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Pneumothorax 

Pneumothorax
Chapter:
Pneumothorax
Author(s):

Stephen Chapman

, Grace Robinson

, John Stradling

, Sophie West

, and John Wrightson

DOI:
10.1093/med/9780198703860.003.0037
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date: 29 November 2021

Clinical features and investigations

Definition

A pneumothorax is air in the pleural space. May occur with apparently normal lungs (1° pneumothorax) or in the presence of underlying lung disease (2° pneumothorax). May occur spontaneously or following trauma.

Epidemiology

  • Annual incidence of 1° pneumothorax is around 9 per 100, 000

  • 1° pneumothoraces occur most commonly in tall thin men aged between 20 and 40. They are less common in women (♂:♀ ≈ 5:1)—consider the possibility of underlying lung disease (e.g. LAM, catamenial pneumothorax)

  • Cigarette or cannabis smoking is a major risk factor for pneumothorax, increasing the risk by a factor of 22 in men and 9 in women. The mechanism is unclear; a smoking-induced influx of inflammatory cells may both break down elastic lung fibres (causing bulla formation) and cause small airways obstruction (increasing alveolar pressure and the likelihood of interstitial air leak)

  • More common in patients with Marfan’s syndrome and homocystinuria

  • May rarely be familial (Birt–Hogg–Dubé syndrome; autosomal dominant mutation in folliculin gene (Chr 17); causes renal and skin tumours and pulmonary cysts).

Causes and pathophysiology

Pathogenesis is poorly understood; pneumothoraces are presumed to occur following an air leak from apical subpleural blebs and bullae, although small airway inflammation is often also present and may contribute by increasing airways resistance, causing ‘emphysema-like changes’ (ELC).

  • Underlying diseases include: COPD (60% of cases), asthma, ILD, necrotizing pneumonia, TB, PCP, CF, LCH, LAM, Marfan’s syndrome, oesophageal rupture, lung cancer, catamenial pneumothorax, and pulmonary infarction

  • Pneumothorax may be the first presentation of the underlying disease.

Clinical features

  • Classically presents with acute onset of pleuritic chest pain and/or breathlessness. Breathlessness is often minimal in young patients and is more severe in 2° pneumothorax

  • Signs of pneumothorax include tachycardia, hyperinflation, reduced expansion, hyperresonant percussion note, and quiet breath sounds on the pneumothorax side. These are frequently absent in small pneumothoraces. Hamman’s sign refers to a ‘click’ on auscultation in time with the heart sounds, due to movement of pleural surfaces with a left-sided pneumothorax

  • May feel ‘bubbles’ and ‘crackles’ under the skin of the torso and neck if there is subcutaneous emphysema

  • Presents in ventilated patients with acute clinical deterioration and hypoxia or increasing inflation pressures.

Investigations

  • CXR is the diagnostic test in most cases, revealing a visible lung edge and absent lung markings peripherally. Blunting of the ipsilateral costophrenic angle due to low-volume bleeding into the pleural space is seen. Pneumothoraces are difficult to visualize on supine films: look for a sharply delineated heart border, hemidiaphragm and costophrenic angle depression (‘deep sulcus sign’), and increased lucency on the affected side

    • Width of the rim of air surrounding the lung on CXR may be used to classify pneumothoraces into small (rim of air measured at level of hilum ≤2cm) and large (>2cm). A 2cm rim of air approximately equates to a 50% pneumothorax in volume

    • Tiny pneumothoraces that are not apparent on PA CXR may be visible on lateral chest or lateral decubitus radiographs

    • CXR appearance may also show features of underlying lung disease, although this can be difficult to assess in the presence of a large pneumothorax

  • CT chest may be required to differentiate pneumothorax from bullous disease and is useful in diagnosing unsuspected pneumothorax following trauma and in looking for evidence of underlying lung disease

  • ABGs frequently show hypoxia and sometimes hypercapnia in 2° pneumothorax.

