from
http://en.wikipedia.org/wiki/Penis_pump#Penis_pump
This is a cylinder that is fitted over the penis, with a manual or motorised pump to create suction. As the apparatus creates a vacuum around the penis, blood is drawn into the penis causing it to become engorged. The higher the vacuum, the higher the blood-pressure becomes within the penis; excessive pressure causes vascular damage rather than a harder penis. Penis pumps have two very different uses:
They can act as valuable sexual aids for men who suffer from impotence, as they can be used to achieve an erection, which can be maintained for up to 30 minutes by the use of a compression ring on the base of the penis. These pumps, which are reputable medical devices, are usually described as vacuum pumps rather than penis pumps. Some people claim to have experience that frequent use of this sort of pump may to some extent reverse impotence due to vascular damage[1].
A "Penis Pump" can also be used to temporarily increase the size of the penis to the maximum size of which it is capable by increasing the amount of blood and other fluids that are in the corpus cavernosa and surrounding tissue. These temporary gains are well proven and abundantly documented on various "hobbyist" websites[citation needed]. However, their efficacy at increasing absolute penis size is very hard to determine. Some practitioners believe the overload principle which stipulates that as a part of the body is pushed past its limits the natural healing process will accommodate for the extra stress when making repairs; for example, muscles get bigger and in this case tissues lengthen and swell. Over time it is believed that regimen of pumping and or other methods will cause gains, however minor, to be realized[citation needed].
Pumping with either type of pump must be done carefully to avoid injury: manufacturers' instructions should be followed. Manual pumps often recommend a gentle pump followed by a pause, then repeated. Over-enthusiastic pumping can burst blood vessels and form blisters. In some cases the testicles can be unexpectedly pulled into the cylinder and cause severe pain and injury. It is also believed that the rim of the cylinder can cut into the skin and over time cause damage to the ligaments surrounding the penis. These dangers are easily avoided by following instructions. Impatiently pumping away without reading any explanatory material can produce too much suction (anything over anything 10 mm Hg) and cause permamnent injury.
Attempts at using vacuum cleaners units for this purpose have resulted in severe injury as the machine produces far too much suction. If the base unit is used without a hose there is also the danger of coming into contact with the rapidly-rotating fan. Articles in medical jourmals describe such cases.
Penis pumps gained some popular culture notoriety in the Austin Powers films.
