Atelectasis
Encyclopedia
Atelectasis is defined as the collapse or closure of alveoli resulting in reduced or absent gas exchange. It may affect part or all of one lung. It is a condition where the alveoli are deflated, as distinct from pulmonary consolidation
.
It is a very common finding in chest x-ray
s and other radiological studies. It may be caused by normal exhalation
or by several medical conditions. Although frequently described as a collapse of lung tissue, atelectasis is not synonymous with a pneumothorax
, which is a more specific condition that features atelectasis. Acute atelectasis may occur as a post-operative complication or as a result of surfactant deficiency. In premature neonates, this leads to infant respiratory distress syndrome
.
), destruction, and scarring (fibrosis).
In acute atelectasis that occurs because of a deficiency in the amount or effectiveness of surfactant, many but not all alveoli collapse, and the degree of collapse is not uniform. Atelectasis in these circumstances may be limited to only a portion of one lung, or it may be present throughout both lungs. When premature babies are born with surfactant deficiency, they always develop acute atelectasis that progresses to neonatal respiratory distress syndrome. Adults can also develop acute atelectasis from excessive oxygen therapy and from mechanical ventilation
glands and occasionally a tumor
. The blocked, contracted lung
may develop pneumonia
that fails to resolve completely and leads to chronic inflammation, scarring, and bronchiectasis
.
In rounded atelectasis (folded lung syndrome), an outer portion of the lung
slowly collapses as a result of scarring and shrinkage of the membrane layers covering the lungs (pleura). This produces a rounded appearance on x-ray
that doctors may mistake for a tumor
. Rounded atelectasis is usually a complication of asbestos
-induced disease of the pleura, but it may also result from other types of chronic scarring and thickening of the pleura.
is composed of 78% nitrogen
and 21% oxygen
. Since oxygen is exchanged at the alveoli-capillary membrane, nitrogen is a major component for the alveoli's state of inflation. If a large volume of nitrogen in the lungs is replaced with oxygen, the oxygen may subsequently be absorbed into the blood reducing the volume of the alveoli, resulting in a form of alveolar collapse known as absorption atelectasis.
It is a common misconception (especially among surgeons) that atelectasis causes fever. A study of 100 post-op patients followed with serial chest X-rays and temperature measurements showed that the incidence of fever decreased as the incidence of atelectasis increased. A recent review article summarizing the available published evidence on the association between atelectasis and post-op fever concluded that there is no clinical evidence supporting this dogma.
and the elderly are at an increased risk. Outside of this context, atelectasis implies some blockage of a bronchiole
or bronchus
, which can be within the airway (foreign body, mucus plug), from the wall (tumor, usually squamous cell carcinoma
) or compressing from the outside (tumor
, lymph node
, tubercle
). Another cause is poor surfactant
spreading during inspiration
, causing the surface tension to be at its highest which tends to collapse smaller alveoli. Atelectasis may also occur during suction, as along with sputum, air is withdrawn from the lungs. There are several types of atelectasis according to their underlying mechanisms or the distribution of alveolar collapse; resorption, compression, microatelectasis and contraction atelectasis.
Another cause of atelectasis is a pulmonary embolism
(PE).
Post-surgical atelectasis will be bibasal in pattern.
is often used as part of the breathing exercises. Ambulation is also highly encouraged to improve lung inflation. People with chest deformities or neurologic conditions that cause shallow breathing for long periods may benefit from mechanical devices that assist their breathing. One method is continuous positive airway pressure
, which delivers pressurized air or oxygen through a nose or face mask to help ensure that the alveoli do not collapse, even at the end of a breath. This is helpful, as partially-inflated alveoli can be expanded more easily than collapsed alveoli. Sometimes additional respiratory support is needed with a mechanical ventilator
.
The primary treatment for acute massive atelectasis is correction of the underlying cause. A blockage that cannot be removed by coughing or by suctioning the airways often can be removed by bronchoscopy. Antibiotics are given for an infection. Chronic atelectasis is often treated with antibiotics because infection is almost inevitable. In certain cases, the affected part of the lung may be surgically removed when recurring or chronic infections become disabling or bleeding is significant. If a tumor is blocking the airway, relieving the obstruction by surgery, radiation therapy, chemotherapy, or laser therapy may prevent atelectasis from progressing and recurrent obstructive pneumonia from developing.
An incentive spirometer
can also be used to prevent or help treat atelectasis after surgery.