Prognosis

  • Untreated, pneumothoraces without an ongoing air leak resolve at rate of ~2% of volume of hemithorax every 24h

  • Average of 30% (range 16–54% in studies) of 1° pneumothoraces recur, most within 2y. Continued smoking increases the risk of recurrence. Risk of recurrence increases with each subsequent pneumothorax; risk of recurrence is around 30% after a first pneumothorax, about 40% after a second, and >50% after a third

  • Mortality of 2° pneumothorax is 10%

  • Recurrence of 2° pneumothorax occurs in 39–47% and is associated with age, pulmonary fibrosis, and emphysema. Recurrence rates may be as high as 80% in patients with LCH or LAM.

Further information

Sahn SA, Heffner JE. Spontaneous pneumothorax. N Engl J Med 2000;342:868–74.Find this resource:

Initial management

There is considerable variation amongst clinicians regarding optimal pneumothorax management. The treatment algorithm presented on Pneumothorax p. [link] (see Fig. 37.1) is taken from the BTS guidelines.

Fig. 37.1 BTS treatment algorithm for spontaneous pneumothorax.

Fig. 37.1 BTS treatment algorithm for spontaneous pneumothorax.

* Disagreement exists regarding this point; in the setting of a relatively asymptomatic patient with a large 1° pneumothorax and no adverse physiology, there may be no justification for intervention. Indeed, the risk of intervention may well outweigh the risk of the pneumothorax, and conservative management is preferable.

§ In our opinion, breathlessness and the degree of physiological compromise are much more important in guiding management than absolute pneumothorax size on CXR. For example, it may be appropriate to insert a CT-guided chest drain in a patient with a <1cm 2° pneumothorax who is particularly compromised while, conversely, an asymptomatic patient with >2cm 2° pneumothorax may be best managed conservatively.

General management points

  • Determine whether the pneumothorax is 1° or 2° (known lung disease/evidence of lung disease clinically or age >50 with significant smoking history)

  • Management is determined by degree of breathlessness and hypoxia, evidence of haemodynamic compromise, presence and severity of any underlying lung disease, and, to a lesser extent, CXR pneumothorax size

  • Severe breathlessness out of proportion to pneumothorax size on a prior CXR may be a feature of impending tension pneumothorax

  • 2° pneumothorax has a significant mortality (10%) and should be managed more aggressively. Treat also the underlying disease.

Aspiration

  • Procedure described on Pneumothorax pp. [link][link]

  • Halt the procedure if painful or if the patient coughs excessively; do not aspirate >1.5L of air, as this suggests a large air leak and aspiration is likely to fail

  • Aspiration is successful if the lung is fully or nearly re-expanded on CXR and patient feels symptomatically better with improved physiology

  • If initial aspiration of a 1° pneumothorax fails, a chest drain is likely to be required if benefits outweigh risks.

Chest drainage

  • Procedure described on Pneumothorax pp. [link][link]

  • Associated with significant morbidity and even mortality, and not required in the majority of patients with 1° spontaneous pneumothorax

  • Small (10–14F) drains are sufficient in most cases; consider large-bore (24–28F) drain in 2° pneumothorax with large air leak, severe subcutaneous emphysema, or in mechanically ventilated patients

  • Never clamp a bubbling chest drain (risk of tension pneumothorax)

  • When air leak appears to have ceased, clamping of the drain for several hours followed by repeat CXR may detect very slow or intermittent air leaks, thereby avoiding inappropriate drain removal; this is controversial, however, and should only be considered on a specialist ward with experienced nursing staff. Addition of washing-up liquid to water in underwater seal bottle aids visualization of bubbling in very slow air leaks

  • If water level in drain does not swing with respiration, the drain is either kinked (check underneath dressing as tube enters skin), blocked, clamped, or incorrectly positioned (drainage holes not in pleural space; check CXR)

  • Heimlich flutter valves (or thoracic vents) are an alternative to underwater bottle drainage and are being used increasingly in some centres. They allow greater patient mobilization and sometimes outpatient management of pneumothorax.

