CONTENTS
- Definitions & classifications
- Symptoms
- Signs
- Radiology:
- POCUS for diagnosis and monitoring
- Chest radiograph
- CT scan
- Causes of pneumothorax
- Management of various situations:
- Additional topics:
- Questions & discussion
abbreviations used in the pulmonary section: 3
- ABPA: Allergic bronchopulmonary aspergillosis 📖
- AE-ILD: Acute exacerbation of ILD 📖
- AEP: Acute eosinophilic pneumonia 📖
- AFB: Acid Fast Bacilli
- AIP: Acute interstitial pneumonia (Hamman-Rich syndrome) 📖
- ANA: Antinuclear antibody 📖
- ANCA: Antineutrophil cytoplasmic antibodies 📖
- ARDS: Acute respiratory distress syndrome 📖
- ASS: Antisynthetase Syndrome 📖
- BAL: Bronchoalveolar lavage 📖
- BiPAP: Bilevel positive airway pressure 📖
- CEP: Chronic eosinophilic pneumonia 📖
- CF: Cystic fibrosis 📖
- COP: Cryptogenic organizing pneumonia 📖
- CPAP: Continuous positive airway pressure 📖
- CPFE: Combined pulmonary fibrosis and emphysema 📖
- CTD-ILD: Connective tissue disease associated interstitial lung disease 📖
- CTEPH: Chronic thromboembolic pulmonary hypertension 📖
- DAD: Diffuse alveolar damage 📖
- DAH: Diffuse alveolar hemorrhage 📖
- DIP: Desquamative interstitial pneumonia 📖
- DLCO: Diffusing capacity for carbon monoxide 📖
- DRESS: Drug reaction with eosinophilia and systemic symptoms 📖
- EGPA: Eosinophilic granulomatosis with polyangiitis 📖
- FEV1: Forced expiratory volume in 1 second 📖
- FVC: Forced vital capacity 📖
- GGO: Ground glass opacity 📖
- GLILD: Granulomatous and lymphocytic interstitial lung disease 📖
- HFNC: High flow nasal cannula 📖
- HP: Hypersensitivity pneumonitis 📖
- IPAF: Interstitial pneumonia with autoimmune features 📖
- IPF: Idiopathic pulmonary fibrosis 📖
- IVIG: Intravenous immunoglobulin 📖
- LAM: Lymphangioleiomyomatosis 📖
- LIP: Lymphocytic interstitial pneumonia 📖
- MAC: Mycobacterium Avium complex 📖
- MCTD: Mixed connective tissue disease 📖
- NIV: Noninvasive ventilation (including CPAP or BiPAP) 📖
- NSIP: Nonspecific interstitial pneumonia 📖
- NTM: Non-tuberculous mycobacteria 📖
- OP: Organizing pneumonia 📖
- PAP: Pulmonary alveolar proteinosis 📖
- PE: Pulmonary embolism 📖
- PFT: Pulmonary function test 📖
- PLCH: Pulmonary Langerhans Cell Histiocytosis 📖
- PPFE: Pleuroparenchymal fibroelastosis 📖
- PPF: Progressive pulmonary fibrosis 📖
- PVOD/PCH Pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis 📖
- RB-ILD: Respiratory bronchiolitis-associated interstitial lung disease 📖
- RP-ILD: Rapidly progressive interstitial lung disease 📖
- TNF: tumor necrosis factor
- UIP: Usual Interstitial Pneumonia 📖
definitions
- Pneumothorax is defined as gas in the pleural space.
- Bronchopleural fistula (BPF) refers to a connection between the bronchial tree and the pleura (e.g., due to a hole in the lung or bronchus). Clinically, this causes a pneumothorax with ongoing re-accumulation if drained.
- Nearly every pneumothorax is due to gas exiting the lung and entering the pleural space – so in some ways pneumothorax and bronchopleural fistula are different terms for describing the same phenomenon. The main difference is that the term bronchopleural fistula usually refers to persistent air leak into the pleura (which is not present in every patient with pneumothorax).
types of pneumothorax
- Traumatic vs. Spontaneous:
- Traumatic: Pneumothorax following trauma (iatrogenic or otherwise).
- Primary spontaneous pneumothorax ⚡️: Pneumothorax which occurs without significant trauma, in the absence of any underlying lung disease.
- Secondary spontaneous pneumothorax ⚡️: Pneumothorax which occurs without significant trauma, due to underlying lung disease (e.g., COPD).
- Tension pneumothorax vs. non-tension:
- Tension pneumothorax ⚡️: A flap of lung tissue functions as a one-way valve that allows air to enter pneumothorax, but doesn't allow air to exit the pneumothorax. Pressure accumulates in the pleura that impairs cardiac and pulmonary function – posing an immediate threat to life.
- Non-tension pneumothorax: Pressure does not accumulate in the pneumothorax (either because the hole in the lung has closed, or because the hole in the lung allows air in and out of the pneumothorax).
- Localized vs. generalized (free-flowing)
- Localized (“loculated”) pneumothorax: Adhesions between the visceral and parietal pleura cause a focal accumulation of gas in only part of the pleura. This may limit the expansion of the pneumothorax, making it less dangerous. Localized pneumothorax is more common in patients with prior chest infection or surgery, which has led to chronic adhesions.
- Generalized (“free-flowing”) pneumothorax: No adhesions are present, so the pneumothorax may involve the entire pleura. In practice, most pneumothoraces are free-flowing.
- Chest pain (nearly universal):
- Usually unilateral, ipsilateral to the pneumothorax.
- May radiate to the shoulder.
- Pain is pleuritic, sharp, and well localized.
- Pain may begin suddenly.
- Dyspnea (common).
- Cough may occur.
- Occasionally, patients may be asymptomatic.
- Tension pneumothorax:
- More severe dyspnea.
- Cardiovascular compromise may cause tachycardia, hypotension, and shock. Eventually this may progress to cardiac arrest.
traditional physical examination signs
- Subcutaneous crepitus is highly suggestive of pneumothorax or pneumomediastinum.
- Reduced breath sounds may be suggestive if detected, but the performance of this finding is variable.
- Tension pneumothorax or larger pneumothorax may cause:
- Tachycardia and tachypnea.
- Jugular vein distension.
