John snow about scientific research and publications

John snow about scientist history and role of John snow in anesthesia

1. JOHN SNOW- CHLOROFORM,HORACE WELLS-NITROUS OXIDE Moderators Presenter Dr sk .Vahida Mam Dr. ch .varshitha Associate professor 1st year PG. Smc,vij. Dr.k.Indira Mam Assistant professor Smc,vij.

2. JOHN SNOW (1813-1858) Snow was born on 15 March 1813 in York, England, the first of nine children born to William and Frances Snow in their North Street home, and was baptised at All Saints' Church, North Street, York. His father was a labourer who worked at a local coal yard, by the Ouse, constantly replenished from the Yorkshire coalfield by barges, but later was a farmer in a small village to the north of York.

3. EARLY LIFE AND EDUCATION At age 14,snow started his medical apprenticeships with a surgeon in Newcastle upon Tyne,followed by further apprenticeships in Yorkshire. William Hardcastle was a friend of Snow's uncle, Charles Empson, who was both a witness to Hardcastle's marriage and executor of his will. Charles Empsom also went to school with Robert Stephenson and it was probably through these connections that Snow acquired his apprenticeship so far from his hometown of York. Snow later worked as a colliery surgeon.

4. Between 1833 and 1836 he was an assistant in practice, first in Burnopfield, Durham, and then in Pateley Bridge, North Yorkshire. In October 1836 he enrolled as a student at the Hunterian school of medicine in Great Windmill Street, London. A year later, he began working at the Westminster Hospital and was admitted a member of the Royal College of Surgeons of England on 2 May 1838. He graduated from the University of London in December 1844, and was admitted to the Royal College of Physicians in 1850.

5. CONTRIBUTIONS TO ANESTHESIA At the Westminster Hospital, he obtained clinical experience and discovered that the inhalation of arsenic vapour caused illnesses among students. He published his findings, leading to a change in the practice of preserving bodies for anatomical dissection.

6. John Snow studied chloroform and realized that accuracy of delivery and patient monitoring were important when administering it. He investigated the death of a 15-year-old girl named Hannah Greener, who died after being administered chloroform. Snow concluded that her death was due to the uncontrolled administration of chloroform and recommended the use of scientifically engineered vaporizers.

7. On April 7, 1853, Queen Victoria asked John Snow to administer chloroform analgesia for the delivery of her eighth child. This was a success and led to medical and religious acceptance of obstetrical anesthesia.

8. Snow was sceptic of the dominant miasma theory that stated that diseases such as cholera or the Black Death were caused by pollution or a noxious form of "bad air. The germ theory was not widely accepted by this time, so he was unaware of the mechanism by which the disease was transmitted, but evidence led him to believe that it was not due to breathing foul air. He first published his theory in an essay On the Mode of Communication of Cholera in 1849 . 1855 a second edition was published, with a much more elaborate investigation of the effect of the water-supply in the Soho, London epidemic of 1854.

9. LEGACY AND HONOURS A plaque commemorates Snow and his 1854 study in the place of the water pump on Broad Street (now Broadwick Street). It shows a water pump with its handle removed. The spot where the pump stood is covered with red granite. A public house nearby was named "The John Snow" in his honour. The John Snow Society is named in his honour, and the society regularly meets at The John Snow pub. An annual Pumphandle Lecture is delivered each September by a leading authority in contemporary public health.

10. His grave in Brompton Cemetery, London, is marked by a funerary monument. In York a blue plaque on the west end of the Park Inn, a hotel in North Street, commemorates John Snow. In 2001 the John Snow College was founded on the University of Durham's Queen's Campus in Stockton-on-Tees.

11. Horace wells (1815-1848) Horace Wells (born January 21, 1815, Hartford, Vermont, U.S.—died January 24, 1848, New York, New York) was an American dentist, a pioneer in the use of surgical anesthesia.

12. EARLY LIFE: Wells was the first of three children of Horace and Betsy Heath Wells. At the age of 19 in 1834, Wells began studying dentistry under a two-year apprenticeship in Boston.

13. CONTRIBUTION TO ANESTHESIA: Wells first witnessed the effects of nitrous oxide on December 10, 1844, when he and his wife Elizabeth attended a demonstration - “A Grand Exhibition of the Effects Produced by Inhaling Nitrous Oxide,Exhilarating, or Laughing Gas.” During the demonstration, a local apothecary shop clerk Samuel A. Cooley became intoxicated by nitrous oxide. After the demonstration, Cooley was unable to recall his actions while under the influence, but found abrasions and bruises on his knees. From this demonstration, Wells realized the potential for the analgesic properties of nitrous oxide. Wells conducted a trial on himself by inhaling nitrous oxide and having John Riggs extract a tooth which went successful.

14. He gave a demonstration to medical students at the Massachusetts General Hospital in Boston on January 20, 1845. However, the gas was improperly administered and the patient cried out in pain. The patient later admitted that although he cried out in pain, he remembered no pain and did not know when the tooth was extracted Following Morton's demonstration in October, Wells published a letter accounting his successful trials in 1844 in an attempt to claim the discovery of anesthesia. Wells moved to New York City and began self-experimenting with ether and chloroform, and he became addicted to chloroform.

