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7. GENERAL ANAESTHESIA
A state of unconsciousness produced by an anesthetic
agent,with absence of pain sensation over the entire
body and a greater or lesser degree of muscle
relaxation
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8. CARDINAL SIGNS -
Loss of all sensations
Unconsciousness (sleep)
Muscle relaxation
Abolition of reflexes
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9. History-
Before 1846 -
- physical methods(packing the limb in ice)
- drugs like alcohol,opium
1776 - Priestley - 1st anesthetic nitrous oxide
1844 - Horace Wells - nitrous oxide - extraction
1846 - William Morton – ether
After 1846
1847 - James Simpson – chloroform
1868 - Edmond Andrews – N2O+ O2
1929 – Cyclopropane
1935 – Thiopentone
1956 - Halothane
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13. STAGES OF
ANAESTHESIA :
Guedel (1920) –
i. Stage of analgesia
ii. Stage of delirium
iii. Stage of surgical
anesthesia
iv. Medullary paralysis
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14. Pharmacokinetics of inhalalational anaesthetics
alveoli blood brain
Factors affecting the transfer of anesthetic agent :
Solubility of the agent in blood
Rate of blood flow through lungs & tissues
Partial pressure of the agent
Elimination :
Halothane – 20% in liver
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15. Open drop method
Through anesthetic machines
- open system
- closed system
METHODS OF ADMINISTRATION
Open systemClosed system
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18. ADVANTAGES :
rapid induction & recovery
No deleterious effects on heart ,kidney ,liver
Nausea, vomiting uncommon
DISADVANTAGES :
Not a potent anesthetic
Co2 accumulation or hypoxia – prolonged administration
Special apparatus required
CONTRAINDICATION :
Patients with collection of air in pericardial, pleural and
peritoneal cavities, COPD.
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22. INTRAVENOUS ANESTHESIA
THIOPENTAL :
Ultra short acting barbiturates
Induction dose : neonates – 5 – 8 mg / kg
adults – 3-5 mg / kg
elderly – 1 - 3 mg / kg
METABOLISM :
Metabolized in liver
USES :
For induction of GA
Anesthetic for short duration surgery
As an anti convulsant
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23. ADVANTAGES :
1. Ease of administration
2. Rapid & pleasant induction
3. Low incidence of nausea & vomiting
4. Quick recovery
DISADVANTAGES :
1. Depth of anesthesia cant be judged
2. Apnea , coughing , laryngospasm ( occasional )
3. Shivering & delirium during recovery
4. Depresses vasomotor centre & myocardium
5. Poor analgesic & muscle relaxant
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24. PROPOFOL :
Oily liquid – 1% emulsion
Unconsciousness – 15 -45 sec
Rapidly metabolised in liver
USES :
Induction
Short duration surgeries
Day care surgery
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25. DISADVANTAGES :
Induction apnea
Respiratory depression – higher doses
Bradycardia
Pain during injection
ADVANTAGES :
rapid induction & recovery
no bronchospasm
low post op nausea & vomiting
safe during pregnancy
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26. KETAMINE :
Non – barbiturate anesthetic
Induces dissociative anesthesia
Primary site of action – cortex ( limbic system)
Dose – 1-3 mg / kg / IV
- 5 – 10 mg /kg / IM
DISADVANTAGES :
Delirium / hallucination
Poor muscle relaxant
Laryngospasm rare
USES :
Children – induction & maintainence of anesthesia
Adults – short surgical procedures
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28. COMPLICATIONS :
During Anaesthesia :
Respiratory depression
Salivation
Hypotension
Cardiac arrhythmias
Aspiration of gastric contents
Delirium , convulsions
After anesthesia :
Nausea , vomiting
Organ toxicity
Emergence delirium
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29. POST ANESTHETIC MEDICATION
Need for:
Relief of pain
Post op nausea & vomiting
DRUGS USED:
Opioids
Anti-emetics
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30. LOCAL ANAESTHESIA
Reversible loss of sensation in a area of the body caused by a
depression of excitation in nerve endings or an inhibition of the
conduction process in peripheral nerves.
