General anaesthesia, anindya

an enigma about general anesthesia for maxillofacial perspective as well as general surgical perspective

1. GENERAL ANESTHESIA By DR. ANINDYA 2 nd YEAR PG OMFS

2. INTRODUCTION General anesthetics (GAs) are drugs which: R eversible loss of all sensations and consciousness. L oss of memory and awareness with insensitivity to painful stimuli, during a surgical procedure. Amnesia- hypnosis Analgesia Areflexia

3. Definition GENERAL ANESTHESIA: It is a controlled state of unconsciousness, accompanied by partial or complete loss of protective reflexes, including the inability to independently maintain an airway or respond purposefully to verbal command. CONCIOUS SEDATION: It is a state of mind obtained by IV administration of combination of anxiolytics, sedatives and hypnotics &/or analgesic that render the patient relaxed, yet allows the patient to communicate, maintain patent airway and ventilate adequately. DEEP SEDATION: It is a depressed level of consciousness with some blunting of protective reflex, although it remains possible to arouse the patient. IATRO SEDATION: A general term used for any technique of anxiety reduction in which no drugs are given Relief of anxiety through the doctor’s behavior - it is one of the form of psychosedation

4. Ether synthesized in 1540 by cordus General anesthesia was absent until the mid-1800s. Ether used as anesthetic in 1842 by dr. Crawford W.Long 1846 – Oliver Wendell Sr.  “Anesthesia” meaning: Insensibility during surgery produced by inhalation of ether. William T. G. Morton (dentist) was the first to publicly demonstrate the use of ether during surgery(1846). Chloroform used as anesthetic in 1853 by dr. John snow 1860 – Albert Niemann  Cocaineas . Endotracheal tube discovered in 1878 Thiopental first used in 1934 Curare first used in 1942 - opened the “Age of anesthesia” HISTORICALBACK GROUND

5. PROPERTIES OF AN IDEAL ANAESTHETIC For the patient – Should be pleasant, Non irritating , Should not cause nausea or vomiting. Induction and recovery should be fast with no after effects. For the surgeon – Should provide adequate analgesia , Immobility and muscle relaxation. It should be noninflammable and nonexplosive so that cautery may be used.

6. For the anaesthetist – Its administration should be easy, controllable and versatile. Margin of safety should be wide - no fall in BP. 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 anaesthesia should be possible. It should be cheap, stable and easily stored. It should not react with rubber tubing or soda lime.

7. BALANCED ANESTHESIA

8. SIGNS & STAGES OF ANAESTHESIA (GUEDEL’S Signs)  Guedel (1920) described four stages with ether anaesthesia, dividing the III stage into 4 planes . The order of depression in the CNS is: Cortical centers→basal ganglia→spinal cord→ medulla

9. Stages of anesthesia Guedel (1920) described four stages with ether anesthesia , dividing the III stage into 4 planes. The order of depression in the CNS is : Cortical centers B asal ganglia Spinal cord Medulla

10. Mechanisms of GA The unitary theory of anesthesia – Meyer-Overton rule (1901 ) Lipid : water partition coefficient GA (gases) are highly lipid soluble and therefore can easily enter in neurones After entry causes disturbances in physical chemistry of neuronal membranes – fluidization theory Finally, obliteration of Na+ channel and refusal of depolarization The unitary theory has been discarded now!

11. Mechanisms of GA For inhalation anesthetics – Minimum Alveolar Concentration (MAC) – 1 (one ) MAC is defined as the minimum alveolar concentration that prevents movement in response to surgical stimulation in 50% of subjects. Correlates with oil/gas partition coefficient Practically – Alveolar concentrations can be monitored continuously by measuring end-tidal anesthetic concentration using spectrometry For Intravenous agents – Potency of IV agent is defined as the free plasma concentration (at equilibrium) that produces loss of response to surgical incision in 50% of subjects. Difficult to measure: no available method to measure blood or plasma concentration continuously Free concentration at site of action cannot be determined (MAC explains only capacity of anaesthetics to enter in CNS and attain sufficient concentration, but not actual MOA)

12. Modern theory on Mechanism of General Anesthesia Major targets – ligand gated ion channels Important one – GABAA receptor gated Cl ¯ channel GABA A receptors - 4 transmembrane (4-TM) ion channel 5 subunits arranged around a central pore: 2 alpha, 2 beta, 1 gamma Each subunit has N-terminal extracellular chain which contains the ligand-binding site 4 hydrophobic sections cross the membrane 4 times: one extracellular and two intracellular loops connecting these regions, plus an extracellular C-terminal chain

