Spontaneous Pneumothorax – Causes, Symptoms, treatment

Spontaneous pneumothorax refers to the abnormal collection of gas in the pleural space between the lungs and the chest wall. Spontaneous pneumothorax occurs without an obvious etiology such as trauma or iatrogenic causes. Spontaneous pneumothorax can be classified as either primary or secondary. Primary spontaneous pneumothorax (PSP) occurs when the patient does not have a history of the underlying pulmonary disease, whereas secondary spontaneous pneumothorax (SSP) is associated with a history of an underlying pulmonary disease

A Pneumothorax is defined as a collection of air outside the lung but within the pleural cavity. It occurs when air accumulates between the parietal and visceral pleurae inside the chest. The air accumulation can apply pressure on the lung and make it collapse. The degree of collapse determines the clinical presentation of pneumothorax. Air can enter the pleural space by two mechanisms, either by trauma causing a communication through the chest wall or from the lung by rupture of visceral pleura. There are two types of pneumothorax: traumatic and atraumatic. The two subtypes of atraumatic pneumothorax are primary and secondary.

Types of Pneumothorax

Pneumothorax can subdivide into three broad categories according to the etiology:

• Traumatic – resulting from blunt or penetrating chest trauma. Majority of all pneumothoraces are traumatic in origin
• Iatrogenic – caused by manipulation by a healthcare provider, such as the insertion of central lines, etc
• Spontaneous – a pneumothorax without any apparent cause or inciting event.
• Iatrogenic – is a subtype of traumatic pneumothorax, where an injury occurs as a result of a diagnostic or therapeutic medical intervention (i.e., insertion of a central line, etc.)
• Catamenial – is a non-traumatic pneumothorax that occurs in women in conjunction with their menstrual period. Although not entirely understood, the cause is believed to be endometriosis of the pleura.

Pneumothorax can also be classified based on their physiology into the following types:

• Simple – when the air in the pleural space does not communicate with an outside atmosphere, and there is no shift in mediastinum or hemidiaphragm. An example is a pleural laceration from a fractured rib.
• Communicating – when there is a defect in a chest wall, such as from a gunshot wound, that causes open communication with an outside atmosphere. This loss of the chest wall integrity can create an air sucking and a paradoxical lung collapse, thus causing significant ventilatory problems.
• Tension – progressive accumulation of air in the pleural cavity causing the shift of the mediastinum to the opposite side, resulting in compression of vena cava and other great vessels, decreased diastolic filling, and ultimately compromised cardiac output. It occurs when a chest injury causes a one-valve situation when the air gets into the pleural cavity but is unable to escape freely and thus gets trapped.

The definition of large vs. small pneumothorax is by the distance between the lung margin and chest wall[rx]:

• Small pneumothorax – the presence of a visible rim of less than 2 cm between the lung margin and the chest wall
• Large pneumothorax – the presence of a visible rim of greater than 2 cm between the lung margin and the chest wall

Causes of Pneumothorax

• Traumatic – results from blunt or penetrating injuries to the chest wall.
• Spontaneous – primary spontaneous pneumothorax occurs in people with no underlying lung disease or inciting event, secondary spontaneous pneumothorax occurs in people with significant underlying parenchymal lung disease and results from some inciting incident, such as a bleb rupture.[rx]
• Iatrogenic – is a subtype of traumatic pneumothorax, where an injury occurs as a result of a diagnostic or therapeutic medical intervention (i.e., insertion of a central line, etc.)
• Catamenial – is a non-traumatic pneumothorax that occurs in women in conjunction with their menstrual period. Although not entirely understood, the cause is believed to be endometriosis of the pleura.
• Chronic obstructive pulmonary disease
• Asthma
• Cystic fibrosis
• Pneumonia (e.g., necrotizing, Pneumocystis jirovecii)
• Pulmonary abscess
• Tuberculosis
• Malignancy
• Interstitial lung disease (e.g., idiopathic pulmonary fibrosis, sarcoidosis, lymphangioleiomyomatosis)
• Connective tissue disease (e.g., Marfan syndrome, Ehlers-Danlos syndrome, rheumatoid arthritis)
• Pulmonary infarct
• Foreign body aspiration
• Catamenial (i.e., associated with menses secondary to thoracic endometriosis)
• Birt-Hogg-Dube syndrome

