Pneumothorax: the BTS 2023 Pathway

A spontaneous pneumothorax on the ward is managed by the British Thoracic Society's 2023 pleural disease guideline, which replaced the old size-first algorithm with a symptoms-first pathway. The decision runs symptoms, then high-risk characteristics, then whether it is safe to intervene, and a high-risk patient goes to a chest drain while a stable one chooses between conservative care, an ambulatory device and needle aspiration. For a CT1 anaesthetics candidate the station is about recognising tension, knowing the six high-risk features, and not putting a drain into a patient who does not need one.

Key takeaways

• The BTS 2023 high-risk characteristics are haemodynamic compromise (tension pneumothorax), significant hypoxia, bilateral pneumothorax, underlying lung disease, age 50 or over with a significant smoking history, and haemopneumothorax.
• A pneumothorax of sufficient size to intervene is, in general, 2 cm or more laterally or apically on the chest X-ray, or any size on CT that can be safely accessed with radiological support.
• Conservative management can be considered for minimally symptomatic or asymptomatic primary spontaneous pneumothorax in adults regardless of size, with outpatient review every 2 to 4 days.
• Ambulatory management should be considered for the initial treatment of primary spontaneous pneumothorax where the expertise and follow-up exist, with review every 2 to 3 days.
• Needle aspiration or tube drainage is for patients not suitable for conservative or ambulatory care; a high-risk patient who is safe to intervene on goes to a chest drain with daily inpatient review.
• A high-risk patient who is not safe to intervene on goes to CT imaging and reassessment rather than a blind procedure.

How do you recognise a pneumothorax on the ward?

You recognise a pneumothorax from sudden pleuritic chest pain and breathlessness with reduced breath sounds and hyper-resonance on one side, confirmed on a chest X-ray, except for tension pneumothorax, which you diagnose clinically from the same signs plus haemodynamic compromise.

The distinction the panel wants is primary versus secondary. A primary spontaneous pneumothorax occurs in someone without known lung disease; a secondary one occurs with underlying lung disease, and the BTS pathway treats underlying lung disease as a high-risk characteristic in its own right.

On the ward, the relevant patients are the COPD patient who suddenly worsens, the asthmatic who does not respond to nebulisers, the patient after a central line, and the ventilated patient in whom airway pressures climb.

That said, the first thing you assess is not the X-ray. It is whether this patient is haemodynamically compromised, hypoxic or bilateral, because those are the features that take the decision away from the flowchart.

What is the A to E and first-hour management of a pneumothorax?

The first hour of a pneumothorax is A to E with oxygen to the BTS target, a decision about tension made at the bedside, and then the chest X-ray and the BTS pathway for everyone who is stable.

Airway and breathing

• Oxygen titrated to an SpO2 of 94 to 98 per cent, or 88 to 92 per cent if the patient is at risk of hypercapnic respiratory failure, as the BTS emergency oxygen guideline sets out.
• Respiratory rate, work of breathing, tracheal position, chest expansion, percussion note and breath sounds on both sides.
• If there is haemodynamic compromise with these signs, treat as tension pneumothorax: call for help and decompress before the X-ray, because the BTS pathway lists haemodynamic compromise as the first high-risk characteristic.
• If stable, a chest X-ray to measure the pneumothorax laterally and at the apex, and a blood gas if the saturations are low.

Circulation, disability and exposure

• Heart rate and blood pressure, which are the haemodynamic compromise the pathway asks about. Intravenous access.
• Analgesia, because pain drives both the breathlessness and the decision about symptomatic versus minimally symptomatic.
• Look for the cause: a recent line, a needle, trauma, or a patient on positive-pressure ventilation.
• Ask about smoking, age and lung disease, because age 50 or over with a significant smoking history is a high-risk characteristic.

What are the BTS 2023 high-risk characteristics and the 2 cm rule?

The BTS 2023 high-risk characteristics for pneumothorax are six: haemodynamic compromise, meaning tension; significant hypoxia; bilateral pneumothorax; underlying lung disease; age 50 or over with a significant smoking history; and haemopneumothorax. Any one of them puts the patient on the intervention arm of the pathway.

The size rule is a footnote in the pathway, not a headline. According to the BTS appendix, a pneumothorax of sufficient size to intervene depends on clinical context but is, in general, usually 2 cm or more laterally or apically on the chest X-ray, or any size on CT that can be safely accessed with radiological support.

In practice, size now answers a different question from the one it used to. It no longer decides whether to treat; it decides whether it is safe to put a needle or a drain in. A small pneumothorax in a high-risk patient goes to CT and reassessment, not to a blind drain.

Say that shift out loud at the station. Candidates who quote the older 2 cm rule as the treatment threshold are quoting a guideline that was replaced in July 2023.

What is the definitive management of a pneumothorax?

