 |
THERMOMETER In Italy, in 1610, Galileo constructed an instrument consisting of a glass bulb with a long tube, which extended downwards into a container of coloured water. Some of the air in the bulb was expelled(1). The first clinical thermometer was constructed by Santonio Santonio, professor at the University of Padua, Italy, in 1626. This water thermometer included a scale to measure temperature(2). In 1641, Ferdinand II, the Grand Duke of Tuscany, had the first sealed thermometer constructed. This thermometer contained alcohol, with 50 marks on its stem - but no fixed point. It became known as the "spirit thermometer". Over twenty years later, Robert Boyle,in 1664, used red dye in his alcohol thermometer which included a scale from one fixed point - the freezing point of water. Boyle`s thermometer was used by the Royal Society in London until 1709. A thermometer with two fixed points - that of snow and boiling water - was developed by Ole Roemer in Sweden, who used it to measure the temperature in Copenhagen(3). Daniel G Fahrenheit, in 1724, invented the mercury thermometer. Sealing a column of mercury within glass, he found a more constant rate of expansion and wider range of temperatures compared to the alcohol thermometers. Fahrenheit produced his own scale - taking the temperature of an ice/salt mix as zero degrees, boiling point of water as 212 degrees, and his own body temperature as 96 degrees(4). Fahrenheit recorded how he established his findings and as to its clinical application "placing the thermometer in a mixture of sal ammoniac or sea salt, ice, and water, a point on the scale will be found which is denoted as zero. A second point is obtained if the same mixture is used without salt. Denote this as 30. A third point, designated as 96, is obtained if the thermometer is placed in the mouth so as to acquire the heat of a healthy man"(5). Since the 18th century, over 30 different scales to measure temperature had been used. In 1730, Rene-Antoine de Reamur set the sacel for the freezingpoint of water at zero, and 80 degrees as the boiling point for water under normal atmospheric pressure. After the death of Fahrenheit in 1736, his scale was recalibrated and human body temperature was designated 98.6 rather than his of 96. In 1742, Andre Celsus produced his own scale - with 0 degrees as thefreezing point of water and 100 degrees as the boing point. This became the metric system for measuring temperature. In 1848, Lord William Thomson Kelvin found absolute zero - which he designated as -273.15 degrees Celsus(6). refs 1. Lynds,BT. "About Temperatures". Unidate of University Corporation for Atmospheric Research. website: www.unidata.ucar.edu/ 2. d`Estrang,V-A G. The Book of Inventions & Discoveries. Queen Anne Macdonald.1992. 3. Lynds,BT. "About Temperatures". Unidate of University Corporation for Atmospheric Research. website: www.unidata.ucar.edu/ 4. website: http://inventors.about.com 5. Fahrenheit,DG. Philosophical Transactions. 33. 78.1724. 6. website: http://inventors.about.com |
|
MEASUREMENT of BLOOD PRESSURE In 1733, Rev Stephen Hales used a 9ft long tube attached to the flexible windpipe of a goose to measure blood pressure in the fermoral and carotid arteries in horses(1). He estimated the cardiac output of a horse at rest was 6 litres of blood per minute. In 8 other experiments on sheep, deer and dogs, Hales reported that blood from the carotid artery rose to a height of 8ft in a measuring tube, but blood from the jugular vein rose less than 1ft. From these experiments, Hales believed that once the blood leaves the heart, arterial pressure becomes less as it travels along smaller peripheral arteries towards the veins. Hales was wrong - and his incorrect theory persisted for almost a century(2). Jean Leonard Marie Poiseuille proposed, in 1828, using a tube partly filled with mercury connected to a cannula, which, in turn, was directly inserted into the artery of an animal - measuring the blood pressure in a non-invasive way(3). Poiseulle`s haemodynamometer was merely an adaption of Hales` equipment of 1733 - except the long tube (used by Hales) was substituted with a shorter tube of a mercury manometer(4). The revised equipment was without any clinical use(5). In 1855. Karl Vierordt claimed that to measure the blood pressure of indirect and non-invasive form, it was necessary for the pulse to cease. His principle was to determine systole pressure (period during which the heart contracts) propagation of pulse waves by the restriction of the radial artery. Vierdordt`s initial experiments failed. Although he built a syphogmograph (the first