2. Local Anaesthesia
 DEFINITION: Local anaesthesia is drug-induced reversible
local blockade of nerve conduction in a specific part of
the body that does not alter consciousness.

3. Prosperities of ideal LA
 Reversible action.
 Non-irritant.
 No allergic reaction.
 No systemic toxicity.
 Rapid onset of action.
 Sufficient duration of action.
 Potent.
 Stable in solutions.
 Not interfere with healing of tissue.
 Have a vasoconstrictor action or compatible with VC.
 Not expensive

4. structural classification of local
anaesthetics
•Examples of
amides include
lidocaine,
bupivacaine and
prilocaine.
Examples of esters
include cocaine,
procaine and
amethocaine.

6. Esters vs Amides
 The ester linkage is more easily broken so the ester drugs
are less stable in solution and cannot be stored for as long
as amides.
 Amide anaesthetics are also heat-stable.
 The metabolism of most esters results in the production
of para-aminobenzoate (PABA) which is associated with
allergic reaction.
 Amides, in contrast, very rarely cause allergic
phenomena. For these reasons amides are now more
commonly used than esters.

7. The mechanism of action of local
anaesthetics
 Disruption of ion
channel function via
specific binding to
sodium channels,
holding them in an
inactive state.
 Disruption of ion
channel function by
the incorporation of
local anaesthetic
molecules into the cell
membrane .

8. Demonstrating video

9.  Small nerve fibres are more sensitive than large nerve
fibres
 Myelinated fibres are blocked before non-myelinated
fibres of the same diameter.
 Thus the loss of nerve function proceeds as loss of
pain, temperature, touch, proprioception, and then
skeletal muscle tone. This is why people may still feel
touch but not pain when using local anaesthesia.

10. LA and pH
 All local anaesthetic agents are weak bases, meaning that
they exist in two forms: unionised (B) and ionised (BH+).
 The pKa of a weak base defines the pH at which both
forms exist in equal amounts.
 As the pH of the tissues differs from the pKa of the
specific drug, more of the drug exists either in its charged
or uncharged form.

12. Local anaesthetics and infection
 The relevant feature of infected tissue is
that it tends to be a more acidic
environment than usual.
 As the pH is reduced the fraction of
unionised local anaesthetic is reduced
and consequently the effect is delayed
and reduced.
 Infected tissue may also have an
increased blood supply and hence more
anaesthetic may be removed from the
area before it can affect the neurone.

13. Physicochemical characteristics of
a local anaesthetic affect its
function
 The aromatic ring structure and hydrocarbon chain length
determine the lipid solubility of the drug.
 The more lipid soluble drug penetrates the cell
membrane more easily to exert its effect.
 Thus bupivacaine – which is highly lipid soluble – is
approximately four times more potent than lidocaine.

14. The duration of action
 The duration of action of the drug is also related to the
length of the intermediate chain joining the aromatic and
amine groups.
 Protein binding , Procaine is only 6% protein bound and
has a very short duration of action, wherease bupivacaine
is 95% protein bound. bupivacaine have a longer duration
of action .

16. Absorption and distribution
 Some of the drug will be absorbed into the systemic
circulation: how much will depend on the vascularity of
the area to which the drug has been applied.
 The distribution of the drug is influenced by the degree of
tissue and plasma protein binding of the drug. the more
protein bound the agent, the longer the duration of
action as free drug is more slowly made available for
metabolism.

17. Metabolism and excretion
 Esters (except cocaine) are broken down rapidly by
plasma esterases to inactive compounds and
consequently have a short half life. Cocaine is hydrolysed
in the liver. Ester metabolite excretion is renal.
 Amides are metabolised hepatically by amidases. This is a
slower process, hence their half-life is longer and they can
accumulate if given in repeated doses or by infusion.

18. Adverse Effects
 CNS: excitation followed by depression
(drowsiness to unconsciousness and
death due to respiratory depression.
 Cardiovascular System: bradycardia,
heart block, vasodilation (hypotension)
 Allergic reactions: allergic dermatitis to
anaphylaxis (rare, but occur most often
by ester-type drugs).

