Subcutaneous emphysema
Encyclopedia
Subcutaneous emphysema, sometimes abbreviated SCE or SE and also called tissue emphysema, or Sub Q air, occurs when gas or air is present in the subcutaneous
layer of the skin. Subcutaneous refers to the tissue
beneath the cutis
of the skin
, and emphysema
refers to trapped air. Since the air generally comes from the chest cavity, subcutaneous emphysema usually occurs on the chest, neck and face, where it is able to travel from the chest cavity along the fascia
. Subcutaneous emphysema has a characteristic crackling feel to the touch, a sensation that has been described as similar to touching Rice Krispies
; this sensation of air under the skin is known as subcutaneous crepitation.
Pneumomediastinum
was first recognized as a medical entity by Laennec
who reported it as a consequence of trauma in 1819. This complication has many causes. It was well described Dr. Louis Hamman in the 1939 in woman after labor and delivery at The Johns Hopkins Hospital. It is sometimes called Hamman's syndrome though usually referred by thoracic surgeons and pulmonologists as Macklin's Syndrome. First reported by L. Macklin in 1939 and later by M.T. Macklin and C.C. Macklin in 1944, the latter two explained the pathophysiology in more detail.
Subcutaneous emphysema can result from puncture of parts of the respiratory
or gastrointestinal systems. Particularly in the chest
and neck, air may become trapped as a result of penetrating trauma
(e.g., gunshot wounds or stab wounds) or blunt trauma
. Infection
(e.g., gas gangrene
) can cause gas to be trapped in the subcutaneous tissues. Subcutaneous emphysema can be caused by medical procedures and medical conditions that cause the pressure in the alveoli of the lung to be higher than that in the tissues outside of them. Its most common causes are pneumothorax
and a chest tube
that has become occluded by a blood clot or fibrinous material. It can also occur spontaneously due to rupture of the alveoli with dramatic presentation. When the condition is caused by surgery it is called surgical emphysema. The term spontaneous subcutaneous emphysema is used when the cause is not clear.
Subcutaneous emphysema is not typically dangerous in and of itself, but the underlying condition (for example, pneumothorax, that it is presenting as a symptom of can be. Although the underlying conditions require treatment, subcutaneous emphysema usually does not; small amounts of air are reabsorbed by the body. However, subcutaneous emphysema can be uncomfortable and may interfere with breathing, and is often treated by removing air from the tissues, for example by using large bore needles, skin incisions or subcutaneous catheterization. Chest tubes should only be used if there is a definite pneumothorax as sometimes the pleural space has been obliterated.
, wheezing and difficulty breathing
. Chest X-ray
s may show air in the mediastinum
, the middle of the chest cavity. A significant case of subcutaneous emphysema is easy to detect by touching
the overlying skin; it feels like tissue paper or Rice Krispies. Touching the bubbles causes them to move and sometimes make a crackling noise. The air bubbles, which are painless and feel like small nodules to the touch, may burst when the skin above them is palpated. The tissues surrounding SCE are usually swollen
. When large amounts of air leak into the tissues, the face can swell considerably. In cases of subcutaneous emphysema around the neck, there may be a feeling of fullness in the neck, and the sound of the voice may change. If SCE is particularly extreme around the neck and chest, the swelling can interfere with breathing. The air can travel to many parts of the body, including the abdomen and limbs, because there are no separations in the fatty tissue
in the skin to prevent the air from moving.
or gunshot wound.
Subcutaneous emphysema is often found in car accident victims because of the force of the crash.
Chest trauma
, a major cause of subcutaneous emphysema, can cause air to enter the skin of the chest wall from the neck or lung. When the pleural membranes are punctured, as occurs in penetrating trauma of the chest, air may travel from the lung to the muscles and subcutaneous tissue of the chest wall. When the alveoli of the lung are ruptured, as occurs in pulmonary laceration
, air may travel beneath the visceral pleura (the membrane lining the lung), to the hilum of the lung
, up to the trachea
, to the neck and then to the chest wall. The condition may also occur when a fractured rib
punctures a lung; in fact, 27% of patients who have rib fractures also have subcutaneous emphysema. Rib fractures may tear the parietal pleura
, the membrane lining the inside of chest wall, allowing air to escape into the subcutaneous tissues.
Subcutaneous emphysema is a frequently found in pneumothorax (air outside of the lung in the chest cavity) and may also result from air in the mediastinum
, pneumopericardium
(air in the pericardial cavity
around the heart). A tension pneumothorax, in which air builds up in the pleural cavity
and exerts pressure on the organs within the chest, makes it more likely that air will enter the subcutaneous tissues through pleura torn by a broken rib. When subcutaneous emphysema results from pneumothorax, air may enter tissues including those of the face, neck, chest, armpits, or abdomen
.
