Pneumothorax: Air Around the Lung Causing Partial or Complete Collapse

A pneumothorax occurs when air enters the pleural space between a lung and the chest wall. The air removes the pressure holding the lung open, causing partial or complete collapse. Symptoms and risk depend on the cause, the person's lung reserve and whether dangerous pressure is building.

What a pneumothorax is A pneumothorax is air within the pleural space surrounding a lung. The air separates the lung surface from the inside of the chest wall. The affected lung then recoils inwards and becomes partly or completely collapsed. Pneumothorax is a pleural condition rather than an infection or ordinary airway narrowing. The pleura Each lung is covered by a thin membrane called the visceral pleura. The inside of the chest wall is lined by the parietal pleura. The narrow potential space between them is the pleural space. It normally contains a very small amount of lubricating fluid but no free air. How the lung stays expanded The lung naturally tends to recoil inwards while the chest wall tends to move outwards. A pressure below atmospheric pressure within the sealed pleural space keeps the two pleural surfaces closely opposed. This mechanical relationship helps the lung expand as the chest enlarges during inspiration. How pleural air causes collapse Air entering the pleural space removes part of the pressure difference holding the lung open. The lung recoils away from the chest wall. A small collection may collapse only a limited outer region. A large collection can collapse most or all of the lung on that side. Collapsed lung is a broad public term Pneumothorax is often called a collapsed lung. Other processes can also reduce lung inflation, including mucus blockage, compression by fluid and postoperative atelectasis. The word collapse therefore does not identify the cause without imaging and clinical assessment. Size and severity are not the same A larger pneumothorax often causes more physiological disturbance, but size alone does not determine risk. A young person with healthy lungs may tolerate a relatively large primary pneumothorax. A person with severe COPD can become critically breathless from a much smaller secondary pneumothorax. Symptoms, oxygen levels, circulation and underlying disease matter alongside imaging size. Main pneumothorax categories A spontaneous pneumothorax occurs without an immediate injury or procedure. It is divided into primary and secondary spontaneous pneumothorax. Traumatic pneumothorax follows blunt or penetrating chest injury. Iatrogenic pneumothorax follows a medical procedure and is often considered separately within traumatic or procedure related care. Primary spontaneous pneumothorax Primary spontaneous pneumothorax is usually shortened to PSP. It occurs without established clinically apparent underlying lung disease. The person may previously have considered their lungs healthy. Small surface abnormalities can still be present even though no chronic disease has been diagnosed. Who commonly develops PSP PSP classically occurs in tall, slim adolescents or younger adults, particularly men. It can occur in women and in people with other body shapes. The demographic pattern changes probability but cannot diagnose the condition. Sudden compatible symptoms require assessment at any age. Blebs and bullae Small air filled spaces can form close to the lung surface. A small space is commonly called a bleb, while a larger one may be called a bulla. Rupture can allow air to leak from the lung into the pleural space. Not every PSP has one clearly identifiable ruptured bleb. Smoking and PSP Cigarette smoking greatly increases the risk of primary spontaneous pneumothorax. It also increases recurrence risk after an episode. Stopping smoking is one of the few modifiable measures likely to reduce future risk. Cannabis smoke and other inhaled substances may also expose the lungs to harmful combustion products. Secondary spontaneous pneumothorax Secondary spontaneous pneumothorax is usually shortened to SSP. It occurs in a person with underlying lung disease. The damaged lung develops a leak without a new external injury. The pneumothorax can be small on imaging yet cause severe clinical deterioration. COPD and emphysema COPD is a common cause of secondary spontaneous pneumothorax. Emphysema destroys lung tissue and can create fragile bullae. If a bulla ruptures, air can enter the pleural space. Reduced baseline lung reserve makes loss of additional functioning lung particularly dangerous. Other causes of SSP Secondary pneumothorax can occur with pulmonary fibrosis, cystic fibrosis and bronchiectasis. Tuberculosis, Pneumocystis pneumonia and necrotising infection can also damage the lung surface. Lung cancer and metastatic disease are less common causes. Asthma is an unusual cause but severe air trapping can occasionally contribute. Cystic and inherited lung disorders Lymphangioleiomyomatosis, called LAM, can cause recurrent pneumothoraces, mainly in women. Birt Hogg Dubé syndrome can cause lung cysts, recurrent pneumothorax, skin changes and kidney tumour risk. Recurrent, bilateral or familial episodes can therefore prompt specialist investigation