13. GABA A Receptor gated Cl ¯ Channel Normally, GABA A receptor mediates the effects of gamma-amino butyric acid (GABA), the major inhibitory neurotransmitter in the brain GABA A receptor found throughout the CNS most abundant, fast inhibitory, ligand-gated ion channel in the mammalian brain located in the post-synaptic membrane Ligand binding causes conformational changes leading to opening of central pore and passing down of Cl - along concentration gradient Net inhibitory effect reducing activity of Neurones General Anaesthetics bind with these channels and cause opening and potentiation of these inhibitory channels – leading to inhibition and anesthesia

14. Inhalation anesthetics Common features of inhaled anesthetics Modern inhalation anesthetics are nonflammable, nonexplosive agents. Decrease cerebrovascular resistance, resulting in increased perfusion of the brain Cause bronchodilation , and decrease both minute ventilation and hypoxic pulmonary vasoconstriction MAC (potency): The alveolar concentration of an anesthetic gas needed to eliminate movement among 50% of patients challenged by a standardized painful stimulus (skin incision). MAC is the ED 50 of the anesthetic . the inverse of MAC is an index of potency of the anesthetic .

15. uptake and distribution of inhalation anesthetics The movement of these agents from the lungs to the different body compartments depends upon their solubility in blood and tissues as well as on blood flow. Because gases move from one compartment to another within the body according to partial pressure gradients, a steady state (SS) is achieved when the partial pressure in each of these compartments is equivalent to that in the inspired mixture.

16. Factors Determine the time course for attaining Steady State: Anesthetic concentration in the inspired air ( Alveolar wash-in ): replacement of the normal lung gases with the inspired anesthetic mixture. The time required for this process is directly proportional to the functional residual capacity of the lung, inversely proportional to the ventilatory rate; it is independent of the physical properties of the gas . Anesthetic uptake: is the product of gas solubility in the blood, cardiac output, and the alveolar to venous partial pressure gradient of the anesthetic. Solubility in the blood: called the blood/gas partition coefficient. The solubility in blood is ranked in the following order : halothane > enflurane > isoflurane > sevoflurane > desflurane > n2o . An inhalational anesthetic agent with low solubility in blood shows fast induction and also recovery time (e.g., N2O), and an agent with relatively high solubility in blood shows slower induction and recovery time (e.g., halothane ). Wash out : when the administration of anesthetics discontinued, the body now becomes the “source” that derives the anesthetic into the alveolar space. The same factors that influence attainment of steady-state with an inspired anesthetic determine the time course of clearance of the drug from the body. Thus N2O exits the body faster than halothane.

17. Inhalation sedation Indication Uncooperative patient Mildly apprehensive patient Medically compromised patient Patient with gaging reflex Contraindication Patient with extreme anxiety Nasal obstruction, sinus problem, common cold URTI Serious psychiatry disorder COPD patient Advantage Easy to administer Rapid onset Rapid uptake Wide margin of safety Nausea-Vomiting uncommon Disadvantage Expensive equipment Occupational hazards from Nitrous Oxide leakage

18. Nitrous oxide (N 2 O) “laughing gas” It is a potent analgesic but a weak general anesthetic. Rapid onset and recovery: Does not depress respiration, and no muscle relaxation. No effect on CVS or on increasing cerebral blood flow The least hepatotoxic, Teratogenic, bone marrow depression . Second gas effect: N2O can concentrate the halogenated anesthetics in the alveoli when they are concomitantly administered because of its fast uptake from the alveolar gas . Diffusion hypoxia: speed of N2O movement allows it to retard oxygen uptake during recovery.

