Deejay, you're confusing open pneumothorax with tesion pneumothorax. But what you said about each is correct. well, some of this is probably beyond step 1 and possibly 2, but if you guys are interested:
Non-minor pneumothoraces and all hemothoraces are ultimately treated by chest tube insertion.
pneumothorax this is just air in the pleural space regardless of the cuase. It comes in 2 flavors regardless of the cause: simple and tension. Tension is immediately life-threatening, simple is not. Tension is defined by mediastinal shift. All pneumothoraces have decreased breath sounds and hyperresonance because you're percussing directly over air. The difference between the two is clinical. Mediastinal shift occurs when air goes in and can't come out by a simple valve mechanism, such as the lung-side pleura being lacerated to form a flap-valve. Clinically, this shift is evidence first by hypotension and increased JVP and lastly by tracheal shift. If you see this, you put a needle in to allow air release and relieve the tension
hemothorax this is just blood in the pleural space. It comes in 2 flavors: simple and massive. There is no tension form of this. Massive hemothorax is defined by volume of immediate blood return (>1500mL) on chest tube (or by volume of return over the course of an hour or so (forget this alternate definition). Massive is life-threatening, simple is not. Both get chest tubes, but one requires immediate surgical treatment.
sucking chest wound/open pneumothorax this is a different entity, and occurs when there is a hole in the chest wall from some form of trauma. this hole is larger than 2/3 of the diameter of the trachea. Remember that air flows through the path of least resistance. If there is less resistance here than the trachea, when the diaphragm descends causing negative chest pressure, air flows into the pleural space here, instead of to the lungs through the trachea. This is treated by placing a piece of petroleum gauze on the wound, taping it down on 3 sides. This creates a flap-valve on the outside that lets air out of the pleural space, but won't let air in. Think of this as creating the opposite of a tension pneumothorax.
EDIT: Everything done here is done in the ED either by the surgeons or the EP's. What would not be done in the ED is definitive repair down the line and surgical repair of a massive hemothorax.