instrument for tracing the pulse wave), it required a tube placed into the artery and was considered unsuitable for clinical use(6). J Falvre made the first accurate measurement of blood pressure in a human in 1856. During a surgical procedure, he catheterized a patient`s femoral artery, bound it to a manometer and detected the pressure in the femoral artery and the brachial artery(7). In 1860 Etienne Marey invented a devise based on Poisseuille`s mercury manometer and Vierdort`s principle(7). With Auguste Chauveau, Marey inserted a catheter through the jugular vein into the right ventricle, and from the carotid artery into the left ventricle of a fully conscious horse. They recorded systole pressure readings of 27mmHg in the right ventricle and 129mmHg in the left(8) but he was unsuitable for humans(9). Frederick Akbar Mahomed studied medicine at Guy`s Hospital in London and became interested in Marey`s sphymograph. Mahomed modified the sphymograph and used it clinically in 1860 to measure pressure in patients with scarlet fever - thereby becoming the first person to discover that raised blood pressure was an early sign of inflammation of the kidneys(9). A Fick reported, in 1873, on the inaccuracy of Marey and Chauveau`s sphymograph, used in their experiments, and developed his own, which differed from that of Marey and Chauveau. Fick`s equipment was accurate and he was able to publish his findings on form and level of blood pressure variations from both sides of the heart(10). A medical history of cardiology has noted: "Fick, convinced of the soundness of his concept never bothered to subject it to experimental proof"(11)(ie he never subjected it to experiments on animals). During the 1870s, the "Invasive catheterization method" - proposed since Hales in 1733 - proved to be dangerous for human patients due to excessive blood loss and the risk of infection(12). In 1876, Samuel Sigfried Ritter von Basch produced the sphymanometer, to measure blood pressure(13), which consisted of a rubber ball full of water with an inner chamber of mercury - the ball compressed the radial artery, promoting a rise in the column of mercury(14). refs: 4. website: www.geocities.com/Paris/2862/organ.htm 5. Luiz,I. Brazilian Archives of Cardiologia. vol 67. 1906
6. website: www.geocities.com/Paris/2862/organ.htm 7. Luiz,I. Brazilian Archives of Cardiologia. vol 67. 1906 8. Chauveau,A. Marey,E. Gazetter Medicine de Paris. 1861. 9. Baldry,PE. The Battle Against Heart Disease. Cambridge Uni Press. 1971 10. Fisherman,AP. Richards,DW. Circulation of the Blood. Oxford Uni Press.1964. 12. Health Perfect. website: www.healthperfect.co.uk/Index/dphistry.htm 13. McMicken,W H. website: httl//: members. tripod.com/-FamilyDoc/ascvid3.htm 14. Luiz,I. Brazilian Archives of Cardiologia. vol 67. 1906 15. Kenner,T. Centennial of Non-Invasive Blood Pressure Measurement. 1996 16. Luiz,I. Brazilian Archives of Cardiologia. vol 67. 1906 18. "History of Blood Pressure Measurement". website: www.eu.omron. com 19. website: www.pmsinstruments.co.uk/methods_of_measuring_blood_press.htm 20. Health Perfect website: www.healthperfect.co.uk/Index/dphistry.htm 21. "History of Blood Pressure Measurement". website: www.eu.omron. com 22. website: www.pmsinstruments.co.uk/methods_of_measuring_blood_press.htm 23. Health Perfect website: www.healthperfect.co.uk/Index/dphistry.htm
|
|
HEART CATHERIZATION Johann Dieffenbach, a Prussian surgeon, is said to have used an elastic catheter on a patient(1) and in 1832 described opening the brachial artery and introduced the catheter "as far as the heart", but even before the procedure, the patient was close to death, he convulsed and died(2). Subsequently, it has been question whether Dieffenbach did actually reach the patient`s heart with his catheter(3). The idea of using cardiac catheterization in physiological experiments was suggested by Magandie to an assistant, Claude Bernard(4), who, in 1844, began a series of experiments on animals, including trying to measure the intracardiac pressures to determine the influence of the nervous system on blood pressure. Bernard inserted a glass tube into the right ventricle of a dog, which was then killed,and it was found that the glass tube had perforated the wall of the ventricle of the animal, but Barnard carried on his animal experiments for a number of years(5). Over 100 years earlier, Rev Stephen Hales, in 1733, had tried measuring the blood pressure of a mare by inserting tubes into the arteries(6) with no clinical application resulting from the experiments(7). It was not until 1855 that Prof Karl Vierordt, using hydrodynamic principles, invented