The presence of cerebral edema may necessitate intravenous isotonic or hypertonic saline administration. Solutions used for intravenous rehydration must be isotonic or hypertonic. There are three types of Osmosis solutions&colon; the isotonic solution, hypotonic solution, and hypertonic solution. Aerosolized medications that help loosen secretions include dornase alfa and hypertonic saline. Inhaled hypertonic saline and salbutamol may also be useful. It is unclear whether mannitol or hypertonic saline is superior, or if they improve outcomes. Hyponatremia can be corrected by intake of hypertonic fluids. A hypertonic solution has a greater concentration of solutes than another solution. Involuntary sustained contraction of a hypertonic type, however, is a pathologic process. A true hypertonic spasm is caused by malfunctioning feedback nerves. These eggs are swelled with perivitelline fluid (PVF), a hypertonic fluid that prevents premature hatching. Plasmolysis is mainly known as shrinking of cell membrane in hypertonic solution and great pressure. In hypertonic solutions, water flows out of the cell which decreases the cell's volume. Plasmolysis is the process in which cells lose water in a hypertonic solution. However, Phillips' efforts failed because the solution he used was excessively hypertonic.