19. Mechanism
•Block nerve conduction reversibly.
Two groups amide
Procaine,chloroprocaine,tetracaine Lidocaine,prillocaine,mepivocaine,bubi
vacaine,ropivacaine
Less common More common
Plasma cholinestrase Metabolized at liver
More side effect less

20. Uses:
 Local anesthesia.
 Ventricular arrhythmia.
 Decrease haemodynamic response to tracheal intubation
also decrease cough.
 Treatment of epileptic fits.

21. Advantage of using adrenaline:
•Epinephrine vasoconstricts arteries reducing bleeding and also delays the
resorption of lidocaine, almost doubling the duration of anaesthesia.
•Bupivacaine has caused several deaths when the epidural anaesthetic
has been administered intravenously accidentally.

22. Treatment of overdose: lipid rescue
 There is animal evidence that Intralipid, a commonly
available intravenous lipid emulsion, can be effective in
treating severe cardiotoxicity secondary to local
anaesthetic overdose.

23. Contraindications
 Heart block, second or third degree (without pacemaker)
 Severe sinoatrial block (without pacemaker).
 Serious adverse drug reaction to lidocaine or amide local
anaesthetics.
 Concurrent treatment with quinidine, flecainide,
disopyramide, procainamide (Class I antiarrhythmic
agents).
 Prior use of Amiodarone hydrochloride.

24.  Hypotension not due to Arrhythmia.
 Bradycardia.
 Accelerated idioventricular rhythm.

26. Six Placement Sites
Surface/topical Local infiltration Peripheral nerve
anesthesia block
Bier block (IV Epidural Spinal anesthesia
regional anesthesia
anesthesia)

27. Topical/Surface anesthesia
For Application to mucous membranes:
Nose- Mouth- Esophagus- Tracheobronchial tree-
Genitourinary tract.
Commonly used drugs:
 Cocaine (4%-10%).
 > 50% of rhinolaryngologic cases (USA).
 Unique pharmacological property: produces
localized vasoconstriction as well as
anesthesia.
 Localized vasoconstriction:
 less bleeding.
 improved surgical field visualization.

28. Cocaine substitution:
 lidocaine (Xylocaine) -oxymetazoline
(Afrin) combinations.
 tetracaine (pontocaine)-
oxymetazoline (Afrin) combinations.
 Tetracaine (pontocaine) (1%-2%).
 Lidocaine (Xylocaine) (2%-4%).
Ineffective agents:
 Procaine (Novocain) & chloroprocaine
(Nesacaine): poor mucous membrane
penetration.

29.  Nebulized lidocaine (Xylocaine)--
surface anesthesia
• Upper & lower respiratory tract
prior to bronchoscopy or fiber-
optic Laryngoscope.
• Treatment for intractable cough.
• Normal subjects: No effect on
airflow resistance (they produce
some bronchodilation).
• Patients with asthma: nebulized
lidocaine (Xylocaine) may increase
airflow resistance
(bronchoconstriction)-- concern if
bronchoscopy is intended for this
patient group.

30.  Systemic concentration following nebulized lidocaine (Xylocaine)
 Following mucosal absorption: systemic.
 concentration may be similar to IV injection.
Reasons:
 Large surface area.
 Significant vascularity of tracheobronchial region.

31. Skin Surface Application
Barrier: keratinized skin layer
 Higher local anesthetic
concentrations required:
o 5% lidocaine (Xylocaine)-
prilocaine (Citanest) cream
{2.5% lidocaine (Xylocaine)
& 2.5% prilocaine
(Citanest)}
 no local irritation.
 even absorption.
 no systemic toxicity.

32. Combination of local anesthetic:
Definition: eutectic mixture of local anesthetics (EMLA) .
General definition: eutectic--said of a mixture which has the lowest melting
point which it is possible to obtain by the combination of the given
components.
Melting point of combined drug is lower then either lidocaine (Xylocaine) or
prilocaine (Citanest) alone.