When subcutaneous emphysema occurs with pneumomediastinum, the condition is known as Hamman's syndrome
. Pneumomediastinum can result from a number of events. For example, foreign body aspiration
, in which someone inhales an object, can cause pneumomediastinum (and lead to subcutaneous emphysema) by puncturing the airways or by increasing the pressure in the affected lung(s) enough to cause them to burst.
Subcutaneous emphysema of the chest wall is commonly among the first signs to appear that barotrauma
, damage caused by excessive pressure, has occurred, and it is an indication that the lung was subjected to significant barotrauma. Thus the phenomenon
may occur in diving injuries.
Trauma to parts of the respiratory system other than the lungs, such as rupture of a bronchial tube, may also cause subcutaneous emphysema. Air may travel upward to the neck from a pneumomediastinum that results from a bronchial rupture, or downward from a torn trachea or larynx
into the soft tissues of the chest. It may also occur with fractures
of the facial bones, neoplasms, during asthma
attacks, when the Heimlich maneuver is used, and during childbirth
. It is estimated to occur with pneumomediastinum in one in every 2000–100,000 deliveries. Injury with pneumatic tool
s, those that are driven by air, is also known to cause subcutaneous emphysema, even in extremities (the arms and legs). It can also occur as a result of rupture of the esophagus
; when it does, it is usually as a late sign.
. It may also occur from surgery around the esophagus, and is particularly likely in prolonged surgery. Other potential causes are positive pressure ventilation for any reason and by any technique, in which its occurrence is frequently unexpected. It may also occur as a result of dental surgery, laparoscopy
, and cricothyrotomy
. In a pneumonectomy
, in which an entire lung is removed, the remaining bronchial stump may leak air, a rare but very serious condition that leads to progressive subcutaneous emphysema. Air can leak out of the pleural space through an incision made for a thoracotomy
to cause subcutaneous emphysema. On infrequent occasions, the condition can result from dental
surgery, usually due to use of high-speed tools that are air driven. These cases result in usually painless swelling of the face and neck, with an immediate onset, the crepitus
(crunching sound) typical of subcutaneous emphysema, and often with subcutaneous air visible on X-ray.
One of the main causes of subcutaneous emphysema, along with pneumothorax, is an improperly functioning chest tube. Thus subcutaneous emphysema is often a sign that something is wrong with a chest tube; it may be clogged, clamped, or out of place. The tube may need to be replaced, or, when large amounts of air are leaking, a new tube may be added.
Since mechanical ventilation
can worsen a pneumothorax, it can force air into the tissues; when subcutaneous emphysema occurs in a ventilated patient, it is an indication that the ventilation may have caused a pneumothorax. It is not unusual for subcutaneous emphysema to result from positive pressure ventilation. Another possible cause is a ruptured trachea. The trachea may be injured by tracheostomy or tracheal intubation
; in cases of tracheal injury, large amounts of air can enter the subcutaneous space. An endotracheal tube can puncture the trachea or bronchi and cause subcutaneous emphysema.
, occurring as a late sign in gas gangrene, of which it is the hallmark
sign. Subcutaneous emphysema is also considered a hallmark of fournier gangrene
. Symptoms of subcutaneous emphysema can result when infectious organisms produce gas by fermentation
. When emphysema occurs due to infection, signs that the infection
is systemic, i.e. that it has spread beyond the initial location, are also present.
(the space behind the abdominal cavity
) because these areas are connected by fascial planes. From the punctured lungs or airways, the air travels up the perivascular
sheaths and into the mediastinum, from which it can enter the subcutaneous tissues.
Spontaneous subcutaneous emphysema is thought to result from increased pressures in the lung that cause alveoli to rupture. In spontaneous subcutaneous emphysema, air travels from the ruptured alveoli into the interstitium and along the blood vessel
s of the lung, into the mediastinum and from there into the tissues of the neck or head.
is used to diagnose the condition or confirm a diagnosis made using clinical signs. On a chest radiograph, subcutaneous emphysema may be seen as radiolucent
striations in the pattern expected from the pectoralis major muscle group. Air in the subcutaneous tissues may interfere with radiography
of the chest, potentially obscuring serious conditions such as pneumothorax. It can also and reduce the effectiveness of chest ultrasound
. On the other hand, since subcutaneous emphysema may become apparent in chest X-ray
s before a pneumothorax does, its presence may be used to infer that of the latter injury. Subcutaneous emphysema can also be seen in CT scans, with the air pockets appearing as dark areas. CT scanning is so sensitive that it commonly makes it possible to find the exact spot from which air is entering the soft tissues. In 1994, M.T. Macklin and C.C. Macklin published further insights into the pathophysiology of spontaneous Macklin's Syndrome occurring from a severe asthmatic attack.
The presence of subcutaneous emphysema in a person who appears quite ill and febrile after bout of vomiting followed by left chest pain is very suggestive of the diagnosis of Boerhaave's syndrome which is a life threatening emergency caused by rupture of the distal esophagus.
. Most of the time, SCE itself does not need treatment (though the conditions from which it results may); however, if the amount of air is large, it can interfere with breathing and be uncomfortable. It occasionally progresses to a state "Massive Subcutaneous Emphysema" which is quite uncomfortable and requires surgical drainage. When the amount of air pushed out of the airways or lung becomes massive, usually due to positive pressure ventilation, the eyes will be obscured by the swollen eyelids making the patient sightless. Also the pressure of the air may impede the blood flow to the areolae of the breast and skin of the scrotum or labia. This can lead to necrosis of the skin in these areas. The latter are urgent situations requiring rapid, adequate decompression. Severe cases can compress the trachea and do require treatment.
In severe cases of subcutaneous emphysema, catheter
s can be placed in the subcutaneous tissue to release the air. Small cuts, or "blow holes", may be made in the skin to release the gas. When subcutaneous emphysema occurs due to pneumothorax, a chest tube is frequently used to control the latter; this eliminates the source of the air entering the subcutaneous space. If the volume of subcutaneous air is increasing, it may be that the chest tube is not removing air rapidly enough, so it may be replaced with a larger one. Suction may also be applied to the tube to remove air faster. The progression of the condition can be monitored by marking the boundaries with a special pencil for marking on skin.
Since treatment usually involves dealing with the underlying condition, cases of spontaneous subcutaneous emphysema may require nothing more than bed rest, medication to control pain, and perhaps supplemental oxygen. Breathing oxygen may help the body to absorb the subcutaneous air more quickly. Reassurance and observation are also part of treatment.
r for the Royal Marines
who had had a tooth extracted: playing the instrument had forced air through the hole where the tooth had been and into the tissues of his face. Since then, another case of spontaneous subcutaneous emphysema was reported in a submariner for the US Navy who had had a root canal
in the past; the increased pressure in the submarine forced air through it and into his face. The cause of spontaneous subcutaneous emphysema was clarified between 1939 and 1944 by Macklin, contributing to the current understanding of the pathophysiology
of the condition.
Subcutaneous tissue
The hypodermis, also called the hypoderm, subcutaneous tissue, or superficial fascia is the lowermost layer of the integumentary system in vertebrates. Types of cells that are found in the hypodermis are fibroblasts, adipose cells, and macrophages...
layer of the skin. Subcutaneous refers to the tissue
Tissue (biology)
Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...
beneath the cutis
Cutis (anatomy)
Cutis is the combined term for the epidermis and the dermis, the two outer layers of the skin. Underneath is the subcutis....
of the skin
Human skin
The human skin is the outer covering of the body. In humans, it is the largest organ of the integumentary system. The skin has multiple layers of ectodermal tissue and guards the underlying muscles, bones, ligaments and internal organs. Human skin is similar to that of most other mammals,...
, and emphysema
Emphysema
Emphysema is a long-term, progressive disease of the lungs that primarily causes shortness of breath. In people with emphysema, the tissues necessary to support the physical shape and function of the lungs are destroyed. It is included in a group of diseases called chronic obstructive pulmonary...
refers to trapped air. Since the air generally comes from the chest cavity, subcutaneous emphysema usually occurs on the chest, neck and face, where it is able to travel from the chest cavity along the fascia
Fascia
A fascia is a layer of fibrous tissue that permeates the human body. A fascia is a connective tissue that surrounds muscles, groups of muscles, blood vessels, and nerves, binding those structures together in much the same manner as plastic wrap can be used to hold the contents of sandwiches...
. Subcutaneous emphysema has a characteristic crackling feel to the touch, a sensation that has been described as similar to touching Rice Krispies
Rice Krispies
Rice Krispies is a breakfast cereal that was created by Clayton Rindlisbacher for the Kellogg company, and later marketed by Kellogg's in 1927 and released to the public in 1928...
; this sensation of air under the skin is known as subcutaneous crepitation.
Pneumomediastinum
Pneumomediastinum
Pneumomediastinum is a condition in which air is present in the mediastinum...
was first recognized as a medical entity by Laennec
René Laennec
René-Théophile-Hyacinthe Laennec was a French physician. He invented the stethoscope in 1816, while working at the Hôpital Necker and pioneered its use in diagnosing various chest conditions....
who reported it as a consequence of trauma in 1819. This complication has many causes. It was well described Dr. Louis Hamman in the 1939 in woman after labor and delivery at The Johns Hopkins Hospital. It is sometimes called Hamman's syndrome though usually referred by thoracic surgeons and pulmonologists as Macklin's Syndrome. First reported by L. Macklin in 1939 and later by M.T. Macklin and C.C. Macklin in 1944, the latter two explained the pathophysiology in more detail.
