Two of the symptoms of flail chest are chest pain and shortness of breath.

The characteristic paradoxical motion of the flail segment occurs due to pressure changes associated with respiration that the rib cage normally resists:

- During normal inspiration, the diaphragm contracts and intercostal muscles pull the rib cage out. Pressure in the thorax decreases below atmospheric pressure, and air rushes in through the trachea. The flail segment will be pulled in with the decrease in pressure while the rest of the rib cage expands.

- During normal expiration, the diaphragm and intercostal muscles relax increasing internal pressure, allowing the abdominal organs to push air upwards and out of the thorax. However, a flail segment will also be pushed out while the rest of the rib cage contracts.

The constant motion of the ribs in the flail segment at the site of the fracture is extremely painful, and, untreated, the sharp broken edges of the ribs are likely to eventually puncture the pleural sac and lung, possibly causing a pneumothorax. The concern about "mediastinal flutter" (the shift of the mediastinum with paradoxical diaphragm movement) does not appear to be merited. Pulmonary contusions are commonly associated with flail chest and that can lead to respiratory failure. This is due to the paradoxical motions of the chest wall from the fragments interrupting normal breathing and chest movement. Typical paradoxical motion is associated with stiff lungs, which requires extra work for normal breathing, and increased lung resistance, which makes air flow difficult. The respiratory failure from the flail chest requires mechanical ventilation and a longer stay in an intensive care unit. It is the damage to the lungs from the flail segment that is life-threatening.

Flail chest is a life-threatening medical condition that occurs when a segment of the rib cage breaks due to trauma and becomes detached from the rest of the chest wall. Two of the symptoms of flail chest are chest pain and shortness of breath.

It occurs when multiple adjacent ribs are broken in multiple places, separating a segment, so a part of the chest wall moves independently. The number of ribs that must be broken varies by differing definitions: some sources say at least two adjacent ribs are broken in at least two places, some require three or more ribs in two or more places. The flail segment moves in the opposite direction to the rest of the chest wall: because of the ambient pressure in comparison to the pressure inside the lungs, it goes in while the rest of the chest is moving out, and vice versa. This so-called "paradoxical breathing" is painful and increases the work involved in breathing.

Flail chest is usually accompanied by a pulmonary contusion, a bruise of the lung tissue that can interfere with blood oxygenation. Often, it is the contusion, not the flail segment, that is the main cause of respiratory problems in people with both injuries.

Surgery to fix the fractures appears to result in better outcomes.

Signs and symptoms vary depending on what part of the tracheobronchial tree is injured and how severely it is damaged. There are no direct signs of TBI, but certain signs suggest the injury and raise a clinician's suspicion that it has occurred. Many of the signs and symptoms are also present in injuries with similar injury mechanisms such as pneumothorax. Dyspnea and respiratory distress are found in 76–100% of people with TBI, and coughing up blood has been found in up to 25%. However, isolated TBI does not usually cause profuse bleeding; if such bleeding is observed it is likely to be due to another injury such as a ruptured large blood vessel. The patient may exhibit dysphonia or have diminished breath sounds, and rapid breathing is common. Coughing may be present, and stridor, an abnormal, high-pitched breath sound indicating obstruction of the upper airway can also occur.

Damage to the airways can cause subcutaneous emphysema (air trapped in the subcutaneous tissue of the skin) in the abdomen, chest, neck, and head. Subcutaneous emphysema, present in up to 85% of people with TBI, is particularly indicative of the injury when it is only in the neck. Air is trapped in the chest cavity outside the lungs (pneumothorax) in about 70% of TBI. Especially strong evidence that TBI has occurred is failure of a pneumothorax to resolve even when a chest tube is placed to rid the chest cavity of the air; it shows that air is continually leaking into the chest cavity from the site of the tear. Air can also be trapped in the mediastinum, the center of the chest cavity (pneumomediastinum). If air escapes from a penetrating injury to the neck, a definite diagnosis of TBI can be made. Hamman's sign, a sound of crackling that occurs in time with the heartbeat, may also accompany TBI.