for an underlying disorder. Older people with past or current smoking BTS identifies age 50 or older with a significant past or current smoking as a high risk characteristic. This reflects the likelihood of reduced reserve or unrecognised lung disease. The person is not managed as though they were a low risk young adult merely because COPD has not yet been formally diagnosed. Traumatic pneumothorax Traumatic pneumothorax follows injury to the chest or lung. Air can enter through a damaged chest wall or leak from injured lung tissue. The injury can coexist with rib fractures, bleeding, lung bruising or damage to other organs. Trauma pathways therefore assess the whole person rather than the pneumothorax alone. Blunt chest injury A fall, road collision or crushing injury can fracture a rib or tear lung tissue. The chest wall may look intact despite internal injury. Symptoms can appear immediately or worsen later as air accumulates. Penetrating chest injury A stab wound, gunshot or another penetrating injury can create a direct route into the pleural space. An open pneumothorax communicates with outside air through the chest wall. It requires immediate trauma care and an appropriate dressing and drainage plan. Iatrogenic pneumothorax A medical procedure can unintentionally allow air into the pleural space. Examples include lung biopsy, central venous access, pleural aspiration, pacemaker insertion and positive pressure ventilation. The risk and treatment depend on the procedure, symptoms and pneumothorax size. A post procedure pneumothorax can still become clinically serious. Positive pressure ventilation Mechanical ventilation pushes air into the lungs under pressure. A lung leak can enlarge more quickly under positive pressure. A simple pneumothorax can progress to tension physiology. Ventilated people therefore require urgent specialist assessment and drainage when pneumothorax is suspected. What tension pneumothorax is Tension pneumothorax is a life threatening form in which pleural pressure rises enough to impair breathing and circulation. Air commonly enters faster than it can escape. The expanding pressure compresses the affected lung and can shift central chest structures. It also reduces blood return to the heart. Why tension pneumothorax causes shock The great veins are compressed by rising intrathoracic pressure. Less blood reaches the heart, so cardiac output falls. The person can develop severe low blood pressure, obstructive shock and cardiac arrest. This deterioration can occur rapidly, especially after trauma or during positive pressure ventilation. Tension is a physiological diagnosis Tension pneumothorax is defined by dangerous respiratory or circulatory compromise, not simply by a large air collection. A radiograph showing mediastinal shift in a stable person is not automatically the same as clinical tension. A critically unstable person can have tension before classic signs or major shift become visible. Do not wait for imaging in unstable tension pneumothorax When tension pneumothorax causes haemodynamic instability or severe respiratory compromise, treatment precedes imaging. Immediate chest decompression releases trapped pressurised air. Needle decompression is a common immediately available method. Trained trauma teams may use open or finger thoracostomy instead, followed by chest drain insertion. Ordinary pneumothorax and tension are different Most pneumothoraces are not under tension. An ordinary stable pneumothorax does not require blind emergency needle decompression. Unnecessary decompression can injure the lung, blood vessels or other structures. The emergency procedure is reserved for a clinically unstable tension pattern. Sudden pleuritic chest pain The usual symptom is sudden pain on one side of the chest. Pleuritic pain becomes sharper during a deep breath, cough or movement. It may spread towards the shoulder or back. The pain can lessen even while pleural air remains present. Breathlessness Breathlessness can begin suddenly with the pain. Its degree depends on pneumothorax size, baseline lung function and speed of development. Some people with PSP report only mild breathlessness. A person with SSP may become severely breathless from a small collapse. Symptoms can be mild A small pneumothorax may cause only brief pain or no recognised symptoms. Mild symptoms do not prove that no pneumothorax is present. The same symptoms can also arise from muscle strain, pleurisy or another condition. Dry cough Some people develop an irritating dry cough. Cough is non specific and is not required for diagnosis. A productive cough or fever raises additional concern for infection or underlying lung disease. Severe symptoms Rapid breathing, fast heart rate, low oxygen and inability to speak normally indicate significant compromise. Faintness, confusion, clammy skin or collapse can signal tension physiology or bleeding. These patterns require a 999 call. Physical examination Breath sounds can be reduced on the affected side. The chest may sound unusually resonant when tapped. The affected side may move less during breathing. These signs can be subtle or absent, especially with a small pneumothorax. Tracheal deviation Tracheal