Some more here from a modern scientific point of veiw, Just to prevent anyone trying this as an actual cure for something and ending up dead or braindamaged.
In short for those who dont care to read. Bloodletting is an old outdated practice based on bad science. It has a highly limited value and is avoided whenever possible by modern medicine.
Bloodletting (or blood-letting) is the withdrawal of often considerable quantities of blood from a patient to cure or prevent illness and disease. It was the most common medical practice performed by doctors from antiquity up to the late 19th century, a time span of almost 2,000 years.[1] The practice has been abandoned for all except a few very specific conditions.[2] It is conceivable that historically, in the absence of other treatments for hypertension, bloodletting could sometimes have had a beneficial effect in temporarily reducing blood pressure by a reduction in blood volume.[3] However, since hypertension is very often asymptomatic and thus undiagnosable without modern methods, this effect was unintentional. In the overwhelming majority of cases, the historical use of bloodletting was harmful to patients.[4]
Bloodletting is one of the oldest medical practices, having been practiced among ancient peoples including the Mesopotamians, the Egyptians, the Greeks, the Mayans, and the Aztecs.[3] In Greece, bloodletting was in use around the time of Hippocrates, who mentions bloodletting but in general relied on dietary techniques.[8] Erasistratus, however, theorized that many diseases were caused by plethoras, or overabundances, in the blood and advised that these plethoras be treated, initially, by exercise, sweating, reduced food intake, and vomiting.[9] Herophilus advocated bloodletting. Archagathus, one of the first Greek physicians to practice in Rome, also believed in the value of bloodletting.[10]
"Bleeding" a patient to health was modeled on the process of menstruation. Hippocrates believed that menstruation functioned to "purge women of bad humors". Galen of Rome, a student of Hippocrates, began physician-initiated bloodletting.[11]
The popularity of bloodletting in Greece was reinforced by the ideas of Galen, after he discovered that veins and arteries were filled with blood, not air as was commonly believed at the time. There were two key concepts in his system of bloodletting. The first was that blood was created and then used up; it did not circulate, and so it could "stagnate" in the extremities. The second was that humoral balance was the basis of illness or health, the four humours being blood, phlegm, black bile, and yellow bile, relating to the four Greek classical elements of air, water, earth and fire. Galen believed that blood was the dominant humour and the one in most need of control. In order to balance the humours, a physician would either remove "excess" blood (plethora) from the patient or give them an emetic to induce vomiting, or a diuretic to induce urination.
Galen created a complex system of how much blood should be removed based on the patient's age, constitution, the season, the weather and the place. Symptoms of plethora were believed to include fever, apoplexy, and headache. The blood to be let was of a specific nature determined by the disease: either arterial or venous, and distant or close to the area of the body affected. He linked different blood vessels with different organs, according to their supposed drainage. For example, the vein in the right hand would be let for liver problems and the vein in the left hand for problems with the spleen. The more severe the disease, the more blood would be let. Fevers required copious amounts of bloodletting.
The Talmud recommended a specific day of the week and days of the month for bloodletting, and similar rules, though less codified, can be found among Christian writings advising which saints' days were favourable for bloodletting. Islamic medical authors too advised bloodletting, particularly for fevers. The practice was probably passed to them by the Greeks; when Islamic theories became known in the Latin-speaking countries of Europe, bloodletting became more widespread. Together with cautery, it was central to Arabic surgery; the key texts Kitab al-Qanun and especially Al-Tasrif li-man 'ajaza 'an al-ta'lif both recommended it. It was also known in Ayurvedic medicine, described in the Susruta Samhita.
The benefits of bloodletting only began to be seriously questioned in the second half of the 1800s. While many physicians in England at the time had lost faith in the general value of bloodletting, some still considered it beneficial in some circumstances, for instance to "clear out" infected or weakened blood or its ability to "cause hæmorrhages to cease"—as evidenced in a call for a "fair trial for blood-letting as a remedy" in 1871.[12] Bloodletting persisted into the 20th century and was even recommended by Sir William Osler in the 1923 edition of his textbook The Principles and Practice of Medicine.[13]
A number of different methods were employed. The most common was phlebotomy, or venesection (often called "breathing a vein"), in which blood was drawn from one or more of the larger external veins, such as those in the forearm or neck. In arteriotomy, an artery was punctured, although generally only in the temples. In scarification (not to be confused with scarification, a method of body modification), the "superficial" vessels were attacked, often using a syringe, a spring-loaded lancet, or a glass cup that contained heated air, producing a vacuum within (see fire cupping). There was also a specific bloodletting tool called a scarificator, used primarily in 19th century medicine. It has a spring-loaded mechanism with gears that snaps the blades out through slits in the front cover and back in, in a circular motion. The case is cast brass, and the mechanism and blades steel. One knife bar gear has slipped teeth, turning the blades in a different direction than those on the other bars. The last photo and the diagram show the depth adjustment bar at the back and sides.
Leeches could also be used. The withdrawal of so much blood as to induce syncope (fainting) was considered beneficial, and many sessions would only end when the patient began to swoon.
William Harvey disproved the basis of the practice in 1628, and the introduction of scientific medicine, la méthode numérique, allowed Pierre Charles Alexandre Louis to demonstrate that phlebotomy was entirely ineffective in the treatment of pneumonia and various fevers in the 1830s. Nevertheless, in 1840, a lecturer at the Royal College of Physicians would still state that "blood-letting is a remedy which, when judiciously employed, it is hardly possible to estimate too highly", and Louis was dogged by the sanguinary Broussais, who could recommend leeches fifty at a time.
Bloodletting was used to treat almost every disease. One British medical text recommended bloodletting for acne, asthma, cancer, cholera, coma, convulsions, diabetes, epilepsy, gangrene, gout, herpes, indigestion, insanity, jaundice, leprosy, ophthalmia, plague, pneumonia, scurvy, smallpox, stroke, tetanus, tuberculosis, and for some one hundred other diseases. Bloodletting was even used to treat most forms of hemorrhaging such as nosebleed, excessive menstruation, or hemorrhoidal bleeding. Before surgery or at the onset of childbirth, blood was removed to prevent inflammation. Before amputation, it was customary to remove a quantity of blood equal to the amount believed to circulate in the limb that was to be removed.[14]
Leeches became especially popular in the early nineteenth century. In the 1830s, the French imported about forty million leeches a year for medical purposes, and in the next decade, England imported six million leeches a year from France alone. Through the early decades of the century, hundreds of millions of leeches were used by physicians throughout Europe.[15]
In the absence of other treatments, bloodletting actually is beneficial in some circumstances, including hemochromatosis, the fluid overload of heart failure, and possibly simply to reduce blood pressure. In other cases, such as those involving agitation, the reduction in blood pressure might appear beneficial due to the sedative effect. In 1844, Joseph Pancoast listed the advantages of bloodletting in "A Treatise on Operative Surgery". Not all of these reasons are outrageous nowadays:
