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

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

2. General anesthetics (GAs) are drugs which:
 Reversible loss of all sensations and consciousness.
 Loss of memory and awareness with insensitivity to
painful stimuli, during a surgical procedure.
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
It is a term used to describe the multidrug approach to managing the patient needs. Balanced
anesthesia takes advantage of drug’s beneficial effects while minimizing each agent’s adverse qualities.
Intraoperatively, an ideal anesthetic drug:
• would induce anesthesia smoothly, rapidly
• permit rapid recovery as soon as administration ceased.
A ‘balanced anesthesia’ is achieved by a combination of I.V and inhaled anesthesia and Preanesthetic
medications

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
Stage of
Analgesia
• analgesia and amnesia, the patient is conscious and conversational. Starts from
beginning of anaesthetic inhalation and lasts upto the loss of consciousness
• Pain is progressively abolished
• Reflexes and respiration remain normal
• Use is limited to short procedures
Stage of
Delirium
• From loss of consciousness to beginning of regular respiration
• Patient may shout, struggle and hold his breath; muscle tone increases, jaws are tightly
closed, breathing is jerky; vomiting, involuntary micturition or defecation may occur
• . Heart rate and BP may rise and pupils dilate due to sympathetic stimulation
• No operative procedure carried out
• Can be cut short by rapid induction, premedication

9. Surgical
anaesthesia
• Extends from onset of regular respiration to cessation of spontaneous breathing.
• This has been divided into 4 planes which may be distinguished as:
• Plane 1 roving eye balls. This plane ends when eyes become fixed.
• Plane 2 loss of corneal and laryngeal reflexes.
• Plane 3 pupil starts dilating and light reflex is lost.
• Plane 4 Intercostal paralysis, shallow abdominal respiration, dilated pupil.
Medullary
paralysis
• Cessation of breathing to failure of circulation and death.
• Pupil is widely dilated, muscles are totally flabby, pulse is thready or
imperceptible and BP is very low

10. 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:
1. Cortical centers
2. Basal ganglia
3. Spinal cord
4. Medulla

11. 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!

12. Modern theory on Mechanism of General Anesthesia
 Major targets – ligand gated ion channels
 Important one – GABAA receptor gated Cl¯ channel
• GABAA 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. GABAA Receptor gated Cl¯ Channel
 Normally, GABAA receptor mediates the effects of gamma-amino
butyric acid (GABA), the major inhibitory neurotransmitter in the
brain
 GABAA 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. General Anesthesia
Inhalational
Gas
Nitrous oxide
Zenon
Volatile
liquids
Ether
Halothane
Enflurane
Isoflurane
Desflurane
Sevoflurane
Methoxyflurane
Intravenous
Slower
acting
Dissociative
anesthesia
Ketamine
Opioid analgesia
Fentanyl
Benzodiazepines
Diazepam
Lorazepam
Midazolam
Inducing agents
Thiopentone sod.
Methohexitone sod.
Propofol
Etomidate
Droperidol

15. 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 ED50 of the anesthetic.
– the inverse of MAC is an index of potency of the anesthetic.

16. 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.

17.  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.

18. 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
o Advantage
o Easy to administer
o Rapid onset
o Rapid uptake
o Wide margin of safety
o Nausea-Vomiting uncommon
 Disadvantage
 Expensive equipment
 Occupational hazards from Nitrous
Oxide leakage

19. Nitrous oxide (N2O) “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.

20. 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

21. 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

22. It is an autosomal dominant genetic disorder of skeletal muscle that occurs in susceptible individuals undergoing general anesthesia with volatile agents and muscle relaxants (eg,
succinylcholine).
The malignant hyperthermia syndrome consists of the
• rapid onset of tachycardia
• hypertension,
• severe muscle rigidity,
• hyperthermia,
• hyperkalemi
• acid-base imbalance.
Rx Dantroline

23. 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

24. 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.

25. Desflurane:
• Rapidity of induction and recovery: outpatient surgery
• Less volatility (must be delivered using a special vaporizer)
• Like isoflurane, it decreases vascular resistance and perfuses all major tissues very well.
• Irritating cause apnea, laryngospasm, coughing, and excessive secretions
Sevoflurane:
• Has low pungency, not irritating the airway during induction; making it suitable for induction
in children
• Rapid onset and recovery:
• Metabolized by liver, releasing fluoride ions; thus, like enflurane, it may prove to be
nephrotoxic.
Methoxyflurane
• The most potent and the best analgesic anesthetic available for
clinical use. Nephrotoxic and thus seldom used.

26. 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

27. 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

28. 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

29. 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
3/21/2016
30

30. 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

31. ketamine
 Sympathomimetic effect:
 stimulates the central sympathetic outflow, causes stimulation of the heart and
increased BP and COP.
This property is especially beneficial
1. in patients with either hypovolemic or cardiogenic shock,
2. 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

32. 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 N2O, Is suitable for burn
dressing, endoscopic examination
33

33. 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.

34. 35
Non-barbiturate induction drugs effects on
BP and HR
Drug Systemic BP Heart Rate
propofol ↓ ↓
etomidate No change or slight
↓
No change
ketamine ↑ ↑

35. Pre-anesthetic evaluation
Use pre-anesthetic medication
↓
Induce by I.V thiopental or suitable alternative
↓
Use muscle relaxant
↓
Intubate
↓
Use, usually a mixture of N2O and a halogenated
hydrocarbon→maintain and monitor.
↓
Withdraw the drugs → recover

36.  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
1. Patient’s History
2. History of useof anesthetics
ordrugs
3. Pre-operative labs
4. Physical examination &
Problem Identification
5. Risk Assessment
6. Plan of Anesthetic
Management
7. Pre-anaesthetic Instructions
Use the ASA and GOLDMAN
scale for anaesthetic risk.

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

38. MALLAMPATI TEST
PATIENT
DOCTOR

39. 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

40. 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.

41. 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.

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

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

44. 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%

45. 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

46. Age up to 49 yrs CBC
Age 50-64yrs CBC,ECG
Age > 65 yrs CBC, ECG, CXR
Urine analysis, LFT, BUN/ Cr, Electrolyte,Blood Sugar

47. 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

48. PRE-ANAESTHETIC
MEDICATIONS

49. 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

50. 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

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

52. 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

53. 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

54. 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

55. 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

56. 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 5HT3 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

57.  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

58. 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

59.  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

60. 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)

61.  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.  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

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.  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

71.  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

72.  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

73. Oxygen Therapy Equipment
 Oxygen Cylinder
 Oxygen flowmeter
 Oxygen Mask
 Nasal Catheter

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

76. 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.

77. 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: N2O + volatile agent (halothane, isoflurane)
 Less often N2O + I.V Opioid analgesic (fentanyl, morphine, pethidine + N.M
blocking agents

78. 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.

79.  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

81. 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

82. 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

83. ThankYou!