Pneumothorax

Key facts:

Authors: Ruth de Souza and Ricky Jones
Top Tips: Small pneumothoraces may require observation only. Tension pneumothoraces are rare but not in trauma patients

Key Differential Diagnoses

• Pneumonia
• Pulmonary embolus

• Emphysematous bulla

Key Investigations

• FBC, CRP, U+E, LFT

• ECG, CXR

Key Treatment

• OXYGEN, high flow

• Chest aspiration/drain

Key Management Decision

• Chest aspiration/drain
   

Background

Even though it is an easy diagnosis, mistakes can be made - eg putting chest drain into a bulla. In tension pneumothorax insert a cannula immediately, if necessary without anaesthetic

Introduction

• By definition, a pneumothorax is any collection of air within the pleural space
• If the amount of air is substantial, normal ventilation becomes impaired; an extreme example of this is tension pneumothorax
• There are two main categories of pneumothorax: those that occur spontaneously and those that occur secondary to trauma (which may be iatrogenic)

Definition

• Any collection of air within the pleural space

Epidemiology

• 25% of first spontaneous pneumothoraces recur in 1 year

Types/causes

There must be a broncho-pleural fistula, which allows air into pleural space from the bronchial tree and then seals (otherwise the pneumothorax would continue to increase in size; it does not seal in a tension pneumothorax)

Spontaneous

• Primary: Occur in patients with no pre-existing clinical lung disease and  usually occurs as a result of rupture of a small apical bleb.
• Secondary: These are spontaneous pneumothoraces that occur in the presence of pre-existing condition such as emphysema, TB CF and P Jerovicii pneumonia.
• Tension: the broncho-pleural fistula has ball valve effect allowing air into pleural cavity, but not to escape, and does not seal. An increasing amount of air in the pleural space develops over time, increasing intra-pleural pressure and compressing adjacent structures. These are rare but not in trauma patients

Traumatic

• Closed: No connection with atmosphere eg blunt trauma causing a rib fracture that damages the lung
• Open: Direct communication with outside air due to trauma such as a stab wound

Risk factors

• Tall, thin, smoking male (20-40 yrs)
• Connective tissue disorders: Marfan Syndrome, Ehlers-Danlos
  [Ref]
• Emphysematous bullae (COPD)
• TB, occupational lung disease, asthma

Symptoms

• Pleuritic pain (rapid onset)
• SOB
  Note: in hospital inpatient may present less obviously - egs, increasing hypoxia in ventilated patient; or, mild SOB after an invasive procedure (eg central line)

Key questions

• "When did the chest pain start?"
• "Have you ever had one before?"
• "Any rare diseases?" (Marfans etc)
• "Any recent trauma or procedures?"
• "Any underlying lung disease?" (eg COPD)

Signs

• Hyper-resonant, reduced breath sounds, reduced movement (on side of lesion)
• If tension, contralateral tracheal deviation, then cardio respiratory collapse

Investigation

Blood

• FBC, CRP, U+E, LFT
• ABG, if hypoxic, SOB or unwell

Other

• ECG
• CXR
   

Key investigation (problems with CXR)

• The pleural line is usually parallel to the chest wall and small collections may be apical. It may be very difficult to see in COPD as the lung is often quite translucent
• Plain erect or supine CXR usually underestimates the size of a pneumothorax and is unreliable
• A lateral decubitus film or CT is more reliable: [Ref]

Specialist investigation

• High resolution CT (HRCT) chest is helpful if there is a possible underlying precipitating pathology and to distinguish diagnosis from bullous disease in COPD

Differential diagnoses

• Pneumonia
• Pulmonary embolus
• Emphysematous bulla (can convert into pneumothorax if try to drain)
  Note: so, if not sure whether the diagnosis is a bulla, do CT before chest drain

Treatment

In primary spontaneous pneumothorax, no therapy is required if the pneumothorax is small (<2cm between lung edge and chest wall, and symptoms minor). Arrangements for follow-up to radiological resolution should be made

Treatment (first line)

Procedures

• In tension pneumothorax, insert a cannula immediately; if necessary without anaesthetic. Fortunately tension pneumothoraces are rare (except in trauma patients). If not a tension, there is a debate about whether simple aspiration or chest drain (if >2cm between lung edge and chest wall or dyspnoea is present independent of size) is 'better':
• Cochrane Library: [Ref] ; and [Ref]
• If a chest drain is placed, perform post-procedure CXR (to check position and ensure lung is re-expanded); remove drain when lung has re-expanded for 24 hrs
  Note: if <2cm and patient well, no need for aspiration/chest drain; will usually resolve spontaneously in <4 weeks. In this case, advise patient to return to ED if experiences worsening chest pain or SOB
• High flow OXYGEN, via non-rebreathe bag; >2cm and chest drain not placed; leads to 4-FOLD increase in rate of resorption of pneumothorax

Drugs

• Analgesia, may require opiates occasionally if a chest drain causes discomfort

Key management decision

• Aspiration or chest drain/not

Treatment (second line)

Procedures

• Pleurodesis (chemical or surgical), if recurs

Admit?

• Usually; certainly if secondary pneumothorax, as compromised underlying lung puts patient at higher risk of complications
• <30% can be managed as OP, with follow-up till radiological resolution

Bed plan

• Medical admission ward
• ± ITU, if tension

Referrals

• Respiratory, if recurrent, tension or technical problems

The Rest

Maxim

• "If you suspect tension pneumothorax, don't wait .. stick a venflon in"

Complications

Of chest drain

• Pain, trauma to adjacent structures - eg intercostal bundle and mediastinum, haemothorax and infection
• Re-expansion pulmonary oedema

Follow-up

• If radiologically resolved, no need for follow up
• If no chest drain, repeat CXRs at 7 days, and 4 weeks; via GP, or acute medical, or respiratory clinic
  Note: most small pneumothoraces should have resolved by 4 weeks
  If recurrent, CT and surgery

Risk stratification
(who can be managed as outpatient)

• <30% of patients with small primary spontaneous pneumothoraces who are well

2° Prevention + Health promotion

• NEVER dive
• No air travel until CXR resolution (say, at least 2 weeks; preferably 6 weeks)
• Small pneumothoraces, though not drained, need follow-up (CXR at 7 days and 4 weeks)
• If think new diagnosis Marfan's Syndrome etc, refer for genetic counselling

Don't forget

• OXYGEN is treatment
• To do CXR after drain
• Keep chest drain under chest height, and DO NOT CLAMP
• Marfan's
• 'NEVER dive' advice
• Do not travel by air until > 2 wks after successful drainage

Red flags

• Tension pneumothorax
• Haemodynamic compromise
• Cyanosis/hypoxia

References

national guidelines	UK/BTS Guidelines for the Management of Spontaneous Pneumothorax (2003)
reviews	Evaluating and managing pneumothorax. Harrison PB et al. Emerg Med; 37(10):18-25, 2005