an apparaturs by which the pulse could be obliterated and the arterial pulsation could be recorded(8). Others followed, including Fick, who in 1873, devised a method for "measurement of the amount ejected by the ventricle of the heart with each systole"(9), which he used clinicially but "never bothered to subject to experimental proof"(10). Despite Fick`s method, not based or tried on animal experiments, being clinically useful, an attempt was made to "improve" it. In 1886, Gerhant and Quinquand reported using their revised method to measure blood flow in experiments on six dogs(11). But, doubts were expressed over the accuracy of the equipment, which was thought to be due to the affect of friction(12). In 1887, Rolleston tried to minimise friction along the catheter`s tube and its connections(13), and in 1892, Porter believed that the problem of friction could be overcome by using a single or double lumen rigid catheter made of silver-plated brass(14). In 1893, Zunzt described how he had combined the blood flow measurement with direct recordings of blood pressure in the pulmonary artery and/or the aorta(15). Five years later, he and Hagermann published a paper on their observations and included an analysis of their work(16). It was not until 1913 that Otto Frank published the first of a series of papers outlining the theoretical and mathematical basis for accurate and reproducible recordings of intracardiac events(17). In 1929, Werner Forsmann, at the Ebersaide Clinic, germany, was developing a method of administering drugs into the heart, when he introduced a catheter through the vein of the arm of a human cadaver and guided the catheter up into the right atrium of the heart(18). With knowledge and capability gained from this, Forsmann used the technique on a patient wth peritonitis, but as there were no antibiotics to prevent infection, the patient died(19). The next steps in his work on catheters, Forsmann punctured the vein in the front of his own forearm, and then - as he had done in the cadaver - passed the catheter into the vein for a distance of 35cm, but had to stop at the insistance of his colleague. A week later, Forsmann decided to conduct another self-experiment. This time he passed the catheter through an opening in his forearm for the whole length of 65cm and proved the progress of the catheter by means of an x-ray picture on a screen(20). Forsmann, later, took this a stage further. He introduced a catheter into the vein of his thigh and pushed it up into his heart. He then injected a radio-opaque material through the catheter and tried to obtain contrast radiographs of his own heart, but although the technique was proved to work, the equipment could not produce the images(21). Although Forsmann had tried his technique out, and proved it could work, on a cadaver, a human patient, and on himself - including the use of radio-opaque material, he turned to experimenting on dogs. For two years, he used radio-opaque susbstances in his animal experiments with catheters, but due to toxicity , the results of the experiments on dogs were "disappointing"(22) - but in his self-experiments he had not experienced any ill effects from the radio-opaque material. When Forsmann`s paper,which included reference to his self-experimentation, appeared in 1929, it was met with a hostile reaction, and fears that the technique was dangerous, but opinions were to change when others tried the method clinically(23). A year after Forsmann`s paper appeared, Klein of Prague wrote of his own experiences with catheters. Out of 18 clinical attempts, he had placed a catheter in the right side of the heart in 11 cases. Using the Fick principle, he measured the cardiac output, and is credited with being the first to establish arterio-venous oxygen differential. Klein tried to convince clinicians in Boston, America, of the feasibility of catherization, but his visit was met with disinterest by the Boston medical authorities(24). In the same year as Klein, and independent of him, Jimenez Diaz and Sanchez Cuena described clinical use f a uretheral catheter by means of a cannula in the vein of the arm of a dying patient, and another paper which offered suggestions of the potential use of catheterization in diagnosis and in therapeutics(25). Andre Cournard, Dickinson Richards, and their colleagues of Columbia University Chest Service, Bellevue Hospital, New York, spent four years - from 1941 to 1945 - improving technical aspects of cardiac catheterization(26). During this time, Cournard reported that the team had been able to advance a catheter into the right ventricle. By 1944, they had succeeded in getting a catheter into the pulmonary artery(27). Richards was to reflect back on the early work "We had vacillated for eight years with nothing but a series of somewhat desultory trials in animals and an unsuccessful attempt in [a] [hu]man to show for it. In 1940, Cournard and Ranges finally carried the procedure through successfully [in a human]. The technique, clumsy at the start, has been perfected and with practice proved remarkably easy, safe and painless, no serious untowards effects having been encountered in over 250 catheterizations"(28). A clinical success after "desultory trials in animals". refs 1. Howard-Jones,N. Lancet. vol 2. 