19. Ether Known as diethyl ether. Prepared by Cordus in1540 – sweet oil of vitriol Blood gas partition coefficient is 15 Guedel stage of anesthesia is described on ether anesthesia On induction – analgesia > excitement > anesthesia Increase CSF pressure, blood glucose level Postoperative nausea and vomiting in 50 % of patient

20. Halothane ADVANTAGE Potent anesthetic, rapid induction & recovery Neither flammable nor explosive, sweet smell, non irritant Low incidence of post operative nausea and vomiting. Not hepatotoxic in pediatric patient, and combined with its pleasant odor, this makes it suitable in children for inhalation induction DISADVANTAGE Weak analgesic (thus is usually coadministerd with N2O, opioids) Is a strong respiratory depressant Is a strong cardiovascular depressant Hypotensive effect Cardiac arrhythmias: if serious hypercapnia develops due to hypoventilation and an increase in the plasma concentration of catecholamines Malignant hyperthermia   (2-bromo-2-chloro-1,1,1-trifluoroethane) Synthesized in 1951 Blood gas partition coefficient 2.5

21. Malignant hyperthermia:

22. ENFLUREN ADVANTAGE Less potent than halothane, but produces rapid induction and recovery ~2% metabolized to fluoride ion, which is excreted by the kidney Has some analgesic activity Differences from halothane : Fewer arrhythmias, less sensitization of the heart to catecholamines greater potentiation of muscle relaxant DISADVANTAGE CNS excitation at twice the MAC, Can induce seizure

23. ISOFLUREN ADVANTAGE A very stable molecule that undergoes little metabolism Not tissue toxic Does not induce cardiac arrhythmias Does not sensitize the heart to the action of catecholamines Produces concentration-dependent hypotension due to peripheral vasodilation It also dilates the coronary vasculature, increasing coronary blood flow and oxygen consumption by the myocardium, this property may make it beneficial in patients with IHD.

24. Intravenous sedation Advantage Highly effective technique Rapid onset of action Patent vein is a safety factor Control of salivary secretion Nausea vomiting less common Disadvantage Venepuncture is necessary Venepuncture complications Infiltration Hematoma thrombophlebitis Intensive monitoring required Delayed recovery

25. Intravenous anesthetics Barbiturates (thiopental, methohexital ) Potent anesthetic but a weak analgesic High lipid solubility; Quickly enter the CNS and depress function, often in less than one minute . Redistribution occur very rapidly as well to other body tissues, including skeletal muscle and ultimately adipose tissue (serve as a reservoir ). Thiopental has minor effects on the CVS but it may cause sever hypotension in hypovolemic or shock patient All barbiturates can cause apnea, coughing, chest wall spasm, laryngospasm , and bronchospasm 28

26. Intravenous anesthetics/ Propofol Phenol derivative It is an IV sedative-hypnotic used in the induction and or maintenance of anesthesia. Onset is smooth and rapid (40 seconds) It is occasionally accompanied by excitatory phenomena, such as muscle twitching, spontaneous movement, or hiccups . Rate of Infusion – 30 mg/kg/min – amnesic - 10 to 50 mg/kg/min – sedative dose Full orientation occur with in 5 to 10 minute after stopping of infusion. Decrease BP without depressing the myocardium, it also reduce intracranial pressure. It is widely used and has replaced thiopental as the first choice for anesthesia induction and sedation, because it produces a euphoric feeling in the patient and does not cause post anesthetic nausea and vomiting. Poor analgesia 29

27. Intravenous anesthetics/ Etomidate Is used to induce anesthesia, it is a hypnotic agent but lacks analgesic activity. Induction is rapid, short acting It is only used for patients with coronary artery disease or cardiovascular dysfunction, No effect on heart and circulation Adverse effects: a decrease in plasma cortisol and aldosterone levels which can persist for up to eight hours. This is due to inhibition of 11-B-hydroxylase 2/25/2016 30

28. ketamine Ketamine (phencyclidine derivative) Non-barbiturate hypnotic 1-2mg/kg – IV or 8-10 mg/kg - IM A short acting anesthetic (up to 15 min) induces a dissociated state in which the patient is unconscious but appear to be awake and does not fell pain. Profound analgesia, less vomiting Provides sedation, amnesia, and immobility Interacts with NMDA receptor, 31

29. ketamine Sympathomimetic effect: stimulates the central sympathetic outflow, causes stimulation of the heart and increased BP and COP. This property is especially beneficial in patients with either hypovolemic or cardiogenic shock, as well as in patients with asthma. Ketamine is therefore used when circulatory depression is undesirable. BP is often increased. It increases cerebral blood flow and induces postoperative hallucinations “nightmares” particularly in adults, No M. relaxation 32

