HISTORY OF ANAESTHESIAANATOMY OF AIRWAY�BASICS OF GENERAL ANESTHESIA .pptx

General Anesthesia (GA) is a reversible condition, where the patient has no sensation, including pain from his body parts

The first general anesthetic administered for a dental extraction is credited to Horace Wells.

Development of endotracheal anesthesia by Stanley Rowbotham and Ivan Magill was a milestone in the history of maxillofacial surgery.

1. HISTORY OF ANAESTHESIA ANATOMY OF AIRWAY BASICS OF GENERAL ANESTHESIA

2. What was done to a patient before an operation ? It was the custom then, as for centuries afterward, to bind the patient to the table with ropes or straps. His screams were disregarded, but if he struggled too Violently, assistants grasped his arms and legs.

3. The word “Anaesthesia“ was coined by Oliver Wendell Holmes in 1846. It originates from the Greek an - "without” and “ aisthēsis” the inhibition refers to of sensation. Oliver Wendell Holmes (1809–1894)

4. Opium , is a very popular ancient pain relieving and euphoria inducing remedy. It is first said to have been cultivated in lower mesopotamia (Southwest Asia) in 3400 BC. Sumerians referred it as “ hul- gil ” which means “ joy plant ” Sumerians passed this “miracle drug” to the Assyrians who in turn passed opium to the Babylonians and then to the Egyptians. 3400 BC

5. The knowledge and use of opium passed on from Egypt across Mediterranean Sea trade routes to various civilizations including the Phoenicians and the Greeks. Later, around 330 BC, Alexander the Great and his armies introduced opium to the people of India, Persia and other eastern and Middle Eastern kingdoms.

6. Prior to the introduction of opium to ancient India and China, these civilizations pioneered the use of cannabis incense and aconitum. By the 8th century AD, Arab traders had brought opium to India and China.

7. Pictographs showing practice of Acupuncture in China on bone and tortoise shells with inscriptions dating from the time of Shang dynasty have been found, and it is thought that these were used for divination in the art of healing. 1600 BC

8. Sushruta in Sushruta Samhita advocated the use of wine with incense of cannabis for anaesthesia. 600 BC

9. Assyrians and Egyptians used carotid compression to produce brief unconsciousness before circumcision or cataract surgery. In a passage in History of Animals, Aristotle says of the jugular veins: “If these veins are pressed externally, men, though not actually choked, become insensible, shut their eyes, and fall flat on the ground." 400 BC

10. German physician Valerius Cordus (1515–1544), is widely credited with developing a method for synthesizing ether. He synthesized diethyl ether by distilling ethanol and sulphuric acid into what he called by the poetic Latin name oleum dulci vitrioli , or "sweet oil of vitriol” 1540

11. The name ether was given to the substance in 1729 by August Sigmund Frobenius. William T. G. Morton was First in the world to publicly and successfully demonstrate the use of ether anesthesia for surgery.

12. Joseph Priestley (1733–1804) was an English chemist who discovered nitrous oxide (1772), nitric oxide, ammonia, hydrogen chloride and oxygen (1774). He originally named nitrous oxide as " nitrous air, diminished ”, on account of his preparative method of allowing NO to standing in contact with moist iron filing . 1771- 1786

13. J ULY , 1800 Even though N 2 O was discovered by Joseph Priestley it was Humphry Davy who spotted its medical potential In 1798, Humphry Davy was appointed laboratory superintendent of the Pneumatic Institute in Bristol, UK. This was an establishment founded on the belief that the recently discovered gases might have curative applications

14. Henry Hill Hickman (1800–1830) experimented with the use of carbon dioxide as an anesthetic in the 1820s. He would make the animal insensible, effectively via almost suffocating it with carbon dioxide, then determine the effects of the gas by amputating one of its limbs. . 1824

15. In 1824, Hickman submitted the results of his research to the Royal Society in a short treatise entitled Letter on suspended animation: with the view of ascertaining its probable utility in surgical operations on human subjects . The response was an 1826 article in The Lancet titled 'Surgical Humbug' that ruthlessly criticized his work. Hickman died four years later at age 30. Though he was unappreciated at the time of his death, his work has since been positively reappraised and he is now recognized as one of the fathers of anesthesia

16. Crawford W. Long had observed in the ether frolics participants gatherings, experienced that some bumps and bruises, but afterward had no recall of what had happened. He postulated that that diethyl ether produced pharmacologic effects similar to those of nitrous oxide. On 30 March 1842, he administered diethyl ether by inhalation to a man named James Venable, in order to remove a cysts from the man's neck. 1842

17. Dr. Horace Wells (1815- 1848) volunteered to inhale nitrous oxide for his own dental extraction back in December of 1844. Wells then began to administer nitrous oxide to his patients, successfully performing several dental extractions over the next couple of weeks. 1845