1949. 2. Dieffenbach,JF. Gustrow. 2nd ed. 1834. 3. Acierno,L. History of Cariology. Parthenon Pub Gp. 1994. 4. Bechat,X. L`Imprimente de L T Celot. 1822. 5. Acierno,L. History of Cardiology. Parthenon pub gp. 1994. 6. Clendening,L. annals of Internal Medicine. 1930. 7. Beddow-Bayley,M. Clinical Medical Discoveries. NAVS. 1961. 8. ibid. 9. Fick,A. 1870. in Fisherman,AP. Richards,DW. Circulation of the Blood. Oxford Uni Press. 1964. 10. Acierno,L. History of Cardiology. Parthenon Pub Gp. 1994. 11. Grehant,N. Quinquand,C. Compt Rend. 1886. 12. Acierno,L. History of Cardiology. Parthenon Pub gp. 1994. 13. Rolleston,H. J og Physiology. vol 8. 1887. 14. Porter,W. J of Physiology. vol 13. 1892. 15. Zunzt,N. Ebenda. vol IV. 1893. 16. Zunzt,N. Hagemann,O. Ebenda. 1893. 17. Frank,O. Z Biol. vol 44. 1903. 18. Bennat,AJ. Lancet. 30 Apr 1949. 19. Acierno,L. History of Cariology. Parthenon Pub Gp. 1994. 20. Forsmann,W. 1929. in Beaumont,GE. Dodds,E. Recent Advances in Medicine. 13th ed. J&A Churchill. 1952. 21. Bennat,AJ. lancet. 30 Apr 1949. 22. Forsmann,W. Munch med Wchschr. vol 78. 1930. 23. Acierno,L. History of Cardiology. Parthenon Pub Gp. 1994. 24. Klein,O. Munch med Wchschr. vol 77. 1930. 25. Diaz,H. Cuenca,S. Arch de Cardio. 1930. 26. Cournard,A. Acta Med Scand. vol 579. 1975. 27. Richards,DW Jnr. Harvey Lectures. vol 39. 1944. 28. ibid |
|
ELECTROCARDIOGRAM (ECG) The development of the electrocardiogram, for the recording of electrical activity of the heart, came from the discovery of electro-motive activity in living tissue, and the development of the galvometer(1). In about 340BC, Aristotle reported on the natural behaviour of torpedo fish which stunned their catch by a shock, which is now known to be electricity(1). No attempts were made to understand the nature of electric current until the 1700s(1). John Sultzer, in 1761, performed an experiment on himself, forming a "V" shape from two different metal strips and touching his tongue with them. The contact caused a tate in his mouth until the contact was broken, but re-appeared when the contact was re-established. Clinicians used electricity to stimulate the heart of human patients(2). Dr Squires, in 1774, successfully applied an electric shock to the chest of a human patient, and recommended the use of electricty for cardiac resuscitation(3). In 1780, Luigi Galvani was dissecting a freshly killed frog when he touched the nerve in the frog`s leg with a metal object, close to a static electricity machine. Galvani noticed that the frog`s leg twitched. This accidental discovery led to him studying the action in frogs for another ten years. During this time, in 1786, Galvani made another accidental discovery. He hung some frog`s legs by copper hooks from iron railings and when the frog`s legs touched the iron railings, the muscles twitched - even though there was no static electricity machine nearby. Galvani concluded that there was a potential difference between the frog`s legs and the iron railings and that the frog`s legs must contain electricity, and in an attempt to "prove" this, he used the nerve muscles of a freshly killed frog(4). Alessando Volta of Pavia University, at first, agreed with Galvani`s suggestion of inherent electricty in animals. But when Volta recalled Sulzer`s self-experiment, he changed his opinion, and reasoned that electricity was generated between two strips of different metals - which would also account for the action between the copper hooks and iron railings as seen by Galvani. Volta concluded that the experiments on frog`s legs had merely indicated that electricity was created by this contact(5). Galavani responded to Volta`s objections and set out to show that a muscle could be made to contract without using metals and that if a nerve was made to touch another tissue at one injured point and one uninjured point the muscle supplied by the nerve would contract. It has been claimed that by these experiments Galvani demonstrated, in 1794, the