confusion
· Bluish discoloration of nails, skin, nose tip, lips, etc.
· Headaches
· Fever
· Dizziness
· Cough
· Chest pain on breathing
· General malaise
Investigations to diagnose ARDS:
· Multiple investigations are required to confirm ARDS. As it is an emergency situation, do not delay when someone experience shortness of breath, and immediately call the ambulance.
· Physical examination such as bluish discoloration and detailed history along with other diagnostic modalities are required to diagnose ARDS.
· If you are suspected of ARDS, your doctor will suggest chest X-ray to analyse heart size, fluid collection.
· Blood tests to determine infection, anaemia.
· CT scan
· Heart tests like electrocardiogram, echocardiogram to determine heart rate, to rule out heart failure,
· ABG analysis, to determine the oxygen concentration in blood.
· Bronchoscopy and lung biopsy when the cause of ARDS are not clear.
How ARDS is treated?
Treatment includes identification and treating underlying precipitating condition. I.e. sepsis, aspiration, trauma.
Oxygen therapy:
The mainstay treatment of ARDS is treating hypoxemia (lowered levels of oxygen) which usually requires tracheal intubation and positive pressure mechanical ventilation. This will force air into the alveoli of the lungs and help in gaseous exchange.
Maintenance of fluid balance:
Administration of IV fluids accordingly to maintain pulmonary capillary wedge pressure at the lowest level compatible with adequate cardiac output. Too little fluid can cause damage and so is high quantity of fluids.
Systemic medications: check for online medicine order in Delhi for trusted drugs.
· Diuretics like furosemide, torsemide to reduce intravascular volume.
· Systemic corticosteroids
· Antibiotics to fight against infections.
· Anti-platelets to prevent clot formation like aspirin.
· Painkillers to alleviate pain.
· Adequate nutrition to improve the immune mechanism. Buy nutrient supplements at a low price from 3MEDS-online pharmacy store in India.
Outlook of ARDS:
ARDS is an acute condition which results in multiple organ failure. Therefore, one must not be careless and immediately take next step of shifting the patient to the hospital. Mortality rate of ARDS is 30-40% and median survival period is about 2 weeks. It also leads to complications like clot formation, collapsing of lungs. Stay alert and seek immediate treatment.