Edema has many possible causes: 1  Prolonged standing or sitting, especially in hot weather, can cause excess fluid to accumulate in the feet, ankles and lower legs. 2  Tiny valves inside the veins of the legs can become weakened, causing a common problem called venous insufficiency.
Cars with nitrous-equipped engines can be identified by the purge of the delivery system that most drivers perform prior to reaching the starting line. A separate electrically operated valve is used to release air and gaseous nitrous oxide trapped in the delivery system.
Inhaled minimal sedation. You breathe nitrous oxide -- otherwise known as laughing gas -- combined with oxygen through a mask that's placed over your nose. The gas helps you relax. Your dentist can control the amount of sedation you receive, and the gas tends to wear off quickly.