Conditions that block the airways, damage lung tissue, weaken the muscles that control breathing, or decrease the drive to breathe may cause respiratory failure.
People may be very short of breath, have a bluish coloration to the skin, and be confused or sleepy.
Doctors use a fingertip sensor (pulse oximetry) to detect low levels of oxygen and blood tests to detect high levels of carbon dioxide in the blood.
Oxygen is given.
Sometimes people need the help of a machine to breathe (mechanical ventilation) until the underlying problem can be treated.
Acute respiratory failure is a medical emergency that can result from
Long-standing lung disease that suddenly gets worse
Severe lung disease that develops suddenly in otherwise healthy people
An example of lung disease that develops suddenly is acute respiratory distress syndrome Acute Respiratory Distress Syndrome (ARDS) Acute respiratory distress syndrome is a type of respiratory (lung) failure resulting from many different disorders that cause fluid to accumulate in the lungs and oxygen levels in the blood... read more .
Chronic respiratory failure is an ongoing breathing problem that can result from long-standing lung disease such as chronic obstructive pulmonary disease Chronic Obstructive Pulmonary Disease (COPD) Chronic obstructive pulmonary disease is persistent narrowing (blocking, or obstruction) of the airways occurring with emphysema, chronic obstructive bronchitis, or both disorders. Cigarette... read more 
(COPD).
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.
Low oxygen level (hypoxemic respiratory failure)
A common cause of hypoxemic respiratory failure is an abnormality of the lung tissue, such as acute respiratory distress syndrome Acute Respiratory Distress Syndrome (ARDS) Acute respiratory distress syndrome is a type of respiratory (lung) failure resulting from many different disorders that cause fluid to accumulate in the lungs and oxygen levels in the blood... read more , severe pneumonia Overview of Pneumonia Pneumonia is an infection of the small air sacs of the lungs (alveoli) and the tissues around them. Pneumonia is one of the most common causes of death worldwide. Often, pneumonia is the final... read more 
, excess fluid in the lungs (for example, caused by heart failure Heart Failure (HF) Heart failure is a disorder in which the heart is unable to keep up with the demands of the body, leading to reduced blood flow, back-up (congestion) of blood in the veins and lungs, and/or... read more 
or kidney failure Overview of Kidney Failure Kidney failure is the inability of the kidneys to adequately filter metabolic waste products from the blood. Kidney failure has many possible causes. Some lead to a rapid decline in kidney function... read more ), or lung scarring. Such abnormalities disrupt the usual ability of the lung tissues to take in oxygen from the air.
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 Pulmonary Embolism (PE) Pulmonary embolism is the blocking of an artery of the lung (pulmonary artery) by a collection of solid material brought through the bloodstream (embolus)—usually a blood clot (thrombus) or... read more ). 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.
High carbon dioxide level (hypercarbic respiratory failure)
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:
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 Asthma Asthma is a condition in which the airways narrow—usually reversibly—in response to certain stimuli. Coughing, wheezing, and shortness of breath that occur in response to specific triggers are... read more 
and chronic obstructive pulmonary disease Chronic Obstructive Pulmonary Disease (COPD) Chronic obstructive pulmonary disease is persistent narrowing (blocking, or obstruction) of the airways occurring with emphysema, chronic obstructive bronchitis, or both disorders. Cigarette... read more ) as well as inhaled foreign objects. Injury to the chest or lungs, as well as weakness of the chest muscles (for example, in people with myasthenia gravis Myasthenia Gravis Myasthenia gravis is an autoimmune disorder that impairs communication between nerves and muscles, resulting in episodes of muscle weakness. Myasthenia gravis results from malfunction of the... read more , Guillain-Barre syndrome Guillain-Barré Syndrome (GBS) Guillain-Barré syndrome is a form of polyneuropathy causing muscle weakness, which usually worsens over a few days to weeks, then slowly improves or returns to normal on its own. With treatment... read more , or amyotrophic lateral sclerosis Amyotrophic Lateral Sclerosis (ALS) and Other Motor Neuron Diseases (MNDs) Motor neuron diseases are characterized by progressive deterioration of the nerve cells that initiate muscle movement. As a result, the muscles stimulated by these nerves deteriorate, become... read more [ALS]), can inhibit breathing and cause hypercarbic respiratory failure.