18. In spite of these convincing results being reported by Wells to the medical society in Boston already in December 1844, this new method was not immediately adopted by other dentists. The reason for this was most likely that Wells, in January 1845 at his first public demonstration to the medical faculty in Boston, had been partly unsuccessful, leaving his colleagues doubtful regarding its efficacy and safety , the partial anesthetic was judged as a " humbug. "

19. HISTORY OF ETHER DOME

20. On became first in the October 16,1846 William world T. G. Morton to publicly and (1819- 1868) successfully demonstrate the use of ether anesthesia for surgery. This occurred at what came to be called " The Ether Dome ," at Massachusetts General Hospital. 1846

21. The Ether Dome is a surgical operating amphitheater in the Bulfinch Building at Massachusetts General Hospital in Boston. It was the site of the first public demonstration of the use of inhaled ether as a surgical anesthetic on 16 October 1846.

22. Crawford Long , had previously administered ether in 1842, but this went unpublished until 1849. The Ether Dome event occurred when William T. G. Morton, used ether to anesthetize Edward Gilbert Abbott. John Collins Warren , the first dean of Harvard Medical School, then painlessly removed part of a tumor from Abbott's neck. After Warren had finished, and Abbott regained consciousness, Warren asked the patient how he felt.

23. Reportedly, Abbott said, " Feels as if my neck's been scratched" . Warren then turned to his medical audience and uttered "Gentlemen, this is no Humbug". This was presumably a reference to the unsuccessful demonstration of nitrous oxide anesthesia by Horace Wells in the same theater the previous year, which was ended by cries of " Humbug! " after the patient groaned with pain..

24. History of Chloroform

25. Chloroform was discovered independently in 1831 by the USA's Samuel Guthrie, France's Eugène Soubeiran, and Germany's Justus von Liebig. Prof. James Y. Simpson (1811- 1870)- Scottish obstetrician begins administering chloroform to women for pain during childbirth. Chloroform quickly became a popular anesthetic for surgery and dental procedures as well. 1847

26. Dr. John Snow (1813-1858) who was a fulltime popularized anesthetist since 1847, obstetric anesthesia by chloroforming Queen Victoria for the birth of Prince Leopold (1853) and Princess Beatrice (1857). 1853 & 1857

27. Knowledge of the narcotic effect of chloroform spread rapidly, but very soon reports of sudden deaths mounted. The first fatality was a 15- year- old girl called Hannah Greener, who died on January 28, 1848. Between 1864 and 1910 numerous commissions in UK studied chloroform, but failed to come to any clear conclusions. The reservations about chloroform could not halt its soaring popularity. Between about 1865 and 1920, chloroform was used in 80 to 95% of all narcoses performed in UK and German- speaking countries.

28. Two hours after the operation, the subject complained of nausea, vomiting, severe headache, and pain in his back and ankle. The vomiting, back and leg pain improved by the following day, but the headache was still present. Bier performed spinal anesthetics on five more subjects for lower extremity surgery, using a similar technique and achieving similar results

29. In 1902, Hermann Emil Fischer (1852– 1919) and Joseph von Mering (1849–1908) discovered that diethylbarbituric acid was an effective hypnotic agent.

30. Also called barbital or Veronal , the trade name assigned to it by Bayer Pharmaceuticals, this new drug became the first commercially marketed barbiturate. It was used as a treatment for insomnia from 1903 until the mid-1950s.

31. Barbitone was prepared by condensing diethylmalonic ester with urea in the presence of sodium ethoxide, and then by adding at least two molar equivalents of ethyl iodide to the silver salt of malonylurea or possibly to a basic solution of the acid. The result was an odorless, slightly bitter, white crystalline powder.

32. 1920 Arthur Guedel publishes his eye signs of Ether anesthesia in the American Journal of Surgery . He also described 4 stages of ether anaesthesia dividing the stage III into 4 planes His Guedel (oral) airway is still used today. He has been memorialized by the Arthur E. Guedel Memorial Anesthesia Center, San Francisco.

33. Sodium thiopental , the 1 st IV anesthetic, was synthesized in 1934 by Ernest H. Volwiler & Donalee L. Tabern , working for Abbott Laboratories. In the mid 1930s, Volwiler and Tabern spent three years screening over 200 candidate compounds in search of a substance which could be injected directly into the blood stream to produce unconsciousness

34. It was first used in humans on 8 March 1934 by Ralph M. Waters in an investigation of its properties, which were short- term anesthesia and surprisingly little analgesia. Three months later, John Silas Lundy started a clinical trial of thiopental at the Mayo Clinic at the request of Abbott Laboratories.

35. On 23 January 1942 Griffith and his resident Enid Johnson administered curare to a young man undergoing appendicectomy.. Dr. Harold Griffith (1894-1985) & Enid Johnson (1909- 2001) 1942

36. Many new intravenous and inhalational anesthetics were developed and brought into clinical use during the second half of the 20th century. Paul Janssen (1926–2003), the founder of Janssen Pharmaceutica, is credited with the development of over 80 pharmaceutical compounds. Janssen synthesized nearly all of the butyrophenone with haloperidol class (1958) of antipsychotic agents, beginning and droperidol (1961).

