My elderly aunt was taken into hospital with a clot in her lung. We’ve been told she is now in respiratory failure. What does this mean?
Respiratory failure (lung failure) is a condition in which the level of oxygen in the blood becomes dangerously low or the level of carbon dioxide becomes dangerously high. Almost any condition that affects breathing or the lungs can lead to respiratory failure.
Certain disorders, such as hypothyroidism or sleep apnoea, can decrease the unconscious reflex that drives people to breathe. An overdose of certain drugs or alcohol can also decrease the drive to breathe by causing profound sedation.
Obstruction of the airways, injury to the lung tissues, damage to the bones and tissues around the lungs, and weakness of the muscles that normally inflate the lungs are also common causes. Respiratory failure can occur if blood flow through the lungs becomes abnormal, as happens in pulmonary embolism (a clot).
Her skin is a very blue colour, particularly around her mouth. Is this normal?
Symptoms of respiratory failure vary with the cause. A child with an obstructed airway due to aspiration of a foreign object may gasp and struggle for breath. People with acute respiratory distress syndrome may become severely short of breath over a period of hours. Someone who is intoxicated or weak may quietly slip into a coma.
Low oxygen levels in the blood cause shortness of breath and cyanosis – a bluish discoloration to the skin. A combination of low oxygen levels, high carbon dioxide levels, and increasing acidity of the blood cause confusion and sleepiness. Loss of consciousness and abnormal heart rhythms (arrhythmias) can develop in some people resulting in death.
Can it be treated?
People with acute respiratory failure are treated in an intensive care unit. Oxygen is given, with the amount adjusted over time to suit the individual needs of the patient.
Occasionally, in people in whom carbon dioxide levels have remained high for some time, excess oxygen can result in slowing of the movement of air in and out of the lungs. This can further increase the carbon dioxide level. In such people, the dosage of oxygen needs to be carefully regulated.
The underlying disorder causing the respiratory failure must also be treated. Antibiotics are used to fight bacterial infection, and bronchodilators are used in people with asthma to open the airways. Other drugs may be given to decrease inflammation or treat blood clots.
Mechanical ventilation is usually necessary unless respiratory failure resolves rapidly.