- Tracheal deviation is difficult to assess in real life. It's dubious whether this adds anything of value to other clinical findings.
pneumothorax presentation in a ventilated patient
- Patients on mechanical ventilation often will not complain of pain or dyspnea (due to sedation and analgesia).
- Hypoxemia may occur (with increasing FiO2 requirement).
- Impaired chest wall compliance may occur:
- In a volume-cycled mode of ventilation, this will lead to high peak and plateau airway pressures.
- In a pressure-cycled mode of ventilation, this will lead to low tidal volumes.
- Tension pneumothorax may cause hemodynamic instability (tachycardia, hypotension, elevated shock index, and eventually cardiac arrest).
- Ventilator mode may affect how rapidly the pneumothorax evolves:
- Volume-cycled modes of ventilation will tend to continue to force volume into the pneumothorax, which may cause more aggressive growth and more rapid/explosive development of tension pneumothorax.
- Pressure-cycled modes of ventilation will provide smaller tidal volumes as the pneumothorax grows. Since the airway pressure is fixed, the pneumothorax may reach equilibrium with the ventilator (wherein additional gas isn't entering the pneumothorax). This may tend to cause the pneumothorax to present in a more gradual/occult fashion.
- 💡 One advantage of pressure-cycled ventilation might be that it causes pneumothoraces to expand more slowly, providing more time for recognition and intervention prior to cardiac arrest.
POCUS for diagnosis of pneumothorax
- POCUS is the definitive tool for bedside assessment of pneumothorax.
- Lung sliding:
- The presence of lung sliding excludes pneumothorax at that point on the thorax.
- Presence of the lung sliding on the anterior chest argues against a large tension pneumothorax, or a free-flowing pneumothorax (it doesn't exclude a loculated pneumothorax involving a different part of the pleura).
- Absence of lung sliding may also be seen in: (Fishman 2023)
- Adhesions between the lung and the chest wall (e.g., due to prior chemical pleurodesis, infection, or fibrosis).
- Right mainstem intubation causes loss of lung sliding on the left.
- Mucus plugging and/or severe atelectasis.
- Lung point:
- Lung point refers to a dynamic transition point between pneumothorax (A-line pattern) and sliding lung.
- The presence of lung point is extremely strong evidence for pneumothorax.
- Lung point may be mimicked by the transition between lung tissue and solid organs (e.g., the border between the lung and the heart). However, in this case there is not a true transition between pneumothorax and sliding lung – there's a transition between soft tissue and sliding lung.
- Disappearing heart sign: In a patient who previously had good echocardiographic windows, if the heart suddenly becomes invisible that should raise concern about pneumomediastinum and/or pneumothorax.
POCUS for monitoring of pneumothorax
- For a free-flowing pneumothorax, the location of the lung point may help monitor the size of the pneumothorax.
- For a tiny pneumothorax, the lung point may be on the anterior chest wall.
- As the pneumothorax expands, the lung point will migrate laterally (wrapping around the thorax, towards the spine).
- If the pneumothorax becomes very large, the lung point will disappear entirely.
- For stable patients, serial POCUS with monitoring of the lung point may help determine if the pneumothorax is stable or expanding. This is applicable only to a pneumothorax which is free-flowing and relatively small. In practice, patients will often receive both POCUS and serial chest radiographs (but POCUS may be useful to provide more immediate assessments of pneumothorax size).
In the ICU, chest radiograph is often obtained as a portable film in a semi-recumbent or fully supine position. This may limit the sensitivity of the study, since air may accumulate anterior to the lung without shifting the lateral pleural margin. Nonetheless, several signs may remain useful.
potential findings of pneumothorax on chest radiograph
Four findings are fundamental.
[#1/4] subcutaneous emphysema
- Subcutaneous emphysema may be visible, especially within the upper chest.
- Subcutaneous emphysema doesn't necessarily indicate the presence of a pneumothorax (since this may also be caused by a pneumomediastinum). However, subcutaneous emphysema should always raise concern for pneumothorax.
[#2/4] visceral pleural line
- 💡 Using the sharp-algorithm processed version of the chest radiograph may help reveal the pleural line (this version of the chest radiograph is usually provided for evaluation of line and tube position).
- Visceral line due to pneumothorax:
- [1] The line should be continuous and traceable for a long distance.
- [2] The line should be thin and often subtle.
- [3] Lung markings should be absent beyond the pleural line.
- Alternatively: clues to suspect a skin fold:
- [1] “Pleural line” is unusually thick and dramatic. With a normal lung, the pleural line is usually subtle. In the context of a normal lung, a strikingly obvious line suggests a skin fold. A skin fold becomes increasingly opaque up to its margin, with abrupt lucency along its outer border (thereby forming an edge rather than a line). (Shepard 2019)
- [2] Lung markings are visible beyond the “pleural line.”
- [3] “Pleural line” disappears abruptly, rather than extending around the lung.
- [4] “Pleural line” has a strange configuration (normally it should run parallel to the chest wall).
- [5] The “pleural line” may sometimes cross outside of the pleura in a way that would be impossible for the lung to do.
- [6] No other features are present to support a pneumothorax diagnosis (e.g., deep sulcus sign, subcutaneous air).
[#3/4] deep sulcus sign
- Potential findings include:
- [1] Basilar lucency that is asymmetric.
- [2] Deepening of the lateral costophrenic sulcus.
- [3] Diaphragm dome may appear unusually sharp.
- [4] Anterior diaphragmatic margin becomes visible (normally it shouldn't be). If both the anterior diaphragmatic margin and the dome of the diaphragm are visible, this creates a “double diaphragm sign.”
- [5] Comparison to prior films may be confirmatory.
- Significance:
- (1) The deep sulcus sign usually occurs in the context of supine patient positioning. In this context, it implies the presence of a large pneumothorax.
- (2) A deep sulcus sign may also occur in upright patients who have a loculated pneumothorax (adhesions inhibit the usual pleural line formation).
[#4/4] tissue shifts due to tension
- Mediastinum shifts away from the pneumothorax.
- Shifts may be easier to appreciate when compared to a prior film.
other potential findings
- Increased sharpness of the mediastinal margin and/or heart.
- Visible inferior border of the collapsed lower lobe.
- Band of air in the minor fissure.
- Visible lateral edge of the right middle lobe. (Walker 2019)
inspiratory vs. expiratory film
- Expiratory films may theoretically accentuate the pneumothorax.
- However, available data and guidelines suggest that the phase of respiration doesn't matter. (34527359)
differential diagnosis of pneumothorax on chest radiograph
skin fold
- Radiographic features of this are discussed above (under the section on the visceral pleural line).
- ⚠️ Skin folds are often misdiagnosed as pneumothorax, even by experienced chest radiologists. Lung POCUS should therefore be used to verify the presence of a pneumothorax prior to any procedure (assuming that the patient is sufficiently stable).
large bullae
- Walls of bullae are convex towards the mediastinum (in the opposite configuration of a pneumothorax).
- A bulla is usually visible only for short segments (it doesn't extend around the entire lung).
- Sometimes, internal lung markings are visible within a bulla. (Walker 2019)
- (A giant bulla under tension can cause mediastinal shift, so the mediastinal shift doesn't necessarily prove the presence of a pneumothorax.)
left upper lobe collapse 📖
- The edge of the collapsed left upper lobe may create a line that mimics pneumothorax (figure below).
- Other features of left upper lobe collapse should be seen:
- Shifts of the trachea and mediastinum to the left.
- Shift of the diaphragm upwards (sometimes with a Juxtaphrenic peak).
- Silhouetting of the left heart border.
- Luftsichel sign can occur (crescentic lucency surrounding the aortic arch).
hydropneumothorax (gas and fluid in the pleural space)
- This is still a pneumothorax, but it's not exactly an isolated pneumothorax.
- The presence of a perfectly flat air-fluid level within the pleura defines the presence of a hydropneumothorax.
guidelines differ on how to define a “large” pneumothorax:
- British guidelines: >2 cm thick at the level of the hilum (measurement b, above). This may have more practical implications, since it implies that it's safe to insert a pigtail catheter or perform needle aspiration without causing lung injury. (34774177)
- American guidelines: >3 cm thick at the apex (measurement a, above). This may overestimate the size of apical pneumothoraces. (34774177)
does it matter?
- The designation of a “large” pneumothorax is rather crude, with poor consistency across different definitions.
- With regards to management, the effect of the pneumothorax on the patient's physiology (e.g., respiratory rate, hemodynamics, symptoms) is often more important than the size of the pneumothorax.
indication for CT scan
- CT scan should be utilized only for stable patients, either:
- (1) Patients in whom a tension pneumothorax has been reasonably excluded.
- (2) Patients who have already had a chest tube inserted.
- CT scan may provide a wealth of information:
- Precise anatomy of the pneumothorax (e.g., loculated vs. free-flowing pneumothorax).
- Presence of any underlying parenchymal lung disease (e.g., COPD or pneumocystis).
CT scan for patient with a chest tube
- Occasional patients may have a large bronchopleural fistula with ongoing air leak. Especially for patients on positive-pressure mechanical ventilation, ongoing suction may be needed to promote lung inflation. If the air leak is sizeable, disconnection from suction may be dangerous.
- Portable suction devices may be used to transport patients to the CT scanner, if there is an ongoing air leak.
- For patients without an ongoing air leak, transportation to CT scan on water seal may be adequate (this will allow air to leave the pleural space, if pressure were to accumulate within the pleura).
- ⚠️ Never clamp a chest tube immediately before transportation to radiology. This exposes the patient to a risk of tension pneumothorax while off the unit.
- Primary spontaneous pneumothorax 📖
- Secondary spontaneous pneumothorax 📖
- Traumatic pneumothorax (including iatrogenic) 📖
- Air tracking from other sites:
- Pneumoperitoneum.
- Pneumomediastinum.
- Pneumothorax ex vacuo (trapped lung 📖) after thoracentesis or chest tube insertion.
basics
- Primary spontaneous pneumothorax refers to spontaneous pneumothorax in a young patient without obvious underlying lung disease. This is a confusing term because, in reality, these patients do have underlying lung disease, but it is subtle (e.g., subtle apical emphysema or blebs are often seen on CT scans).
diagnosis of primary spontaneous pneumothorax
clinical presentation
- The chief complaint is often chest pain, rather than dyspnea. (34774177)
- This is a relatively benign entity that rarely causes tension pneumothorax. Inpatient mortality is <0.1% (Shah 2019)
- After one pneumothorax, the recurrence rate is ~33%, with most recurrences occurring within the first year. (34774178) With increasing numbers of recurrences, the frequency of additional recurrences increases (e.g., after one recurrence, the risk of a second recurrence is ~60%). Recurrence usually occurs on the ipsilateral side (with only a 5-10% risk of contralateral pneumothorax). (Fishman 2023)
radiology
- Apical blebs can be seen on CT scans in ~80% of patients. (Fishman 2023) If seen, these suggest a higher rate of recurrence.
epidemiology of primary spontaneous pneumothorax
- Patients with primary spontaneous pneumothorax are invariably younger (~20-40 years old). British Thoracic Guidelines suggest that patients >50 years old should generally be considered to have a secondary spontaneous pneumothorax. (34774177)
- ~90% of cases occur in patients who currently/previously smoked tobacco or cannabis. (Fishman 2023) Cannabis, in particular, causes accelerated bullae formation in the lung apices. (ERS handbook 3rd ed.)
- There is a ~4:1 male predominance.
- Patients are often tall and thin (intrapleural pressure is most negative at the lung apices, with a magnitude that depends on how tall the lungs are). (Fishman 2023)
differential diagnosis
- Among women of reproductive age with spontaneous pneumothorax, catamenial pneumothorax should be considered. 📖 Recurrent pneumothorax in this patient population may be due to catamenial pneumothorax in up to 25% of patients. (Fishman 2023)
- The British Thoracic Society recommends that pneumothorax in patients >50 years old or with a substantial smoking history shouldn't be considered to have primary spontaneous pneumothorax since there is an increasing likelihood of underlying lung disease. (Murray 2022)
- Some patients who appear to have primary spontaneous pneumothorax may have a family history of pneumothorax. If there is a mutation in the folliculin gene, this may be the forme fruste of Birt-Hogg-Dube syndrome. Other considerations in such patients include various genetic disorders of connective tissue integrity (e.g., Ehlers-Danlos syndrome, Marfan syndrome). (Walker 2019)
management of primary spontaneous pneumothorax
Primary spontaneous pneumothorax is a fundamentally benign entity. A variety of different management strategies may be utilized (which may depend on local norms). Regardless of how the patient is managed, nearly all patients will do extremely well. The primary goal of therapy is often to avoid excessive iatrogenesis and hospital admission. There are generally four initial treatment options: conservative management, simple aspiration, pigtail chest drain, or a pleural vent.
universal therapy for all patients: smoking cessation
- Tobacco and cannabis cessation likely decreases the risk of recurrence (even relatively light use).
