Tension Pneumothorax

Related Subjects: Asthma |Acute Severe Asthma |Exacerbation of COPD |Pulmonary Embolism |Cardiogenic Pulmonary Oedema |Pneumothorax |Tension Pneumothorax |Respiratory (Chest) infections Pneumonia |Fat embolism |Hyperventilation Syndrome |ARDS |Respiratory Failure |Diabetic Ketoacidosis

A clinical diagnosis - do not wait for radiology to treat a patient with Immediate needle thoracocentesis. Consider where there is a suspected PTX and a fall in BP. Pressure akin to a balloon inflating builds in pleural space and impairs cardiac filling and death ensues if untreated. Pop the balloon with a needle and let the air out!

About

• Needs to be decompressed with a needle. Will cause a "Hiss of air under pressure"
• If no tension then little harm is done - remove needle and CXR and look for other cause

Aetiology

• Air into pleural space cannot escape due to valve-like effect
• If intrathoracic pressure > Diastolic filling pressure then Cardiac output falls
• As cardiac output falls death ensues

Causes

• Trauma (traumatic pneumothorax)
  • Penetrating trauma e.g. stab wound or # ribs
  • Blunt trauma e.g. RTA
• Iatrogenic trauma: May be compounded by positive pressure ventilation
  • Central line insertion (Jugular/subclavian)
  • Pacing (Jugular/subclavian)
  • Lung biopsy
  • Barotrauma due to positive pressure ventilation
  • Percutaneous tracheostomy
  • Thoracentesis
  • Bronchoscopy
  • Cardiopulmonary resuscitation
  • Intercostal nerve block
• Non Iatrogenic
  • Diving
  • Flying
  • Rib #
• Atraumatic pneumothoraces
  • Primary (unknown etiology)
  • Secondary (patient with an underlying pulmonary disease)

Clinical

• Ventilated patient, post chest trauma, rub #
• Post Central venous cannulation/other procedure
• Subcutaneous emphysema as air may escape
• Cardinal signs are tachycardia, cyanotic, anxious and deteriorating
• Raised JVP due to raised intrathoracic pressures
• Absent breath sounds on the ipsilateral side.
• Hypotension is a late and deadly sign
• May be an obvious chest wound on the affected side

CXR shows TPTX - usually patients too ill to get CXR

Investigations

• CXR can usually wait if you suspect a tension pneumothorax and the patient is deteriorating and in extremis. It would be reasonable to go ahead and first insert the cannula and then the chest drain. Findings are
  • A thin line vertical line representing the edge of the visceral pleura
  • Effacement of lung markings distally to this line
  • Complete ipsilateral lung collapse
  • Mediastinal shift away from the PTX
  • Subcutaneous emphysema
  • Trachea deviates to the opposite side
  • Flattening of the hemidiaphragm on the same side (tension)
• Ultrasound: 94% sensitive and 100% specific. Needs skilled operator. Ultrasound findings include the absence of lung sliding and the presence of a lung point
• Hypoxia is due to loss of total lung capacity and ventilation-perfusion mismatch as the lung which is collapsed is not being aerated

Management

• ABCDE assessment. Sit up and give 15L/min O2. If the patient is stable, then diagnostic imaging (CXR) can be done prior to treatment.
• In extremis then a cannula should be inserted immediately
  • Classically in the 2nd or 3rd intercostal space in the midclavicular line
  • Alternative is 4th or 5th space anterior axillary line in the safe triangle
  • Listen for hiss and leave in situ. If after inserting the cannulae there is no hiss, try and place another one or consider an alternative diagnosis.
• Chest drain: The side should be the more resonant and the trachea is pushed away. Do not wait for radiology. This will buy time for a quick chest drain insertion and the hiss of high-pressure air and relief of some symptoms will help confirm the diagnosis. If a chest tube is malpositioning or becomes plugged, it can cease to function, and the pneumothorax can recur.