O2

All hospitalized patients should receive high-flow (10L/min) inspired O2 (unless CO2 retention is a problem). This reduces the partial pressure of nitrogen in blood, encouraging removal of air from the pleural space and speeding up resolution of the pneumothorax.

Persistent air leak

  • Arbitrarily defined as continued bubbling of chest drain 48h after insertion

  • Consider drain suction (–10 to –20cmH2O), insertion of large-bore drain, and/or thoracic surgical referral

  • Check that persistent bubbling is not the result of ‘outside’ air being sucked down the drain, e.g. following drain displacement such that a hole lies outside the pleural cavity, or if enlargement of the drain track occurs, allowing outside air to enter and then be aspirated down the drain.

Discharge

Prior to discharge, discuss flying and diving (see Pneumothorax pp. [link] and [link] respectively), and advise to return to hospital immediately if breathlessness worsens. Document this in medical notes.

Further management

Outpatient follow-up

  • Repeat CXR to ensure resolution of pneumothorax and normal appearance of underlying lungs

  • Discuss risk of recurrence, and emphasize smoking cessation, if appropriate

  • Ascent to altitude with a pneumothorax is potentially hazardous. Guidelines recommend that patients should not fly for at least 1 week from the resolution of spontaneous pneumothorax on CXR. This time interval is arbitrary, however, and patients should understand that there is a high initial risk of recurrence that falls with time, and they may wish to avoid flying for a longer period, e.g. 1y

  • Advise never to dive in the future, unless patient has undergone a definitive surgical procedure.

Surgical management

Indications for cardiothoracic surgical referral

  • Second ipsilateral pneumothorax

  • First contralateral pneumothorax

  • Bilateral spontaneous pneumothorax

  • Persistent air leak or failure of lung to re-expand (3–5 days of drainage)

  • Spontaneous haemothorax

  • Professions at risk (e.g. pilots, divers) after first pneumothorax.

Note that these are guidelines only, and patient choice will of course also influence the decision for surgical intervention.

Surgical treatments

aim to repair the apical hole or bleb and close the pleural space. Options:

  • VATS Recurrence rates are higher than for open thoracotomy (4% vs 1.5%) although less invasive procedure and shorter hospital stay. Apical blebs/bullae are stapled, and mechanical pleural abrasion and/or parietal pleurectomy (rather than talc poudrage) is usually favoured for closure of the pleural space. Often the procedure of choice in young patients with 1° pneumothorax

  • Open thoracotomy Same range of operative interventions undertaken as for VATS but associated with longer recovery (albeit with marginally lower recurrence rates)

  • Transaxillary mini-thoracotomy uses a relatively small axillary incision and may be a less invasive alternative to open thoracotomy.

Chemical pleurodesis

  • Talc or tetracycline most commonly used (although difficulties obtaining tetracycline); procedure described on Pneumothorax pp. [link][link]

  • Can be performed via intercostal drain or at VATS

  • Failure rates around 10–20% and some concern about the long-term safety of intrapleural talc; therefore not recommended in younger patients

  • Consider pleurodesis via intercostal drain only as a last resort in older patients with recurrent pneumothorax in whom surgery would be high risk (e.g. patients with severe COPD)

  • Likelihood of successful pleurodesis in the setting of an incompletely re-expanded lung with a persistent air leak remains uncertain, although it may be attempted if surgery is not an option.

Algorithm for treatment of spontaneous pneumothorax

Fig. 37.1 is an adapted version of the BTS guidance for treatment of a spontaneous pneumothorax.

