Pneumothorax is defined as presence of free gas in the pleural space. You can get spontaneous or traumatic pneumothorax. Spontaneous can be divided into primary and secondary. What is the difference?
- primary spontaneous pneumothorax - underlying lung is normal -> often result from rupture of subpleural bulla, smoking seen as chief cause, proximity to loud sound, scuba diving, sudden change in atm pressure are some other factors that can cause this
- secondary spontaneous pneumothorax - occur in presence of underlying lung pathology - COPD (70%), asthma, CF, lung infections, interstitial lung disease, connective tissue disorders etc.
basically any respiratory disorder can cause a 2o pneumothorax, it seems
Some patients may be asymptomtic, but what are the clinical features (signs + symptoms) of a pneumothorax?
- increasing dyspnoea
- sudden onset pleuritic chest pain
- reduced chest movement on affected side
- hyper-resonant ipsilateral hemithorax
- ipsilateral absent or reduced breath sounds
- tracheal deviation (tension)
What are key risk factors for developing a pneumothorax?
- cigarette smoking
- FHx
- tall + slender body build
- male sex
- young age
- COPD, severe asthma, TB, PJP, CF
- Marfan’s syndrome
What is a tension pneumothorax?
- where a breach in lung surface acts as a one-way valve, admitting air into pleural cavity when the patient inhales
- but preventing its escape when patient exhales
- with every breath, more air enters + cannot be released
- this air must be let out by surgical incision
- there is severe hypoxia despite administration of oxygen
- capable of causing sudden cardiac arrest + death
Why is tension pneumothorax life-threatening?
- increased pressure incisde the cavity causes ipsilateral lung to collapse -> resulting in hypoxia
- further pressure build-up causes the mediastinum to shift toward contralateral side + impinge on both the contralateral lung and the vasculature entering the right atrium of the heart
- this leads to worsening hypoxia + compromised venous return
- the IVC is thought to be first to kink + restrict blood flow back to heart, soon followed by SVC
- cardiac output decreased due to reduced stroke volume (reduced venous return)
- if underlying problem remains untreated, the hypoxaemia + decreased CO -> cardiac arrest + death
What are the clinical features of tension pneumothorax?
- extreme dyspnoea
- tachypnoea
- compensatory tachycardia
- cold extremities
- hyperexpansion of affected side (decreased movement relative to other side)
- hyper-resonant percussion note on affected side
- decreased breath sounds on affected side
- cyanosis, confusion, hypotension
- increased JVP - distended neck veins
- deviation of trachea + mediastinum away from affected side
What is the emergency management of a tension pneumothorax?
- immediate decompression by needle thoracocentesis
- insert large bore (14-16G) cannula w/ syringe, partially filled w/ 0.9% saline, into the pleural space at intersection of the midclavicular line and the 2nd or 3rd intercostal space on the side of the pneumothorax
- remove plunger to allow the trapped air to bubble through the syringe (with saline as a water seal) until a chest tube can be placed
- any open chest wound is covered, as it carries high risk of leading to tension pneumothorax, ideally w/ a dressing called the Asherman seal
What are differentials for pleuritic chest pain?
- ACS, CHF, pericarditis
- IBD, pancreatitis, spontaneous bacterial pleuritis
- malignancy, sickle cell crisis
- asbestosis
- infection
- COPD, pneumothorax, PE
- lupus pleuritis, rheumatoid pleuritis, Sjörgen syndrome
What other characteristics of the pleuritic chest pain may be present in a patient with pericarditis?
- retrosternal/precordial pleuritic chest pain
- relieved by sitting forward
- may radiate to trapezius ridge/neck/shoulder
- viral prodrome common
Another cause of pneumothorax is traumatic. This is divided into iatrogenic and accidental. What are examples of iatrogenic causes of pneumothorax?
- CVP line insertion
- ventilation
- liver biopsy
What investigations are important for confirmation of pneumothorax?
- CXR* - presence of an area of devoid of lung markings, peripheral to the edge of the collapsed lung, an air rim of 2cm+ means that the pneumothorax occupies about 50% of the pleural cavity
- CT chest - more sensitive than CXR, used in traumatic injuries, helps to distinguish between pneumothorax and bullous emphysema
- USS chest - useful in blunt chest trauma, when upright PA CXR cannot be obtained (and supine AP CXR not as sensitive), USS also used as screening for these pts
- bronchoscopy - particularly useful in setting of pneumothorax ex vacuo
- ABG - in dyspnoeic pts + those w/ chronic lung disease
*only perform once chest drain or similar in situ if tension pneumothorax
Management of pneumothorax depends on whether it is 1o or 2o as well as the size + symptoms. Small spontaneous pneumothoraces typically resolve by themselves and require no treatment, especially in those w/ no underlying lung disease.
What is the treatment algorithm for primary pneumothorax?
All pts admitted should receive high-flow oxygen (10L/min) to inc absorption of air from the pleural cavity.
- If rim < 2cm + pt asymptomatic → discharge
- If rim > 2cm or pt SoB → aspiration
- If above fails (> 2cm + still SoB) → chest drain
If still unsuccessful: Refer to chest physician after 48h and to thoracic surgeon after 5 days
- pts may be considered for negative pressure suction
- then use of video-assisted thoracoscopy with stapling of the air leak and pleurodesis is the procedure of choice in most circumstances
- thoracoscopic wedge resection is an alternative procedure to stem the air leak should it persist
What is the management for patients with a small (rim ≤ 2cm) primary pneumothorax?
Clinically stable patients who are experiencing a small primary spontaneous pneumothorax can be observed and treated conservatively with supplemental high-concentration (10 L/min) oxygen and observation, without invasive intervention.
As these patients are typically young and otherwise healthy, they can often be managed as outpatients. If they remain stable in the emergency department for 4 to 6 hours, they can be released with follow-up in several days. However, they should be instructed to seek medical attention immediately should they become short of breath.
What is the management for patients with a secondary pneumothorax?
All patients should remain in hospital
- If < 1cm → admit + observe 24h
- If 1-2cm → aspiration
- If >50 + >2cm rim and/or breathless → chest drain
What is the treatment for a traumatic pneumothorax?
- chest drain insertion is usually the key treatment for this
- inserted in the “safe triangle”
What is the prognosis of pneumothorax and the likelihood of reccurance?
- primary - 30-50% recurrence after a single pneumothorax. If there is no interventon undertaken after 1st pneumothorax, a third and fourth event can be expected in 62% and 83% of patients
- secondary - greater risk than primary pneumothorax
-
Respiratory (differentials)22
-
Asthma37
-
COPD28
-
Respiratory failure36
-
Tuberculosis16
-
Pneumothorax16
-
Pneumonia22
-
Deep Venous Thrombosis22
-
Pulmonary Embolus17
-
Carcinoma of Bronchus28
-
Pleural effusion + disease11
-
Chest trauma + haemothorax10
-
Bronchiectasis and CF8
-
Sarcoidosis6
-
Interstitial Lung Disease8
-
Obstructive Sleep Apnoea5
-
Occupational lung disease0
