Ralph passed the next test....they removed the fluid from his lung Friday morning (and re-inflated his lung - ouch!) and determined he did not have a blood clot that causing his problem.  Now he is breathing easier, except for the soreness from the procedure.  He has an appointment next week to see the results from the tests on the fluid they removed.  I guess it is good that they can't find anything - maybe that makes it just an anomaly that won't happen again???