All liquids and solids have a tendency to evaporate into a gaseous form, and all gases have a tendency to condense back to their liquid or solid form. The atmospheric pressure boiling point of a liquid (also known as the normal boiling point) is the temperature at which the vapor pressure equals the ambient atmospheric pressure. With any incremental increase in that temperature, the vapor pressure becomes sufficient to overcome atmospheric pressure and lift the liquid to form vapour bubbles inside the bulk of the substance. Bubble formation deeper in the liquid requires a higher pressure, and therefore higher temperature, because the fluid pressure increases above the atmospheric pressure as the depth increases. The vapor pressure that a single component in a mixture contributes to the total pressure in the system is called partial vapor pressure. Liquid pressure
When a person swims under the water, water pressure is felt acting on the persons eardrums. The deeper that person swims, the greater the pressure. The pressure felt is due to the weight of the water above the person. As someone swims deeper, there is more water above the person and therefore greater pressure. The pressure a liquid exerts depends on its depth. Liquid pressure also depends on the density of the liquid. If someone was submerged in a liquid more dense than water, the pressure would be correspondingly greater. Thus, we can say that the depth, density and liquid pressure are directly proportionate.
Purple glove syndrome (PGS) is a poorly understood skin disease in which the extremities become swollen, discoloured and painful. PGS is potentially serious, and may require amputation. PGS is most common among elderly patients and those receiving multiple large intravenous doses of the epilepsy drug phenytoin. Compartment syndrome is a complication of PGS. Cause
Purple glove syndrome is caused by the intravenous anticonvulsant phenytoin. This medication has many already established neurological side effects, however glove syndrome is a rare, but very serious adverse effect that may lead to limb amputations. This may occur due to the administration of phenytoin with or without extravasation. The defining characteristic is a purplish to black discoloration of the extremity followed by peripheral edema and pain distal to the site of infusion. Onset is generally seen within the first few hours of administration. The true pathology of purple glove syndrome is not fully elucidated, however it is believed to be due to the crystallization of phenytoin within the blood and extravasates into the surrounding interstitium. Another mechanism may be due to the disruption of endothelial transcellular junctions followed by leaking of phenytoin into the surround soft tissues. Diagnosis
Treatment
Doctors recommend discontinuing the use of phenytoin. The application of heat can help to relieve pain. Oral phenytoin can also result in development of purple glove syndrome. References
External links
FDA: Potential Signals of Serious Risks/New Safety Information Identified by the Adverse Event Reporting System (AERS) -- January - March 2008