A fistula (plural: fistulas or fistulae ; from Latin fistula, "tube, pipe") in anatomy is an abnormal connection between two hollow spaces (technically, two epithelialized surfaces), such as blood vessels, intestines, or other hollow organs. Types of fistula can be described by their location. Anal fistulas connect between the anal canal and the perianal skin. Anovaginal or rectovaginal fistulas occur when a hole develops between the anus or rectum and the vagina. Colovaginal fistulas occur between the colon and the vagina. Urinary tract fistulas are abnormal openings within the urinary tract or an abnormal connection between the urinary tract and another organ such as between the bladder and the uterus in a vesicouterine fistula, between the bladder and the vagina in a vesicovaginal fistula, and between the urethra and the vagina in urethrovaginal fistula. When occurring between two parts of the intestine, it is known as an enteroenteral fistula, between the small intestine and the skin as an enterocutaneous fistula, and between the colon and the skin as a colocutaneous fistula.Fistulas can result from an infection or inflammation, injury or surgery. Fistulas are sometimes surgically created as part of a treatment, for example arteriovenous fistulas for hemodialysis.Treatment for fistula varies depending on the cause and extent of the fistula, but often involves surgical intervention combined with antibiotic therapy. In some cases the fistula is temporarily covered using a fibrin glue or plug. Catheters may be required to drain a fistula.Globally, every year between 50,000 and 100,000 women are affected by fistula relating to childbirth.
This altitude is known as Armstrongs Line. In practice bodily fluids do not boil off at this altitude. This is because the skin and outer organs have enough strength to withstand this pressure, thus pressure inside the body would be significantly higher—however, nitrogen bubbles are starting to form, creating a hazard. Prevention
To prevent ebullism, a pure oxygen (O2) atmosphere was used in early space flights to eliminate nitrogen in the blood. There are major fire hazards associated with using pure O2 as a breathing gas, which was central to the death of three astronauts in a fire during a ground test with Apollo 1. Nonetheless, NASA continued to use a nominally pure oxygen atmosphere throughout the Apollo Program but switched to air for the follow-on Space Transport System "Space Shuttle". Russian cosmonauts used pure oxygen before changing to a higher-pressure nitrox mixture, leading to incompatibility problems in 1975 on the Apollo-Soyuz Test Project. Space suits are often pressurized to several psi lower than stations capsules or shuttles and since they still use pure O2, an acclimation period is common in the airlock to remove nitrogen and other gases from the bloodstream. Etymology
The term "space ebullism" was introduced by Captain Julian E. Ward in his paper "The True Nature of the Boiling of Body Fluids in Space", published in Aviation Medicine in October 1956. It was suggested "because the word ebullism does not connote the addition of heat to produce vapor." It comes from Latin ebullire, meaning "to bubble out, or to boil up."