Although multiple definitions exist, a tension pneumothorax is generally considered to be present when a pneumothorax (primary spontaneous, secondary spontaneous, or traumatic) leads to significant impairment of respiration and/or blood circulation. Tension pneumothorax tends to occur in clinical situations such as ventilation, resuscitation, trauma, or in patients with lung disease.

The most common findings in people with tension pneumothorax are chest pain and respiratory distress, often with an increased heart rate (tachycardia) and rapid breathing (tachypnea) in the initial stages. Other findings may include quieter breath sounds on one side of the chest, low oxygen levels and blood pressure, and displacement of the trachea away from the affected side. Rarely, there may be cyanosis (bluish discoloration of the skin due to low oxygen levels), altered level of consciousness, a hyperresonant percussion note on examination of the affected side with reduced expansion and decreased movement, pain in the epigastrium (upper abdomen), displacement of the apex beat (heart impulse), and resonant sound when tapping the sternum. This is a medical emergency and may require immediate treatment without further investigations (see below).

Tension pneumothorax may also occur in someone who is receiving mechanical ventilation, in which case it may be difficult to spot as the person is typically receiving sedation; it is often noted because of a sudden deterioration in condition. Recent studies have shown that the development of tension features may not always be as rapid as previously thought. Deviation of the trachea to one side and the presence of raised jugular venous pressure (distended neck veins) are not reliable as clinical signs.

A primary spontaneous pneumothorax (PSP) tends to occur in a young adult without underlying lung problems, and usually causes limited symptoms. Chest pain and sometimes mild breathlessness are the usual predominant presenting features. People who are affected by PSPs are often unaware of potential danger and may wait several days before seeking medical attention. PSPs more commonly occur during changes in atmospheric pressure, explaining to some extent why episodes of pneumothorax may happen in clusters. It is rare for PSPs to cause tension pneumothoraces.

Secondary spontaneous pneumothoraces (SSPs), by definition, occur in individuals with significant underlying lung disease. Symptoms in SSPs tend to be more severe than in PSPs, as the unaffected lungs are generally unable to replace the loss of function in the affected lungs. Hypoxemia (decreased blood-oxygen levels) is usually present and may be observed as cyanosis (blue discoloration of the lips and skin). Hypercapnia (accumulation of carbon dioxide in the blood) is sometimes encountered; this may cause confusion and – if very severe – may result in comas. The sudden onset of breathlessness in someone with chronic obstructive pulmonary disease (COPD), cystic fibrosis, or other serious lung diseases should therefore prompt investigations to identify the possibility of a pneumothorax.

Traumatic pneumothorax most commonly occurs when the chest wall is pierced, such as when a stab wound or gunshot wound allows air to enter the pleural space, or because some other mechanical injury to the lung compromises the integrity of the involved structures. Traumatic pneumothoraces have been found to occur in up to half of all cases of chest trauma, with only rib fractures being more common in this group. The pneumothorax can be occult (not readily apparent) in half of these cases, but may enlarge - particularly if mechanical ventilation is required. They are also encountered in patients already receiving mechanical ventilation for some other reason.

Upon physical examination, breath sounds (heard with a stethoscope) may be diminished on the affected side, partly because air in the pleural space dampens the transmission of sound. Measures of the conduction of vocal vibrations to the surface of the chest may be altered. Percussion of the chest may be perceived as hyperresonant (like a booming drum), and vocal resonance and tactile fremitus can both be noticeably decreased. Importantly, the volume of the pneumothorax can show limited correlation with the intensity of the symptoms experienced by the victim, and physical signs may not be apparent if the pneumothorax is relatively small.