15. LEGACY The Parisian Medical Society voted and honored him as the first to discover and perform surgical operations without pain. He was elected an honorary member and awarded an honorary MD degree. The American Dental Association honored Wells posthumously in 1864 as the discoverer of modern anesthesia, and the American Medical Association recognized his achievement in 1870. Hartford, Connecticut, has a statue of Horace Wells in Bushnell Park.

16. Nitrous oxide Properties Colourless & odourless. Non-irritant gas. Although nonexplosive and nonflammable,nitrous oxide is as capable as oxygen of supporting combustion. Unlike the potent volatile agents,nitrous oxide is a gas at room temperature and ambient pressure. It can be kept as a liquid under pressure because it’s critical temperature lies above room temperature.

17. MAC-104 The blood/gas solubility coefficient -0.42 It does not undergo metabolism. Eliminate unchanged mainly through LUNGS. Stored in blue color cylinders at pressure of 760 psi. Pin index for nitrous oxide is 3 and 5.

18. Systemic Actions CVS : In vitro it depresses myocardium in vivo this effect is countered by stimulation of sympathetic system, therefore can be used safely for cardiac patients and shock. CNS :Increases cerebral metabolic rate and raises the intracranial tension. Respiratory system: Respiration is minimally depressed. Immunologic system: Effects chemotaxis and motility of leukocytes.

19. concentration effect: When an inhaled anesthetic, such as nitrous oxide is administered in high concentrations, the gas is rapidly taken up into blood, at a very high rate initially (1 L/min). Since Nitrous oxide is about 30 times more soluble than nitrogen, the volume of N20 entering the pulmonary capillaries is greater than the N2 leaving the blood and entering the alveolus. This leads to a reduction in lung volume.

20. Second gas effect The second gas effect refers to the effect of nitrous oxide administration in increasing the alveolar concentration of a concurrently administered volatile inhalational agent. If a second gas (like halothane, is administered at the same time as nitrous oxide, the concentration of the second gas rises faster in the alveoli, than it would in the absence of nitrous oxide. This is termed the second gas effect and is due to the uptake of large volumes of nitrous oxide in the alveoli that leads to both concentrating the residual second gas in a smaller lung volume and an augmentation of alveolar ventilation. This process can speed induction of inhalational anesthesia.

21. Diffusion Hypoxia (Fink Effect) Towards the end of surgery when nitrous oxide delivery is stopped, the gradient reverses and the nitrous oxide from blood gushes in alveoli replacing the oxygen from there causing hypoxia. This is called as diffusion hypoxia. To avoid this diffusion hypoxia 100% oxygen should be given for 5-10 minutes after discontinuing nitrous oxide.

22. TOXICITY •Long term exposure of nitrous oxide– analgesia Inhibits Vit B12 dependent enzymes methionine synthase Thymidate synthase – DNA synthesis leads to : •Peripheral neuropathy •Megaloblastic anaemia • Subacute combined degeneration of cord •Teratogenicity

23. Chloroform Chloroform is an organic compound with formula CHCl3. It is one of the four chloromethane. The colourless, sweet smelling,dense liquid is a trihalomethane,and is considered hazardous. Many kinds of seaweed produce chloroform,and fungi are believed to produce chloroform in soil,thus are the natural sources of chloroform.

24. PHYSICAL PROPERTIES Chloroform has the following physical properties: (1) It is a sweet smelling colourless liquid. (2) It is practically insoluble in water but dissolves in organic solvents such as ether, alcohol etc. (3) It is non-inflammable but its vapours may burn with green flame. (4) It brings temporary unconsciousness when vapours are inhaled for sufficient time.

25. Molecular Formula: CHC|3 Molar Mass : 119.38 g/mol Appearance : Colorless liquid Density : 1.483 g/cm3 Melting Point : 63.5 °C Boiling Point : 61.2 °C Molecular shape : Tetrahedral

26. HEALTH HAZARDS Toxic by inhalation or ingestion. Harmful, irritant and possibly carcinogenic after prolonged exposure. Immediate effects after inhalation or injection include excitement and nausea followed by dizziness,drowsiness,convulsions,coma. Delayed effects may include kidney and liver damage. Inhalation causes shortness of breath and dryness of the mouth and throat. Ingestion causes a burning sensation of the mouth and throat and stomach upset. Skin or eye contact may cause irritation and inflammation.

27. Uses In the late 19th and early 20th centuries, chloroform was used as an inhaled anesthetic during surgery. However, safer, more flexible drugs have entirely replaced it in this role. The major use of chloroform today is in the production the freon refrigerant R-22. However, this use can be expected to decline as F is replaced by refrigerants that are less liable to result in ozone depletion. Smaller amounts of chloroform are used as a solvent in the pharmaceutical industry, and for producing dyes and pesticides. Chloroform is often used as a tool in kidnapping, especially in books and movies. Chloroform containing deuterium (heavy hydrogen), CDCI3, is the most common solvent used in Nuclear Magnetic Resonance (NMR) spectroscopy.

28. Chloroform was mainly used as a anaesthetic during ancient time when the anaesthesia was not invented. Queen Victoria asked John Snow to administer chloroform analgesia for the delivery of her eighth child. This was a success and led to medical and religious acceptance of obstetrical anesthesia.