deviation away from the affected side is traditionally associated with tension pneumothorax. It is a late and inconsistent sign. Emergency treatment must not wait for visible or palpable deviation. Neck veins and blood pressure Raised neck veins can occur when venous return is obstructed. They may not be visible during blood loss, dehydration or severe shock. Low blood pressure is a particularly concerning sign of tension physiology. No single sign is sufficiently reliable in isolation. Subcutaneous emphysema Air can track from the chest into tissues under the skin. The neck or chest may swell and feel crackly, like bubble wrap, when touched. This is called subcutaneous emphysema. It can accompany trauma, a chest drain or a persistent air leak. Haemopneumothorax A haemopneumothorax contains both air and blood within the pleural space. It can follow trauma or occur rarely with spontaneous pneumothorax. The person can develop respiratory compromise and blood loss shock. It is a high risk presentation requiring hospital drainage and surgical assessment where appropriate. Bilateral pneumothorax A bilateral pneumothorax affects both pleural spaces. Even modest collapse on each side can significantly reduce breathing capacity. Bilateral disease raises concern for trauma or an underlying cystic or systemic lung disorder. It is a high risk presentation. Other causes of sudden chest pain Pulmonary embolism, acute coronary syndrome and aortic dissection can cause sudden chest symptoms. Pneumonia, pericarditis, pleurisy and musculoskeletal pain are other possibilities. Several alternatives are also life threatening. Home symptom comparison cannot safely separate them. Initial clinical assessment The clinician identifies symptom onset, trauma and recent procedures. They review smoking, COPD, asthma, fibrosis, infection and previous pneumothorax. Pulse, blood pressure, respiratory rate, oxygen saturation and consciousness are assessed. The first question is whether tension or another unstable emergency is present. Chest X ray A chest X ray is the usual first imaging test for a stable suspected spontaneous pneumothorax. It can show a visible visceral pleural line with no lung markings beyond it. The lung may appear partly retracted towards the hilum. The X ray also provides clues to underlying lung disease or trauma. Upright and portable radiographs An upright chest X ray can make pleural air easier to identify. Critically ill or injured people may require a portable supine film. Pleural air can collect in less familiar positions when someone is lying flat. Clinical context and expert interpretation remain important. Measuring pneumothorax size Radiographic size estimates the distance between the lung edge and chest wall. Different guidelines and studies have used different measurement methods. BTS 2023 places greater emphasis on symptoms, physiological compromise and high risk features than on size alone. Size still affects whether aspiration or drainage can be performed safely. A large PSP may still be managed without drainage Current BTS guidance allows conservative management for a minimally symptomatic or asymptomatic PSP regardless of radiographic size. This requires clinical stability, reliable follow up and clear safety netting. It does not mean that every large PSP should be left untreated. The person's preferences and local expertise also matter. A small SSP may need intervention Underlying disease reduces the person's ability to tolerate lost lung volume. A small pneumothorax can therefore cause hypoxia or major breathlessness. SSP is treated as a high risk condition and commonly requires admission and drainage assessment. Chest CT CT is more sensitive than chest X ray for small, loculated or unusual pneumothoraces. It can distinguish pleural air from a giant bulla and show underlying emphysema, cysts or fibrosis. CT is used when the diagnosis is uncertain, anatomy is complex or a safe procedure needs radiological planning. A stable straightforward PSP does not always require CT. Thoracic ultrasound Bedside ultrasound can rapidly support pneumothorax diagnosis in trauma and critical care. Absence of normal pleural sliding and other signs can raise suspicion. Operator skill and clinical context affect accuracy. Ultrasound must not delay decompression of an unstable tension pneumothorax. Blood tests and blood gases No blood test confirms pneumothorax. Blood gases can assess oxygen, carbon dioxide and acid base disturbance in severe disease. Other tests investigate infection, bleeding or an alternative diagnosis. Management goals Immediate treatment aims to maintain oxygenation and circulation. It also aims to relieve significant symptoms and allow the lung leak to seal. Longer term care reduces recurrence risk and investigates underlying disease. The least invasive safe option is preferred after discussion with the person. Pain relief Pleuritic pain can be severe even when the pneumothorax is small. Appropriate analgesia helps the person breathe and move more normally. Pain relief does not determine whether the lung has re expanded. Oxygen treatment Oxygen is given when blood oxygen is below the appropriate target or the person is