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.
Symptoms of Respiratory Failure
Hypoxemic respiratory failure and hypercarbic respiratory failure often cause similar symptoms. People are usually very short of breath. Low oxygen levels in the blood cause shortness of breath and result in a bluish coloration to the skin (cyanosis Cyanosis Cyanosis is a bluish or grayish discoloration of the skin resulting from an inadequate amount of oxygen in the blood. Cyanosis occurs when oxygen-depleted (deoxygenated) blood, which is bluish... read more ) in light-skinned people and gray or whitish coloration in the mouth, around the eyes, and under the nails in dark-skinned people. Low oxygen levels, high carbon dioxide levels, and increasing acidity of the blood cause confusion and sleepiness.
If the drive to breathe is normal, the body tries to rid itself of carbon dioxide by deep, rapid breathing. If the lungs cannot function normally, however, this breathing pattern may not help. Eventually, the brain and heart malfunction, resulting in drowsiness (sometimes to the point of becoming unconscious) and abnormal heart rhythms Overview of Abnormal Heart Rhythms Abnormal heart rhythms (arrhythmias) are sequences of heartbeats that are irregular, too fast, too slow, or conducted via an abnormal electrical pathway through the heart. Heart disorders are... read more 
(arrhythmias), both of which can lead to death.
Some symptoms of respiratory failure vary with the cause. If the drive to breathe is abnormal (for example, after an overdose of alcohol or sedatives), people may be extremely sleepy, breathe too slowly, and quietly slip into a coma. A child with an obstructed airway due to the inhalation (aspiration) of a foreign object (such as a coin or a toy) may suddenly gasp and struggle for breath.
Diagnosis of Respiratory Failure
Measurements of the amount of oxygen and carbon dioxide in the blood
Chest x-ray and other tests to determine the cause
A doctor may suspect respiratory failure because of the symptoms and physical examination findings.
The level of oxygen in the blood can be measured without taking a blood sample by using a sensor placed on a finger or an earlobe—a procedure called pulse oximetry Pulse oximetry Both arterial blood gas testing and pulse oximetry measure the amount of oxygen in the blood, which helps determine how well the lungs are functioning. Arterial blood gas tests are invasive... read more .
A test done on a sample of blood taken from an artery confirms the diagnosis of respiratory failure when it shows a dangerously low level of oxygen and/or a dangerously high level of carbon dioxide.
Chest x-rays and usually other tests are done to determine the cause of respiratory failure.
Treatment of Respiratory Failure
Supplemental oxygen
Mechanical ventilation
Treatment of the cause
People with acute respiratory failure are treated in an intensive care unit Types of units People who need specific types of care while hospitalized may be put in special care units. Intensive care units (ICUs) are for people who are seriously ill. These people include those who have... read more (ICU).
Supplemental oxygen is given to correct any lack of oxygen in people with respiratory failure. Oxygen can be given using small plastic prongs placed in the nose (nasal cannula) or using a face mask, depending on how much oxygen people need. Oxygen is usually given initially in a greater amount than is needed and adjusted down later.
Mechanical ventilation Mechanical Ventilation Mechanical ventilation is use of a machine to aid the movement of air into and out of the lungs. Some people with respiratory failure need a mechanical ventilator (a machine that helps air get... read more corrects the problem of ventilating the lungs (and decreases carbon dioxide levels) in people with hypercarbic respiratory failure. In mechanical ventilation, a machine (ventilator) is used to help air get in and out of the lungs. The air is delivered under pressure from the machine through a face mask (noninvasive positive pressure ventilation) or other device or through a tube placed in the windpipe (invasive positive pressure ventilation).
Doctors often try noninvasive methods first, but invasive mechanical ventilation may be necessary unless respiratory failure resolves rapidly with noninvasive treatment. Most people with respiratory failure are treated with both supplemental oxygen and some kind of mechanical ventilation.
The underlying disorder causing the respiratory failure must be treated. For example, antibiotics are used to fight pneumonia caused by bacterial infection, and bronchodilators are used in people with asthma to open the airways. Other drugs may be given, for example, to decrease inflammation or treat blood clots.