Subcutaneous emphysema can result from puncture of parts of the respiratory
Respiratory system
The respiratory system is the anatomical system of an organism that introduces respiratory gases to the interior and performs gas exchange. In humans and other mammals, the anatomical features of the respiratory system include airways, lungs, and the respiratory muscles...
or gastrointestinal systems. Particularly in the chest
Thorax
The thorax is a division of an animal's body that lies between the head and the abdomen.-In tetrapods:...
and neck, air may become trapped as a result of penetrating trauma
Penetrating trauma
Penetrating trauma is an injury that occurs when an object pierces the skin and enters a tissue of the body, creating an open wound. In blunt, or non-penetrating trauma, there may be an impact, but the skin is not necessarily broken. The penetrating object may remain in the tissues, come back out...
(e.g., gunshot wounds or stab wounds) or blunt trauma
Blunt trauma
In medical terminology, blunt trauma, blunt injury, non-penetrating trauma or blunt force trauma refers to a type of physical trauma caused to a body part, either by impact, injury or physical attack; the latter usually being referred to as blunt force trauma...
. Infection
Infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...
(e.g., gas gangrene
Gas gangrene
Gas gangrene is a bacterial infection that produces gas tissues in gangrene. It is a deadly form of gangrene usually caused by Clostridium perfringens bacteria. It is a medical emergency....
) can cause gas to be trapped in the subcutaneous tissues. Subcutaneous emphysema can be caused by medical procedures and medical conditions that cause the pressure in the alveoli of the lung to be higher than that in the tissues outside of them. Its most common causes are 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...
and a chest tube
Chest tube
A chest tube is a flexible plastic tube that is inserted through the side of the chest into the pleural space. It is used to remove air or fluid , or pus from the intrathoracic space...
that has become occluded by a blood clot or fibrinous material. It can also occur spontaneously due to rupture of the alveoli with dramatic presentation. When the condition is caused by surgery it is called surgical emphysema. The term spontaneous subcutaneous emphysema is used when the cause is not clear.
Subcutaneous emphysema is not typically dangerous in and of itself, but the underlying condition (for example, pneumothorax, that it is presenting as a symptom of can be. Although the underlying conditions require treatment, subcutaneous emphysema usually does not; small amounts of air are reabsorbed by the body. However, subcutaneous emphysema can be uncomfortable and may interfere with breathing, and is often treated by removing air from the tissues, for example by using large bore needles, skin incisions or subcutaneous catheterization. Chest tubes should only be used if there is a definite pneumothorax as sometimes the pleural space has been obliterated.
Symptoms and signs
Signs and symptoms of spontaneous subcutaneous emphysema vary based on the cause, but it is often associated with swelling of the neck and chest pain, and may also involve sore throat, neck pain, difficulty swallowingDysphagia
Dysphagia is the medical term for the symptom of difficulty in swallowing. Although classified under "symptoms and signs" in ICD-10, the term is sometimes used as a condition in its own right. Sufferers are sometimes unaware of their dysphagia....
, wheezing and difficulty breathing
Dyspnea
Dyspnea , shortness of breath , or air hunger, is the subjective symptom of breathlessness.It is a normal symptom of heavy exertion but becomes pathological if it occurs in unexpected situations...
. Chest 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...
s may show air in the mediastinum
Mediastinum
The mediastinum is a non-delineated group of structures in the thorax, surrounded by loose connective tissue. It is the central compartment of the thoracic cavity...
, the middle of the chest cavity. A significant case of subcutaneous emphysema is easy to detect by touching
Palpation
Palpation is used as part of a physical examination in which an object is felt to determine its size, shape, firmness, or location...
the overlying skin; it feels like tissue paper or Rice Krispies. Touching the bubbles causes them to move and sometimes make a crackling noise. The air bubbles, which are painless and feel like small nodules to the touch, may burst when the skin above them is palpated. The tissues surrounding SCE are usually swollen
Edema
Edema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...
. When large amounts of air leak into the tissues, the face can swell considerably. In cases of subcutaneous emphysema around the neck, there may be a feeling of fullness in the neck, and the sound of the voice may change. If SCE is particularly extreme around the neck and chest, the swelling can interfere with breathing. The air can travel to many parts of the body, including the abdomen and limbs, because there are no separations in the fatty tissue
Adipose tissue
In histology, adipose tissue or body fat or fat depot or just fat is loose connective tissue composed of adipocytes. It is technically composed of roughly only 80% fat; fat in its solitary state exists in the liver and muscles. Adipose tissue is derived from lipoblasts...
in the skin to prevent the air from moving.