Risk factors for primary spontaneous pneumothorax

• Smoking
• Tall thin body habitus in an otherwise healthy person
• Pregnancy
• Marfan syndrome
• Familial pneumothorax

Diseases associated with secondary spontaneous  pneumothorax

• COPD
• Asthma
• HIV with pneumocystis pneumonia
• Necrotizing pneumonia
• Tuberculosis
• Sarcoidosis
• Cystic fibrosis
• Bronchogenic carcinoma
• Idiopathic pulmonary fibrosis
• Severe ARDS
• Langerhans cell histiocytosis
• Lymphangioleiomyomatosis
• Collagen vascular disease
• Inhalational drug use like cocaine or marijuana
• Thoracic endometriosis

Causes of iatrogenic pneumothorax

• Pleural biopsy
• Transbronchial lung biopsy
• Transthoracic pulmonary nodule biopsy
• Central venous catheter insertion
• Tracheostomy
• Intercostal nerve block
• Positive pressure ventilation

Causes of traumatic pneumothorax

• Penetrating or blunt trauma
• Rib fracture
• Diving or flying

Causes of tension pneumothorax

• Penetrating or blunt trauma
• Barotrauma due to positive pressure ventilation
• Percutaneous tracheostomy
• Conversion of spontaneous pneumothorax to tension
• Open pneumothorax when occlusive dressing work as one way valve

Causes of pneumomediastinum

• Asthma
• Parturition
• Emesis
• Severe cough
• Traumatic disruption of oropharyngeal or esophageal mucosa

Symptoms Of Pneumothorax

Symptoms of pneumothorax may hardly be noticeable at first and can be confused with other disorders. The symptoms of pneumothorax can vary from mild to life-threatening and may include:

• Shortness of breath
• Chest pain, which may be more severe on one side of the chest
• Chest pain that usually has a sudden onset.
• The pain is sharp and may lead to feelings of tightness in the chest.
• Sharp pain when inhaling
• Pressure in the chest that gets worse over time
• Blue discoloration of the skin or lips
• Increased heart rate
• Rapid breathing
• Confusion or dizziness
• Loss of consciousness or coma
• A steady ache in the chest
• Dyspnea
• Your skin is bluish.
• You’re tired.
• You breathe rapidly.
• Your heartbeat speeds up.
• Breaking out in a cold sweat
• Tightness in the chest
• Turning blue, or cyanosis
• Severe tachycardia, or a fast heart rate

Diagnosis of

In primary spontaneous pneumothorax, the patient is minimally symptomatic as otherwise healthy individuals tolerate physiologic consequences well. The most common symptoms are chest pain and shortness of breath. The chest pain is pleuritic, sharp, severe, and radiates to the ipsilateral shoulder. In SSP, dyspnea is more severe because of decreased underlying lung reserve.

The history of pneumothorax in the past is important as recurrence is seen in 15-40% cases. Recurrence on the contralateral side can also occur.

On examination, the following findings are noted

• Respiratory discomfort
• Increased respiratory rate
• Asymmetrical lung expansion
• Decreased tactile fremitus
• Hyperresonant percussion note
• Decreased intensity of breath sounds or absent breath sounds

In tension pneumothorax following additional findings are seen

• Tachycardia more than 134 beats per minute
• Hypotension
• Jugular venous distension
• Cyanosis
• Respiratory failure
• Cardiac arrest

Plain Radiograph

A pneumothorax is, when looked for, usually easily appreciated. Typically they demonstrate