Definitive management of a pneumothorax follows the BTS 2023 pathway: no symptoms and no high-risk features means conservative care with review; symptoms without high-risk features means the patient chooses between procedure avoidance, an ambulatory device and needle aspiration; a high-risk feature means a chest drain.

Conservative and ambulatory care

The BTS guideline says conservative management can be considered for minimally symptomatic or asymptomatic primary spontaneous pneumothorax regardless of size, with regular outpatient review every 2 to 4 days and a chest drain if the pneumothorax enlarges or symptoms develop. Secondary pneumothorax managed conservatively is reviewed as an inpatient.

Ambulatory management should be considered for the initial treatment of primary spontaneous pneumothorax in adults with good support, in centres with the expertise and follow-up, with review every 2 to 3 days and the device removed when resolved.

Aspiration, drain and surgery

For patients not suitable for conservative or ambulatory management, needle aspiration or tube drainage should be considered. A patient who wants rapid relief by short-term drainage has a needle aspiration; a high-risk patient has a chest drain with daily inpatient review, removed when the lung has re-expanded and symptoms have improved.

The guideline says thoracic surgery can be considered at first presentation where recurrence prevention matters, for example after a tension pneumothorax or in a high-risk occupation, and that talc pleurodesis can be considered on a first episode in patients such as those with severe COPD in whom a repeat would be hazardous. Everyone leaves with discharge and activity advice and an outpatient review at 2 to 4 weeks.

When do you escalate a pneumothorax, and who do you call?

You escalate a pneumothorax the moment you suspect tension, and you call for senior help before you decompress, because a tension pneumothorax is a peri-arrest emergency and the BTS pathway sends haemodynamic compromise straight to a chest drain.

For a stable patient the calls are to the medical registrar and the respiratory team, because the ambulatory and conservative arms of the pathway need a local service with follow-up. The BTS good practice points ask for the emergency department, general medicine and respiratory medicine to plan those pathways together.

As the anaesthetic CT1, two situations are yours. The ventilated patient whose airway pressures rise and blood pressure falls has a tension pneumothorax until proven otherwise. And any pneumothorax in a patient about to be anaesthetised needs a conversation with the consultant, because positive-pressure ventilation will enlarge it.

Name the person doing the drain. A chest drain is a procedure with a well-documented complication rate, and a good answer says it is done by someone trained, with ultrasound where fluid is present, and not by you alone at night.

What is the human-factors and reflective-practice angle in pneumothorax?

The human-factors angle in pneumothorax is anchoring: once a breathless patient has a diagnosis of asthma or COPD on the board, the pneumothorax hiding inside the same symptoms is missed for hours.

A good answer says you re-examine the chest, both sides, every time a respiratory patient fails to respond to the treatment that should have worked, and that you look at the film yourself rather than reading the report.

Reflective practice wants an example. Candidates often have one from a central line insertion, a trauma call, or a ventilated patient with rising pressures. Describe what you noticed, what you did, and what you now check before and after every line.

Working under pressure is the tension pneumothorax itself: a clinical diagnosis, a decision to act before imaging, and the discipline to call for help at the same time rather than after.

What are the common mistakes candidates make with pneumothorax?

The commonest mistake with pneumothorax at interview is quoting the pre-2023 algorithm, where size decided treatment. The BTS 2023 pathway decides on symptoms and high-risk features first, and uses size only to judge whether intervention is safe.

• Sending a patient with haemodynamic compromise for a chest X-ray before treating tension.
• Draining an asymptomatic primary pneumothorax because it measures more than 2 cm. The guideline allows conservative care regardless of size in that patient.
• Missing underlying lung disease or the age-and-smoking criterion, and so managing a high-risk patient as low risk.
• Putting a drain into a small pneumothorax in a high-risk patient rather than getting CT and reassessing.
• Forgetting that positive-pressure ventilation and nitrous oxide enlarge a pneumothorax, which matters to the anaesthetist more than anyone.
• Not arranging follow-up. Every arm of the pathway ends with outpatient review at 2 to 4 weeks.

How this comes up at the CT1 anaesthetics interview

Pneumothorax comes up at the CT1 anaesthetics interview as a ward call, a post-line complication or a ventilated patient with rising pressures, in the clinical judgement station that ANRO marks on clinical judgement and decision making, reflective practice and working under pressure.

Clinical judgement is knowing the six high-risk features and the 2 cm safety footnote. Decision making is calling tension at the bedside and acting before the film. Reflective practice is the line you put in and checked afterwards. Working under pressure is decompressing while someone else calls the registrar.

The panel commonly turns the stem: the pneumothorax is now in a patient who needs an anaesthetic tomorrow. The anaestheticinterview bank's 340 questions include that turn, and its AI-marked spoken practice scores whether you name the consultant conversation.