It’s the 6th December, so naturally this weekend I started listening to more Christmas music than is usually considered healthy in polite society. Christmas decorations have gone up around the hospital, and my blog has had a seasonal update. But even a day spent listening to howling babies just back from surgery can’t dampen my festive spirits. So while ‘O Holy Night’ starts up for the eighth time this evening and the smell of mince pies warming in the oven creeps through my flat, I’ve decided to write a new post. I wasn’t sure what to cover, so I’ve picked something from our official learning objectives.
Plural, pneumothoraces. For those of you out who can be found glued to your smart phone playing words with friends, you might be interested to know that apparently “PNEUMOTHORAX” will garner you a whopping 27 points. Traditionalists, I’m afraid you’ll only get 24 points for the same offering in a game of scrabble. Hard luck. If you want those extra three points, you’re welcome to come and join us in the 21st century.
A pneumothorax can occur following trauma or spontaneously and is basically air in the pleural space. Spontaneous pneumothorax is commonest in young males (M:F ratio 6:1). Causes of spontaneous pneumothorax include congenital defects in alveolar wall connective tissue (Primary spontaneous pneumothorax). Secondary causes of spontaneous pneumothorax include diseases that disrupt the lung structure, like COPD (the usual cause in patients aged 40+), asthma, TB, Cystic Fibrosis, Marfan’s and bronchial carcinoma (Secondary spontaneous pneumothorax).
Traumatic causes: Stabbing, RTA (that’s Road Traffic Accident for those of you out there who don’t watch Casualty), rib fracture.
Iatrogenic causes: Pleural fluid aspiration (see previous posting on PLEURAL EFFUSIONS), biopsy, central line insertion etc.
There’s yet another type of pneumothorax, the dreaded TENSION PNEUMOTHORAX. In this condition, there is access to the pleural cavity by which air can enter in inspiration but not leave during expiration. This leads to increasing intrathoracic pressure, which can cause a shift of the mediastinum (see X-ray below), compression of functioning lung and decreased venous return (which itself can lead to decreased cardiac output and shock). Tension pneumothorax should be diagnosed based on clinical signs, and shouldn’t be sent to x-ray due to time.
Pneumothoraces can be localised or generalised, and once there is air within the pleural space the lung begins to deflate due to a loss of it’s elastic recoil pressure.
In a young, healthy person a patient might not report any symptoms if the pneumothorax is small. A patient might present with sudden onset dyspnoea (which can get progressively worse), with or without pleuritic pain.
Clinical Signs include reduced expansion (the lung has lost its ability to recoil due to the increased pressure in the pleural space), hyper-resonance on percussion and reduced breath sounds over the affected area on auscultation. In a tension pneumothorax, the trachea will deviate AWAY FROM the affected side, like this:
CXR for pneumothorax (but not for tension pneumothorax!)- look for pleural line, decreased pulmonary vasculature and tracheal deviation.
ABG– decreased pO2 (increased pCO2)
If there is no communication between the pleural space and the airways, the air in the pleural space will gradually be reabsorbed (at a rate of 1.25% of total radiographic volume of hemithorax/day). So a small pneumothorax can be left untreated and followed up if asymptomatic.
Right. Time for a mince pie.