Presentation may be subtle; people with mild contusion may have no symptoms at all. However, pulmonary contusion is frequently associated with signs (objective indications) and symptoms (subjective states), including those indicative of the lung injury itself and of accompanying injuries. Because gas exchange is impaired, signs of low blood oxygen saturation, such as low concentrations of oxygen in arterial blood gas and cyanosis (bluish color of the skin and mucous membranes) are commonly associated. Dyspnea (painful breathing or difficulty breathing) is commonly seen, and tolerance for exercise may be lowered. Rapid breathing and a rapid heart rate are other signs. With more severe contusions, breath sounds heard through a stethoscope may be decreased, or rales (an abnormal crackling sound in the chest accompanying breathing) may be present. People with severe contusions may have bronchorrhea (the production of watery sputum). Wheezing and coughing are other signs. Coughing up blood or bloody sputum is present in up to half of cases. Cardiac output (the volume of blood pumped by the heart) may be reduced, and hypotension (low blood pressure) is frequently present. The area of the chest wall near the contusion may be tender or painful due to associated chest wall injury.

Signs and symptoms take time to develop, and as many as half of cases are asymptomatic at the initial presentation. The more severe the injury, the more quickly symptoms become apparent. In severe cases, symptoms may occur as quickly as three or four hours after the trauma. Hypoxemia (low oxygen concentration in the arterial blood) typically becomes progressively worse over 24–48 hours after injury. In general, pulmonary contusion tends to worsen slowly over a few days, but it may also cause rapid deterioration or death if untreated.

Tracheobronchial injury (TBI) is damage to the tracheobronchial tree (the airway structure involving the trachea and bronchi). It can result from blunt or penetrating trauma to the neck or chest, inhalation of harmful fumes or smoke, or aspiration of liquids or objects.

Though rare, TBI is a serious condition; it may cause obstruction of the airway with resulting life-threatening respiratory insufficiency. Other injuries accompany TBI in about half of cases. Of those people with TBI who die, most do so before receiving emergency care, either from airway obstruction, exsanguination, or from injuries to other vital organs. Of those who do reach a hospital, the mortality rate may be as high as 30%.

TBI is frequently difficult to diagnose and treat. Early diagnosis is important to prevent complications, which include stenosis (narrowing) of the airway, respiratory tract infection, and damage to the lung tissue. Diagnosis involves procedures such as bronchoscopy, radiography, and x-ray computed tomography to visualize the tracheobronchial tree. Signs and symptoms vary based on the location and severity of the injury; they commonly include dyspnea (difficulty breathing), dysphonia (a condition where the voice can be hoarse, weak, or excessively breathy), coughing, and abnormal breath sounds. In the emergency setting, tracheal intubation can be used to ensure that the airway remains open. In severe cases, surgery may be necessary to repair a TBI.

Pulmonary contusion and laceration are injuries to the lung tissue. Pulmonary laceration, in which lung tissue is torn or cut, differs from pulmonary contusion in that the former involves disruption of the macroscopic architecture of the lung, while the latter does not. When lacerations fill with blood, the result is pulmonary hematoma, a collection of blood within the lung tissue. Contusion involves hemorrhage in the alveoli (tiny air-filled sacs responsible for absorbing oxygen), but a hematoma is a discrete clot of blood not interspersed with lung tissue. A collapsed lung can result when the pleural cavity (the space outside the lung) accumulates blood (hemothorax) or air (pneumothorax) or both (hemopneumothorax). These conditions do not inherently involve damage to the lung tissue itself, but they may be associated with it. Injuries to the chest wall are also distinct from but may be associated with lung injuries. Chest wall injuries include rib fractures and flail chest, in which multiple ribs are broken so that a segment of the ribcage is detached from the rest of the chest wall and moves independently.

Hemothorax tends to occur following blunt or penetrating trauma to the thorax or thoracoabdominal area. It may also follow thoracic surgery, or may be spontaneous. Chest pain, dyspnea, and tachypnea are common presenting features. Other symptoms of hemothorax are dependent on the mechanism of injury, but may include:

- Cyanosis

- Decreased or absent breath sounds on affected side

- Tracheal deviation to unaffected side

- Dull resonance on percussion

- Unequal chest rise

- Tachycardia

- Hypotension

- Pale, cool, clammy skin

- Possible subcutaneous emphysema

- Narrowing pulse pressure

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. Pulmonary laceration is commonly caused by penetrating trauma but may also result from forces involved in blunt trauma such as shear stress. A cavity filled with blood, air, or both can form. The injury is diagnosed when collections of air or fluid are found on a CT scan of the chest. Surgery may be required to stitch the laceration, to drain blood, or even to remove injured parts of the lung. The injury commonly heals quickly with few problems if it is given proper treatment; however it may be associated with scarring of the lung or other complications.

