Ventilation-perfusion (V/Q) scan is a specialized test that uses a radioactive substance to show the parts of the lungs that are getting oxygen (ventilation scan) and getting blood flow (perfusion scan) to see if there are portions of the lungs with differences between ventilation and perfusion.
Moleskin may be the first commercial blister treatment and prevention product I remember using. My dad always kept some moleskin in his pack and at the first complaint of any hot or sore feet, out it would come.
Wear stockings with your shoes if you can to help prevent the friction that causes painful blisters on your feet. Also, minimize walking in uncomfortable shoes. Take your shoes off if you can do so discreetly, and be prepared to slip back into them quickly when it is time to stand up again.