Trauma
Conditions that cause subcutaneous emphysema may result from both blunt and penetrating trauma; SCE is often the result of a stabbingStabbing
A stabbing is penetration with a sharp or pointed object at close range. Stab connotes purposeful action, as by an assassin or murderer, but it is also possible to accidentally stab oneself or others.Stabbing differs from slashing or cutting in that the motion of the object used in a stabbing...
or gunshot wound.
Subcutaneous emphysema is often found in car accident victims because of the force of the crash.
Chest trauma
Chest trauma
Chest trauma is a serious injury of the chest. Thoracic trauma is a common cause of significant disability and mortality, the leading cause of death from physical trauma after head and spinal cord injury. Blunt thoracic injuries are the primary or a contributing cause of about a quarter of all...
, a major cause of subcutaneous emphysema, can cause air to enter the skin of the chest wall from the neck or lung. When the pleural membranes are punctured, as occurs in penetrating trauma of the chest, air may travel from the lung to the muscles and subcutaneous tissue of the chest wall. When the alveoli of the lung are ruptured, as occurs in pulmonary laceration
Pulmonary laceration
A pulmonary laceration is a chest injury in which lung tissue is torn or cut. An injury that is potentially more serious than pulmonary contusion, pulmonary laceration involves disruption of the architecture of the lung, while pulmonary contusion does not...
, air may travel beneath the visceral pleura (the membrane lining the lung), to the hilum of the lung
Hilum of lung
Above and behind the cardiac impression is a triangular depression named the hilum, where the structures which form the root of the lung enter and leave the viscus. These include the pulmonary artery, superiormost on the left lung, the superior and inferior pulmonary veins, lymphatic vessels and...
, up to the trachea
Vertebrate trachea
In tetrapod anatomy the trachea, or windpipe, is a tube that connects the pharynx or larynx to the lungs, allowing the passage of air. It is lined with pseudostratified ciliated columnar epithelium cells with goblet cells that produce mucus...
, to the neck and then to the chest wall. The condition may also occur when a fractured rib
Rib fracture
A rib fracture is a break or fracture in one or more of the bones making up the rib cage.The first rib is rarely fractured because of its protected position behind the clavicle . However, if it is broken serious damage can occur to the brachial plexus of nerves and the subclavian vessels...
punctures a lung; in fact, 27% of patients who have rib fractures also have subcutaneous emphysema. Rib fractures may tear the parietal pleura
Parietal pleura
The portion of the pleura external to the pulmonary pleura lines the inner surface of the chest wall, covers the diaphragm, and is reflected over the structures occupying the middle of the thorax; this portion is termed the parietal pleura....
, the membrane lining the inside of chest wall, allowing air to escape into the subcutaneous tissues.
Subcutaneous emphysema is a frequently found in pneumothorax (air outside of the lung in the chest cavity) and may also result from air in the mediastinum
Pneumomediastinum
Pneumomediastinum is a condition in which air is present in the mediastinum...
, pneumopericardium
Pneumopericardium
Pneumopericardium is a medical condition where air enters the pericardial cavity.It can be congenital, or introduced by a wound.-External links:* http://history.amedd.army.mil/booksdocs/wwii/thoracicsurgeryvolII/chapter2figure19.jpg...
(air in the pericardial cavity
Pericardial cavity
The pericardial cavity is a potential space between the parietal pericardium and visceral layer. It contains a supply of serous fluid. The serous fluid that is found in this space is known as the pericardial fluid....
around the heart). A tension pneumothorax, in which air builds up in the pleural cavity
Pleural cavity
In human anatomy, the pleural cavity is the potential space between the two pleura of the lungs. The pleura is a serous membrane which folds back onto itself to form a two-layered, membrane structure. The thin space between the two pleural layers is known as the pleural cavity; it normally...
and exerts pressure on the organs within the chest, makes it more likely that air will enter the subcutaneous tissues through pleura torn by a broken rib. When subcutaneous emphysema results from pneumothorax, air may enter tissues including those of the face, neck, chest, armpits, or abdomen
Abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
.
When subcutaneous emphysema occurs with pneumomediastinum, the condition is known as Hamman's syndrome
Hamman's syndrome
Hamman's syndrome is a syndrome of spontaneous subcutaneous emphysema and pneumomediastinum , sometimes associated with pain....
. Pneumomediastinum can result from a number of events. For example, foreign body aspiration
Pulmonary aspiration
Pulmonary aspiration is the entry of material from the oropharynx or gastrointestinal tract into the larynx and lower respiratory tract...
