You arrive to find an infant (lets say 6 months old) that is cyanotic, sats in the 70s, all other vital signs normal for age (a little bit tachy). The mom says the patient was diagnosed with plastic left heart and was discharged from the children's hospital after having the first stage / procedure, "A Norwood" performed a few weeks ago.
You check out the home health folder and find that the patient has "Hypoplastic Left Heart Syndrome"
This is the cause of the cyanosis, there is no trick here, or some other hidden condition that should require you to play Dr. House. I have given you the diagnosis, so now the question is how many of us know what this is, and the proper way to treat it in the field.
So start googling, and tell me why the child is blue, and what kinds of treatment you would offer in the field. P.S. The children's hospital is 50 miles away, there are closer adult facilities, and you can not fly the patient due to weather.
This is not as uncommon as you may think, especially if you have a Pediatric Hospital (with cardiac capabilities) nearby that draws people in from great distances.