critically unwell. It is not a substitute for decompression or drainage when those are required. Routine uncontrolled high flow oxygen can be harmful in some people with chronic carbon dioxide retention. Conservative management Conservative management means no immediate pleural procedure. The body gradually absorbs pleural air after the leak seals. The person receives assessment, pain treatment, follow up imaging and emergency return advice. Conservative care is active monitoring rather than neglect. Who may receive conservative care BTS considers it for adults with minimally symptomatic or asymptomatic PSP and no physiological compromise. Radiographic size does not automatically exclude this option. Reliable access to urgent help and scheduled follow up are essential. High risk secondary, bilateral, traumatic or tension presentations follow different pathways. Observation and follow up A stable person may be observed initially to ensure symptoms and vital signs do not worsen. Those managed by observation alone usually need respiratory follow up and repeat chest X ray within about two to four weeks. Local pathways may arrange earlier reviews when the pneumothorax is larger or symptoms persist. Ambulatory management An ambulatory device allows pleural air to leave through a one way valve while the person remains mobile outside hospital. BTS considers this for selected PSP in centres with expertise, support and frequent follow up. The person must understand drain care and emergency symptoms. Ordinary ambulatory PSP pathways are not recommended for secondary spontaneous pneumothorax. Needle aspiration Needle aspiration removes pleural air through a needle or small catheter attached to a syringe or one way system. It can provide rapid symptom relief without leaving a chest tube in place. A repeat X ray and clinical review assess whether improvement is sustained. Further drainage may be needed if aspiration fails or the leak continues. Chest drain insertion A chest drain is a tube placed through the chest wall into the pleural space. It connects to an underwater seal or one way drainage system. Air leaves while the lung re expands and the leak seals. Small bore drains are suitable for many spontaneous pneumothoraces. When a chest drain is more likely Tube drainage is commonly required for significant symptoms, physiological compromise or failed aspiration. It is frequently used for SSP, bilateral pneumothorax and traumatic pneumothorax. Tension pneumothorax requires definitive chest drainage after immediate decompression. Haemopneumothorax may require a different drain strategy because blood must also be removed. Chest drain safety Chest drains can cause pain, bleeding, infection or injury to nearby structures. They can become blocked, displaced or disconnected. A person should not clamp, remove or reconnect a drain without trained clinical instruction. Sudden breathlessness after drain movement requires immediate review. PSP management is individualised A stable minimally symptomatic PSP may be managed conservatively. Ambulatory treatment can offer symptom relief while limiting hospital stay. Needle aspiration or tube drainage is considered when the other options are unsuitable. The final decision reflects symptoms, safety, preference and local services. SSP requires greater caution The underlying lung is already abnormal and respiratory reserve may be limited. People with SSP commonly require admission, oxygen assessment and active drainage when breathless or the pneumothorax is accessible. The underlying disease and precipitating infection are treated at the same time. Early respiratory and thoracic surgical input may be needed. Traumatic pneumothorax management Trauma care assesses airway, breathing, circulation and associated injuries. A small stable occult pneumothorax may sometimes be observed within a monitored trauma pathway. A symptomatic, enlarging or ventilated traumatic pneumothorax commonly requires chest drainage. An open chest wound needs immediate trauma management and monitoring for tension. Emergency treatment of tension pneumothorax An unstable tension pneumothorax is decompressed immediately before imaging. Needle thoracostomy releases pressurised air when it is the fastest available technique. NICE trauma guidance prefers open thoracostomy when suitable expertise is immediately available. A chest drain then provides definitive continuing drainage. Decompression can fail A needle may not reach the pleural space or can become blocked or displaced. The person's response is reassessed immediately. Persistent shock or severe respiratory compromise requires repeat or alternative decompression by trained clinicians. Persistent air leak Most leaks seal after the lung is drained or managed conservatively. An ongoing leak can prevent full re expansion. The BTS quality standard defines prolonged air leak as continuing after three to five days of chest drain treatment. Clinically appropriate cases should be discussed early with a thoracic surgery team. Pleurodesis Pleurodesis deliberately causes the pleural surfaces to adhere. This reduces the space into which the lung can collapse again. It can be performed surgically or by introducing