• Visible visceral pleural edge is seen as a very thin, sharp white line
• No lung markings are seen peripheral to this line
• Peripheral space is radiolucent compared to the adjacent lung
• The lung may completely collapse
• Mediastinum should not shift away from the pneumothorax unless a tension pneumothorax is present (discussed separately)
• Subcutaneous emphysema and pneumomediastinum may also be present
• Lateral decubitus radiograph:
  • should be done with the suspected side up
  • the lung will then ‘fall’ away from the chest wall
• Expiratory chest radiograph:
  • the lung becomes smaller and denser
  • pneumothorax remains the same size and is thus more conspicuous: although some authors suggest that there is no difference in detection rate
• Chest CT scanning – A CT scan is more sensitive than a chest radiograph in the evaluation of small pneumothoraces and pneumomediastinum, although the clinical significance of these occult pneumothoraces is unclear, particularly in the stable nonintubated patient.[rx] The occult pneumothorax is being diagnosed more frequently as methods of evaluating and diagnosing trauma patients become more sensitive. At present, CT scan is the gold standard for detecting occult traumatic pneumothorax not apparent on supine chest X-ray radiograph.[rx]
• Ultrasonography – Use of bedside ultrasonography in the diagnosis of pneumothorax is a relatively recent development. In some trauma centers, pneumothorax detection is included as part of their focused abdominal sonography for trauma (FAST) examination.[rx] Ultrasonographic features used in the diagnosis of pneumothorax include the absence of lung sliding (high sensitivity and specificity), absence of comet-tail artifact (high sensitivity, lower specificity), and presence of lung point (high specificity, lower sensitivity). In a study, ultrasonography performed on patients with blunt thoracic trauma had 94% sensitivity and 100% specificity for pneumothorax detection compared with spiral CT scanning[rx,rx] .
• Arterial blood gas analysis – Arterial blood gas (ABG) does not replace physical diagnosis nor should treatment be delayed while awaiting results if the symptomatic pneumothorax is suspected. However, ABG analysis may be useful in evaluating hypoxia, hypercarbia, and respiratory acidosis.
• Electrocardiography – In left-sided pneumothorax electrocardiogram (ECG) shows rightward shift of the frontal QRS axis, diminution of the precordial R voltage, decrease in QRS amplitude, and precordial T-wave inversion. With right pneumothorax, ECG may show diminution of the precordial QRS voltage, right axis deviation, and a prominent R wave in V2 with associated loss of S wave voltage, mimicking posterior myocardial infarction. All these changes are thought to be due to mechanical effects and should not be taken for cardiac ischemia or infarction.

Other tests you might have include

• Pulse oximetry  – a device is clipped to your finger or ear lobe, and a light on it measures how much oxygen is in your blood.
• Blood tests, including a complete blood count (CBC) – to see if you have anemia (when your body doesn’t make enough red blood cells) or infection and other tests to check for a blood clot or fluid in your lungs.
• Chest X-ray or a computerized tomography (CT) scan – to see if you have pneumonia, blood clot in your lung, or another lung disease. A CT scan puts several X-rays taken from different angles together to make a more complete picture.
• Electrocardiogram (ECG) –  to measure the electrical signals from your heart to see if you’re having a heart attack and find out how fast your heart is beating and if it has a healthy rhythm.
• Patients should be tested for electrolyte abnormalities – endocrine disorders (specifically hyperthyroid) drug-induced causes, infections, drug or chemical withdrawal, and echocardiography to check for structural heart disease. In patients presenting with ischemic stroke and with no prior history of AF, 72-hour Holter monitoring improves the detection rate of silent paroxysmal.[rx]
• Screening spirometry – Can assess how much air you can breathe
• Complete pulmonary function testing – Can evaluate your breathing capabilities in more detail than screening spirometry by measuring how much air you can breathe in and out, as well as how quickly
• Arterial blood gas measurement – Provides a measure of the oxygen content of your blood, which alerts your doctors if you are becoming low in oxygen
• Echocardiography – May be ordered if your EKG suggests that you have heart disease
• Standard exercise treadmill testing – Evaluates your breathing when you have increased oxygen demands
• Complete cardiopulmonary exercise testing – Evaluates your heart and lung function in detail.

Treatment Of Pneumothorax

First Aid

• Airway breathing – and circulation should be checked in all the patients of chest trauma. Patency of the airway and the adequacy of the ventilatory efforts should be evaluated with the assessment of the integrity of the chest and the circulatory status as pericardial tamponade can also cause signs and symptoms similar to tension pneumothorax. Upright positioning may be beneficial if there is no contraindication to it like a spinal injury.
• Penetrating wounds – (also known as ‘sucking chest wounds’) require immediate coverage with an occlusive or pressure bandage made air-tight with clean plastic sheeting. The sterile inside of a plastic bandage packaging can be used in an emergency situation. No patient with penetrating chest wound should be left unattended as tension pneumothorax or another immediately life-threatening respiratory emergency can arise.
• A thin needle – can be used for this purpose, to relieve the pressure and allow the lung to reinflate in suspected tension pneumothorax. An untreated pneumothorax is an absolute contraindication for evacuation or transportation by flight.
• Breathing cooler air by lowering the temperature in a room
• Breathing cleaner air by opening a window, using a humidifier, or getting rid of smoke and pet dander
• Getting a sense of open space by seeing a view of the outside, opening windows, or being in an empty room
• Keeping your head lifted, for example, by using pillows so that you are nearly sitting
• Practicing techniques that take your focus away from the problem, such as relaxation and meditation

