PNEUMOTHORAX

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n the healthy body, the lungs are inside the pleural sac and intern they are surrounded by the rib cage. This gives the room for expansion and also protection.
But Sometimes this protection doesn’t help. There occurs one phenomenon where the lung is collapsed and the breathing becomes difficult progressively and puts the person in respiratory distress.
This condition is called as PNEUMOTHORAX and is defined as, “air in the pleural cavity with the collapse of surround lung.”
To be clear, the air is inside the pleural cavity. Normally air is inside the lungs and doesn’t leak out.

Causes of Pneumothorax –
1.    Spontaneous pneumothorax
a.     Primary spontaneous
b.    Secondary Spontaneous.
2.    Traumatic pneumothorax
a.     Iatrogenic pneumothorax
i.                Accidental
ii.              Artificial
b.    Non-iatrogenic pneumothorax

Primary Pneumothorax is caused directly by substances without underlying any trauma or any secondary pathology.

Causes of primary pneumothorax-
1.    Changes in atmospheric pressure
2.    Loud noises
3.    Sharp inner border of 1st and 2nd rib
4.    Tall-thin patients
5.    Male gender.
6.    Genetic association may be present, example in BIRT HOGG DUBE SYNDROME (Benign skin growth, pulmonary cysts and renal cancer)
7.    HLA specific like HLA-A2, HLA-B40, etc
Secondary Pneumothorax occurs when there is underlying pathology in the pulmonary structure. Air enters the pleural space via distended, damaged or compromised alveoli. Seen in conditions like –
1.    COPD
2.    Bronchopneumonia
3.    Cystic Fibrosis
4.    Interstitial Lung Diseases
5.    Pneumonia (Fungal, HIV)
6.    Bronchogenic Carcinoma or metastatic lesions.
Iatrogenic Pneumothorax is caused because of medical procedures that lead to trauma. It occurs in cases like –
1.    Thoracocentesis
2.    Trans thoracic needle aspiration techniques
3.    Pleural and transbronchial lung biopsy
4.    Tracheostomy
5.    CPR
6.    Mechanical ventilation (peak pressure)

Artificial Pneumothorax stands for deliberate introduction of air inside the pleural cavity by needle. It was done earlier to treat Tuberculosis before the invention of anti-tubercular drugs.

Traumatic Pneumothorax –
1.    Stab wounds
2.    Gunshot wounds
3.    Blunt chest injury in RTA
4.    Explosion wounds

Tension Pneumothorax is seen when the inside pressure is more than atmospheric pressure, where injury to pleura creates a tissue flap that causes the opening and closing of the tissue valve on inspiration and expiration respectively (like a ball and valve mechanism).

Signs and symptoms of Tension pneumothorax –
1.    Severe dyspnoea
2.    Tachycardia
3.    Cyanosis
4.    Hypotension
5.    Tracheal deviation
6.    Subcutaneous emphysema
7.    Mediastinal shift on CXR (chest x ray)
8.    Respiratory acidosis seen in ABG analysis (arterial blood gas).

Treatment of Tension Pneumothorax –
1.    High flow O2
2.    Immediate tube thoracostomy.

Signs and Symptoms of Pneumothorax –
1.    Sharp, stabbing unilateral chest pain (exacerbation on deep inspiration or postural change).
2.    Dry cough and irritation of diaphragm.
3.    Shortness of breath.
4.    Generalised malaise.
5.    High resonance on affected side.
6.    Diminished breath sounds.
7.    Decreased Tactile vocal fremitus.
8.    Scratch sounds heard.
9.    Sudden decline in sPO2 Stats (seen in pneumothorax in patients with mechanical ventilation).
10.  ECG shows ST segment elevation in II, III, AVF and V4-6
11.  Radiologically sharply defined convex shadow of lungs
12.  Deep costophrenic angle.
13.  CT shows multiple Bullae and blebs.
Differential diagnosis –
1.    ACS (Acute Coronary Syndrome).
2.    ARDS (Acute Respiratory Distress Syndrome).
3.    Asthma, COPD, Emphysema.
4.    CHF (Congestive Heart Failure).
5.    Pulmonary edema
6.    Esophageal tear, rupture.
7.    Myocarditis.
8.    Mediastenitis.
9.    Pericarditis.
10.  Foreign body in trachea.
11.  Pleural Effusion.
12.  Pulmonary Embolism.
13.  Aspiration Pneumonia.
The percentage of pneumothorax is measured by the Light’s method.


Light’s method –
% of pneumothorax = (1 − L3/H3) × 100; where H = hemithorax diameter and L = diameter of the collapsed lung 

Management of Pneumothorax –
1.    Observation
2.    Supplemental oxygen
3.    Simple Aspiration
4.    Tube-thoracostomy
5.    Medial-thoracostomy
The choice of treatment depends on the situation.

Complications –
1.    Tension Pneumothorax
2.    Broncho-pleural fistula
3.    Pyothorax
4.    Haemothorax
5.    Re-expansion of pulmonary edema






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