- Regardless of which strategy is utilized for the treatment of pneumothorax, cessation of smoking (or illicit inhaled drugs) will help prevent the recurrence or expansion of the pneumothorax.
[#1/4] conservative management (observation on an outpatient basis)
- Conservative management is the preferred approach for patients with few symptoms (e.g., able to walk comfortably) and preserved oxygenation. Patients may be observed for 4 hours with a repeat radiograph and then discharged home with adequate return instructions and precautions (listed below). (34857696)
- The size of the pneumothorax is less important than symptoms and physiology. A large pneumothorax may be observed, provided that there are minimal symptoms and adequate oxygenation. (31995686)
- Advantages of conservative management include:
- Avoids hospital admission.
- Avoids complications associated with procedural intervention.
- Minimizes costs.
- Discharge instructions:
- Patients must not dive or travel in an airplane.
- Counseling to avoid smoking, cannabis, or other inhalational drug use (with medication to assist with tobacco cessation as appropriate).
- Return to the hospital immediately for any worsening in dyspnea.
- Follow-up appointment with pulmonology or thoracic surgery, including a chest radiograph, within 2-4 weeks.
[#2/4] needle aspiration
- Basics: One-time needle aspiration may be used to reduce the size of the pneumothorax. If this is successful, the patient may be observed for ~6 hours to establish stability and subsequently be discharged home (with the same discharge plan as for conservative management, discussed above). The advantage of needle aspiration is that it allows for symptomatic improvement while avoiding hospitalization or indwelling chest tube insertion.
- Indications:
- Large pneumothorax that is symptomatic.
- The patient elects to undergo needle aspiration with the goal of symptomatic improvement.
- Contraindications to needle aspiration:
- The pneumothorax isn't large enough to safely enter (pneumothorax should have a rim of air >2 cm at the level of the hilum). (23656667)
- Tension pneumothorax or hemodynamic instability.
- Underlying pulmonary disease.
- Bilateral pneumothorax.
- History of recurrent pneumothorax.
- Bleeding disorders. (23656667)
- Advantages of needle aspiration: Reduces hospital length of stay (as compared to chest tube insertion).
- Drawback of needle aspiration: Increased need for further pleural procedures (as compared to placing a chest tube). (37433578)
- Needle aspiration is extremely similar to a thoracentesis procedure (including using the same kit). Some procedural aspects include the following: (video here)
- The patient should be positioned at a 30-45-degree upward angle to cause air to rise into the anterior portion of the chest.
- Needle insertion occurs over the third rib in the midclavicular line.
- Use ultrasound to confirm pneumothorax, avoid any blood vessels, and estimate the depth of the pleura.
- The catheter should be inserted only a few mm into the pleural space (unlike a pleural effusion overlying the diaphragm, wherein the catheter may be inserted deeper).
- The amount of air removed should be measured by counting the number of times the syringe is emptied. Avoid draining >2.5 liters volume (which could suggest the presence of an air leak). (23656667) If this occurs, consider converting of the procedure into a pigtail chest tube insertion.
[#3/4] pigtail chest tube
- There are many ways to utilize a pigtail catheter for pneumothorax, but the following approach may often be helpful.
- (#1) Attempt to use the pigtail chest tube as a “glorified needle aspiration:”
- Start by placing the chest tube to -20 cm suction for a brief period of time (30-60 minutes), then check a chest radiograph.
- If the lung inflates adequately and there is no ongoing air leak, clamp the tube for four hours and obtain a repeat chest radiograph to evaluate for pneumothorax recurrence. If the lung stays inflated, the chest tube may be removed, and the patient can be discharged. Prompt clamping and discontinuation of the chest tube may potentially allow the patient to be discharged home directly from the emergency department (using the chest tube as a glorified needle aspiration). (31995686)
- The advantage of this strategy, as compared to needle aspiration, is that if the pneumothorax expands, a second procedure is not needed (the patient already has a chest tube). The disadvantage is that a chest tube insertion is more invasive than a simple needle aspiration of air.
- (#2) If the above strategy fails (e.g., due to incomplete lung expansion or pneumothorax recurrence), then two options exist:
- (a) The pigtail chest tube may be connected to a Heimlich valve. The patient may be discharged home, with ongoing drainage of air via the Heimlich valve. This may facilitate rapid disposition from the hospital if adequate follow-up care is available (with a success rate of 83%). (Folch 2023)
- (b) The patient may be admitted to the hospital for ongoing chest tube management. To prevent chest tube blockage, the tube should be flushed with 10 ml of saline every 8-12 hours. (34774178)
[4/4] Rocket Pleural Vent (or similar device)
- The Rocket Pleural Vent is essentially a single device that combines an 8-French chest tube plus a one-way valve to allow air drainage (see a video describing it here).
- This device has been demonstrated to be safe and capable of avoiding hospitalization for patients with primary spontaneous pneumothorax. (32622394) There is a small risk of adverse events (e.g., device malfunction in 2%).
- The drawbacks of this device are primarily logistics.
- (a) Most hospitals don't have one.
- (b) Most healthcare systems lack sufficient outpatient resources to closely follow up on patients following device insertion.
pleurodesis is discussed below: ⚡️
basics
- Secondary spontaneous pneumothorax is due to underlying lung pathology. This has a substantially higher morbidity than primary spontaneous pneumothorax – especially among patients with more severe underlying lung disease.
- Management of the pneumothorax is more aggressive than in patients with primary spontaneous pneumothorax (as patients are sicker and less likely to spontaneously resolve).