The main symptom is usually severe central chest pain. Other symptoms include laboured breathing, voice distortion (as with helium) and subcutaneous emphysema, specifically affecting the face, neck, and chest. Pneumomediastinum can also be characterized by the shortness of breath that is typical of a respiratory system problem. It is often recognized on auscultation by a "crunching" sound timed with the cardiac cycle (Hamman's crunch).

Pnemomediastinum may also present with symptoms mimicking cardiac tamponade as a result of the increased intrapulmonary pressure on venous flow to the heart.

Breath sounds on the side of the rupture may be diminished, respiratory distress may be present, and the chest or abdomen may be painful. Orthopnea, dyspnea which occurs when lying flat, may also occur, and coughing is another sign. In people with herniation of abdominal organs, signs of intestinal blockage or sepsis in the abdomen may be present. Bowel sounds may be heard in the chest, and shoulder or epigastric pain may be present. When the injury is not noticed right away, the main symptoms are those that indicate bowel obstruction.

Signs one may have a broken rib are:

- Pain on inhalation

- Swelling in chest area

- Bruise in chest area

- Increasing shortness of breath

- Coughing up blood (rib may have damaged lung)

Because children have more flexible chest walls than adults do, their ribs are more likely to bend than to break; therefore the presence of rib fractures in children is evidence of a significant amount of force and may indicate severe thoracic injuries such as pulmonary contusion. Rib fractures are also a sign of more serious injury in elderly people.

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 swallowing, wheezing and difficulty breathing. Chest X-rays 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.

Pneumomediastinum (from Greek "pneuma" – "air", also known as mediastinal emphysema) is (abnormal presence of air or other gas) in the mediastinum. First described in 1819 by René Laennec, the condition can result from physical trauma or other situations that lead to air escaping from the lungs, airways, or bowel into the chest cavity.

Diaphragmatic rupture (also called diaphragmatic injury or tear) is a tear of the diaphragm, the muscle across the bottom of the ribcage that plays a crucial role in respiration. Most commonly, acquired diaphragmatic tears result from physical trauma. Diaphragmatic rupture can result from blunt or penetrating trauma and occurs in about 5% of cases of severe blunt trauma to the trunk.

Diagnostic techniques include X-ray, computed tomography, and surgical techniques such as laparotomy. Diagnosis is often difficult because signs may not show up on X-ray, or signs that do show up appear similar to other conditions. Signs and symptoms included chest and abdominal pain, difficulty breathing, and decreased lung sounds. When a tear is discovered, surgery is needed to repair it.

Injuries to the diaphragm are usually accompanied by other injuries, and they indicate that more severe injury may have occurred. The outcome often depends more on associated injuries than on the diaphragmatic injury itself. Since the pressure is higher in the abdominal cavity than the chest cavity, rupture of the diaphragm is almost always associated with herniation of abdominal organs into the chest cavity, which is called a traumatic diaphragmatic hernia. This herniation can interfere with breathing, and blood supply can be cut off to organs that herniate through the diaphragm, damaging them.

In 1988, a group led by R.B. Wagner divided pulmonary lacerations into four types based on the manner in which the person was injured and indications found on a CT scan. In type 1 lacerations, which occur in the mid lung area, the air-filled lung bursts as a result of sudden compression of the chest. Also called compression-rupture lacerations, type 1 are the most common type and usually occur in a central location of the lung. They tend to be large, ranging in size from 2–8 cm. The shearing stress in type 2 results when the lower chest is suddenly compressed and the lower lung is suddenly moved across the vertebral bodies. Type 2, also called compression-shear, tends to occur near the spine and have an elongated shape. Type 2 lacerations usually occur in younger people with more flexible chests. Type 3, which are caused by punctures from fractured ribs, occur in the area near the chest wall underlying the broken rib. Also called rib penetration lacerations, type 3 lacerations tend to be small and accompanied by pneumothorax. Commonly, more than one type 3 laceration will occur. Type 4, also called adhesion tears, occur in cases where a pleuropulmonary adhesion had formed prior to the injury, in which the chest wall is suddenly fractured or pushed inwards. They occur in the subpleural area and result from shearing forces at sites of transpleural adhesion.

