Confused. Question (may contain spoilers).

I'm a little confused and would like clarification from those knowledgable in this area but .... I don't understand why the Ray Oakum (sexy Scott Heindl) is unable to speak in the hospital when he was shot in the chest area near the heart. He was not lying horizontal, did not have an oxygen mask on or oxygen tube in his nose, was not shot in the throat, mouth, lungs or even diaphragm. Thanks for anyone that might be able to explain.