- Management nearly always involves hospital admission.
causes of secondary spontaneous pneumothorax
airway disease
- COPD:
- COPD is the most common cause, accounting for ~70% of secondary spontaneous pneumothorax. (10807811)
- COPD is also a risk factor for postprocedural pneumothorax (e.g., following transthoracic lung biopsy).
- Pneumothorax is especially common among patients with apical bullae.
- Asthma.
- Cystic fibrosis. 📖
infection
- Pneumocystis.
- Necrotizing pneumonia.
- Tuberculosis, or Mycobacterium kansasii.
- Coccidioidomycosis.
- Aspergilloma.
- COVID-19.
interstitial lung disease involving cysts/cavitations/honeycombing
- LAM (Lymphangioleiomyomatosis).*
- BHD (Birt-Hogg-Dube syndrome).*
- PLCH (pulmonary Langerhans cell histiocytosis).
- GPA (granulomatosis with polyangiitis).
- IPF (idiopathic pulmonary fibrosis).
- NSIP (nonspecific interstitial pneumonia).
- CTD-ILD (connective tissue disease-related interstitial lung disease), including LIP (lymphocytic interstitial pneumonia).
- Sarcoidosis (rare manifestation, usually late in the disease course).
malignancy (20%)
- Primary lung cancer.
- Metastatic malignancy to the lung (most often sarcomas).
- Complications of chemotherapy.
other
- Catamenial pneumothorax due to thoracic endometriosis.
- Pulmonary infarction (due to pulmonary embolism).
- Connective tissue weakness:
- Marfan syndrome.*
- Ehlers-Danlos syndrome.*
- Radiation fibrosis.
a * Indicate causes of familial pneumothorax.
management of secondary spontaneous pneumothorax
[0] treatment of underlying lung disease
- Any causative or underlying process should be treated.
- For patients on mechanical ventilation, airway pressures should be reduced as possible.
[#1/2] observation
- Admission with observation may be reasonable for patients with a very small pneumothorax (especially if the pneumothorax is so small that drainage might be difficult to accomplish safely).
[#2/2] chest tube insertion
- Chest tube drainage is often needed, especially among patients with substantial underlying lung disease who have poor physiological reserve. The presence of dyspnea may be an indication for drainage. (Shah 2019)
- Whether the chest tube should immediately be placed to suction is debatable.
- In most cases, the pneumothorax will resolve over a few days. The chest tube may subsequently be clamped for a day. If there is no recurrence of the pneumothorax, the chest tube may then be removed. (Clamping the chest tube for a day prior to removal ensures that there isn't an occult, intermittent air leak – in which case removal of the chest tube could be dangerous.)
- Additional management considerations:
- Pleurodesis may be considered (as discussed in the section below 👇). If the patient is going to be admitted regardless, early pleurodesis could be achieved without increasing the hospital length of stay.
- If the air leak is persistent, then it may be managed as described in the section below on persistent air leak. 📖
related sections on pleurodesis:
Pleurodesis may be achieved either via VATS surgery, or via a chest tube (using doxycycline or talc). VATS is often preferred for pneumothorax management, since it allows for removal of blebs as well as pleurodesis. Patients with primary spontaneous pneumothorax are usually excellent surgical candidates, so they generally undergo VATS. Although VATS may also be used for secondary pneumothorax, most patients with secondary pneumothorax are poor candidates for surgery – so chest tube pleurodesis is more frequently utilized. This following discussion explores the role of pleurodesis to prevent pneumothorax recurrence.
factors to consider when considering pleurodesis for pneumothorax prevention:
- (1) How likely is a pneumothorax recurrence?
- (2) Would a recurrent pneumothorax be high risk? This is a concern in several situations:
- (a) Patient with limited respiratory reserve who significantly decompensates with pneumothorax.
- (b) Patients who present with tension pneumothorax or bilateral pneumothorax.
- (c) Situations that make recurrent pneumothorax more dangerous (e.g., airplane pilot, diver, military personnel, world traveler with poor access to healthcare).
- (3) Patient preferences.
pleurodesis for primary spontaneous pneumothorax
- Pleurodesis is generally considered after 2-3 pneumothoraces. However, pleurodesis after the first pneumothorax may be reasonable in selected patients (see considerations listed above).
- VATS (video-assisted thoracoscopic surgery) is the most definitive approach. This typically involves stapling apical blebs plus pleurodesis. VATS reduces the recurrence rate to <5%. Patients with primary spontaneous pneumothorax are generally excellent surgical candidates and can easily undergo this procedure.
- Chemical pleurodesis reduces recurrence to <25%. This could be considered as a second-line therapy (e.g., if a patient prefers not to undergo VATS or is not a surgical candidate).
pleurodesis for secondary spontaneous pneumothorax
- When should pleurodesis generally be considered?
- The recurrence rate of secondary spontaneous pneumothorax is fairly high (perhaps ~25% in one year, and ~50% over five years). (Folch 2023)
- Chemical pleurodesis can be considered for preventing recurrence even during the first episode (e.g., patients with severe COPD who significantly decompensate in the presence of a pneumothorax). (37433578)
- Lymphangioleiomyomatosis: Recurrence rates are high, so a single pneumothorax may be an indication for pleurodesis (more on this here: 📖).
- Cystic fibrosis: Pleurodesis may be considered following either one or two pneumothoraces. (discussed further here: 📖).
- COPD:
- COPD accounts for 70% of secondary pneumothorax, so there is substantial overlap between these topics. (10807811)
- Persistent bronchopleural fistula is common in COPD, with air leak >5 days in a third of patients. (2214100)
- Due to the risk of recurrence with respiratory dysfunction, pleurodesis should be considered for management of the first spontaneous pneumothorax (either chemical or surgical pleurodesis, depending on patient and logistic considerations). (Fishman 2023)
definition & differential diagnosis
definition of a persistent air leak?
- The longer the air leak persists, the less likely it is to stop spontaneously.
- Ongoing air leak longer than >72-96 hours suggests that the leak may not close with conservative therapy, so more aggressive treatment might be needed. (Fishman 2023)
- A persistent air leak is often defined as an air leak lasting >~5 days. (Folch 2023)
natural history of a persistent air leak
- Primary spontaneous pneumothorax: (9713636)
- Day 7: 75% of patients will resolve.
