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.
1 After the procedure, deliver 100 percent oxygen to the patient for 5 minutes before removing the mask. 2  This will purge the system, and the patient, of any residual nitrous oxide. 3  Periodically, personnelâparticularly those who work with the nitrous oxide deliveryâcan be assessed for exposure.