Consolidation (medicine)
Consolidation is a clinical term for solidification into a firm, dense mass. It is more specifically used in reference to a region of lung tissue that, normally compressible, has filled with liquid, a condition marked by induration of a normally aerated lung...
.
It is a very common finding in chest x-ray
Chest X-ray
In medicine, a chest radiograph, commonly called a chest X-ray , is a projection radiograph of the chest used to diagnose conditions affecting the chest, its contents, and nearby structures...
s and other radiological studies. It may be caused by normal exhalation
Exhalation
Exhalation is the movement of air out of the bronchial tubes, through the airways, to the external environment during breathing....
or by several medical conditions. Although frequently described as a collapse of lung tissue, atelectasis is not synonymous with a pneumothorax
Pneumothorax
Pneumothorax is a collection of air or gas in the pleural cavity of the chest between the lung and the chest wall. It may occur spontaneously in people without chronic lung conditions as well as in those with lung disease , and many pneumothoraces occur after physical trauma to the chest, blast...
, which is a more specific condition that features atelectasis. Acute atelectasis may occur as a post-operative complication or as a result of surfactant deficiency. In premature neonates, this leads to infant respiratory distress syndrome
Infant respiratory distress syndrome
Infant respiratory distress syndrome , also called neonatal respiratory distress syndrome or respiratory distress syndrome of newborn, previously called hyaline membrane disease, is a syndrome in premature infants caused by developmental insufficiency of surfactant production and structural...
.
Classification
Atelectasis may be an acute or chronic condition. In acute atelectasis, the lung has recently collapsed and is primarily notable only for airlessness. In chronic atelectasis, the affected area is often characterized by a complex mixture of airlessness, infection, widening of the bronchi (bronchiectasisBronchiectasis
Bronchiectasis is a disease state defined by localized, irreversible dilation of part of the bronchial tree caused by destruction of the muscle and elastic tissue. It is classified as an obstructive lung disease, along with emphysema, bronchitis, asthma, and cystic fibrosis...
), destruction, and scarring (fibrosis).
Acute Atelectasis
Acute atelectasis is a common postoperative complication, especially after chest or abdominal surgery. Acute atelectasis may also occur with an injury, usually to the chest (such as that caused by a car accident, a fall, or a stabbing). Atelectasis following surgery or injury, sometimes described as massive, involves most alveoli in one or more regions of the lungs. In these circumstances, the degree of collapse among alveoli tends to be quite consistent and complete. Large doses of opioids or sedatives (notable in patients experiencing sickle cell crisis), tight bandages, chest or abdominal pain, abdominal swelling (distention), and immobility of the body increase the risk of acute atelectasis following surgery or injury, or even spontaneously.In acute atelectasis that occurs because of a deficiency in the amount or effectiveness of surfactant, many but not all alveoli collapse, and the degree of collapse is not uniform. Atelectasis in these circumstances may be limited to only a portion of one lung, or it may be present throughout both lungs. When premature babies are born with surfactant deficiency, they always develop acute atelectasis that progresses to neonatal respiratory distress syndrome. Adults can also develop acute atelectasis from excessive oxygen therapy and from mechanical ventilation
Mechanical ventilation
In medicine, mechanical ventilation is a method to mechanically assist or replace spontaneous breathing. This may involve a machine called a ventilator or the breathing may be assisted by a physician, respiratory therapist or other suitable person compressing a bag or set of bellows...
Chronic Atelectasis
Chronic atelectasis may take one of two forms—middle lobe syndrome or rounded atelectasis. In right middle lobe syndrome (also known as Andy Wilson's Disease), the middle lobe of the right lung contracts, usually because of pressure on the bronchus from enlarged lymphLymph
Lymph is considered a part of the interstitial fluid, the fluid which lies in the interstices of all body tissues. Interstitial fluid becomes lymph when it enters a lymph capillary...
glands and occasionally a tumor
Tumor
A tumor or tumour is commonly used as a synonym for a neoplasm that appears enlarged in size. Tumor is not synonymous with cancer...
. The blocked, contracted lung
Lung
The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...
may develop pneumonia
Pneumonia
Pneumonia is an inflammatory condition of the lung—especially affecting the microscopic air sacs —associated with fever, chest symptoms, and a lack of air space on a chest X-ray. Pneumonia is typically caused by an infection but there are a number of other causes...
that fails to resolve completely and leads to chronic inflammation, scarring, and bronchiectasis
Bronchiectasis
Bronchiectasis is a disease state defined by localized, irreversible dilation of part of the bronchial tree caused by destruction of the muscle and elastic tissue. It is classified as an obstructive lung disease, along with emphysema, bronchitis, asthma, and cystic fibrosis...
