Senior Airman Kara Nicholas, a medic with the 161st Air Refueling Wing, Arizona National Guard, and 2nd Lt. Tomas Chavez, a flight surgeon candidate with the same, check the vital signs of an incoming patient during Exercise Vigilant Guard, March 25, in Camp Santiago, Puerto Rico. Vigilant Guard is an exercise that tests disaster readiness, and the 161st's response with the Expeditionary Medical Support system, a full-service deployable field hospital.