Recommended initial management depending on the clinical condition

Pneumothorax type	Treatment purpose	Recommended treatment
Tension pneumothorax	To recover from acute respiratory dysfunction	Any intervention First: aspiration (diagnosis) Second: tube drainage
Bilateral pneumothorax	To recover from acute respiratory dysfunction	Drainage of at least one side of the lung
With severe lung disease	To recover from acute respiratory dysfunction	Any intervention
Suspected air leak	To avoid acute respiratory dysfunction	Any intervention
Completely collapsed lung	To avoid acute respiratory dysfunction	Any intervention
Symptomatic	To avoid acute respiratory dysfunction Symptomatic relief	Any intervention (aspiration > drainage)
Supposed absence of air leak	To maintain stoppage of air leak	Observational treatment

Tube drainage or repeating aspiration.

Three-step management of pneumothorax

Step	Treatment objective	Recommended treatment
Step 1a	Acute respiratory dysfunction
	To recover from respiratory function To avoid respiratory dysfunction	Tube drainage (or simple aspiration) Tube drainage (or simple aspiration)
Step 2	Air leak
	To maintain stoppage of air leak To stop air leak To stop air leak after drainage	Observational treatment Repeating aspiration (vs tube drainage) Water seal management in tube drainage, surgery (bullectomy, bulla ligation, etc.), pleurodesis, bronchial intervention, others
Step 3	Recurrence
	To prevent recurrence	Pleurodesis, surgery (bullectomy, pleurectomy, etc.), others

step 1 is defined as initial management.

efficacy of tube drainage in preventing recurrence is controversial.