.
In rounded atelectasis (folded lung syndrome), an outer portion of the lung
Lung
The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...
slowly collapses as a result of scarring and shrinkage of the membrane layers covering the lungs (pleura). This produces a rounded appearance on x-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
that doctors may mistake for a tumor
Tumor
A tumor or tumour is commonly used as a synonym for a neoplasm that appears enlarged in size. Tumor is not synonymous with cancer...
. Rounded atelectasis is usually a complication of asbestos
Asbestos
Asbestos is a set of six naturally occurring silicate minerals used commercially for their desirable physical properties. They all have in common their eponymous, asbestiform habit: long, thin fibrous crystals...
-induced disease of the pleura, but it may also result from other types of chronic scarring and thickening of the pleura.
Absorption Atelectasis
The atmosphereEarth's atmosphere
The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...
is composed of 78% nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
and 21% oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
. Since oxygen is exchanged at the alveoli-capillary membrane, nitrogen is a major component for the alveoli's state of inflation. If a large volume of nitrogen in the lungs is replaced with oxygen, the oxygen may subsequently be absorbed into the blood reducing the volume of the alveoli, resulting in a form of alveolar collapse known as absorption atelectasis.
Signs & symptoms
- coughCoughA cough is a sudden and often repetitively occurring reflex which helps to clear the large breathing passages from secretions, irritants, foreign particles and microbes...
, but not prominent - chest painChest painChest pain may be a symptom of a number of serious conditions and is generally considered a medical emergency. Even though it may be determined that the pain is non-cardiac in origin, this is often a diagnosis of exclusion made after ruling out more serious causes of the pain.-Differential...
- breathing difficulty
- low oxygen saturationOxygen saturationOxygen saturation or dissolved oxygen is a relative measure of the amount of oxygen that is dissolved or carried in a given medium. It can be measured with a dissolved oxygen probe such as an oxygen sensor or an optode in liquid media, usually water.It has particular significance in medicine and...
- pleural effusionPleural effusionPleural effusion is excess fluid that accumulates between the two pleural layers, the fluid-filled space that surrounds the lungs. Excessive amounts of such fluid can impair breathing by limiting the expansion of the lungs during ventilation.-Pathophysiology:...
(transudate type) - cyanosisCyanosisCyanosis is the appearance of a blue or purple coloration of the skin or mucous membranes due to the tissues near the skin surface being low on oxygen. The onset of cyanosis is 2.5 g/dL of deoxyhemoglobin. The bluish color is more readily apparent in those with high hemoglobin counts than it is...
(late sign) - increased heart rate
It is a common misconception (especially among surgeons) that atelectasis causes fever. A study of 100 post-op patients followed with serial chest X-rays and temperature measurements showed that the incidence of fever decreased as the incidence of atelectasis increased. A recent review article summarizing the available published evidence on the association between atelectasis and post-op fever concluded that there is no clinical evidence supporting this dogma.
Causes
The most common cause is post-surgical atelectasis, characterized by splinting, i.e. restricted breathing after abdominal surgery. SmokersTobacco
Tobacco is an agricultural product processed from the leaves of plants in the genus Nicotiana. It can be consumed, used as a pesticide and, in the form of nicotine tartrate, used in some medicines...
and the elderly are at an increased risk. Outside of this context, atelectasis implies some blockage of a bronchiole
Bronchiole
The bronchioles or bronchioli are the first airway branches that no longer contain cartilage or glands in their submucosa. They are branches of the bronchi.The bronchioles terminate by entering the circular sacs called alveoli.- Structure :...
or bronchus
Bronchus
A bronchus is a passage of airway in the respiratory tract that conducts air into the lungs. The bronchus branches into smaller tubes, which in turn become bronchioles....
, which can be within the airway (foreign body, mucus plug), from the wall (tumor, usually squamous cell carcinoma
Squamous cell carcinoma
Squamous cell carcinoma , occasionally rendered as "squamous-cell carcinoma", is a histologically distinct form of cancer. It arises from the uncontrolled multiplication of malignant cells deriving from epithelium, or showing particular cytological or tissue architectural characteristics of...