, in which someone inhales an object, can cause pneumomediastinum (and lead to subcutaneous emphysema) by puncturing the airways or by increasing the pressure in the affected lung(s) enough to cause them to burst.
Subcutaneous emphysema of the chest wall is commonly among the first signs to appear that barotrauma
Barotrauma
Barotrauma is physical damage to body tissues caused by a difference in pressure between an air space inside or beside the body and the surrounding fluid...
, damage caused by excessive pressure, has occurred, and it is an indication that the lung was subjected to significant barotrauma. Thus the phenomenon
Phenomenon
A phenomenon , plural phenomena, is any observable occurrence. Phenomena are often, but not always, understood as 'appearances' or 'experiences'...
may occur in diving injuries.
Trauma to parts of the respiratory system other than the lungs, such as rupture of a bronchial tube, may also cause subcutaneous emphysema. Air may travel upward to the neck from a pneumomediastinum that results from a bronchial rupture, or downward from a torn trachea or larynx
Larynx
The larynx , commonly called the voice box, is an organ in the neck of amphibians, reptiles and mammals involved in breathing, sound production, and protecting the trachea against food aspiration. It manipulates pitch and volume...
into the soft tissues of the chest. It may also occur with fractures
Bone fracture
A bone fracture is a medical condition in which there is a break in the continuity of the bone...
of the facial bones, neoplasms, during asthma
Asthma
Asthma is the common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm. Symptoms include wheezing, coughing, chest tightness, and shortness of breath...
attacks, when the Heimlich maneuver is used, and during childbirth
Childbirth
Childbirth is the culmination of a human pregnancy or gestation period with the birth of one or more newborn infants from a woman's uterus...
. It is estimated to occur with pneumomediastinum in one in every 2000–100,000 deliveries. Injury with pneumatic tool
Pneumatic tool
A pneumatic tool or air tools is a tool driven by a gas, usually compressed air supplied by a gas compressor. Pneumatic tools can also be driven by compressed carbon dioxide stored in small cylinders allowing for portability...
s, those that are driven by air, is also known to cause subcutaneous emphysema, even in extremities (the arms and legs). It can also occur as a result of rupture of the esophagus
Esophagus
The esophagus is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach...
; when it does, it is usually as a late sign.
Medical treatment
Subcutaneous emphysema is a common result of certain types of surgery; for example it is not unusual in chest surgeryThoracic surgery
Thoracic surgery is the field of medicine involved in the surgical treatment of diseases affecting organs inside the thorax . Generally treatment of conditions of the lungs, chest wall, and diaphragm....
. It may also occur from surgery around the esophagus, and is particularly likely in prolonged surgery. Other potential causes are positive pressure ventilation for any reason and by any technique, in which its occurrence is frequently unexpected. It may also occur as a result of dental surgery, laparoscopy
Laparoscopy
Laparoscopy is an operation performed in the abdomen or pelvis through small incisions with the aid of a camera...
, and cricothyrotomy
Cricothyrotomy
A cricothyrotomy is an incision made through the skin and cricothyroid membrane to establish a patent airway during certain life-threatening situations, such as airway obstruction by a foreign body, angioedema, or massive...
. In a pneumonectomy
Pneumonectomy
A pneumonectomy is a surgical procedure to remove a lung. Removal of just one lobe of the lung is specifically referred to as a lobectomy, and that of a segment of the lung as a wedge resection .-Indications:...
, in which an entire lung is removed, the remaining bronchial stump may leak air, a rare but very serious condition that leads to progressive subcutaneous emphysema. Air can leak out of the pleural space through an incision made for a thoracotomy
Thoracotomy
Thoracotomy is an incision into the pleural space of the chest. It is performed by a surgeon, and, rarely, by emergency physicians, to gain access to the thoracic organs, most commonly the heart, the lungs, the esophagus or thoracic aorta, or for access to the anterior spine such as is necessary...
to cause subcutaneous emphysema. On infrequent occasions, the condition can result from dental
Dentistry
Dentistry is the branch of medicine that is involved in the study, diagnosis, prevention, and treatment of diseases, disorders and conditions of the oral cavity, maxillofacial area and the adjacent and associated structures and their impact on the human body. Dentistry is widely considered...
surgery, usually due to use of high-speed tools that are air driven. These cases result in usually painless swelling of the face and neck, with an immediate onset, the crepitus
Crepitus
Crepitus is a medical term to describe the grating, crackling or popping sounds and sensations experienced under the skin and joints.-Causes:...
(crunching sound) typical of subcutaneous emphysema, and often with subcutaneous air visible on X-ray.