Pharmacological Treatment

• Supplemental oxygen – If the pneumothorax is very small, the patient may only require supplemental oxygen. Patients should be observed to see whether their condition remains stable. Additional chest X-rays might be taken during that period.
• Needle aspiration – A needle attached to a syringe is inserted into the chest cavity to remove air via suction.
• Percutaneous chest tube drainage – If the pneumothorax is large or if the patient has trouble breathing, a small plastic tube may be inserted into the pleural space to remove air. The collapsed lung will reinflate as the pressure on the lung decreases. Ultrasound or other imaging methods may be used to guide the placement of the chest tube.
• Open chest thoracotomy – An incision is made to allow insertion of a small-bore catheter or chest tube to remove air under suction pressure.
• Video-assisted thoracoscopic surgery (VATS) – This is a minimally invasive procedure in which a tiny fiber-optic camera (thoracoscope) and surgical instruments are inserted through one or more small incisions. The camera displays video images on a monitor while the surgeon removes lung tissue.
• Chemical pleurodesis – This procedure involves introducing a chemical irritant into the pleural space in order to attach the outside of the lung to the chest cavity. It is performed to prevent the lung from collapsing again.
• Mechanical pleurodesis – This procedure is similar to chemical pleurodesis, except it is performed by a surgeon who uses a piece of dry gauze to roughen the pleural membrane.
• Antianxiety medications – If you are experiencing anxiety with your pneumothorax, depending on the cause, your healthcare provider may prescribe an anti-anxiety medication, called an anxiolytic.  These medications will help you to relax. These may include lorazepam or alprazolam. It is important to take these medications only when you are feeling anxious. Do not operate heavy machinery, or drive an automobile while taking these. These medications must be used very cautiously if you have a severe pneumothorax. Discuss the risks and benefits of taking this medication with your doctor or healthcare provider.
• Antibiotics – If your doctor or healthcare provider suspects that you have a lung infection, he or she may order antibiotic pills or intravenous (IV), depending on how severe your illness is, and your overall health status. Commonly prescribed antibiotics for bronchitis, pneumonia and respiratory (breathing) problems include azithromycin and levofloxacin. If you are prescribed antibiotic pills, take the full prescription. Do not stop taking pills once you feel better.
• Anticoagulants – These medications prevent your blood from clotting, or may be ordered by your healthcare provider if you have a blood clot. Each of them works in a variety of ways. Depending on your overall health status, the kind of chemotherapy you are receiving, and the location of the blood clot, your healthcare provider may suggest warfarin sodium or enoxaparin ).
• Anticholinergic agents – these drugs are given to persons with chronic bronchitis, emphysema, and chronic obstructive lung disease (COLD). Anticholinergic agents work in a complex manner by relaxing the lung muscles, which will help you to breathe easier. A commonly prescribed drug is ipratropium bromide.
• Bronchodilators – These drugs work by opening (or dilating) the lung passages, and offering relief of symptoms, including shortness of breath. These drugs, typically given by inhalation (aerosol), but are also available in pill form.
• Beta-adrenergic receptor agonists (beta-agonists) – Beta-agonists can be considered bronchodilators, as these drugs relax airway smooth muscle, and block the release of substances that cause bronchoconstriction, or narrowing of your lungs if you are having a lung “spasm.” Drugs such as albuterol, or terbutaline, are commonly used.
• Corticosteroids – Steroids work by decreasing inflammation and swelling, which may be present with certain lung disorders. People may benefit from steroids, either inhaled, by pill form, or in the vein (IV).
• Beclomethasone –  an inhaled steroid, is useful in the treatment of chronic asthma and bronchitis.  Inhaled steroids act directly on the lung tissue, so there are fewer long-term side effects, compared with a pill or IV form. People who have an outbreak of severe shortness of breath and airway inflammation may be ordered a steroid pill, such as prednisone, for a short period of time. This is usually given with inhaled steroids. Patients with severe asthma may require IV administration of another steroid, methylprednisolone.
• Cough medications/Decongestants – may help you to be more comfortable if you are coughing a lot. Guaifenesin is an active ingredient in many cough medications, may be given alone, but is often combined with other drugs, such as codeine, to help your cough.  Guaifenesin may also be combined with pseudoephedrine as a decongestant, or anyone of many medications, depending on your symptoms.  Another common medication you may receive is Hydrocodone Bitartrate-Homatropine Methylbromide. This is a narcotic antitussive (anti-cough medication), which will help relieve your cough.
• Diuretics – may be known as “water pills” as they work to prevent or treat lung congestion by making you urinate out extra fluid. Some examples of this medication may include furosemide and Hydrochlorothiazide. You may receive this medication alone or in combination with other medications.
• Oxygen therapy – Gas within the pleural cavity is absorbed by diffusion and can be facilitated by changing the composition of the intra-pleural cavity gas. Oxygen is absorbed 62 times faster than nitrogen, and carbon dioxide (CO₂) is absorbed 23 times faster than oxygen. When the patient inhales 100% oxygen, nitrogen will disappear from the pleural cavity, leaving only oxygen, which is absorbed faster from the pleural cavity into veins[rx].
• Simple aspiration – Aspiration of a pneumothorax is performed using a small catheter. The catheter is inserted into the pleural cavity and either removed immediately after evacuating the air from the pleural cavity or left inserted while the patient if observed. When left inserted in the thoracic wall, the catheter is still considered a chest tube despite its small size. In patients diagnosed with spontaneous pneumothorax, the mean success rate of aspiration is between 53% and 58%. Specifically, the mean success rate for PSP is 75%, which is comparatively higher than the SSP mean success rate of approximately 37%[rx].

Aspiration Procedures Of Pneumothorax

Complications

• Conversion to tension pneumothorax
• Hypoxemic Respiratory Failure
• Shock
• Respiratory arrest
• Cardiac arrest
• Empyema
• Re-expansion pulmonary edema
• Iatrogenic complications from the needle decompression or thoracostomy procedure – the failure of the lung to re-expand, lung laceration, infection of the insertion site and pleural space, laceration of intercostal vessels or internal mammary artery, hemothorax, persistent air leak, damage to the intercostal neurovascular bundle, etc
• Chest tube-induced arrhythmia
• Pneumomediastinum – air from the pneumothorax can track into the mediastinum. This can be visualized on the chest X-ray as air leuncy around the heart.  Additionally, a crunching sound may be asculated during the cardiac examination.  This is called Hamman’s crunch and is best heard in the left lateral decubitus position.
• Respiratory failure or arrest
• Cardiac arrest
• Pyopneumothorax
• Empyema
• Rexpansion pulmonary edema
• Pneumopericardium
• Pneumoperitoneum
• Pneumohemothorax
• Bronchopulmonary fistula
• Damage to the neurovascular bundle during tube thoracostomy
• Pain and skin infection at the site of tube thoracostomy

References

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