Pneumothorax

Introduction

Primary Spontaneous Pneumothorax (PSP) – No prior lung disease
Secondary Spontaneous Pneumothorax – Underlying lung disease (esp. COAD)
Traumatic
- Iatrogenic
- Non-iatrogenic
Risk factors
- Smoking (#1)
- COAD, TB, CF, pulmonary neoplasms and interstitial lung disease
Haemothorax is seen in 2-7% of spontaneous pneumothoraces
- Mandates larger ICC (24-36Fr)
Dyspnoea and hypoaemia result from reduced vital capacity and altered VQ relationship

Primary spontaneous PTX

Secondary spontaneous PTX

COAD
Asthma
CF (8-20% lifetime prevalence)
Interstitial lung disease
HIV (5% of patients) due to subpleural necrosis by Pneumocystis
- Carries high mortality
- Simple aspiration fails due to underlying necrosis of lung tissue and continued air leak
TB
Necrotising bacterial pneumonia
Lung abscess
Marfan’s/Ehlers-Danlos
Scleroderma
RA
Lung cancer or metastatic disease
Catamenial pneumothorax
Haemopneumothorax occurs in 2-7% of secondary pneumothorax

Clinical features

Typically acute pleuritic chest pain
Large volume can cause dyspnoea, hypoxia, hypotension and tachycardia
Tension pneumothorax
- Principal life-threatening event seems to be hypoxic respiratory arrest from poorly ventilated lung and VQ mismatch vs. reduced venous return
In traumatic pneumothorax, PPV of ipsilateral decreased breath sounds is 86%-97%
Except in trauma, physical examination alone is not sensitive enough to exclude the diagnosis
- Spontaneous PTX tend to be small and ipsilateral decreased breath sounds, hyperresonance to percussion and decreased or absent tactile fremitus are usually absent
Clinical hallmarks of tension PTX
- Tracheal deviation away, hyperresonance of affected side, hypotension and significant dyspnoea

Diagnosis

Diagnosis

Diagnosis

Ultrasound
- 98-99% sensitive and specific in trauma
- Absence of lung sliding
  - Normal lung sliding has sensitivity approaching 100% but NOT specific
- Lung point
  - 66% sensitivity and near 100% specificity
- Absence of normal comet tails artefacts
- Pleural adhesions, effusions, parenchymal disease, severe asthma (with resultant very small tidal volume) and loculations may limit lung sliding
CT
- 100% sensitive and should be performed if clinical suspicion remains after negative CXR

Pneumothorax size

Light index
- % of pneumothorax = 100 – (Diameter of collapsed lung^3/Diameter of hemithorax^3 x 100)s
American College of Chest Physicians
- Small = <3cm from thoracic apex to lung cupola
British Thoracic Society
- Small = <2cm from chest wall at level of hilum
- Large = >2cm
Practical
- Small = Partial dehiscence of lung from chest wall
- Large = Complete dehiscence of lung from chest wall

Stable patient?

BTS Guideline

Treatment

Tension PTx – Consider needle decompression or just straight to tube thoracostomy
- Needle decompression
  - 14G needle for adults (18G for children)
  - 59% success rate (41% failure rate) for actually entering the pleural cavity on small postmortem study
Oxygen administration (>28% FiO2)
- Increases pleural air resorption 3-4 fold over baseline 1.25% reabsorbed per day
- 3L/min NP to 10L/min by mask guided by patient status
Conservative management can be considered for all asymptomatic or minimally symptomatic primary spontaneous PTx regardless of size
Conservative management is recommended for only asymptomatic secondary spontaneous pneumothoraces with inpatient review
All patients with high-risk features warrant a chest drain inserted (if feasible)

Aspiration or tube thoracostomy for patients with no high-risk features, symptomatic and/or wishing for rapid symptom relief
- Factors to consider
  - Patient preference
  - Clinician preference/skill

Needle or catheter aspiration

Aspiration
- As effective as thoracostomy for first episode small primary or secondary spontaneous PTX with success from 37-75% or higher in primary spontaneous PTX
- Can use large-gauge needle or small-bore catheter with catheter technique having advantage of both aspiration and chest tube placement
- Less successful if over 50 or aspirated volume >2.5L
Small-size catheters
- Three-way stopcock with aspiration until cough, then close and repeat CXR to ensure re-expansion
- If >4L, suggests large leak and need large tube
- If failure to re-expand, attempt aspiration again or formal tube thoracostomy
Pigtail using Seldinger
- Smaller incision, less tissue dissection and smaller scar
Tube thoracostomy
- Indicates for large PTX, recurrent or bilateral PTX, coexistent haemothorax or instability
- Success rate of 95%
- Moderate size if suspected large air leak e.g. mechanical ventilation or underlying pulmonary disease

Treatment complications

Re-expansion pulmonary oedema

Uncommon but serious cause of non-cardiogenic pulmonary oedema
Seen following delayed presentation of large pTX, often in young people
Onset within hours in 1% of pneumothorax re-expansions
- Can be delayed up to 24-48 hours rarely
Often described with patient on suction
Thought to be due to permeability oedema related to endothelial changes after collapse for >3 days
Risk factors
- Large pneumothorax, large volume pleural drainage (>3L), young patients, collapse >7 days, diabetes
CXR shows unilateral pulmonary oedema on side of PTX
Managed with aggressive fluid resuscitation if in shock, supportive ventilation
Mortality rate up to 20%
Prevention: BTS suggest limiting pleural drainage to 1.5L at a time

Iatrogenic PTX

Subset of traumatic PTX and occurs more often than spontaneous
50% due to transthoracic needle procedures
25% due to subclavian CVL insertion
- 0.5-3% rate for each subclavian CVL inserted
Up to 1/3 of CVL-associated PTX are not diagnosed until later as post-line CXR are often done in supine position and rapidly with inadequate time for obvious PTX to develop on CXR
If stable with small PTX and not requiring PPV, can observe or treat with simple catheter aspiration (effective in 60-80% of patients)
Long-term recurrence is not a concern

Last Updated on May 14, 2024 by Andrew Crofton

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