- Day 14: 97% of patients will resolve.
- Secondary spontaneous pneumothorax: (9713636)
- Day 7: 61% of patients will resolve.
- Day 14: 80% of patients will resolve.
differential diagnosis – leaky chest tube system
- Leakage of air into the chest tube system at any location may mimic a persistent air leak, for example:
- Air leaks around the chest tube where it enters the skin.
- There is a loose connection between the chest tube and the connecting tubing.
- Leak of air into the chest tube system may be excluded by troubleshooting the chest tube:
- Inspect the chest tube insertion site to see if there is evidence of air entering the chest.
- Inspect the tubing for any loose connections.
- Pinch the chest tube closed as it exits the patient's body for a few seconds. If the air leak persists, it must be coming from the chest tube system itself (not the patient's body).
initial management for all patients
- For patients on mechanical ventilation:
- Reduce airway pressures as much as possible (e.g., reduce PEEP and tidal volume).
- Extubate patients as soon as possible.
- Treat bronchospasm aggressively, if present (again, with a goal of reducing airway pressures).
- Use the least amount of chest tube suction required to maintain lung inflation.
- Excess chest tube suction will increase the pressure gradient across the bronchopleural fistula, thereby keeping it open.
- If possible, place the chest tube on water seal.
subsequent management of ongoing air leak
[#1/5] ongoing observation
- Persistent air leaks might eventually resolve over time.
- Spontaneous resolution is more likely for a small leak, which seems to improve over time. (28267436)
[#2/5] pleurodesis
- Failure to close after >72 hours suggests a lower likelihood of closing spontaneously, so pleurodesis should be considered (either surgical or chemical). (Fishman 2023)
- Pleurodesis serves two purposes:
- (1) Promotes sealing the air leak.
- (2) Reduces the risk of recurrent pneumothorax.
- Evidence regarding this application of chemical pleurodesis is unfortunately scant.
- Pleurodesis requires that the lung expand fully when the chest tube is placed to suction.
- How to perform pleurodesis: 📖
[#3/5] blood patch
- Blood patch has some similarities to pleurodesis. Thrombus formation and pleural inflammation may favor the closure of the air leak. (Folch 2023)
- Advantages of blood patch:
- (1) Blood patch is often better tolerated than chemical pleurodesis (it doesn't require analgesia).
- (2) Blood patch can be performed in situations where there isn't complete re-expansion of the lung.
- (3) There is a reasonable evidentiary basis to support blood patch treatment. Overall, blood patches appear to have a high success rate (~92%) among patients following lung resection or with spontaneous pneumothorax. (15519179, 28267436) Two RCTs have been performed, demonstrating the success of this technique, albeit with a small enrollment. (35268264)
- Disadvantages of blood patch:
- Technical details:
- The patient's own whole blood is used in a similar fashion as compared to doxycycline or talc. ~100 ml of blood is instilled into the chest tube, followed by a saline flush. (34527359)
- The chest tube is placed on water seal. The tubing needs to be draped over an IV pole to prevent blood from immediately draining out of the thorax. This configuration should allow air to drain out of the chest (avoiding tension pneumothorax) while keeping the blood within the thorax.
- After allowing a two-hour dwell time, the chest tube is placed to suction.
- Several applications of the blood patch may be required if the first isn't effective. (35268264)
[#4/5] endobronchial valves
- One-way valves may be placed to prevent air entry into the segment with a bronchopleural fistula.
- To date, this intervention has not been investigated with an RCT. Available retrospective series show variable results. (35268264)
- Requirements:
- (1) Brisk air leak (the leak must be fast enough to determine when it has been plugged off during bronchoscopy).
- (2) The patient's lung function must be sufficient to tolerate a functional lobectomy (valve placement will cause functional loss of those lobes).
- (3) Absence of active pulmonary infection.
[#5/5] discharge home with a Heimlich valve
- This may be an option for highly selected patients who have small air leaks and very close follow-up. (28267436)
- For patients with secondary spontaneous pneumothorax, there is some data to support discharge home with a combination of a 12-French pigtail chest drain plus a Heimlich valve. However, integrated devices such as the Rocket Pleural Vent that contain an 8-French catheter may be prone to occlusion or kinking, with a reduced success rate for secondary spontaneous pneumothorax. (35268264)
causes of traumatic pneumothorax
chest trauma
- Blunt trauma.
- Cardiopulmonary resuscitation.
- Penetrating trauma.
iatrogenic lung injury
- Thoracentesis (~2% risk):
- (1) Pneumothorax due to lung laceration.
- (2) Pneumothorax ex vacuo due to trapped lung.
- Central line insertion (~1% risk).
- Interventional radiology biopsy:
- Transthoracic lung biopsy (~20% risk).
- Pleural biopsy (~10% risk).
- Bronchoscopy (especially with transbronchial lung biopsy).
- Endobronchial valve placement (~25% risk).
- Feeding tube insertion into bronchus (rare, may occur in deeply sedated patients who lack a cough reflex).
- Airway laceration during intubation (e.g., bougie inserted too far).
invasive mechanical ventilation causing barotrauma
- Pneumothorax is especially likely if there is right main bronchus intubation.
- Pneumothorax may occur even with lung-protective ventilation (especially if the underlying lung tissue is abnormal).
- Lung hyperinflation due to over-aggressive bag-mask ventilation may cause pneumothorax.
management
- Management should be tailored to the specifics of each patient.
- Overall a conservative strategy is often adequate (e.g., serial observation).
non-iatrogenic traumatic pneumothorax
- Observation with serial imaging is often sufficient (with escalation to drainage if the pneumothorax expands or is causing symptoms).
- One RCT demonstrated equivalent outcomes with 14- versus 28-French chest tubes, so if a tube is inserted, a pigtail drain should generally be adequate. (24375295)
post-procedure pneumothorax
- Overall, this may resemble the management of primary spontaneous pneumothorax.
- Observation may be adequate for patients with stable pneumothorax and without substantial symptoms.
- Insertion of a small-bore chest tube plus Heimlich valve or analogous all-in-one device (e.g., Rocket Pleural Vent) may avoid hospitalization.