30. Adjuvants / Opioids ( fentanyl , sufentanil ) Benzodiazepine (midazolam, lorazepam and diazepam) Are used in conjunction with anesthetics to sedate the patient. Opioids: Analgesic, not good amnesic, used together with anesthetics. They are administered either I.V, epidurally , or intrathecally All cause hypotension, respiratory depression and muscle rigidity as well as post anesthetic nausea and vomiting, antagonized by naloxone. Neuroleptanesthesia : Is a state of indeffernce and immobilization (analgesia and amnesia) produced when patient become analgesic, deeply seated and partially or wholly amnesic but yet remain capable of obeying commands and answering simple question. it occurs while fentanyl is used with droperidol and N 2 O, Is suitable for burn dressing, endoscopic examination 33

31. 34 Properties of Intravenous Anesthetic Agents Drug Induction and Recovery Main Unwanted Effects Notes thiopental Fast onset (accumulation occurs, giving slow recovery) Hangover Cardiovascular and respiratory depression Used as induction agent declining. ↓ CBF and O2 consumption Injection pain etomidate Fast onset, fairly fast recovery Excitatory effects during induction Adrenocortical suppression Less cvs and resp depression than with thiopental, Injection site pain propofol Fast onset, very fast recovery cvs and resp depression Pain at injection site. Most common induction agent. Rapidly metabolized; possible to use as continuous infusion. Injection pain. Antiemetic ketamine Slow onset, after-effects common during recovery Psychotomimetic effects following recovery, Postop nausea, vomiting ， salivation Produces good analgesia and amnesia. No injection site pain midazolam Slower onset than other agents Minimal CV and resp effects. Little resp or cvs depression. No pain. Good amnesia.

32. 35 Non-barbiturate induction drugs effects on BP and HR Drug Systemic BP Heart Rate propofol ↓ ↓ etomidate No change or slight ↓ No change ketamine ↑ ↑

33. Surgical Period and GA protocol Pre-anesthetic evaluation Use pre-anesthetic medication ↓ Induce by I.V thiopental or suitable alternative ↓ Use muscle relaxant ↓ Intubate ↓ Use, usually a mixture of N 2 O and a halogenated hydrocarbon→maintain and monitor. ↓ Withdraw the drugs → recover

34. Pre- Anesthetic Evaluation Meet the patient personally . Choose the right technique by the preferences , case and patient . Goal Increase Quality of preoperative care Reduce Morbidity and mortality of surgery Reduce Cost of preoperative care Reduce Anxiety Patient’s History History of use of anesthetics or drugs Pre-operative labs Physical examination & Problem Identification Risk Assessment Plan of Anesthetic Management Pre- anaesthetic Instructions Use the ASA and GOLDMAN scale for anaesthetic risk.

35. Physical Examination: General examination Airway assessment Respiratory system Cardiovascular system System related problems identified from the history

36. MALLAMPATI TEST PATIENT DOCTOR Upright, maximal jaw opening, tongue protrusion without phonation

37. Class I = visualize the soft palate, uvula, anterior and posterior pillars. Class II = visualize the soft palate and uvula. Class III = visualize the soft palate and the base of the uvula . Class IV = soft palate is not visible at all. Mallampati Classification

38. ULBT (Upper Lip Bite Test) Class 1: Lower incisors can bite upper lip above vermillion line. Class 2: Lower incisors can bite upper lip below vermillion line. Class 3: Lower incisors cannot bite the upper lip.

39. Interincisor distance (IID) Generally greater than 2.5 to 3 fingerbreadths (depending on observers fingers) Less than or equal to 4.5 cm is considered a potentially difficult intubation.

40. Thyromental distance(TMD) Upright, neck extension, mouth closed, Distance < 6.5cm difficult intubation

41. Sternomental Distance (SMD ) Extended head and neck, mouth closed, distance <12.5cm is a difficult intubation

42. medical status mortality ASA I Normal healthy patient without organic, biochemical, or psychiatric disease 0.06-0.08% ASA II Mild systemic disease with no significant impact on daily activity e.g. mild diabetes, controlled hypertension, obesity . Unlikely to have an impact 0.27-0.4% ASA III Severe systemic disease that limits activity e.g. angina, COPD, prior myocardial infarction Probable impact 1.8-4.3% ASA IV An incapacitating disease that is a constant threat to life e.g. CHF, unstable angina, renal failure ,acute MI, respiratory failure requiring mechanical ventilation Major impact 7.8-23% ASA V Moribund patient not expected to survive 24 hours e.g. ruptured aneurysm 9.4-51% ASA Physical Status Classification System For emergent operations, you have to add the letter ‘E’ after the classification.