One of the main causes of subcutaneous emphysema, along with pneumothorax, is an improperly functioning chest tube. Thus subcutaneous emphysema is often a sign that something is wrong with a chest tube; it may be clogged, clamped, or out of place. The tube may need to be replaced, or, when large amounts of air are leaking, a new tube may be added.
Since 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...
can worsen a pneumothorax, it can force air into the tissues; when subcutaneous emphysema occurs in a ventilated patient, it is an indication that the ventilation may have caused a pneumothorax. It is not unusual for subcutaneous emphysema to result from positive pressure ventilation. Another possible cause is a ruptured trachea. The trachea may be injured by tracheostomy or tracheal intubation
Tracheal intubation
Tracheal intubation, usually simply referred to as intubation, is the placement of a flexible plastic or rubber tube into the trachea to maintain an open airway or to serve as a conduit through which to administer certain drugs...
; in cases of tracheal injury, large amounts of air can enter the subcutaneous space. An endotracheal tube can puncture the trachea or bronchi and cause subcutaneous emphysema.
Infection
Air can be trapped under the skin in necrotizing infections such as gangreneGangrene
Gangrene is a serious and potentially life-threatening condition that arises when a considerable mass of body tissue dies . This may occur after an injury or infection, or in people suffering from any chronic health problem affecting blood circulation. The primary cause of gangrene is reduced blood...
, occurring as a late sign in gas gangrene, of which it is the hallmark
Hallmark
A hallmark is an official mark or series of marks struck on items made of precious metals — platinum, gold, silver and in some nations, palladium...
sign. Subcutaneous emphysema is also considered a hallmark of fournier gangrene
Fournier gangrene
Fournier's gangrene is a type of necrotizing infection or gangrene usually affecting the perineum.It was first described by Baurienne in 1764 and is named after a French venereologist, Jean-Alfred Fournier following five cases he presented in clinical lectures in 1883.-Cause:In the majority of...
. Symptoms of subcutaneous emphysema can result when infectious organisms produce gas by fermentation
Fermentation (biochemistry)
Fermentation is the process of extracting energy from the oxidation of organic compounds, such as carbohydrates, using an endogenous electron acceptor, which is usually an organic compound. In contrast, respiration is where electrons are donated to an exogenous electron acceptor, such as oxygen,...
. When emphysema occurs due to infection, signs that the infection
Infection
An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...
is systemic, i.e. that it has spread beyond the initial location, are also present.
Pathophysiology
Air is able to travel to the soft tissues of the neck from the mediastinum and the retroperitoneumRetroperitoneum
The retroperitoneal space is the anatomical space in the abdominal cavity behind the peritoneum. It has no specific delineating anatomical structures...
(the space behind the abdominal cavity
Abdominal cavity
The abdominal cavity is the body cavity of the human body that holds the bulk of the viscera. It is located below the thoracic cavity, and above the pelvic cavity. Its dome-shaped roof is the thoracic diaphragm , and its oblique floor is the pelvic inlet...
) because these areas are connected by fascial planes. From the punctured lungs or airways, the air travels up the perivascular
Perivascular cell
A perivascular cell is in the periphery of vasculature, and may refer to:*Pericyte, a connective tissue cell that occurs about small blood vessels*Smooth muscle cells...
sheaths and into the mediastinum, from which it can enter the subcutaneous tissues.
Spontaneous subcutaneous emphysema is thought to result from increased pressures in the lung that cause alveoli to rupture. In spontaneous subcutaneous emphysema, air travels from the ruptured alveoli into the interstitium and along the blood vessel
Blood vessel
The blood vessels are the part of the circulatory system that transports blood throughout the body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and...
s of the lung, into the mediastinum and from there into the tissues of the neck or head.
Diagnosis
Significant cases of subcutaneous emphysema are easy to diagnose because of the characteristic signs of the condition. In some cases, the signs are subtle, making diagnosis more difficult. Medical imagingMedical imaging
Medical imaging is the technique and process used to create images of the human body for clinical purposes or medical science...
is used to diagnose the condition or confirm a diagnosis made using clinical signs. On a chest radiograph, subcutaneous emphysema may be seen as radiolucent
Radiodensity
Radiodensity refers to the relative inability of electromagnetic radiation, particularly X-rays, to pass through a particular material. Radiolucency indicates greater transparency or "transradiancy" to X-ray photons...
striations in the pattern expected from the pectoralis major muscle group. Air in the subcutaneous tissues may interfere with radiography
Radiography
Radiography is the use of X-rays to view a non-uniformly composed material such as the human body. By using the physical properties of the ray an image can be developed which displays areas of different density and composition....
of the chest, potentially obscuring serious conditions such as pneumothorax. It can also and reduce the effectiveness of chest ultrasound
Ultrasound
Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
. On the other hand, since subcutaneous emphysema may become apparent 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 before a pneumothorax does, its presence may be used to infer that of the latter injury. Subcutaneous emphysema can also be seen in CT scans, with the air pockets appearing as dark areas. CT scanning is so sensitive that it commonly makes it possible to find the exact spot from which air is entering the soft tissues. In 1994, M.T. Macklin and C.C. Macklin published further insights into the pathophysiology of spontaneous Macklin's Syndrome occurring from a severe asthmatic attack.