) or compressing from the outside (tumor
Tumor
A tumor or tumour is commonly used as a synonym for a neoplasm that appears enlarged in size. Tumor is not synonymous with cancer...
, lymph node
Lymph node
A lymph node is a small ball or an oval-shaped organ of the immune system, distributed widely throughout the body including the armpit and stomach/gut and linked by lymphatic vessels. Lymph nodes are garrisons of B, T, and other immune cells. Lymph nodes are found all through the body, and act as...
, tubercle
Tuberculosis
Tuberculosis, MTB, or TB is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis usually attacks the lungs but can also affect other parts of the body...
). Another cause is poor surfactant
Pulmonary surfactant
Pulmonary surfactant is a surface-active lipoprotein complex formed by type II alveolar cells. The proteins and lipids that surfactant comprises have both a hydrophilic region and a hydrophobic region...
spreading during inspiration
Inhalation
Inhalation is the movement of air from the external environment, through the air ways, and into the alveoli....
, causing the surface tension to be at its highest which tends to collapse smaller alveoli. Atelectasis may also occur during suction, as along with sputum, air is withdrawn from the lungs. There are several types of atelectasis according to their underlying mechanisms or the distribution of alveolar collapse; resorption, compression, microatelectasis and contraction atelectasis.
Another cause of atelectasis is a pulmonary embolism
Pulmonary embolism
Pulmonary embolism is a blockage of the main artery of the lung or one of its branches by a substance that has travelled from elsewhere in the body through the bloodstream . Usually this is due to embolism of a thrombus from the deep veins in the legs, a process termed venous thromboembolism...
(PE).
Diagnosis
- chest X-rayX-rayX-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
Post-surgical atelectasis will be bibasal in pattern.
- computed tomographyComputed tomographyX-ray computed tomography or Computer tomography , is a medical imaging method employing tomography created by computer processing...
- bronchoscopyBronchoscopyBronchoscopy is a technique of visualizing the inside of the airways for diagnostic and therapeutic purposes. An instrument is inserted into the airways, usually through the nose or mouth, or occasionally through a tracheostomy. This allows the practitioner to examine the patient's airways for...
Treatment
Treatment is directed at correcting the underlying cause. Post-surgical atelectasis is treated by physiotherapy, focusing on deep breathing and encouraging coughing. An incentive spirometerIncentive spirometer
An incentive spirometer is a medical device used to help patients improve the functioning of their lungs. It is provided to patients who have had any surgery that might jeopardize respiratory function, particularly surgery to the lungs themselves, but also commonly to patients recovering from...
is often used as part of the breathing exercises. Ambulation is also highly encouraged to improve lung inflation. People with chest deformities or neurologic conditions that cause shallow breathing for long periods may benefit from mechanical devices that assist their breathing. One method is continuous positive airway pressure
Continuous positive airway pressure
Positive airway pressure is a mode of respiratory ventilation used primarily in the treatment of sleep apnea, for which it was first developed. PAP ventilation is also commonly used for those who are critically ill in hospital with respiratory failure, and in newborn infants...
, which delivers pressurized air or oxygen through a nose or face mask to help ensure that the alveoli do not collapse, even at the end of a breath. This is helpful, as partially-inflated alveoli can be expanded more easily than collapsed alveoli. Sometimes additional respiratory support is needed with a mechanical ventilator
Medical ventilator
A medical ventilator can be defined as any machine designed to mechanically move breatheable air into and out of the lungs, to provide the mechanism of breathing for a patient who is physically unable to breathe, or breathing insufficiently....
.
The primary treatment for acute massive atelectasis is correction of the underlying cause. A blockage that cannot be removed by coughing or by suctioning the airways often can be removed by bronchoscopy. Antibiotics are given for an infection. Chronic atelectasis is often treated with antibiotics because infection is almost inevitable. In certain cases, the affected part of the lung may be surgically removed when recurring or chronic infections become disabling or bleeding is significant. If a tumor is blocking the airway, relieving the obstruction by surgery, radiation therapy, chemotherapy, or laser therapy may prevent atelectasis from progressing and recurrent obstructive pneumonia from developing.
An incentive spirometer
Incentive spirometer
An incentive spirometer is a medical device used to help patients improve the functioning of their lungs. It is provided to patients who have had any surgery that might jeopardize respiratory function, particularly surgery to the lungs themselves, but also commonly to patients recovering from...
can also be used to prevent or help treat atelectasis after surgery.