History :
1860 – Neimann isolated cocaine
1884 – Sigmond Frued – cocaine induced localised numbness
1884 – Koller introduced cocaine as LA
1884 – Nash used cocaine for extraction
1905 – Einhorn developed procaine
1943 – Lofgren synthesized lignocaine
1948 – Gordh used lignocainewww.indiandentalacademy.com
31. CLASIFICATION :
I. BASED ON APPLICATION :
INJECTABLE SURFACE ANAESTHETICS
Low potency/short duration Soluble
procaine, chloroprocaine cocaine, lignocaine
Intermediate potency/duration Insoluble
lignocaine, prilocaine benzocaine
High potency/long duration
tetracaine, bupivacaine
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32. II. BASED ON CHEMICAL STRUCTURE :
Esters Amides
Benzioc acid esters lignocaine
cocaine prilocaine
Para-amino benzoic esters mepivacaine
procaine / tetracaine bupivacaine
benzocaine / chloroprocaine
III. BASED ON ORIGIN :
a. Natural : Cocaine
b. Synthetic: PABA derivatives – procaine / tetracaine
Acetanilide derivatives – lignocaine
Quinolone derivatives – cinchocaine
Acrinide derivatives – bucricaine
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33. CHEMISTRY :
Amphiphilic in nature
LA consists of :
Hydrophobic
group
Aromatic
residue
Hydrophilic
group
Tertiary
amine
Intermediate
alkyl
Intermediate
alkyl
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34. Ester:
Amide:
R —COO—R —N
R —NHCO—R —N
1 2
R
R3
4
21
R
R3
4
R — Lipophilic aromatic residue.
R — Aliphatic intermediate connector.
R , R — Alkyl groups, occasionally
H. Constitute with N the hydrophilic
terminus.
1
2
3 4
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35. IDEAL REQUIREMENTS :
Non irritating to tissues
Not cause permanent alteration in the nerve
Low systemic toxicity
Highly effective
Rapid onset of anesthesia
Long duration of action
No allergic reactions
Readily undergo biotransformation
Should be stable in solution
Should be sterile
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36. MECHANISM OF ACTION :
STRUCTURE OF A NERVE CELL –
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37. Differential sensitivity of nerve fibre
CLASS MYLENATION DIAMETER CONDUCTION
VELOCITY
FUNCTIONS
Aα
heavy 12-20 70-120 Motor and propioception
Aβ
Moderate 5-12 30-70 Touch and pressure
Aχ
Moderately 3-6 15-30 Motor to muscle spindle
Aδ
lightly 2-5 12-30 Pain, temperature, touch
B lightly 1-3 3-15 Preganglionic autonomic
C None
none
0.4-1.2
0.3-1.3
0.7-1.3
0.7-1.3
Pain & reflex response
Postganglionic sympathetics
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39. MECHANISM OF ACTION :
THEORIES :
Acetylcholine theory
Calcium displacement theory
Surface charge theory
Membrane expansion theory
Specific receptor theory – most accepted
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41. HOW DOES LA WORK ?
Displacement of Ca2+ from Na channel receptor site
which permits
Binding of LA to the receptor site which produces
Blockade of Na+ channel &
Decrease in Na conductance which leads to
Depression of rate of electrical depolarisation &
Failure to achieve threshold potential , along with a
Lack of development of propagated action potential
which is called conduction blockade
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43. Factors Affecting the Reaction of Local Anesthetics
Lipid solubility
Increase in the lipid solubility leads to faster nerve penetration,
block sodium channels, and speed up the onset of action..
Local anesthetics have two forms, ionized and nonionized. The
nonionized form can cross the nerve membranes and block the
sodium channels.
So, the more nonionized present, the faster the onset of action.
pH influence
Usually at range 7.6 – 8.9
Decrease in pH shifts equilibrium toward the ionized form,
delaying the onset action.
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44. Vasodilation
Affects the anesthetic potency & duration of action .
Lower vasodilator activity of a local anesthetic leads to a slower
absorption and longer duration of action
Protein binding
Protein binding regulate the duration of anaesthetic activity
Highly protein bound LA will remain for a long time Procaine
6% protein bound
Ropi, bupi, etidocaine 94-96% protein bound
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45. Local anesthetic metabolism
NHC
CH 3
O
CH N
R1
R2
R3
Hydroxylation
and conjugation
N-dealkylation
(and cyclization)
R4
Hydrolysis
Hydrolysis
AmideAmide
EsterEster
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60. Basic Emergency Management
P – position
unconscious – supine with feet elevated slightly
conscious – based upon patients comfort
A – airway
unconscious – assess and maintain the airway
conscious – assess the airway
B – breathing
unconscious – assess and ventilate if necessary
conscious – assess breathing
C – circulation
unconscious – assess and provide external cardiac
compression if necessary
conscious – assess circulation
D – Definitive care
Diagnosis
Management: Emergency drugs and/or assistancewww.indiandentalacademy.com
62. ALLERGY
Hypersensitive state due to exposure to a particular allergen, re-
exposure to which produces a heightened capacity to react.
• Causes –
Methyl paraben
Sodium bisulfite
Epinephrine
• Signs and symptoms –
Skin reactions
Urticaria, Angioedema
Respiratory reactions
Respiratory distress, Wheezing, Dyspnea, Cyanosis
Generalized anaphylaxis
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63. MANAGEMENT
ELECTIVE DENTAL CARE
-treatment postponed
EMERGENCY DENTAL CARE
-no treatment of invasive nature
-use GA
-histamine blockers as local anesthetics
-electronic dental anesthesia
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