33. Clinical uses of EMLA applications-- pain relief for:
 Venipuncture
 Lumbar puncture
 Arterial cannulation

34. Special uses
 In combination with nitroglycerin ointment -- makes venous
cannulation easier by causing vasodilation.
 EMLA use in blood sampling: no effect on blood analysis.
Factors affecting EMLA analgesia time to onset, duration of action, & efficacy
 Skin blood flow.
 Epidermal/girl thickness.
 Application duration.
 Presence of pathology.

35. Contraindications/Concerns
 EMLA cream not recommended for mucosal application
due to faster lidocaine (Xylocaine)/prilocaine (Citanest)
absorption.
 EMLA cream not recommended for application to skin
wounds (wound infection risk, increased)
 EMLA cream: contraindicated in patients are allergic to
amide local anesthetics

36. Local Infiltration
 Definition: Extravascular placement of the local anesthetic in the region to
be anesthetized.
 Example: subcutaneous local anesthetic injection in support of
intravascular cannula placement.
 Preferred local anesthetics for local infiltration:
 Most common: lidocaine (Xylocaine).
 Other choices: 0.25% Ropivacaine (Naropin) or Bupivacaine (Marcaine)
(effective for pain management at inguinal operative location),

37.  Duration of action:
 Duration extended by 2x using 1:200,000 epinephrine.
 Caution: Epinephrine-containing local anesthetic solution should not be
injected intracutaneously (intradermal) or into tissues supplied by
"end-arteries" such as ears, nose, fingers because vasoconstriction may
be sufficiently severe to produce tissue ischemia and gangrene.

38. Peripheral Nerve Block
 Procedure: local anesthetic injection into tissues around individual nerves
or nerve plexuses (e.g. brachial plexus).
 Mechanism:
 Local anesthetic diffusion path: nerve outer surface (mantle) to the
nerve core [driving force: concentration gradient].
 Anesthetized first: mantle fibers (innervating more proximal
structures).
 Anesthetized last: core fibers (innervating more distal anatomy)
 Explanation of why anesthesia develops proximately first.
 Recovery in the opposite direction (sensation returns proximally first;
lastly the distal anatomy).

39. •The median nerve is blocked
by inserting the needle
between the tendons of the
palmaris longus and flexor
carpi radialis. The needle is
inserted until it pierces the
deep fascia. Three to 5 mL of
local anesthetic is injected.
Although the piercing of the
deep fascia has been described
to result in a fascial "click", it is
more reliable to simply insert
the needle until it contacts the
bone. The needle is then
withdrawn 2-3 mm and the
local anesthetic is injected.

42.  Mixed peripheral nerves: (motor/sensory)
 Sequence of onset & recovery (motor anesthesia first or sensory
anesthesia first): dependent on anatomical locations within the nerve
fiber.
 Not recommended: Tetracaine (pontocaine): slow onset & more likely to
cause systemic toxicity; not recommended for peripheral nerve block or for
local infiltration.

43. Duration of action-dependencies
• Prolongation of drug effect:
safer with added vasoconstrictor (e.g. epinephrine) than
by increasing local anesthetic dose.
 Example: bupivacaine (Marcaine) + epinephrine:
peripheral nerve block may last 14 hours (in some
reports).

44. Intravenous Regional Anesthesia
(Bier Block)
Procedure:
Local anesthetic injection into an
extremity isolated by tourniquet.
Result: rapid anesthesia onset; skeletal
muscle relaxation.
Duration of anesthetic action:
Dependent on how long the tourniquet
is kept inflated.
Following tourniquet deflation: rapid
recovery as blood dilutes local
anesthetic concentration.
Probable Mechanism:
Drug action on nerve endings & nerve
trunks.

46. Lidocaine Prilocaine
Higher lower plasma prilocaine
(Citanest) concentrations
following tourniquet
deflation, compared to
lidocaine
Less Safer
Agents not recommended:
 Chloroprocaine (Nesacaine) -- High incidence of thrombophlebitis.
 Bupivacaine (Marcaine) -- More likely than other local anesthetic to
cause cardiotoxicity upon tourniquet deflation.
 Ropivacaine (Naropin)-Might also cause cardiotoxicity upon
tourniquet deflation (less likely than with bupivacaine (Marcaine)).