The presence of subcutaneous emphysema in a person who appears quite ill and febrile after bout of vomiting followed by left chest pain is very suggestive of the diagnosis of Boerhaave's syndrome which is a life threatening emergency caused by rupture of the distal esophagus.
Treatment
Subcutaneous emphysema is usually benignBenign
A benign tumor is a tumor that lacks the ability to metastasize. Common examples of benign tumors include moles and uterine fibroids.The term "benign" implies a mild and nonprogressive disease. Indeed, many kinds of benign tumors are harmless to human health...
. Most of the time, SCE itself does not need treatment (though the conditions from which it results may); however, if the amount of air is large, it can interfere with breathing and be uncomfortable. It occasionally progresses to a state "Massive Subcutaneous Emphysema" which is quite uncomfortable and requires surgical drainage. When the amount of air pushed out of the airways or lung becomes massive, usually due to positive pressure ventilation, the eyes will be obscured by the swollen eyelids making the patient sightless. Also the pressure of the air may impede the blood flow to the areolae of the breast and skin of the scrotum or labia. This can lead to necrosis of the skin in these areas. The latter are urgent situations requiring rapid, adequate decompression. Severe cases can compress the trachea and do require treatment.
In severe cases of subcutaneous emphysema, catheter
Catheter
In medicine, a catheter is a tube that can be inserted into a body cavity, duct, or vessel. Catheters thereby allow drainage, administration of fluids or gases, or access by surgical instruments. The process of inserting a catheter is catheterization...
s can be placed in the subcutaneous tissue to release the air. Small cuts, or "blow holes", may be made in the skin to release the gas. When subcutaneous emphysema occurs due to pneumothorax, a chest tube is frequently used to control the latter; this eliminates the source of the air entering the subcutaneous space. If the volume of subcutaneous air is increasing, it may be that the chest tube is not removing air rapidly enough, so it may be replaced with a larger one. Suction may also be applied to the tube to remove air faster. The progression of the condition can be monitored by marking the boundaries with a special pencil for marking on skin.
Since treatment usually involves dealing with the underlying condition, cases of spontaneous subcutaneous emphysema may require nothing more than bed rest, medication to control pain, and perhaps supplemental oxygen. Breathing oxygen may help the body to absorb the subcutaneous air more quickly. Reassurance and observation are also part of treatment.
Prognosis
Air in subcutaneous tissue does not usually pose a lethal threat; small amounts of air are reabsorbed by the body. Once the pneumothorax or pneumomediastinum that causes the subcutaneous emphysema is resolved, with or without medical intervention, the subcutaneous emphysema will usually clear. However, spontaneous subcutaneous emphysema can, in rare cases, progress to a life-threatening condition, and subcutaneous emphysema due to mechanical ventilation may induce ventilatory failure.History
The first report of subcutaneous emphysema resulting from air in the mediastinum was made in 1850 in a patient who had been coughing violently. In 1900, the first recorded case of spontaneous subcutaneous emphysema was reported in a bugleBugle (instrument)
The bugle is one of the simplest brass instruments, having no valves or other pitch-altering devices. All pitch control is done by varying the player's embouchure, since the bugle has no other mechanism for controlling pitch. Consequently, the bugle is limited to notes within the harmonic series...
r for the Royal Marines
Royal Marines
The Corps of Her Majesty's Royal Marines, commonly just referred to as the Royal Marines , are the marine corps and amphibious infantry of the United Kingdom and, along with the Royal Navy and Royal Fleet Auxiliary, form the Naval Service...
who had had a tooth extracted: playing the instrument had forced air through the hole where the tooth had been and into the tissues of his face. Since then, another case of spontaneous subcutaneous emphysema was reported in a submariner for the US Navy who had had a root canal
Endodontic therapy
Endodontic therapy is a sequence of treatment for the pulp of a tooth which results in the elimination of infection and protection of the decontaminated tooth from future microbial invasion...
in the past; the increased pressure in the submarine forced air through it and into his face. The cause of spontaneous subcutaneous emphysema was clarified between 1939 and 1944 by Macklin, contributing to the current understanding of the pathophysiology
Pathophysiology
Pathophysiology is the study of the changes of normal mechanical, physical, and biochemical functions, either caused by a disease, or resulting from an abnormal syndrome...
of the condition.