Rib fractures can occur with or without direct trauma during recreational activity. Cardiopulmonary resuscitation (CPR) has also been known to cause thoracic injury, including but not limited to rib and sternum fractures. They can also occur as a consequence of diseases such as cancer or rheumatoid arthritis. While for elderly individuals a fall can cause a rib fracture, in adults automobile accidents are a common event for such an injury.

Barrel chest generally refers to a , deep chest found on a man. A man described as barrel chested will usually have a naturally large ribcage, very round torso, large lung capacity, and can potentially have great upper body strength. It can sometimes be a sign of acromegaly (a syndrome resulting from excess levels of human growth hormone (HGH) in the body). It is most commonly related to osteoarthritis as individuals age. Arthritis can stiffen the chest causing the ribs to become fixed in their most expanded position, giving the appearance of a barrel chest.

Barrel chest also refers to an increase in the anterior posterior diameter of the chest wall resembling the shape of a barrel, most often associated with emphysema. There are two main causes of the barrel chest phenomenon in emphysema:

1. Increased compliance of the lungs leads to the accumulation of air pockets inside the thoracic cavity.

2. Increased compliance of the lungs increases the intrathoracic pressure. This increase in pressure allows the chest wall to naturally expand outward.

Barrel chest occurs naturally in native people who live at altitudes of over 5500 m, e.g. the Himalayas or the Andes. These natives also have polycythemia and other accommodations for high altitude life.

May have no signs and symptoms or they may include:

- cough, but not prominent;

- chest pain (not common);

- breathing difficulty (fast and shallow);

- low oxygen saturation;

- pleural effusion (transudate type);

- cyanosis (late sign);

- increased heart rate.

It is a common misconception 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 doctrine.

Hemopneumothorax, or haemopneumothorax, is a medical term describing the combination of two conditions: pneumothorax, or air in the chest cavity, and hemothorax (also called hæmothorax), or blood in the chest cavity.

A hemothorax, pneumothorax or both can occur if the chest wall is punctured. To understand the ramifications of this it is important to have an understanding of the role of the pleural space. The pleural space is located anatomically between the visceral membrane, which is firmly attached to the lungs, and the parietal membrane which is firmly attached to the chest wall (a.k.a. ribcage and intercostal muscles, muscles between the ribs). The pleural space contains pleural fluid. This fluid holds the two membranes together by surface tension, as much as a drop of water between two sheets of glass prevents them from separating. Because of this, when the intercostal muscles move the ribcage outward, the lungs are pulled out as well, dropping the pressure in the lungs and pulling air into the bronchi, when we 'breathe in'. The pleural space is maintained in a constant state of negative pressure (in comparison to atmospheric pressure).

A hemothorax is a type of pleural effusion in which blood accumulates in the pleural cavity. This excess fluid can interfere with normal breathing by limiting the expansion of the lungs. The term is from "" + "thorax".

Subcutaneous emphysema is a common result of certain types of surgery; for example it is not unusual in chest surgery. 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 oral 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.

Atelectasis is the collapse or closure of a lung resulting in reduced or absent gas exchange. It may affect part or all of a lung. It is usually unilateral. It is a condition where the alveoli are deflated down to little or no volume, as distinct from pulmonary consolidation, in which they are filled with liquid. It is often called a collapsed lung, although that term may also refer to pneumothorax.

It is a very common finding in chest x-rays and other radiological studies, and may be caused by normal exhalation or by various 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.

The term uses combining forms of "atel-" + "", from , "incomplete" + ἔκτασις, "extension".

This can be remembered by 4 'S'

- Straight line dullness

- Shifting dullness

- splash

- Sound of coin

- fullness of chest