- One study supported the use of simple aspiration for pneumothorax following transthoracic lung biopsy. (11948047)
definition of a tension pneumothorax
- Tension pneumothorax is a pathophysiologic diagnosis rather than a radiological diagnosis (e.g., many patients with mediastinal shift don't have a tension pneumothorax). (34774177)
- Tension pneumothorax refers to obstructive shock attributable to pneumothorax (e.g., tachycardia, hypotension, elevated shock index, dilated inferior vena cava). A pneumothorax large enough to cause obstructive shock will almost invariably also cause acute respiratory failure (e.g., dyspnea, tachypnea).
- Tension pneumothorax is most common among patients receiving positive-pressure, volume-cycled ventilation.
treatment of tension pneumothorax
Tension pneumothorax is an emergency. Nonetheless, tension pneumothorax patients span a range of severity, from patients who can wait 10-20 minutes for a procedure, to patients who are in the process of cardiopulmonary arrest.
emergent needle decompression
- Problems:
- (1) If there isn't a large pneumothorax, the needle will lacerate the lung tissue.
- (2) If there is a sizable bronchopleural fistula (especially for patients on mechanical ventilation), a small-bore needle may not be sufficient to drain air from the pneumothorax. In some cases, air may enter the pneumothorax faster than it's able to drain out via the needle.
- (3) In larger patients, the needle may fail to enter the pleura.
- (4) Drainage of the pneumothorax may actually make it harder and more dangerous to insert a chest tube.
- Technique:
- Insertion at the mid axillary line at the level of the fifth intercostal space might be optimal.
- Traditionally, the needle has been inserted at the 2nd intercostal space at the midclavicular line. That's OK for most patients, but remember the following:
- i) In larger patients, it may be difficult to penetrate into the pleura.
- ii) Remember that the clavicle extends to the shoulder, so midclavicular should actually be towards the lateral edge of the thorax. If the needle is inserted too medially it may lacerate the internal mammary artery.
- Needle decompression is only a temporizing maneuver, as a bridge to insertion of a chest tube.
surgical chest tube
- Surgical chest tube may be preferred in the following situations:
- Tension pneumothorax with cardiac arrest or peri-arrest.
- Tension pneumothorax in a patient on positive pressure ventilation. For a patient with a larger bronchopleural fistula on positive pressure ventilation, a pigtail drain won't always remove air quickly enough to resolve the pneumothorax.
- For a crashing patient, any large sterile tube can be temporarily inserted into the pleural space to decompress the pneumothorax (while awaiting a chest tube). An endotracheal tube can function nicely here.
pigtail chest tube
- Pigtail chest tube may be useful for patients who aren't intubated and aren't crashing.
Administration of 100% inhaled oxygen may accelerate absorption of the pneumothorax. The reason oxygen works isn't really the oxygen, but rather the fact that the patient isn't inhaling any nitrogen (denitrogenation). By decreasing the partial pressure of nitrogen gas in the blood, a gradient is set up that promotes more rapid absorption of nitrogen from the pleural space.
reasons this doesn't actually work
- Inhalation of 100% oxygen is only marginally effective (e.g., absorption of an extra 10 ml of gas per day). (4938315; 37445335) The reason it doesn't work well might be that the pleura has a low surface/volume ratio.
- Administration of 100% oxygen will make it impossible to monitor the patient for mild deterioration of pulmonary function (by the time the patient desaturates, they have profoundly deranged pulmonary physiology).
- Prolonged exposure to high levels of oxygen may cause oxygen toxicity.
- Attempting to administer 100% FiO2 for prolonged periods in the hospital will invariably lead to chaos, confusion, and consternation (especially on the hospital ward).
- Administration of high levels of oxygen may impair ventilation-perfusion matching, which may cause increased hypercapnia in patients with chronic hypercapnia and borderline ventilatory function.
For these reasons, 100% inhaled oxygen is unhelpful in the management of pneumothorax.
The choice of pigtail versus surgical chest drain is controversial. Literature is increasingly favoring pigtail drains, but there are still some situations where a surgical drain may be safer or more effective.
pigtail chest tube insertion
- Pigtail chest tube insertion may be useful for a patient with a larger pneumothorax who is relatively stable.
- ⚠️ Insertion of a pigtail chest tube is safe only for patients with a moderate/large pneumothorax. If the pneumothorax is small, there is a risk that the finder needle could pierce through the pneumothorax and lacerate the lung – leading to placement of the pigtail drain into the lung parenchyma.
- Advantages of pigtail chest tubes:
- More comfortable than surgical tubes.
- Often easier to insert than surgical tubes (especially in obesity).
- Disadvantages of pigtail chest tubes:
- Pigtail chest tubes can only remove gas from the pleura with a limited flow rate (because they are small). For patients on mechanical ventilation with a large bronchopleural fistula, the rate of gas entry into the pleura may out-strip the amount of gas that can be drained by the pigtail chest tube. Thus, even if the pigtail chest drain is placed correctly, it may not be able to drain gas fast enough to resolve the pneumothorax.
- Pigtail chest tubes may tend to clot off over time, especially if they aren't flushed periodically.
surgical chest tube insertion
- Surgical chest tube insertion may be appropriate for patients who aren't a good candidate for a pigtail chest drain. For example:
- (1) Patients on mechanical ventilation with a large bronchopleural fistula.
- (2) Patients who are crashing due to tension pneumothorax.
- (3) Patients with a small pneumothorax, in whom insertion of a pigtail drain isn't safe (due to a risk of lacerating the underlying lung tissue).
- If a surgical chest tube is placed, a moderate size is usually adequate (e.g., 24-28 French).
- ⚠️ Please note that a surgical chest tube is almost never indicated for primary spontaneous pneumothorax.
basics
- Pleural endometriosis usually reflects migration of cells from the abdominal/pelvic cavity into the chest through defects in the diaphragm (usually on the right side). Less commonly, hematogenous transmission of cells results in endometriosis involving the airway or lung parenchyma.
epidemiology
- Thoracic endometriosis may account for a significant fraction of spontaneous pneumothorax among women of childbearing age (e.g., perhaps ~15%). (Fishman 2023) However, spontaneous pneumothorax in this patient population is quite rare overall.
- Average age is ~35 years old.