37. These agents were rapidly integrated into the practice of anesthesia. In 1960, Janssen's team synthesized fentanyl, the first of the piperidinone-derived opioids. Fentanyl was followed by sufentanil (1974), alfentanil (1976), carfentanil (1976), and lofentanil (1980). Janssen and his team also developed etomidate (1964),a potent intravenous anesthetic induction agent.

38. clinically introduces Dr. Michael Johnstone the first modern- day brominated general 1956 - UK's halothane, anesthetic. 1963 - Dr. Edmond I. Eger, II described minimum alveolar concentration (MAC) , later characterized as "the concentration of inhaled anesthetic producing immobility in 50% of patients subjected to a noxious stimulus."

39. 1964- Dr. Günter Corssen et al. begin human trials of the dissociative intravenous anesthetic ketamine. 1966- Dr. Robert Virtue et al. begin human trials of the inhalational anesthetic enflurane. 1972 - Isoflurane is clinically introduced as an inhalational anesthetic. 1992- Desflurane is clinically introduced as an inhalational anesthetic. 1994- Sevoflurane is clinically introduced as an inhalational anesthetic.

40. Anatomy of airway and it’s significance

41. DEFINA TION Airway is defined as a passage through which the air/gas passes during respiration. OR In practice of airway management it is described as any artificial device with a lumen to aid ventilation&/or serve as a conduit to endotracheal intubation. These include- Nasopharyngeal airway Oropharyngeal airway Laryngeal mask airway

42. CLASSIFICATION OF AIRWAY UPPER AIRWAY- Oral cavity, Nasal cavity, Pharynx, Larynx MOST VULNERABLE AREA FOR OBSTRUCTION LOWER AIRWAY– Trachea, Bronchi, Bronchioles, Alveoli SIGNIFICANCE - Upper airway serves to warm, filter, humidify the air/gas before it enters the lower airway. Bypassing these structures during ETT Intubation ,makes it essential to provide warm humidified air/gas while patient breath spontaneously or are on assisted/ controlled ventilation. Lower airway serves in exchange of gases.

43. ORAL CAVITY Extends from lips to oropharyngeal isthmus (i.e. Anterior tonsillar pillar.) Tongue is a muscular organ which makes up most of the floor of oral cavity. Genioglossus most clinically relevant to anesthesiologist which connects the tongue to the mandible. BOUNDARIES- ROOF F L O O R LATERAL WALLS POSTERIOR Hard and soft palates Soft tissues, which include a muscular diaphragm and the tongue Cheeks aperture of the oral cavity is the oropharyngeal isthmus

44. SIGNIFICANCE - Mallampati grading helps in assessment of airway during PAC. JAW THRUST MANUEVER- This maneuver uses the sliding component of temporomandibular joint to move the mandible and attached tongue anteriorly relieving airway obstruction caused by posterior displacement of tongue into oropharynx (During sleep, decreased consciousness, during general anesthesia). Caution should be maintained during laryngoscopy as lips can be injured Loose/bucked tooth can lead to difficult intubation Depletion of buccal fat (old age) –Difficult mask ventilation.

45. NOSE AND NASAL CAVITY Nose is divided into two regions- INTERNAL NOSE - Vestibule - Nasal cavity proper EXTERNAL NOSE Bony part Cartilaginous part EXTERNALLY ALAE NASI - Lateral margins of the nostrils. Rounded & mobile Flaring of ala nasi Airway obstruction Media l wall Lateral wall Roof Floor Infolded while introducing any tube via the nostril Distance from alae nasi to various points on external ear( tragus, meatus) Estimate the length of airway device introduced for relieving airway obstruction

46. Lateral wall: Lateral wall of nasal cavity has 3 conchae ( turbin at es) and o penin g of pa r ana s a l sinu s . APPLIED ANATOMY: Inferior meatus is the preferred pathway for passage of nasal airway device; Improper placement of object in nose can result in avulsion of a turbinate. Prolonged nasotracheal intubation has most often associated with infection of maxillary sinus due to obstruction and lack of drainage through ostia. Medial wall: Nasal septum form the medial wall Has highly vascular little’s area in the anterior inferior part of nasal septum. APPLIED ANATOMY: This is the commonest site of epistaxis As it is highly vascular , nasal vasoconstrictor should be applied usually topically, before instrumentation of nose to avoid epistaxis.

47. NASAL SEPTUM DEVIATION is common in adults therefore the more patent side should be determined before passing instrumentation through nasal passage. Floor : Formed by palatine process of maxilla, palatine bone APPLIED ANATOMY : floor of nasal cavity is almost perpendicular to the plane of face so tracheal tube is inserted at right angle to the plane of face. R o o f: Formed cribriform plate of ethmoid bone APPLIED ANATOMY: Disruption of cribriform plate leads to CSF rhinorrhea , is a contraindication for passing nasogastric tube insertion(Ryle’s tube) and nasotracheal intubation.

