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.
Oral surgeons and dentists typically use nitrous oxide / oxygen as minimal sedation, although it may also be considered moderate sedation. [14, 18] Nitrous Oxide (Laughing Gas) / Oxygen Sedation. Nitrous oxide is commonly known as laughing gas and one is awake and aware of what is going on around them.