43. GOLDMAN RISK ASSESMENT SCALE ( 1977 ) Factors Value History Age > 70 years (5 point) Myocardial infection with in 6 month (10 points) Cardiac Exam Signs of CHF: ventricular gallop or JVD (11 points) Significant aortic stenosis (3 points) Electrocardiogram Arrhythmia other than sinus or premature atrial contractions (7 points) 5 or more PVC's per minute (7 points) General Medical Conditions PO2 < 60; PCO2 > 50; K < 3; HCO3 < 20; BUN > 50; Creat > 3; elevated SGOT; chronic liver disease; bedridden (3 points) Operation Emergency (4 points) Intraperitoneal , intrathoracic or aortic (3 points) 0-5 Points: Class I 1% Complications 6-12 Points: Class II 7% Complications 13-25 Points: Class III 14% Complications 26-53 Points: Class IV 78% Complications

44. Recommended test Guidelines For Asymptomatic Patient

45. Disease based identification Tests Alcohol abuse CBC, PT/PTT, AST/ Alkp , ECG, Plt Adrenal cortical Disease CBC, Elec , Glu , Plt Anemia CBC, Plt Cancer, except skin, without known metastases CBC, CXR, Plt Diabetes Elec , BUN/Cr, Glu , ECG Hematologic abnormalities CBC, T/S &AB, PT/PTT, Plt Exposure to hepatitis AST/ Alkp , BUN/Cr Hepatic disease PT/PTT, BUN/Cr, AST/ Alkp Malignancy with chemotherapy CBC, PT/PTT, BUN/Cr, AST/ Alkp , CXR, Plt Malnutrition CBC, T/S &AB, PT/PTT, Plt Morbid obesity BUN/Cr, Glu , ECG Peripheral vascular disease or stroke CBC, Glu , BUN/Cr, ELEC, Plt

46. Disease based identification tests Personal or family history of bleeding CBC, PT/PTT, Plt Poor exercise tolerance or “real age” over 60 CBC, BUN/Cr, Glu , Plt Possibly pregnant HCG, CXR+ Pulmonary disease CBC, Elec , BUN/Cr , Glu , Plt Renal disease CBC, Elec , BUN/Cr, Plt Rheumatoid arthiritis CBC, ECG, CXR+, Plt Sleep apena CBC, ECG, Plt Smoking>40 pk /yr CBC, ECG, CXR+, Plt Suspected UTI r prosthesis insertion U A Systematic lupus BUN/Cr, ECG, CXR+

47. Therapy based indications TESTS Radiation therapy CBC, ECG, CXR, Plt Use of anticoagulants CBC, PT/PTT, Plt Use of digoxin and diurectics Elec , Bun/Cr, ECG Use of statins AST/ Alkp , ECG Use of steroid Eelc , Bun/ Cr, Glu Procedure based indications Procedure with significant blood loss CBC, T/S & ALB, Plt Procedure with radiographic dye Bun/Cr Class C Procedure CBC, T/S & ALB, Elec , Bun/Cr, Plt

48. INGESTED MATERIAL MINIMUM FASTING PERIOD, APPLIED TO ALL AGES (hr) Clear liquids 2 Breast milk 4 Infant formula 6 Nonhuman milk 6 Light meal (toast and clear liquids) 6 Fasting Recommendations

49. Pre- anaesthetic Medications

50. Preanaesthetic medication “It is the term applied to the administration of drugs prior to general anaesthesia so as to make anaesthesia safer for the patient” Ensures comfort to the patient & to minimize adverse effects of anesthesia

51. Pre- anaesthetic Medications Serve to Relief of apprehension or anxiety Sedation Analgesia Amnesia of perioperative events Antisialogogue effect Reduction of stomach acidity Prevention of nausea and vomiting Vagolytic action Facilitation of anesthetic induction Prophylactic against allergies

52. Preanesthetic Medicine: Benzodiazepines; midazolam or diazepam: Anxiolysis & Amnesia. Barbiturates; pentobarbital: sedation Diphenhydramine: prevention of allergic reactions: antihistamines H2 receptor blocker- ranitidine: reduce gastric acidity.