existance of electricity in living tissue - but it was not until 1820 that Oersted - working with the "voltaic pile" which Volta had constructed during his objections to Galvani`s ideas -discovered electromagnetism in 1820. Recordings and measurement of the electrical potential of living tissue was not achieved until 1843(6). The first galvanometers, capable of measuring action currents from living tissue, were used by Nobil in 1825, and by Schweigger in 1826. These galvanometers were of a moving coil type and were relatively insensitive(6). In 1842, Carlo Matteucci studied animal electricity and described the action potential from sketeal muscle and how a muscle could e made to contract when the nerve was brought into contact with a second muscle which was in an excited state. This became known as the "rheoscope frog". Matteucci sent his published paper to Baron von Humbolt, who passed it to Johannes Muller. Muller showed an interest and forwarded the paper to Emil DuBois-Reymond and encouraged him to perform similar experiments to those of Matteucci. DuBois-Reymond showed "injury potential" of muscle, but there was nothing new in this - 50 years earlier, Galvani had noticed that a partly injured muscle, of frogs, regenerates electric current, when he observed a contraction in a second muscle. In 1850, DuBois-Reymond constructed his own galvanometer - known as the "rheotome" - capable of sampling the magnitude of an electric current for brief periods. Although experimenters tried using the "rheoscopic frog" galvonometers, the problem was that rather than measure electricity, the equipment sensed it. Plus, even though it "sensed" electricity, the "rheoscopic frog" itself was relatively insensitive(6). Jules Bernstein, a pupil of DuBois-Reymond, modified the "rheotome" so as to plot the time course of negative variation, and in 1868 introduced the "differential rheotome". With this equipment, Marchand, showed the intensity of the electrical current at various intervals during the cycle of a frog`s heart in 1877, A year later, Englemann published, what is claimed to be, the first electrocardiograms, which showed the average of 33 measurements of the time course of the variations in electrical potential of the heart; and in that year, Burdon-Sanderson recorded the potential variations of the heart of a tortoise. Although the "differential rheotome" could record the time course of the variations of the action potential of the heart, the instrument lacked sensitivity and the final curves were laboriously reconstructed from many recordings(6). An instrument for measuring biochemical current, the "capillary electrometer", was developed by Gabriel Lippmann in 1872, which became popular with electro-physiologists. In 1876, Marey devised a way of using this equipment and photographing the potential variation(6). None of the animal experimenters realized that the electrical activity associated with the heart beat could also be recorded from the intact heart from the chest wall, over the region of the thorax immediately over the heart. In 1887, Augustus Waller, a London physiologist, became the first person to record electrical activity of the human heart, by using a capillary electrometer, and without opening the chest of the human patient and exposing the heart(6). The instrument also allowed a fine column of mercury to be photographed onto a moving plate. Initially, Waller called his recordings an "electrogram", but a year later, in 1888, in a lecture at St Mary`s Hospital Medical School, London, he refered to the recordings as "cardiograms"(7). In 1909, `The Times` carried an article in which Gladstone, Secretary of State, told of Waller placing the paws of a bulldog in containers of water containing sodium chloride connected to a galvanometer. Gladstone offered no explanation or "justification" for the experiment(8). But there was a problem with the capillary electrometer - it could detect the tiny currents of a beating heart, but was too sluggish to follow the heart`s fast electrical variations(9). As there are electrical differences between the heart of a dog and that of a human(10), Waller`s experiment on the bulldog had no clinical bearing and it was his trial on a patient in 1887 which showed the potential. For almost six years, from 1894 to 1900, Willem Einthoven studied action potential from animal tissue, using the capillary electrometer. He set about trying to modify and improve it, but was dissatisfied with the results he was getting(11). In 1897, Ader constructed a string galvanometer to study underwater cables, whch were being laid at the time for trans-Atlantic