lung and airway disorders
Respiratory Failure
Causes of Respiratory Failure
Almost any condition that affects breathing or the lungs can lead to respiratory failure. Respiratory failure can occur in two ways: The level of oxygen in the blood becomes too low (hypoxemic respiratory failure). The level of carbon dioxide in the blood becomes too high (hypercarbic respiratory failure). Sometimes people have both low oxygen and high carbon dioxide levels. A common cause of hypoxemic respiratory failure is an abnormality of the lung tissue, such as Acute Respiratory Distress Syndrome (ARDS) , severe Hypoxemic respiratory failure can also occur if blood flow through the lungs becomes abnormal, as happens when a blood clot blocks a lung artery ( Pulmonary Embolism (PE) ). This disorder does not disrupt the usual ability of the lung tissues to take in oxygen, but without blood flowing to a portion of the lungs, oxygen is not properly extracted from the air. With hypercarbic respiratory failure, the level of carbon dioxide is too high usually because something prevents the person from breathing normally. Common examples of such causes include the following: A low level of thyroid hormone ( Hypothyroidism ) Sleep Apnea None Sedation due to an overdose of opioids or alcohol Blockage or narrowing of the airways Injury to the lungs Damage to bones and tissues around the lungs Weakness of muscles that normally inflate the lungs Hypothyroidism, sleep apnea, and an overdose of opioids or alcohol all decrease the unconscious reflex that drives people to breathe. Blockage or narrowing of the airways can result from disorders (such as Asthma and People who are not breathing adequately also may have a low oxygen level, but they are not considered to have hypoxemic respiratory failure if they do not also have a disorder of their lung tissue. High levels of carbon dioxide tend to cause the blood to become more acidic and leads to abnormalities in body chemistry. Age-related reductions in lung function place older people at higher risk of severe symptoms after developing pneumonia. 