53. Anti-anxiety drugs Provide relief from apprehension & anxiety Post-operative amnesia Benzodiazepine anxiolytics but no analgesia – should not be given with opioids Midazolam Iv – 0.05-0.1 mg/kg (2 to 5 mg in 0.5 mg increment) – return to normal within 4 hr Intra-nasal dose – 0.6 mg/kg Diazepam Gold standard Oral doses – 5-10 mg With opioid can produce respiratory and cardiovascular depression Flumezanil Drug antagonized the sedative and amnestic effect of midazolam 0.1 -0.5 mg Short acting – preferably given in infusion form

54. Sedatives-hypnotics Barbiturates Priorly used but now generally no use Replaced by benzodiazepine Doses – 50-200 mg orally Action within 15 to 20 minute – duration last – 2 to 4 hr Butyrophenon Mainly antiemetic but can produce sedation Doses – IV/IM – 2.5 to 7.5 mg Phenothiazine Sedation, anticholinergic and antio emetic effect Always used with opioids Lytic cocktail – 50 mg pethidine + 25 mg promethazine + 10 mg chlorpromazine Promethazine Antisialogogue + antihistaminic + sedative Doses – Orally – 10 – 25 mg Trimeperezine tartrate Doses – 3-4 mg/kg – 2 hr preoperatively

55. ANALGESIC AGENT Morphine Well absorbed after IM injection Onset – 15 to 30 minute Peak effect – 45 to 90 minute Lasting for 4 hr May cause – orthostatic hypotension, respiratory distress, addiction Fentanyl (preferred most now a days/ given just before induction) 50 to 125 times potent than morphine Respiratory depression is high Dose – 1-2umg/kg Onset – 30 to 60 second Route – intranasally , orally, transdermally Pethidine Doses – 50 to 100 mg – IM / IV – single dose lasts for 2 to 4 hour Buprenorphine Highly potent drug 3 to 6 umg /kg – IM/IV Respiratory depression

56. Anticholinergic agents Actions Vagolytic Increase heart rate by blocking acetylcholine on muscarinic receptor in SA node Atropine is more effective than glycopyrolate / scopolamine Useful in preventing intraoperative bradycardia resulting from vagal stimulation or carotid sinus stimulation Atropine (0.5mg IM) also helps in preventing vasovagal attack Antisialogogue Induce drying of salivary, gastric, tracheobronchial and sweat gland secretion Glycopyrolate (0.1-0.3 mg IM) is more potent – long acting drying effect Should be given 30 minute prior to the procedure Sedation and amnetia Atropine and scopolamine cross blood-brain barrier Atropine cause delirium in elderly Scopolamine has good sedative and amnesic effect Side Effects Pupillary dilatation Tachycardia, cardiac arrhythmia Delirium, confusion, restlessness Increase body temperature

57. Antiemetics - - Metoclopramide (10mg i.m .) used as antiemetic & as prokinetic gastric emptying agent prior to emergency surgery – 30-60 minute prior to surgery - Domperidone (10mg oral) more preferred (does not produce extrapyramidal side effects) - Ondansetron (4-8mg i.v .), a 5HT 3 receptor antagonist, found effective in preventing post-anaesthetic nausea & vomiting Drugs reducing acid secretion - - Ranitidine (150-300mg oral) or Famotidine (20-40mg oral) given night before & in morning along with Metoclopramide reduces risk of gastric regurgitation & aspiration pneumonia - Proton pump inhibitors like Omeprazole (20mg) with Domperidone (10mg) is preferred nowadays

58. DIFFERENT ASPECTS OF PREMEDICATION For OUT PATIENT DENTAL SURGERY Atropine/ Glycopyrolate – 30 min prior to surgery Diazepam (0.25mg/kg) – orally night before procedure For longer procedure – Midazolam (0.05-0.1mg/kg) – IM- 30 min prior to surgery If pt. having pain – fentanyl (100mg) may be added to midazolam For MAJOR MAXILLOFACIAL SURGERY Atropine / Glycopyrolate + Pethidine + Promethazine – 30 min prior to surgery Promethazine act for drying secretion + Sedation + prevent Histamine release For PEDIATRIC / CHILD PATIENT Vagus activity more predominant with small air passage Presence of secretion may cause deleterious effect Anticholinergic mandatory IM/IV Syrup TRIMEPERAZINE / Promethazine (0.6mg/kg) – to sedate Ketamine can also be given

