understanding pneumothorax

[zacarias, ASN, RN]

Hello all,

I'm having trouble understanding specific points of pathophysiology regarding pneumothoraces. I understand why tension pneumos are so deadly, but I have a couple questions.

When you have an open wound due to a gun shot or knife wound, is it the air leaking out of traumatized alveoli causing the pneumothorax, or is air directly going into the wound and thus pleural space from the outside?

Also, a spontanenous pneumothorax, the kind that young tall thin men get, why can't that be a tension also? The chest wall is intact so I assume that every time one breathes, the air could continue to build up in the pleural space...? Maybe it flows in and out.

Z

[OCRN3]

A puncture to the thoracic cavity changes the negative pressure inside the lung making it collapse.

[OCRN3]

Spontaneous pneumothorax without a known cause is usually related to high risk factors.

I think the thinness of the male with less fat make the thoracic cavity more exposed then your average person IMO.

[Rose_Queen, BSN, MSN, RN]

You may find this helpful:

Thoracic System Pathology

An open, traumatic wound leading to pneumothorax: the air can come from either an injured lung, the outside, or both. Think about how respiration occurs- the diaphragm retracts, causing negative pressure. In order to balance the pressure, the lungs would normally fill with air. However, in someone with a "sucking chest wound", that negative pressure can cause air from the outside to enter the thoracic cavity or a large amount of air to leak out of the lung.

A tension pneumo occurs when the air inside the chest cavity accumulates faster than it is removed, thus leading to lung collapse, shifting of the mediastinum towards the unaffected side, and impaired bloodflow. Theoretically, any pneumo could become a tension pneumo. Probably (and this is just my conjecture) a spontaneous pneumo is rarely going to become a tension pneumo because the injury to the lung is generally small. Of the ruptured (and non ruptured) blebs I've watched surgeons remove, many are smaller than a marble, although they may be multiple and "clustered". It's more likely that a severe injury with a sucking chest wound would accumulate air in the pleural space faster than it can be removed and cause more severe problems.

We frequently see patients for pleurodesis following spontaneous pneumo. They have all been younger than 30, male, very tall, and skinny. When a patient has a spontaneous pneumo, recurrence rate is pretty high. These patients not only get a chest tube to evacuate the pneumo, but at some point will come to the OR where the surgeon uses either a talc spray or mechanical methods that will lead to the lung adhering to the chest wall in hopes of not having it happen again.

[AnnieOaklyRN, BSN, RN, EMT-P]

You can get a tension from a spontaneous pneumo, but those tend to be almost immediately symptomatic and the "hole" is small, so it would take a longer time to develop a tension. These folks are generally awake and alert and would have symptoms long before a tension develops!

A pneumothorax caused by a traumatic injury is caused by both air entering the wound and, if the lung is injured, air exiting the lung. Its a two fold problem.

Hope this helps!

HPRN