telegraphy(11). Einthoven acknowledged that he knew of the existance of Ader`s manometer, when in 1901, he described his string galvanometer. Einthoven encountering many technical difficulties in constructing his electrocardiogram, and improvements were made after consultations with Snellen and Donders(11). In 1906, Einthoven published accounts of electrocardiograms of experimental heart-block induced in dogs(12), and direct arterial blood pressure in dogs(13). In the same paper, Einthoven included descriptions and photographs of patients undergoing electrocardiography(14). Given that the carotid "tree" of the dog differs from that of a huamn(15) and there are mechanical and electrical differences between the heart of a dog and that of a human(16), it was the electrocardiograms of human patients which showed a possible clinical application. As a history of cardiography points out "In 1908, the clinicians looked on such instruments as the rheotome and capillary electrometer as gadgets to be used by physiologists in the study of frogs and turtles. As far as clinicans were concerned, the string galvanometer was just another gadget which could not possibly be of any concern to a physician busy practising his profession". It was to be Einthoven`s clinical use in, as he put it, "simultaneous recordings of carotid pulse and normal electro-cardiograms in [hu]man[s]" and "electrocardiograms of various disease states [of people]", which "demonstrated that the elctrocardiogram would have to be taken seriously be physicians"(17). Following Einthoven`s paper of 1908, Thomas Lewis was allowed to see the equipment in Leiden, and in 1909 published his own account - the first electrocardiogram of complete heart block with ventricular hypertrophy(17). In 1910, Eppinger and Rothberger, in Vienna, produced experimental bundle-branch block in dogs for the first time(17). But as was pointed out later, "work on human subjects has thrown doubt on the applicability to [hu]man[s] of these conclusions drawn from animal experiments, and there is therefore uncertainty as to which type of curve corresponds with right or left block"(18). Following the discovery of the atrioventricular (A-V node) by Tawara in 1906, and the sino-arial (S-V node) by Keith and Flack in 1907(19), studies began on ventricular premature systole - the period during which the heart, prematurely, contract. At the time, the two types that occur were called left and right ventricular premature systoles. From experiments on dogs, experimenters believed that in left ventricular premature systole, and right bundle-branch block, the main ventricular deflection was upright in Lead I and inverted in Lead III; and that with right ventricle premature systole, and left bundle-branch block, the deflections were in the opposite direction(20). It was not until 1930 that Barker, McLeod and Alexander were to introduce the new terminology - the exact opposite of the old terminology, based on animal experiments(21). refs. 1. Burch,GE. DePasquale,N. A History of Electrocardiography. Year Book Medical Pub. 1964. 2. Stevens,L. Explorers of the Brain. Scientific Book Club. 1974. 3. Hawes,W. Trans of Royal Humane Soc. 1774-94. Nichols. 1795. 4. Venzmer,G. 5000 Years of Medicine. Macdonald. 1972. 5. Stevens,L. Explorers of the Brain. Scientific Book Club. 1974. 6. Burch,GE. DePasquale,N. A History of Electrocardiography. Year Book Medical Pub. 1964. 7. Beaumont,GE. Dodds,EC. Recent Advances in Medicine. 13th ed. 1952 8. The Times. 9 Jul 1909. 9. Stevens,L. Explorers of the Brain. Scinetific Book Club. 1974. 10. Nelson,C. Geselowitz,D. The Theoretical Basis of Electrocardiology. Clarendon. 1976. 11. Burch,GE. DePasquale,N. A Dictionary of Electrocardiography. Year Book Medical Pub. 1964. 12. Einthoven,W. Arch Intern Physiol. vol 4. 1906. 13. Burch,GE. DePasquale,N. A History of Electrocardiography. Year Book Medical Pub. 1964. 14. Einthoven,W. Arch Intern Physiol. vol 4. 1906. 15. MacDowall,D. Lancet. vol1. 1964. 16. Nelson,CV. Geselowitz,DB. The Therapeutical Basis of Electrocardiology. Clarendon. 1976. 17. Burch,GE. DePasquale,N. A History of Electrography. Year Book Medical Pub. 1964. 18. Beaumont,GE. Dodds,EC. Recent Advances in Medicine. 13th ed. 1952. 19. Burch,GE. DePasquale,N. A History of Cardiography. Year Book Medical Pub. 1964. 20. Beaumont,GE. Dodds,EC. Recent Advances in Medicine. 13th ed. 1952. 21. Barker et al. Amer Heart J. vol 5. 1930. |
|
