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Hypoxic respiratory failure occurs when there is insufficient oxygen for the body tissues to function. This can be a result of a low oxygen level in the blood, an inefficient blood supply to the tissues or a toxic substance which prevents cells from using the oxygen that is supplied. An affected individual may appear disorientated and drowsy, and exhibit breathing difficulty with rapid, shallow breaths. The nails and lips may appear blue. Sudden respiratory failure is a life-threatening condition that should be treated as an emergency.
When the pressure of oxygen in the blood is too low, this is called hypoxemia. It can lead to the tissues of the body having insufficient oxygen to function, a condition known as hypoxia. Hypoxemia, and resulting hypoxia, may occur at altitude, in association with lung diseases such as pneumonia, or in heart conditions which shunt blood away from the lungs. It may also result from failure of the mechanical action of breathing, due to an obstruction in the lung or respiratory muscle fatigue.
In cases where hypoxic respiratory failure is sudden, or acute, patients are generally admitted to the hospital as soon as possible. Chronic respiratory insufficiency, which occurs over time in diseases such as emphysema, is more likely to be treated with oxygen at home. Acute cases may require artificial ventilation, with a tube supplying oxygen inserted into the airway. A ventilating machine might be used if it is important to rest the respiratory muscles.
Asthma is a common cause of hypoxic respiratory failure, and a severe attack can be fatal. The illness consists of episodes of coughing and wheezing accompanied by a tightness inside the chest that results from constriction of the airways. Although the true cause is unknown, many triggers have been recognized, including cold air and certain drugs, such as aspirin. Treatment involves administering oxygen, asthma medication in breathable form and steroids. Often, patients, their families or carers fail to appreciate the severity of an attack and many deaths are thought to be preventable.
Sometimes hypoxic respiratory failure results from insufficient blood supply to the tissues. For example, during what is called congestive heart failure, where blood is not pumped efficiently around the body, vital organs including the brain may be starved of oxygen and damaged. As the condition tends to worsen gradually, treatment should begin long before the condition becomes life-threatening. It can include lifestyle changes, medication and possibly a heart transplant.
Cyanide is a substance which prevents cells from using oxygen, leading to hypoxic respiratory failure. It is produced when burning plastic or rubber and may be breathed in or accidentally ingested, as it is present in some plants and solvents. Fortunately there are antidotes to cyanide which can be given, and if the poison has been consumed fairly recently, the stomach can be pumped to wash it out.