The Pneumothorax in JFK's Right Lung

[Bob Prudhomme]

Bob: Do you know how much time it takes for the deviation of the trachea to occur after the injury that causes the pneumothorax? Is it a matter of one breath or two, or does it take a more substantial period of time?

Hi Drew

Long time no see!

It all depends on the breathing rate of the patient. If the patient is conscious and aware of his condition, he will be breathing rapidly and aggressively trying to consume oxygen. As the pleural cavity is the same basic size as the lung filling it, in less than a minute it is possible to draw and trap enough air through a tear in a lung to completely fill the pleural cavity and begin exerting pressure on the other side of the chest. If a patient is unconscious and breathing shallowly, it may take a few minutes more. Much also depends on the size of the compromise in the lung itself, and how much obstruction damaged lung tissue may provide to incoming air.

It is important to remember that the deviation of the trachea is entirely due to the build up of air pressure that is trapped in the affected lung, and this deviation can be used to gauge just how bad the condition of the patient is. A severely deviated trachea indicates the heart is being squeezed, the veins (superior and inferior vena cava) are being squeezed as well and the unaffected lung is being flattened inside its pleural cavity, pulling the bronchus and trachea over with it and giving us the deviated trachea. This patient will die within a couple of minutes due to impaired function of heart, lung and circulatory system.

However, if a patient requires assistance with breathing, things change dramatically, as positive pressure breathing, through a mechanical bag valve mask for example, is now forcing air into the pleural cavity under pressure (greater than inspiration by the diaphragm), and allows that pressure to stay there.

It would be likely that JFK's pneumothorax began as an "open" pneumothorax (sucking chest wound) and stayed as such all the time he was in the limo, simply because there was nothing to seal this wound. But, when he was laid on the table, just by fluke, the back entrance wound would have been in contact with the table, and the weight of his body would have effected a seal; thus beginning the tension pneumothorax.

As assisted ventilation was begun immediately on JFK, although only partly successful due to the tear in his trachea, it is more than possible that a certain volume of the oxygen being applied actually made it past the tear in the trachea and into the chest cavity. Under pressure, it would not have taken that many ventilations to inflate the right pleural cavity, although it should be noted the trachea was observed as being only "slightly deviated", indicating the tension pneumothorax was not as advanced as it could have been.