a chemical through a chest drain. Pain relief is important because chemical pleurodesis can be painful. Surgery Surgery can remove or staple visible blebs or bullae and create pleural adhesion. Video assisted thoracoscopic surgery, called VATS, uses small ports and a camera. Procedures can include bullectomy, pleural abrasion, pleurectomy or chemical pleurodesis. Surgery reduces recurrence risk but does not make recurrence impossible. When surgery is considered after recurrence BTS advises considering elective surgery after a second pneumothorax on the same side. It is also considered after the first pneumothorax on the opposite side. A persistent air leak or failure of the lung to re expand can prompt earlier surgical review. Surgery after a first episode Recurrence prevention may be especially important after a first tension pneumothorax. It may also matter for divers, pilots, military personnel and others whose work makes recurrence particularly hazardous. Severe SSP can justify chemical pleurodesis or surgical discussion even after the first episode. Recurrence risk A spontaneous pneumothorax can recur on the same or opposite side. Risk is highest during the first few years but does not disappear completely later. Smoking, underlying lung disease and some inherited or cystic conditions increase risk. One person's exact recurrence probability cannot be predicted from size alone. Smoking cessation BTS advises smoking cessation because smoking increases recurrence risk. Stopping also reduces COPD, cancer and cardiovascular risk. Evidence based behavioural and medicine support improves the chance of sustained cessation. Follow up after discharge Every person should receive written and verbal advice about recurrent breathlessness. Respiratory follow up confirms radiological resolution and reviews underlying lung disease. It also provides recurrence, smoking, flying and activity advice. Activity after pneumothorax Normal light activity can usually increase gradually as pain and breathlessness settle. Strenuous exercise, heavy lifting and contact activity should wait until the treating team confirms recovery. Physical activity does not replace follow up imaging. Sudden recurrent symptoms require urgent reassessment. Air travel with an unresolved pneumothorax Commercial aircraft cabins have lower pressure than sea level. Pleural gas can expand as ambient pressure falls. Most people with an untreated or unresolved pneumothorax must not fly. Medical oxygen does not remove the expansion risk. Flying after resolution BTS advises waiting until a chest X ray confirms complete resolution. The person should then wait a further seven days before commercial air travel. Airlines and travel insurers can impose additional conditions. People with chronic localised air collections need specialist assessment rather than applying the general rule themselves. Scuba diving Compressed gas expands during ascent from a dive. A recurrent pneumothorax underwater can rapidly become tension pneumothorax and cause arterial gas embolism. BTS therefore discourages scuba diving permanently after spontaneous pneumothorax unless a highly secure definitive surgical prevention strategy has been completed. Specialist diving medicine assessment is required even after surgery. Swimming and snorkelling Ordinary surface swimming is not the same pressure exposure as scuba diving. Return should still wait until clinical and radiographic recovery and adequate fitness. Breath hold diving can also involve pressure changes and requires specialist advice after pneumothorax. Prognosis after PSP Most otherwise healthy people recover fully after the lung re expands. The episode does not necessarily cause permanent loss of lung function. The principal long term concern is recurrence. Prognosis after SSP Outcome depends heavily on the underlying lung disease and respiratory reserve. Hospital stay, complications and mortality are higher than with uncomplicated PSP. Treating COPD, infection, fibrosis or another cause is part of preventing further deterioration. Emotional effects Sudden chest pain and emergency procedures can be frightening. Fear of recurrence may affect exercise, sleep and travel. Clear follow up, an emergency plan and specialist discussion can reduce avoidable restriction and anxiety. What this lesson should not be used for This lesson cannot diagnose pneumothorax from pain, breath sounds or a home oxygen reading. It cannot determine whether a pneumothorax is primary, secondary, traumatic or under tension without clinical assessment. Do not attempt needle decompression, aspiration or chest drain manipulation outside trained emergency care. Do not fly before confirmed resolution or return to scuba diving without specialist clearance. Call 999 for severe breathlessness, collapse, blue or grey colour or rapidly worsening symptoms.

A pneumothorax is air in the pleural space that separates the lung from the chest wall and causes partial or complete collapse. Management depends more on symptoms, physiological compromise and underlying lung disease than on size alone. Tension pneumothorax is a distinct life threatening emergency requiring immediate decompression before imaging.