X-RAYS On 8 Nov 1895, William Conrad Roentgen, at the Physical Institute of Julius-Maximilliams University, Wurzburg, Bavaria, passed an electrical discharge from an induction coil through a glass Crookes tube covered with black paper, and noticed a paper screen covered with fluorescent material was illuminated(1). It appeared that invisible rays had passed through the black paper covering the Crookes tube. He tried the rays on other materials - playing cards, a book, wood, rubber, and various metals - finding only lead would stop the rays from passing through(2). Aware that the rays darkened photographic plates(2), on 22 Dec 1895, Roentgen exposed his wife`s hand to the rays and saw the bones(3). Papers, illustrated with photographic shadow-images including a human hand, were published(4). He referred to the images as "shadow pictures"; and, later, the terms skiagraphs, radiograms, rontograms were used before "radiographs" was generally accepted(5). The first radiograph in England was taken on 8 Jan 1896 by A A Cambell-Swinton, an electrical engineer in London, using a Crooks tube to produce x-rays for clinical use(6). On 23 Jan 1986, Roentgen gave his only public lecture - in Wurzburg(7) where Allbrecht von Kolliker, an anatomist, volunteered to have an x-ray taken of his hand, which showed the bones and joints on a dark plate(8). X-rays of the hand of Roentgen`s wife, the clinical application by Cambell-Swinton, the demonstration on the hand of Kolliker had all taken place before animal were used as test subjects or to illustrate publications - including fish, frogs, a puppy, the feet of a dog, a rabbit and chicken, a canary, a cat which had swallowed a hat-pin, a mole, and chameleons(9). During the time that radiographs were being taken of animals, x-rays were being used clinically for internal examination(10). refs 1. Mould,RF. A Century of X-rays and Radioactivity in Medicine. Institute of Physics Pub. 1993. 2. Porter,R. The Greatest Benefits to Mankind. Fontana Press. 1999. 3. d`Estrand V-A G. Book of Inventions & Discoveries. Queen Anne Macdonald. 1992. 4. Lloyd,WEB. A Hundred Years of Medicine. Paperduck. 1971. 5. Mould,RF. A Century of X-rays and Radioactivity in Medicine. Institute of Physics Pub. 1993. 6. Merrington,WR. University College Hospital & Its Med Schoold. Heinemann. 1976. 7. Mould,RF. A Century of X-rays and Radioactivity in Medicine. Institute of Physics Pub. 1993. 8. Shippen,KB. Men of Medicine. Dobson Books. 1959. 9. Mould,RF. A Century of X-rays and Radioactivity in Medicine. Institute of Physics Pub. 1993. 10 Porter,R. The Greatest Benefits to Mankind. Fontana Press. 1999. |
|
C.A.T. SCANNER In 1917, the principles of CAT scanning were discovered by Johann Radon, an Austrian mathematician, who was the first to prove that two-dimensional and three-dimensional images can be reconstructed uniquely from its projections. Within five years, ordinary tomographic images, or "slices", through the human body were being made by using x-rays as a source(1). In the 1970s, Godfrey Houndsfield began working on the CAT scanner which he had developed. Initially he and his colleagues took images of blocks of Perspex. A local hospital provided a specimen of a human brain, and with their equipment, Houndsfield and his team produced the first picture of a human brain showing the grey and white matter. Unfortunately, formalin, used to preserve the specimen, enhanced the readings and gave exaggerated results. Because of the problem with formalin-preserved human brain, Houndsfield turned to brains of freshly-killed bullocks - but variation in tissue density was less pronounced. Sections through the area of the kidney of pigs were also used in tests with their CAT scanner. But in vitro experiments with animal tissue still left unanwered questions, as Houndsfield stated in his speech when he collected Nobel Prize in 1979 "we were still very worried whether tumours would show up at all. To test this, we had to build a much faster and more sophisticated machine that would scan the brains of living patients in hospital"(2). In 1971, the first human patient, with a suspected brain lesion, was scanned with a CAT, which revealed a dark, circular cyst(2) - a clinical success. 1. Lehrer,S. Explorers of the Body. Doubleday. 1979. 2. Houndsfield,G. Nobel Lecturer. |
|
HYPODERMIC SYRINGE In 1852, Charles Parvaz, of Lyons, France, invented the hypodermic syringe, which he used for the injection of perchloride of iron into aneurism. The following year, Alexander Wood, of Edinburgh, Scotland, used themethod for administering injection of morphine for the relief of neuralgia, and thus began the use of the hypodermic syringe for giving local anesthetics(1). ref 1. Clinical Excerpts. vol XI. 1936. |
c. Scientific Anti-Vivisectionism
Create a
free website at Webs.com