- Thoracic endometriosis often begins several years after pelvic endometriosis. However, only 20-70% of patients with thoracic endometriosis have pelvic endometriosis. (Murray 2022)
clinical manifestations
catamenial pneumothorax (73% of cases).
- 90% are right-sided (but left-sided or bilateral pneumothorax are also possible).
- Pneumothorax occurs within 3 days before or after menstruation.
- Symptoms usually include chest pain and dyspnea.
- Pneumothorax is usually small to moderate.
- Pneumothorax is usually recurrent. Usually several recurrent events occur prior to correct diagnosis.
catamenial hemothorax (14% of cases).
- Usually right-sided. (35809944)
catamenial hemoptysis (7% of cases):
- Usually scant, but can be severe.
- Occurs within 3 days before or after menstruation.
asymptomatic pulmonary nodules (6% of cases).
- Single or multiple nodules may occur, which can evolve into thin-walled cysts.
diagnosis
CT scan
- Ideally, scanning should be performed within 48-72 hours of menses (when lesions enlarge).
- Potential findings may include:
- Pleural nodules.
- Diaphragmatic abnormalities.
- Bullae, small cavities.
- The diagnostic performance isn't great. The main role of CT scan is to exclude alternative diagnoses (e.g., lymphangioleiomyomatosis).
differential diagnosis of spontaneous pneumothorax in women of childbearing age
- Primary spontaneous pneumothorax.
- LAM (Lymphangioleiomyomatosis).
- Pneumocystis.
- Catamenial pneumothorax (accounts for ~25%). (26527442)
management
catamenial pneumothorax is typically managed with VATS (video-assisted thoracoscopic surgery):
- VATS may be utilized to staple blebs, close any visible diaphragmatic defects, remove any visible endometrial tissue, and perform pleurodesis.
- VATS may help confirm the diagnosis.
- Unfortunately, residual endometrial tissue in the thorax may still cause pain.
catamenial hemoptysis
- Options may include surgical resection or bronchial artery embolization.
hormonal manipulation (e.g., oral contraception, progestins)
- Hormonal therapies may be utilized to minimize estrogen secretion.
- This usually isn't effective, but may be utilized if other measures fail. (35809944)
- This isn't an option in women who are trying to conceive.
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References
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- 26527442 Albores J, Fishbein G, Bando J. A 34-Year-Old Woman With Recurrent Right-Sided Chest Pain and Dyspnea. Chest. 2015 Nov;148(5):e148-e151. doi: 10.1378/chest.15-0813 [PubMed]
- 28267436 Dugan KC, Laxmanan B, Murgu S, Hogarth DK. Management of Persistent Air Leaks. Chest. 2017 Aug;152(2):417-423. doi: 10.1016/j.chest.2017.02.020 [PubMed]
- 35268264 Nava GW, Walker SP. Management of the Secondary Spontaneous Pneumothorax: Current Guidance, Controversies, and Recent Advances. J Clin Med. 2022 Feb 22;11(5):1173. doi: 10.3390/jcm11051173 [PubMed]
- 34527359 Thachuthara-George J. Pneumothorax in patients with respiratory failure in ICU. J Thorac Dis. 2021 Aug;13(8):5195-5204. doi: 10.21037/jtd-19-3752 [PubMed]
- 34774177 Huan NC, Sidhu C, Thomas R. Pneumothorax: Classification and Etiology. Clin Chest Med. 2021 Dec;42(4):711-727. doi: 10.1016/j.ccm.2021.08.007 [PubMed]
- 34774178 DeMaio A, Semaan R. Management of Pneumothorax. Clin Chest Med. 2021 Dec;42(4):729-738. doi: 10.1016/j.ccm.2021.08.008 [PubMed]
- 34857696 Aragaki-Nakahodo A. Management of pneumothorax: an update. Curr Opin Pulm Med. 2022 Jan 1;28(1):62-67. doi: 10.1097/MCP.0000000000000839 [PubMed]
- 35809944 Moguillansky N, Samra RS, Ataya A. A 36-Year-Old Woman With Recurrent Pneumothoraces. Chest. 2022 Jul;162(1):e15-e18. doi: 10.1016/j.chest.2022.02.037 [PubMed]
- 37433578 Roberts ME, Rahman NM, Maskell NA, Bibby AC, Blyth KG, Corcoran JP, Edey A, Evison M, de Fonseka D, Hallifax R, Harden S, Lawrie I, Lim E, McCracken DJ, Mercer R, Mishra EK, Nicholson AG, Noorzad F, Opstad K, Parsonage M, Stanton AE, Walker S; BTS Pleural Guideline Development Group. British Thoracic Society Guideline for pleural disease. Thorax. 2023 Jul;78(Suppl 3):s1-s42. doi: 10.1136/thorax-2022-219784 [PubMed]
Books:
- Shah, P. L., Herth, F. J., Lee, G., & Criner, G. J. (2018). Essentials of Clinical pulmonology. In CRC Press eBooks. https://doi.org/10.1201/9781315113807
- Shepard, JO. (2019). Thoracic Imaging The Requisites (Requisites in Radiology) (3rd ed.). Elsevier.
- Walker C & Chung JH (2019). Muller’s Imaging of the Chest: Expert Radiology Series. Elsevier.
- Palange, P., & Rohde, G. (2019). ERS Handbook of Respiratory Medicine. European Respiratory Society.
- Rosado-De-Christenson, M. L., Facr, M. L. R. M., & Martínez-Jiménez, S. (2021). Diagnostic imaging: chest. Elsevier.
- Murray & Nadel: Broaddus, V. C., Ernst, J. D., MD, King, T. E., Jr, Lazarus, S. C., Sarmiento, K. F., Schnapp, L. M., Stapleton, R. D., & Gotway, M. B. (2021). Murray & Nadel’s Textbook of Respiratory Medicine, 2-Volume set. Elsevier.
- Fishman's: Grippi, M., Antin-Ozerkis, D. E., Cruz, C. D. S., Kotloff, R., Kotton, C. N., & Pack, A. (2023). Fishman’s Pulmonary Diseases and Disorders, Sixth Edition (6th ed.). McGraw Hill / Medical.
- Folch E, Tabba M, and slate J. Principles and Practice of Pleural Diseases. (2023)