48. N e r v e sup p l y - - Olfactory nerves - Nerves of common sensation- Anterior ethmoidal nerve Sphenopalatine nerve Infraorbital nerve - Autonomic nerves Blood supply - Upper part of nasal cavity :Anterior & posterior ethmoidal arteries Lower part of nasal cavity :Sphenopalatine branch of maxillary artery L a t e r al w all

49. PHARYNX Extends from base of skull to cricoid cartilage anteriorly and to inferior border of sixth cervical vertebra posteriorly. 12-14 cm long 3.5cm wide at its base(Hyoid bone) 1.5cm at pharyngo-esophageal junction (narrowest part of digestive tract apart from the appendix) which is MC site for obstruction with foreign body aspiration. Posterior pharyngeal wall made up of buccopharyngeal fascia which separates pharyngeal structures from retropharyngeal space. Improper placement of gastric or tracheal tube can result in laceration of fascia The wall of pharynx contain two layer of muscle Circular(external) Lo n gitu d inal(i nt ernal)

50. Internal layer muscles- Stylopharyngeus, salpingopharyngeus , palatopharyngeus They elevate the pharynx and shortens the larynx during deglutition. External layer muscles- Superior constrictor, middle constrictor, inferior constrictor They advance the food from oropharynx to esophagus. Nerve supply : Internal layer by Glossopharyngeal nerve. External layer innervated by pharyngeal plexus formed by- *Vagus *Glossopharyngeal *External branch of superior laryngeal nerve The inferior constrictor also innervated by recurrent laryngeal N. The pharynx divided in to –Nasopharynx Oropharynx Laryngopharynx/Hypopharynx

51. NAS O P HA R Y NX It extends from posterior nasal aperture to the posterior pharyngeal wall above the soft palate. Consists of nasal cavity, septum, turbinates, and adenoids. APPLIED ANATOMY: Ends at soft palate , this area is called velopharynx & is common site for airway obstruction in both awake and anaesthetized patient. Roof of nasopharynx forms an acute angle with the posterior pharyngeal wall –while passing any tube through the nose into the oropharynx a simple maneuver of extension of head will straighten out this angle & facilitates the passage of tube. Adenoids are located in its roof which are frequently hypertrophied during childhood & may cause obstruction or hemorrhage while passing any tube through the nose.

52. OROPHARYNX Extends from soft palate to superior edge of epiglottis. It includes tonsils, uvula, and the epiglottis. Most important area in terms of airway obstruction & management as it is made of collapsible soft tissue all around. VALLECULA- The entire space between epiglottis & base of tongue & has paired depression of the two sides of median glossoepiglottic fold. APPLIED ANATOMY: Laryngoscope blade tip lies in vallecula during classical Macintosh laryngoscopy. The vallecula is a common site of impaction of foreign bodies, such as fish bones, in the upper airway.

53. WALDEYER’S RING The ring includes masses of lymphoid tissue or tonsils, including – Two large palatine tonsils Lingual tonsil Eustachian tubal tonsils Nasopharyngeal Tonsil(Adenoids) Patient with Enlarge tonsils (kissing tonsil) are more prone to difficult ventilation when put to sleep. So avoid sedative premedication. The lingual tonsils are located between the base of the tongue and the epiglottis. Lingual tonsillar hypertrophy, which is usually asymptomatic, has been reported as a cause of unanticipated difficult intubation and fatal upper airway obstruction.

54. LARYNGOPHARYNX Extends from superior border of epiglottis to inferior border of cricoid cartilage. APPLIED ANATOMY: 1.Pyriform fossa (sinus)- sia. Internal laryngeal nerve runs submucosally in the lateral wall of the pyriform sinus and thus is easily accessible for local anesthe 2. Postcricoid area- It is the part of the anterior wall of laryngopharynx between the upper and lower borders of cricoid lamina. It is a common site for carcinoma in females suffering from Plummer–Vinson synd. Pharynx open from behind

55. LARYNX SITUATION AND EXTENT- It lies in the midline of neck opposite C3 to C6 vertebra in adult & C1 to C4 vertebra in children. It extends from the upper border of epiglottis to lower border of cricoid cartilage. MEASUREMENT- MALE FEMALE Vertical Length 44mm 41mm Transverse diameter 36mm 36mm A P diameter 43mm 26mm The glottis is the narrowest part in adult. The subglottis (cricoid ring) narrowest part in children up to the age of 5yrs. That’ s why in children uncuffed endotracheal tube can be used.

56. SKELETON OF LARYNX- Larynx consists of 3 paired cartilages and 3 unpaired cartilages. Unpaired cartilages- Thyroid Cricoid Epiglo t ts Paired cartilages- Arytenoid C orni c ul at e Cuneiform Thyroid cartilage is the largest cartilage. Cricoid cartilage is the only complete cartilaginous ring in airway.