47. Indications for local anesthesia
 Most frequent use: regional anesthesia.
 Analgesic espescially post operative pain.
 Lidocaine (Xylocaine) also reduces blood pressure response to direct
laryngoscopic tracheal intubation, an effect probably secondary to
generalized cardiovascular depression.
 Treatment of intractable cough.

49. 1-Causes.
2-Factors reducing toxicity.
3-Signs and symptoms.
4-Treatment of toxicity.

50. Causes :
 Accidental rapid
intravenous injection
 Rapid absorption, such as
from a very vascular site
ie mucous membranes.
 Overdose .

51. Factors reducing toxicity:
 Decide on the concentration of the local anaesthetic that
is required for the block to be performed. Calculate the
total volume of drug that is allowed according to the
table below

53.  Use the least toxic drug available
 Use lower doses in frail patients or at the extremes of
ages
 Always inject the drug slowly (slower than 10ml /minute)
and aspirate regularly looking for blood to indicate an
accidental intravenous injection
 Injection of a test dose of 2-3ml of local anaesthetic
containing adrenaline will often (but not always) cause a
significant tachycardia if accidental intravenous injection
occurs

54.  Add adrenaline (epinephrine) to reduce the speed of
absorption. The addition of adrenaline will reduce the
maximum blood concentration by about 50%. Usually
adrenaline is added in a concentration of 1:200,000, with
a maximum dose of 200 micrograms.
 Make sure that the patient is monitored closely by the
anaesthetist or a trained nurse during the administration
of the local anaesthetic and the following surgery.

55. Signs and Symptoms of Local
Anaesthetic Toxicity:
1-CNS toxicity :
 Early or mild toxicity: light-headedness, dizziness,
tinnitus, circumoral numbness, abnormal taste, confusion
and drowsiness.
 Severe toxicity: tonic-clonic convulsion leading to
progressive loss of consciousness, coma, respiratory
depression, and respiratory arrest.

56. 2-CVS toxicity:
 Early or mild toxicity: tachycardia and rise in blood
pressure. This will usually only occur if there is adrenaline
in the local anaesthetic. If no adrenaline is added then
bradycardia with hypotension will occur.
 Severe toxicity: Usually about 4 - 7 times the convulsant
dose needs to be injected before cardiovascular collapse
occurs. Collapse is due to the depressant effect of the
local anaesthetic acting directly on the myocardium.

58. Essential Precautions:
 Secure intravenous access before injection of any dose
that may cause toxic effects
 Always have adequate resuscitation equipment and drugs
available before starting to inject.

59. Treatment of Toxicity:
Treatment is based on the A B C D of Basic Life Support :
 A. Ensure an adequate airway, give oxygen in high
concentration if available
 B. Ensure that the patient is breathing adequately.
Ventilate the patient with a self inflating bag if there is
inadequate spontaneous respiration. Intubation may be
required if the patient is unconscious and unable to
maintain an airway.

60. C Treat circulatory failure with intravenous fluids and
vasopressors such as ephedrine (10mg boluses) if
hypotension occurs. Adrenaline may be used cautiously
intravenously in boluses of 0.5 - 1ml of 1:10,000 (1mg in
10ml) if ephedrine is either not available or not effective
in correcting the hypotension. Treat arrhythmias

61. D Drugs to stop fitting such as Diazepam 0.2-0.4mg/kg
intravenously slowly over 5 minutes repeated after 10
minutes if required, or 2.5mg - 10 mg rectally.
Thiopentone 1-4 mg/kg intravenously may also be used in
theatre
 Treatment of local anaesthetic toxicity is likely to have a
good outcome if toxicity is recognised and basic
resuscitation is started early. Monitor patients closely
when using local anaesthetics. If a reaction occurs.

62. Advantages of local anaesthesia
 Non inflammable.
 Excellent muscle relaxant effect.
 During local anesthesia the patient remains conscious.
 It requires less skilled nursing care as compared to other
anesthesia like general anesthesia.
 Maintains his own airway.

