Respiratory

Pneumothorax

Air in the pleural space abolishes the negative pressure holding the lung expanded, so the lung recoils inwards, and a one-way leak raises that pressure until venous return fails.

In a nutshell

A pneumothorax is air in the pleural space. Suspected tension physiology is decompressed at the bedside before any imaging: a 14 gauge cannula into the second intercostal space, mid-clavicular line.

Classic presentation

A tall, thin man in his twenties with sudden right-sided pleuritic chest pain and breathlessness, reduced breath sounds and a hyper-resonant percussion note on that side.

Key points

The six high-risk characteristics: haemodynamic compromise, significant hypoxia, bilateral pneumothorax, underlying lung disease, age 50 or over with a significant smoking history, haemopneumothorax.
The British Thoracic Society (BTS) also classes anyone over 50 with a smoking history as secondary disease, not only patients with known lung disease.
Conservative care means outpatient review every 2 to 4 days in primary disease and inpatient review in secondary disease. Ambulatory devices are reviewed every 2 to 3 days.
Lifetime recurrence after primary spontaneous pneumothorax is about 30%, from a European Respiratory Society review. BTS states no headline recurrence figure.
Aspiration shortens stay by about 2.55 days against a drain but more often needs a further pleural procedure. BTS does not rank the two.
Point-of-care ultrasound may identify tension pneumothorax as a treatable cause of cardiac arrest, but must not prolong interruptions in chest compressions.
Talc pleurodesis can be considered at a first pneumothorax in high-risk patients in whom a repeat would be hazardous, such as severe COPD.

First-line investigation

Erect chest X-ray in a stable patient. In suspected tension pneumothorax there is no first investigation, because you decompress before you image.

Management

Tension pneumothorax: decompress now

Clinical diagnosis, so do not image first. Insert a 14 gauge cannula in the second intercostal space, mid-clavicular line, passing just above the third rib.^2,3
No improvement: second attempt with a 14 gauge cannula in the fifth intercostal space anterior to the mid-axillary line. A 4.5 cm cannula may not reach.^3,2
An audible release of air does not confirm placement. Judge by saturations, blood pressure and work of breathing. Then prepare finger thoracostomy and an intercostal drain.²

Stabilise, relieve pain, confirm

Oxygen to a target of 94 to 98%, or 88 to 92% where hypercapnic respiratory failure is a risk, which covers most COPD.⁶
Paracetamol 1 g orally or intravenously every 4 to 6 hours, maximum 4 g daily. Severe pain: morphine 5 mg by slow intravenous injection every 4 hours.^7,8
Erect chest X-ray. CT if the film is equivocal, the disease is loculated, or you need to know whether a small pneumothorax can be accessed safely.^1,4

Work the BTS pathway

Symptomatic? High risk: haemodynamic compromise, significant hypoxia, bilateral, underlying lung disease, age 50 or over with significant smoking history, haemopneumothorax? Safe to intervene? Then chest drain.⁴
Safe to intervene means usually 2 cm or more laterally or apically on chest X-ray, or any size on CT safely accessible with radiological support.⁴
Asymptomatic or minimally symptomatic primary disease: conservative care regardless of size. Review as an outpatient every 2 to 4 days; secondary disease is reviewed as an inpatient.^1,4
Ambulatory device where support, expertise and follow-up exist; review every 2 to 3 days. Otherwise needle aspiration or intercostal drain, with no BTS preference between them.^1,4

Do the procedure safely

Triangle of safety: anterior border of latissimus dorsi, lateral border of pectoralis major, a line level with the nipple. Insert above a rib. No posterior approach.^3,9
Lidocaine 1% down to the pleura. BTS reports up to 3 mg/kg (maximum 250 mg) with no consensus on the maximum, so take your dose from the BNF.⁹
Holding suture on every drain, chest X-ray within a few hours, and avoid suction soon after insertion because of re-expansion pulmonary oedema.⁹

Persistent leak and recurrence prevention

Surgery for a persistent air leak beyond 5 to 7 days of drainage, failed re-expansion, a second ipsilateral or first contralateral pneumothorax, or an at-risk profession.¹
Chemical pleurodesis can be considered to prevent recurrent secondary pneumothorax, for example severe COPD that decompensates, even after the first episode.¹

Follow up and advise

Chest X-ray at 2 to 4 weeks after observation or aspiration, with respiratory follow-up to confirm resolution and address the underlying lung disease.¹
No flying with an unresolved pneumothorax. Fly 7 days after the film shows full resolution, an interval chosen to exclude early recurrence.^1,10
Scuba diving discouraged permanently unless a secure definitive prevention strategy such as surgical pleurectomy has been done. Smoking cessation reduces recurrence.^1,11

Exam traps

Size no longer decides whether to treat. It decides whether an intervention can be done safely. The old 2 cm at the hilum rule is withdrawn.
Do not wait for tracheal deviation, and do not rely on a hiss of air to confirm the needle. Tracheal deviation is late and uncommon.
UK guidance decompresses first at the second intercostal space, mid-clavicular line. The fifth space anterior to the mid-axillary line is the second attempt.
Conservative care is offered regardless of size when the patient is asymptomatic or minimally symptomatic: no significant pain, no breathlessness, no physiological compromise.
Flying is allowed 7 days after the chest X-ray shows full resolution, not 7 days after the pneumothorax.
In COPD target 88 to 92%, not 94 to 98%. Most secondary spontaneous pneumothorax is COPD.

Illustrations

Loss of negative pleural pressureDiagram showing normal apposition of visceral and parietal pleura versus air entering the pleural space and the lung collapsing under its own elastic recoil.PassFinals · original

Tension pneumothorax and mediastinal compressionIllustration of a one-way valve air leak causing progressive pleural pressure rise, mediastinal shift and compression of venous return.PassFinals · original

Traumatic pneumothorax on CT and chest X-rayChest radiograph with a visible pleural line and absent peripheral lung markings on the affected side, linked to the corresponding CT appearance.Cerevisae, Wikimedia Commons · CC-BY-SA-4.0

Key sources

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.