59. Concurrent Drug therapy To be continued To be modified To be discontinued Antiarrythmics Insulin Diuretic- on the day of surgery Antiasthmatic Oral-anticoagulant Oral hypoglycemic Antibiotics Steroid cover Aspirin – 1 wk prior Antiepileptic Mono Amine Inhibitor – 2 wk prior to surgery B-blocker Oral contraceptive – 1 mnth cycle Ca channel blocker Eye drops Sedative/anxiolytic immunosuppressant

60. ANESTHETIC EQUIPMENT Anesthesia & Resuscitation equipment Anesthesia machine Breathing circuit Anesthetic mask Laryngoscope Endotracheal tube Airways Magill’s forceps Mouth prop Resuscitation bag Monitoring equipment Blood pressure monitor Cardioscope Pulse oximeter Capnometer Respiratory gas monitor Oxygen therapy Equipment Oxygen cylinder Oxygen flowmeter Oxygen mask Nasal catheter/ prongs Intravenous infusion equipment Scalp needle Intravenous cannula Bivalve (three way) Infusion set Intravenous fluids

61. Anesthesia Machine To deliver a desired concentration of a mixture of anesthetic agents in an inhalation form with oxygen and/or air – act as a vehicle to carry this mixture to the outlet of the equipment. Consist of Cylinder of gases Flow meter Vaporizer Oxygen flush / emergency oxygen knob Working platform and tray Two type Intermediate flow (Walton 5 machine) Continuous flow (Boyle machine)

62. Intermediate machine Gas flows on patient demand through DEMAND VALVE – now a days obsolete Continuous flow machine Oxygen/ nitrous oxide – individual flow meter Vaporizer – meant for setting desired percentage of anesthetic agent Disadvantage Delivery of hypoxic gas mixture Lead to – brain damage / coma/ cardiac arrest/ death To avoid newer anesthetic machine has – hypoxic gas mixture alarm

63. Breathing system Component Reservoir bag Excursion (rhythmical inflation + deflation) – allows visual monitoring of patient breathing Long corrugated breathing tube Flexible Prevent kinking Plastic body – light weight – less drag on mask Expiratory valve Spring loaded valve ( Heidbrink Valve) Non-rebreathing valve Types Magill’s system – a single corrugated tubing Bain’s system – coaxial tubing Closed circuit – double tubing – inspiratory / expiratory

64. Anesthetic mask Allows administration of gases from breathing unit Type Face mask Nasal mask Parts Connector / mount Body Edge / seal Size 1,2,3,4,5

65. Laryngoscope Designed for doing direct laryngoscopy Parts Handle Blade with light Size Neonate Pediatric Adult Extra large Type MacIntosh Miller’s Method of insertion Patient in supine position with neck flexon and head extension Entered through right – tongue pushed to left – extended till valecula

66. AIRWAY TUBES Oropharyngeal airway Nasopharyngeal airway LMA (Laryngeal Mask Airway) Esophageal tracheal combi - tube Endotracheal tube Nasotracheal tube Flexo-matalic tube Ring Adair Ellwyn (RAE) South pole North pole

67. Tracheal intubation Intubation after induction of GA Oral – OROTRACHEAL intubation Nasal – NASOTRACHEAL intubation Awake intubation Blind oral Blind nasal Retrograde – rail road technique Fiberoptic scope

68. Resuscitation Bag Consisting of Self inflating bag Non-breathing valve facemask Verities With reservoir bag Without reservoir bag Size Infant Child adult

69. Monitoring Equipment Blood pressure monitor Generally monitor on the right / left upper arm Types- Simple sphygmomanometer / aneroid dial Noninvasive automatic blood pressure monitor Invasive blood pressure monitor Cardioscope Help to monitor ECG Heart rate, rhythm Type of arrhythmia It may be either 3 lead or 12 lead

70. Pulse oximeter Non invasive equipment to monitor the oxygen saturation of the patient A small probe attached on any of the finger/ toes/ ear lobule It is important because hypoxia can occur from anesthetic gas mixture/ breathing circuit got disconnected Hypoxia can lead to brain death , coma and even cardiac arrest