Further information

MacDuff A et al. Management of spontaneous pneumothorax: British Thoracic Society pleural disease guideline 2010. Thorax 2010;65(Suppl. 2):ii18–31.Find this resource:

Specific situations

Tension pneumothorax

  • Pneumothorax acts as a one-way valve, with air entering the pleural space on each inspiration and unable to escape on expiration. The progressive increase in pleural pressure compresses both lungs and mediastinum and inhibits venous return to the heart, leading to hypotension and potentially cardiac arrest

  • Occurrence is not related to pneumothorax size, and tension can occur with very small pneumothoraces in the context of air trapping in the lung from obstructive lung disease

  • Typically presents with acute respiratory distress, agitation, hypotension, raised JVP, and tracheal deviation away from the pneumothorax side. Reduced air entry on affected side

  • May present with cardiac arrest (pulseless electrical activity) or with acute deterioration in ventilated patients.

See Box 37.1.

Iatrogenic pneumothorax

  • Causes include TBB, transthoracic needle lung biopsy, subclavian line insertion, mechanical ventilation, pleural aspiration, pleural biopsy, external cardiac massage, and percutaneous liver biopsy

  • Presentation may be delayed, even several days after procedure

  • Most cases do not require intervention and improve with observation, although aspiration is sometimes required

  • Drainage is seldom needed although is more commonly required in patients with COPD. The exception is mechanically ventilated patients, who will require an intercostal drain in the majority of cases.

Traumatic pneumothorax

  • Up to half may not be clinically apparent or visible on CXR; chest CT is required for diagnosis

  • Majority of patients require intercostal drain. Ensure adequate analgesia; intercostal nerve block may be required

  • Consider VATS early if persistent air leak.

Subcutaneous (or ‘surgical’) emphysema

  • Occurs as air tracks below skin under pressure from the pleural space

  • May result from large air leaks, particularly in the presence of underlying lung disease such as COPD. Also may occur if chest drain is blocked or displaced so that holes lie subcutaneously

  • Harmless in majority of cases although rarely may result in significant respiratory compromise from upper airway compression

  • Treat with high-flow (10L/min) inspired O2 (unless CO2 retention a problem). Check that the drain is patent (swinging, bubbling)

  • Management if unwell: O2, large-bore chest drain on suction. If the airway is compromised, consider anaesthetizing and incising areas of affected skin, and ‘milking’ out subcutaneous air; subcutaneous drains are sometimes used, and, in rare cases, tracheostomy is required.

Pneumothorax in pregnancy

  • Increased risk of pneumothorax recurrence during pregnancy

  • Standard 1° pneumothorax treatment is usually effective, but close liaison with obstetricians and thoracic surgeons

  • Elective assisted delivery (forceps/ventouse) near term with epidural anaesthesia is advocated

  • Consider VATS after pregnancy.

Pneumothorax in HIV

  • Most commonly occurs as a result of PCP. Empirical treatment of PCP is advised (see Pneumothorax pp. [link][link])

  • Use of nebulized pentamidine may increase the risk of pneumothorax

  • Consider early intercostal drainage and surgical referral.

Pneumothorax in CF

Catamenial pneumothorax

  • Pneumothorax occurring at the same time as menstruation

  • Usually recurrent

  • Pathogenesis is unknown; possibilities include pleural endometriosis or transfer of air into pleural spaces through a diaphragmatic defect from the peritoneal cavity at menstruation

  • Treatment options: VATS, pleurodesis, ovulation-suppressing drugs.

Re-expansion pulmonary oedema

  • Occurs in up to 14% of cases following treatment and causes breathlessness and cough, with evidence of oedema in the re-expanded lung (and sometimes both lungs) on CXR

  • More common in young patients with large 1° pneumothoraces and may be associated with late presentations to hospital

  • May be precipitated by early use of suction (<48h)

  • Self-resolving in most cases although may rarely be fatal.

Further information

MacDuff A et al. Management of spontaneous pneumothorax: British Thoracic Society pleural disease guideline 2010. Thorax 2010;65(Suppl. 2):ii18–31.Find this resource: