Obviously this is hard to say for certain without being able to actually eyeball the patient and without a complete history and physical, but when I read the case description, my first impression was "dying as a result of the natural course of their disease." In a case like this you MUST be proactive and gain a solid understanding of what the goals of care are for the patient -- talk to the family, figure out how aggressively the patient wants to be treated if he can't tell you himself. I agree totally with the assessment strategies mentioned (ekg, capno, etc.) and if the patient wants to be aggressively resuscitated, everything said here regarding treatment is right on the money. However, there's a good chance a patient like this will have some sort of advance directive (DNR/DNI, etc.) If they do, this DOES NOT mean do not treat. A doc I worked with used to say that palliative care is intensive care. You still need to do everything in your power to make the patient comfortable...in this particular case, you need to treat the patient's "air hunger." That may be as simple as supplemental O2, a warm blanket, and an easy ride, or it may mean nebs, lasix, or CPAP if they'll allow it. If you're going to be with the patient for a while (long txp), small doses of morphine or are useful (but good luck getting that order from medical control.) The patient may (probably) still be dying, but if you can make the process more comfortable and less stressful, you've done right by him.