71. Capnometer / capnograph Equipment that continuously record CO2 tension (in mm Hg or %) of expired gas Value – 35-45 mm Hg Also known as End Tidal CO2 monitor . Help anesthesiologist to decide Pt breathing adequately Whether tube is in trachea or oesophagus Breathing circuit is in position or not

72. Oxygen Therapy Equipment Oxygen Cylinder Oxygen flowmeter Oxygen Mask Nasal Catheter

73. Intravenous Infusion Equipment Scalp needle Intravenous cannula Bivalve ( three way) Infusion set IV fluid

74. Induction of anesthesia the period of time from the onset of administration of the anesthetic to the development of effective surgical anesthesia in the patient. It depends on how fast effective concentrations of the anesthetic drug reach the brain. During induction it is essential to avoid the dangerous excitatory phase (stage II delirium) that was observes with the slow onset of action of some earlier anesthetics. GA is normally induced with an I.V thiopental, which produces unconsciousness within 25 seconds after injection. At that time, additional inhalation or IV drugs comprising the selected anesthetic combination (skeletal M. relaxants) may be given to produce the desired depth of surgical stage III anesthesia. Inhalation induction: For children without IV access, non pungent agents, such as halothane or sevoflurane , are used to induce GA.

75. Maintenance of anesthesia Anesthesia is usually maintained by the administration of volatile anesthetics, because these agents offer good minute-to-minute control over the depth of anesthesia. Opioids such as fentanyl are often used for pain along with inhalation agents, because the later are not good analgesics. Usually: N 2 O + volatile agent (halothane, isoflurane ) Less often N 2 O + I.V Opioid analgesic (fentanyl, morphine, pethidine + N.M blocking agents

76. Recovery the time from discontinuation of administration of the anesthesia until consciousness and protective physiologic reflexes are regained. It depends on how fast the anesthetic drug diffuses from the brain. For most anesthetic agents, recovery is the reverse of induction; that is, redistribution from the site of action (rather than metabolism) underlies recovery.

77. Postoperative period N.M blocking agents and Opioids induced respiratory depression have either worn off or have been adequately reversed by antagonists. Regained consciousness and protective reflex restored Relief of pain: NSAIDs Postoperative vomiting: metoclopramide , prochlorperazine

78. Pre - Per- Post operative complications of GA

79. Complications Cause Management Coughing Irritation of airways, secretion By deepening of anesthesia / induce muscle relaxant Hiccup Afferent impulse from abdominal/ thoracic viscous via vagus Deepen anesthesia / induce muscle relaxant Wheezing Reflex under light anesthesia, ETT inserted too far, aspiration Rule out mechanical obstruction Deepen the level of anesthesia Aminophyline IV 250-500 mg Adrenaline IV 1-3 ml (1:10000) Salbutamol IV 250mg / 2.5mg inhalation Cyanosis Misplaced ETT Disconnection Airway obstruction Oxygen supply failure Properly position ETT Connect circuit properly Check gas supply Monitor ET CO2 SaO2 Hypertension Light anesthesia Hypoventilation Hypercarbia Use vasodilator Deep anesthesia level Ventilate properly Hypotension Due to anesthetic drug Blood loss B-blockers Volume load IV Atropine IV Vasopressor (dopamine) hypoxemia Failed oxygen delivery Obstructed airway Esophageal intubation Ventilate with self inflating bag Rule out disconnection Check ETT position

80. Hypercarbia Hypocarbia Hypothermia Malignant hyperthermia Pulmonary aspiration Laryngospasm Upper airway obstruction

81. Complications Management Nausea & Vomiting Keep patient supine Promethazine 12.5 mg- 25 mg IM/IV Metaclopromide 10-20 mg orally Ranitadine 50 mg IV Postoperative hypertension Passage of urine Oxygenate properly Chlorpromazine 2-5 mg IV Sodium nitro preside infusion Respiratory inadequacy Ventilate adequately with 100% oxygen Asses neuromascular block – IV Atropine/ Neostigmine (not more than 5 mg) Naloxane administer if narcotics used (0.4 mg dilute to 4 ml – 0.1 mg increament ) Respiratory obstruction Clear the airway Ventilate with bag and mask Oxygenate If require intubate SOS / Tracheostomy Postoperative shivering Oxygenation Warm the patient Stop any blood infusion

82. Thank You!