Sunday, 21 December 2014

Spontaneous Pneumothorax

There's a lot of of information out there about traumatic pneumothoraces - but the spontaneous ones are much more exciting! They're the ones we get to put drains in without butting a trauma team out of the way! And they are the ones we can make a big difference to by not putting drains into.

Definitions and Numbers
Primary: occurs in healthy people. Thought to be due to rupture of a bleb.
Secondary: underlying lung disease or smokers >50.

Causes 16.7 per 100 000 in men and 5.8 per 100 000 hospital admissions per year.

Risk Factors
Smoking - increases risk in healthy men from 0.1 to 12%
Tall stature, and age over 60 years.

Secondary Risk Factors:
COPD, Asthma
Pulmonary fibrosis, Cystic fibrosis
Pneumonia, TB
Lung cancer
Respiratory complications of HIV and AIDS
Thoracic endometriosis (catamenial pneumothorax) - occurs at the time of (or within 72 hours of) menstruation. Accounts for approximately 5% of pneumothoraces in women. Typically affects 30 - 40 year olds, right lung in 90% of cases. Known endometriosis in a third of cases. Half of cases get a recurrence.
Approximately 1-2% of HIV infected patients and 5-10% of patients with pneumocystis jiroveci (formerly PCP) develop a pneumothorax.

Clinical
Sudden onset of pleuritic chest pain and dyspnoea at rest. Symptoms do not indicate size of the pneumothorax. In many cases the symptoms are mild and approximately half of patients will present after more than 2 days of symptoms.

Diagnosis
CXR- 80- - 85% sensitivity
  if supine, often don't see air in the same place as you would elsewhere.
  Lateral or decubitus - 18% more PTX, more helpful than an expiratory phase CXR if PTX suspected.
  Look for - the deep sulcus sign: when the costophrenic angle is deepened by pleural air, the appearance is referred to as a deep sulcus sign.
Americans measure apex-to-copula distance and judges any distance greater than 3 cm to represent a large pneumothorax. 2010 BTS guidelines clarified that the measurement should be performed at the level of the hilum.



  After removal of a chest drain, you may see the track on x-ray.

CT - considered gold standard
USS- operator dependent



Treatment
Oxygen - a pneumothorax resolves four times faster if the patient is on high flow oxygen.  Without oxygen, they resolve at 2% of the hemi-thorax volume per day. A 1cm pneumothorax (~25% pneumothorax) would be expected to fully resolve in approximately 12 days. A 2cm pneumothorax (~30-50% pneumothorax) may take 3-4 weeks to fully resolve.


Aspiration - Initial success rate of 60-70%. Successful aspiration is associated with a much higher likelihood of discharge than chest drain insertion with fewer complications. After aspiration, need observation.  The BTS guidelines recommend use of a cannula no greater than 16G in diameter for aspiration though evidence that larger cannulae are more likely to cause a persistent pleural leak is limited.

Chest drain for bilateral pneumothoraces or tension pneumothorax, or after a failed needle aspiration.

Suction is not advised, as it often causes re-expansion pulmonary oedema (cough, SOB or chest tightness after insertion of a drain). There is a theory that suction keeps the deficit in the pleura open. Oedema occurs in up to 14% of cases.

Referral
You should refer to a thoracic surgeon if a patient:
Has a second ipsilateral pneumothorax
Has a first contralateral pneumothorax
Has a synchronous bilateral spontaneous pneumothorax
Has a persistent air leak despite five to seven days of chest tube drainage
Has no underlying lung disease and has a persistent air leak despite 5 - 7 days of chest tube drainage
Patients with underlying lung disease, or those with a large air leak, should be referred earlier, after two to four days
Has a failure of lung re-expansion
Has a spontaneous haemothorax
Is in a high risk profession, such as pilots and divers
Is pregnant.

Advice
If the breathlessness recurs, they should return to the ED immediately
They should avoid air travel for at-least a week after the pneumothorax has resolved radiologically. If the pneumothorax was traumatic in origin, two weeks should elapse following confirmed resolution.
They should permanently avoid all types of diving, including scuba.


References
http://learning.bmj.com/learning/module-intro/spontaneous-pneumothorax.html?moduleId=10043183&searchTerm=%E2%80%9Cpneumothorax%E2%80%9D&page=1&locale=en_GB
http://www.enlightenme.org/the-curriculum-zone/medicine/respiratory/spontaneous-pneumothorax/context-and-definition
http://www.enlightenme.org/knowledge-bank/cempaedia/spontaneous-pneumothorax
http://www.enlightenme.org/learning-zone/pneumothorax
http://www.enlightenme.org/the-curriculum-zone/node/12244
http://www.enlightenme.org/the-curriculum-zone/medicine/respiratory/spontaneous-pneumothorax/certificate-0
http://www.enlightenme.org/learning-zone/pop-goes-lung
http://www.enlightenme.org/the-curriculum-zone/node/2157
http://learning.bmj.com/learning/module-intro/.html?moduleId=10048797&searchTerm=%E2%80%9Cpneumothorax%E2%80%9D&page=1&locale=en_GB
http://learning.bmj.com/learning/module-intro/pneumothorax-interpreting-radiology.html?moduleId=10012767&searchTerm=%E2%80%9Cpneumothorax%E2%80%9D&page=1&locale=en_GB
http://learning.bmj.com/learning/module-intro/tension-pneumothorax.html?moduleId=10033841&searchTerm=%E2%80%9Cpneumothorax%E2%80%9D&page=1&locale=en_GB - not in my subscription
http://learning.bmj.com/learning/module-intro/intercostal-drain-open-technique.html?moduleId=10033847&searchTerm=%E2%80%9Cpneumothorax%E2%80%9D&page=1&locale=en_GB - not in my subscription
http://learning.bmj.com/learning/module-intro/chest-x-rays-guide-interpretation-part-2.html?moduleId=10008275&searchTerm=%E2%80%9Cpneumothorax%E2%80%9D&page=1&locale=en_GB
http://lifeinthefastlane.com/ebm-spontaneous-pneumothorax/
http://lifeinthefastlane.com/ccc/pneumothorax-spontaneous/

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