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.
1 Exfoliate the feet, especially the heels, while washing. Use a wash cloth, pumice stone, or loofah and rub the skin gently to slough off dead skin.  Dry the feet thoroughly. Dry well between the toes since fungus and bacteria like to grow in warm, moist, dark places.