57. THYROID CARTILAGE Longest laryngeal cartilage & largest structure in larynx. Consist of 2 quadrilateral laminae, fuse along their inferior two third anteriorly to form laryngeal prominence. Vocal cords are attached to its middle. Thyroid angle in female 120 and in male 90 " BURP“TECHNIQUE- (Backwards Upwards Rightwards Pressure) maneuver, which is used to improve the view of the glottis during laryngoscopy and tracheal intubation. It requires a clinician to apply pressure on the thyroid cartilage posteriorly, then cephalad (upwards) and, finally, laterally towards the patient's right.

58. CRICOID CARTILAGE Cricoid doesn’t allow space for edema to spread outwards and thus any injury in this area can worsen quickly. SELLICK’S MANEAUVER In patients who are at risk of gastric aspiration, during airway management downward pressure over cricoid cartilage will prevent passive regurgitation without subsequent airway obstruction. This is known as Sellick’s Maneuver.

59. EPIGLOTTIS It is leaf like elastic cartilage forming anterior wall of laryngeal inlet. Free end Broad and notched in midline A t t ached part Long and narrow connect to thyroepiglottic ligament Sides: Attached to arytenoids by aryepiglottic fold. ARYTENOID S – Pyramidal in shape CORNICULATES – lie at apex of arytenoids. CUNEIFORM - rod shaped and lie in front of corniculate cartilages.

60. LARYNGEAL CAVITY Extends from laryngeal inlet down to lower border of cricoid cartilage where it continues in to trachea. By paired upper and lower mucosal fold projecting into lumen laryngeal cavity divided into- UPPER(SUPRAGLOTTI) MIDDLE(GLOTTIC) LOWER(SUBGLOTTIC) Upper fold: Vestibular fold(FALSE VOCAL CORD) Pink in color Lower fold: Vocal fold(TRUE VOCAL CORD) Pearly white in color

61. G L O T TIS It is the narrowest part of the laryngeal cavity. It is elongated space b/w vocal cord anteriorly and Vocal process and base of arytenoid posteriorly. In adult. A-P length: - Male –24mm Female –16mm It is divided into two part– I –Anterior inter-membranous part (2/3) – Situated between the two vocal fold. II-Posterior inter-cartilaginous part (1/3) – Passes between the two arytenoids cartilage.

62. MUSCLES OF LARYNX EXTRINSIC MUSCLE – which attaches larynx to the surrounding structures INTRINSIC MUSCLE -- which attaches laryngeal cartilages to each other and affect glottic movement EXTRINSIC MUSCLE SUPRAHYOID MUSCLE – Attaches larynx to the hyoid bones & elevate the larynx e.g.– Geniohyoid, Stylohyoid, Mylohyoid, Diagastric, Thyrohyoid, Stylopharyngeus. INFRAHYOID MUSCLE – Strap muscle, in addition to lowering of larynx, can modify the internal relationship of laryngeal cartilage & folds to one another. e.g.. –Sternohyoid , Sternothyroid , Omohyoid.

63. INTRINSIC MUSCLE –ACTING ON VOCAL CORD Abductor – Posterior cricoarytenoid Adductor – Lateral cricoarytenoid, Transverse & oblique arytenoid Tensor (Elongation) – Cricothyroid, Partly Vocalis Relaxer (Shortening) – Thyroarytenoid, Partly Vocalis –ACTING ON LARYNGEAL INLET Openers – Thyroepiglottic , Thyroarytenoid Closer – Aryepiglottic , Oblique arytenoid

64. NERVE SUPPLY OF LARYNX SENSORY – Above the vocal cord– Internal laryngeal nerve (branch of SLN) Below the vocal cord- Recurrent laryngeal nerve MOTOR – All intrinsic muscle of the larynx are supplied by RLN except cricothyroid which is supplied by external laryngeal nerve which is a branch of SLN. Both SLN & RLN are branches of vagus nerve

65. ARTERIAL SUPPLY & VENOUS DRAINAGE ABOVE THE VC - Superior laryngeal artery, a branch of superior thyroid artery. Superior laryngeal vein, drains into superior thyroid vein BELOW THE VC – Inferior laryngeal artery, a branch of inferior thyroid artery. Inferior laryngeal vein, drains into Inferior thyroid vein. LYMPHATIC DRAINAGE ABOVE THE VC - Pre laryngeal & Jugulo–Digastric LN. BELOW THE VC – Pre tracheal & Para tracheal LN.

66. SENSORY NERVE SUPPLY OF AIRWAY *The sensory supply to the upper airway is derived from the cranial nerves. *The mucous membranes of the nose are innervated by the ophthalmic division (V1) of the trigeminal nerve anteriorly (anterior ethmoidal nerve) and by the maxillary division (V2) posteriorly (sphenopalatine nerves). *The palatine nerves provide sensory fibers from the trigeminal nerve (V2) to the superior and inferior surfaces of the hard and soft palate. *The lingual nerve (a branch of the mandibular division [V3] of the trigeminal nerve) and the glossopharyngeal nerve (cranial nerve IX) provide general sensation to the anterior two-thirds and posterior one-third of the tongue, respectively.

67. APPLIED ANATOMY: THE EFFECTS OF LARYNGEAL NERVE INJURY ON VOICE In complete paralysis of both recurrent and SLN the cords are held in mid position(cadaveric position) Cords are also in cadaveric position during GA with muscle relaxants. RLN Injury

68. AWAKE INTUBATION Glossopharyngeal nerve block - supplying posterior third of tongue & oropharynx. bilateral superior laryngeal nerve block – sensory supply to upper part of larynx Trans-tracheal (translaryngeal) block – supply trachea and vocal cords.

69. TEST FOR ASSESSING ADEQUACY OF THE OROPHARYNX FOR LARYNGOSCOPY AND INTUBATION Mallampati grading (samsoon and young’s modification) Narrowness and arching of the hard palate – a narrow , high arched palate offer very little space for laryngoscopy and endotracheal intubation. MODIFIED MALLAMPATI GRADING Suggest optimal tongue size in relation to oropharyngeal cavity permitting easy laryngoscopy. Indicate amount of space with in the oral cavity to accommodate the laryngoscope & ETT.

70. Assessed when the patient is - Seated Upright with head protruding forward Mouth open Tongue protruded as much as possible No phonation. Th e o b se r v e r ’ s e y e A t the le v el o f p a tie n t ’ s open mouth . Higher scores poor visibility of the oropharyngeal structures Large tongue relative to the size of the oropharyngeal space Difficult laryngoscopy Grade 0: Epiglottis seen on mouth opening and tongue protrusion

71. CORMACK –LEHANE GRADING Grading at direct laryngoscopy Grade1: Full exposure of glottis (anterior + posterior commissure) Grade2: Anterior commissure not visualized Grade3: Epiglottis only Grade4: No glottic structure visible. Grade I = success & ease of intubation

72. WILSON’S SCORING SYSTEM: score <=5 easy laryngoscopy score 6- 7 moderate difficulty score 8–10 severe difficulty in laryngoscopy Parameter 1 2 Weight <90 90-110 >110 Head and neck movement >90 =90 <90 Jaw movement (inter incisor gap) >5 cm = 5 cm <5 cm Receding mandible none moderate severe Buck teeth none moderate severe

73. BENUMOF’S 11 PARAMETER ANALYSIS: Parameter Minim a l a c c e p t a b l e v a l ue Significance Inter- incisor gap >3cm Easy insertion of laryngoscope blade Buck Teeth No overriding Cause blade to enter cephalad Length of upper incisor Short incisors (<1.5cm) Long prevent alignment of OPA Voluntary protrusion of mandibular teeth anterior to maxillary teeth Mandibular teeth can be protruded beyond the maxillary teeth Suggest optimal TMJ function, both rotatory and sliding Mallampati class Class 2 or less Easy laryngoscopy Palate configuration No arching or narrowness Reduce space for laryngoscope blade Thyromental distance >5cm/>3 finger breadth Optimally placed larynx Mandibular space Soft to palpation Allows easy tongue compressibility Neck length Qualitative Thick short neck decrease Neck thickness Qualitative Not well significant Head /neck movement Normal range 3 axes aligned 4-2-2-3 rule 4 for tooth 2 for inside of mouth for mandibular space for neck e x am i n a tion

74. Contents: Introduction Pre anesthetic assessment Definition Stages of anesthesia Anesthetic equipment Classification of Drugs Inhalational drugs Intravenous drugs Complication

75. Introduction: Gene r al Anes t hes ia (GA) is a re v er si b le co n dit i on, where t h e pa t ie n t has no sensation, including pain from his body parts The first general anesthetic administered for a dental extraction is credited to Horace Wells. Development of endotracheal anesthesia by Stanley Rowbotham and Ivan Magill was a milestone in the history of maxillofacial surgery.

76. Preanesthetic assessment

77. Objectives of pre anesthetic assessment: To obtain information about the patient’s medical history, physical and mental condition . To determine the need for a medical consultation and other kind of investigations required. To identify the factors that significantly increase the risk of procedure and modify the procedure accordingly. To educate the patient about anesthesia, postoperative care . To choose the anesthetic plan to be followed. To obtain informed consent . Ref : Neelima Anil Malik; Textbook of Oral and Maxillofacial surgery; 4 th edition

78. Routine Preanesthetic Evaluation: History Current problems Other systemic diseases, if any, Treatment/medicines for the diseases Current medications being used History of known drug allergies and previous blood transfusions. Social history Prior anesthetic exposure Family history General health and review of organ systems

79. Mallampati test: Class I: Visualization of the soft palate, fauces, uvula, anterior and the posterior pillars. Class II: Visualization of the soft palate, fauces and uvula. Class III: Visualization of soft palate and base of uvula. Class IV: Only hard palate is visible. Soft palate is not visible at all.

80. Patil’s test Thyromental distance Thyromental distance

81. Ref : Neelima Anil Malik; Textbook of Oral and Maxillofacial surgery; 4 th edition

82. General anesthesia: Definition: According to American Society of Anesthesiologists (ASA) “ Drug-induced reversible state of unconsciousness, during which patients are not arousable, even by painful physical stimulation ” Ref : Neelima Anil Malik; Textbook of Oral and Maxillofacial surgery; 4 th edition

83. Phases of general anesthesia: Induction: Begins with the onset of administration of general anesthesia to the development of surgical anesthesia. Preoxygenation, Induction, Muscle relaxants, Mask ventilation, Intubation and ETT position confirmation are the steps to be followed. Maintenance: Sustaining the state of general anesthesia. Usually done with an admixture of Nitrous oxide and halogenated hydrocarbon Recovery: At the end of surgical procedure, administration of anesthetic agents is stopped and consciousness regains. Ref : Neelima Anil Malik; Textbook of Oral and Maxillofacial surgery; 4 th edition

84. Bilal A. Siddiqui; Peggy Y. Kim ; Anesthesia Stages; StatPearls publishing; 2020 Jan Stages of A n esthes i a B ased on Guedel's Classifica t ion Stage 1 - Analges i a or Dis or i ent a tion: This stage can be initiated in a preoperative anesthesiology holding area, where the patient is given medication and may begin to feel its effects but has not yet become unconscious. Usually described as the "induction stage.“ Patient progresses from analgesia free of amnesia to analgesia with concurrent amnesia. This stage comes to an end with the loss of consciousness.

85. Stage 2 - Excitement or Delirium: Marked by features such as disinhibition, delirium, uncontrolled movements, loss of eyelash reflex, hypertension, and tachycardia. Airway reflexes remain intact during this phase and are often hypersensitive to stimulation. Airway manipulation during this stage of anesthesia should be avoided, including both the placement and removal of endotracheal tubes and deep suctioning maneuvers. Fast-acting agents help to reduce the time spent in stage 2 as much as possible and to facilitate entry to stage 3. Bilal A. Siddiqui; Peggy Y. Kim ; Anesthesia Stages; StatPearls publishing; 2020 Jan

86. Stage 3 – Su r gic al Anesthe s ia: Ceased eye movements and respiratory depression are the hallmarks of this stage. Airway manipulation is safe at this level. Plane 1: Regular spontaneous breathing, constricted pupils. However, eyelid, conjunctival, and swallow reflexes usually disappear in this plane. Plane 2 : Intermittent cessations of respiration along with the loss of corneal and laryngeal reflexes. Halted ocular movements and increased lacrimation may also occur. Plane 3 : “ True surgical anesthesia " Complete relaxation of the intercostal and abdominal muscles and loss of the pupillary light reflex. Plane 4 : Irregular respiration, paradoxical rib cage movement and full diaphragm paralysis resulting in apnea. Bilal A. Siddiqui; Peggy Y. Kim ; Anesthesia Stages; StatPearls publishing; 2020 Jan

87. Stage 4 - Overdose: Occurs when too much anesthetic agent is given relative to the amount of surgical stimulation, which results in worsening of an already severe brain or medullary depression. Begins with respiratory cessation and ends with potential death. Skeletal muscles are flaccid, and pupils are fixed and dilated at this stage. Blood pressure is typically significantly lower than normal, with weak and thready pulses due to the suppression of the cardiac pump and vasodilation in the peripheral bloodstream. Without cardiovascular and respiratory support, this stage is lethal. Bilal A. Siddiqui; Peggy Y. Kim ; Anesthesia Stages; StatPearls publishing; 2020 Jan

88. Equipment in General anesthesia

89. Anesthetic equipment : Anesthetic and resuscitation equipment Monitoring equipment Oxygen delivery equipment Intravenous infusion equipment

90. Anesthesia and resuscitation equipment: Anesthesia machine Anesthetic mask Laryngoscope Airway Nasop h aryngeal Oropharyngeal Laryngeal mask Magill’s forceps Resuscitation bag

91. Anesthesia and resuscitation equipment: Anesthesia machine Anesthetic mask Laryngoscope Airway Nasopharyngeal Oropharyngeal Magill’s forceps Mouth prop Resuscitation bag

92. Monitoring equipment: Blood pressure monitor Cardioscope (ECG) Pulse oximeter Capnometer/ Capnograph Temp

93. Oxygen delivering equipment : Oxygen cylinder Black in color with a shoulder painted white. Used on anesthesia machines have a flushed valve whereas those used in the wards have a bull-nose valve. Oxygen flow meter Oxygen masks Nasal catheter/ prongs

94. Intravenous infusion equipments : Intravenous cannula Bivalve Infusion set Intravenous fluid

95. Anesthetic agents

96. Properties of ideal anesthetic agents: For the patient: It should be pleasant, nonirritating, should not cause nausea or vomiting. Induction and recovery should be fast with no after-effects. For the surgeon: It should provide adequate analgesia, immobility and muscle relaxation. It should be noninflammable and nonexplosive, so that cautery may be used.

97. For an anesthetist: Its administration should be easy, controllable and versatile. Margin of safety should be wide—no fall in blood pressure. Heart, liver and other organs should not be affected. It should be potent, so that low concentrations are needed and oxygenation of the patient does not suffer. Rapid adjustments in depth of anesthesia should be possible. It should be cheap, stable and easily stored. It should not react with rubber tubing or soda lime.

98. Classification of General anesthesia:

99. INHAL A T I ON A L AG E NTS

100. INHALATIONAL – VOLATILE LIQUIDS Halothane: Volatile liquid, easily vaporized, stable and nonflammable Most potent inhalational anesthetic agent Colorless liquid, pleasant smell and nonirritating to respiratory tract 2–4% for induction and 0.5–1.5% for maintenance. May be administered with either oxygen or a mixture of oxygen and nitrous oxide. Pharmacokinetics: 60–80% eliminated unchanged. 20% retained in body for 24 hours and metabolized. 20% metabolized in liver by oxidative pathways

101. Indications: Indicated for the induction and maintenance of general anesthesia. Advantages: Potent anesthetic, rapid smooth speedy induction and recovery. Suitable in children for inhalation induction. Minimal stimulation of salivary and bronchial secretion. Low incidence of postoperative nausea and vomiting. It causes moderate skeletal muscle relaxation—less requirement for nonpolarizing muscle relaxant.

102. Disadvantages: Progressively depresses respiration. Weak analgesic. It may cause decrease in mucociliary function, which leads to sputum retention. It causes bronchodilation. Hypoxia, acidosis, or apnea may develop during deep anesthesia. Halothane anesthesia reduces the blood pressure and causes bradycardia

103. INHALATIONAL – VOLATILE LIQUIDS Isoflurane It is an halogenated ether derivative. Colourless, volatile liquid, pungent odour and stable. Induction dose is 1.5–3% and maintenance dose is 1–2% It causes dose dependent depression of ventilation. Cerebral blood flow is increased while the cerebral metabolism is reduced. It causes dose dependent muscle relaxation

104. Advantages Rapid induction and recovery. Little risk of hepatic or renal toxicity. Low nausea and vomiting. Produces adequate muscle relaxation. Non-cardiotoxic, non-hepatotoxic, non-nephrotoxic, non-tissue toxic. Disadvantages Pungent odor. Irritating vapor, therefore not commonly used for induction. Maintenance only Volatile anesthetic. Respiratory depression.

105. INHALATIONAL – VOLATILE LIQUIDS Sevoflurane New drug, non inflammable, pleasant smell, MAC value is 2% and stable. The most commonly used agent is sevoflurane , because it causes less irritation than other inhaled gases ( inhalation induction agent ). Metabolized by liver, releasing fluoride ions: it may be nephrotoxic. Rapidly eliminated and allows rapid awakening. Non irritant, may cause respiratory depression.

106. Advantages Nonirritating, useful for inhalational induction, especially in children. Well tolerated , even at high concentrations, making this the agent of choice for inhalational induction. Rapid induction and recovery : Fastest for induction. Does not sensitize the myocardium to catecholamines as much as halothane. Disadvantages Less potent than similar halogenated agents. Postoperative agitation may be more common in children then seen with halothane. About 5% is metabolized and elevation of serum fluoride levels has led to concerns about the risk of renal toxicity.

107. INHALATIONAL – GAS Nitrous oxide: Only inorganic gas used for anesthesia Properties: Sweet smelling, nonirritating, colorless gas, nonflammable, and tasteless. Minimum alveolar concentration = 105% It is a potent analgesic, but a weak anesthetic Rapid onset and recovery. Rapid elimination, primarily through the lungs, small amount through skin, sweat glands, urine,and intestinal gas.

108. Advantages: Non-inflammable and non-irritant. Rapid induction and recovery. Very potent analgesic (low concentration). No nausea and vomiting. Nontoxic to liver, kidney and brain. Disadvantages: Not potent alone (supplementation). Hypoxia Inhibits vitamin B12 metabolism.

109. Zones of N2O : Four zones of N2 O anesthesia have been described: Moderate analgesia (6–25%): Moderate analgesia Dissociative analgesia (26–45%): Gives rise to psychological symptoms and lack of ability to concentrate. Analgesic anesthesia (46–65%): Near complete analgesia. Patient may respond to commands. Light anesthesia (66–80%): Complete analgesia and amnesia, not possible to communicate with the patient.