63.  Less pulmonary complication.s
 Aspiration of gastric contents unlikely.
 Less nausea and vomiting.
 Contracted bowel so helpful in abdominal and pelvic surgery.
 Postoperative analgesia.
 There is reduction surgical stress.
 Earlier discharge for outpatients.

64.  Suitable for patients who recently ingested food or fluids.
 Local anesthesia is useful for ambulatory patients having
minor
 procedures.
 Ideal for procedures in which it is desirable to have the patient
awake and cooperative.
 Less bleeding.
 Expenses are less.

65. Disadvantages of local anaesthesia
 There are individual variations in response to local anesthetic
drugs.
 Rapid absorption of the drug into the bloodstream can cause
severe, potentially fatal reactions.
 Apprehension may be increased by the patient's ability to see
and hear. Some patients prefer to be unconscious and
unaware.

66.  Direct damage of nerve.
 Post-dural headache from CSF leak.
 Hypotension and bradycardia through blockade of the
sympathetic nervous system.
 Not suitable for extremes of ages.
 Multiple needle bricks may be needed.

68. Introduction
 Spinal anesthesia also
called spinal analgesia or
sub-arachnoid block (SAB),
is a form of regional
anesthesia involving
injection of a local
anesthetic into the
subarachnoid space,
generally through a fine
needle.

69. Difference from epidural anesthesia
 Epidural anesthesia is a technique whereby a local
anesthetic drug is injected through a catheter placed into
the epidural space. This technique has some similarity to
spinal anesthesia, and the two techniques may be easily
confused with each other.

70. Differences include:
 The involved space is larger for an epidural, and
consequently the injected dose is larger, being about 10–
20 mL in epidural anesthesia compared to 1.5–3.5 mL in a
spinal.
 In an epidural, an indwelling catheter may be placed that
avails for additional injections later, while a spinal is
almost always a one-shot only.
 The onset of analgesia is approximately 15–30 minutes in
an epidural, while it is approximately 5 minutes in a
spinal.

71. Injected substances
 Bupivacaine (Marcaine) is the local anaesthetic most
commonly used, although lignocaine (lidocaine),
tetracaine, procaine, ropivacaine, levobupivicaine and
cinchocaine may also be used.
 Sometimes a vasoconstrictor such as epinephrine is
added to the local anaesthetic to prolong its duration.

72. Mechanism
 Regardless of the anesthetic agent (drug) used, the
desired effect is to block the transmission of afferent
nerve signals from peripheral nociceptors.
 Sensory signals from the site are blocked, thereby
eliminating pain.
 The degree of neuronal blockade depends on the amount
and concentration of local anesthetic used and the
properties of the axon.

73. Limitations
 Spinal anesthetics are typically limited to procedures
involving most structures below the upper abdomen.
 To administer a spinal anesthetic to higher levels may
affect the ability to breathe by paralyzing the intercostal
respiratory muscles, or even the diaphragm in extreme
cases (called a "high spinal", or a "total spinal", with
which consciousness is lost).

74. Indications
 This technique is very useful in patients having an irritable
airway (bronchial asthma or allergic bronchitis),
anatomical abnormalities which make endotracheal
intubation very difficult (micrognathia), borderline
hypertensives where administration of general anesthesia
or endotracheal intubation can further elevate the blood
pressure, procedures in geriatric patients.

75. Contraindications
 Non-availability of patient's consent, local infection or
sepsis at the site of lumbar puncture, bleeding disorders,
space occupying lesions of the brain, disorders of the
spine and maternal hypotension.

76. Operations
All surgical interventions below the umbilicus, is the general
guiding principle:
 Abdominal & vaginal hysterectomies
 Laparoscopy Assisted Vaginal Hysterectomies (LAVH)
combined with general anesthesia
 Caesarean sections
 Hernia (inguinal or epigastric)
 Piles fistulae & fissures
 orthopaedic surgeries on the pelvis, femur, tibia and the ankle
 nephrectomy

77. Complications
Can be broadly classified as immediate (on the operating
table) or late (in the ward or in the P.A.C.U. post-anesthesia
care unit):
 Spinal shock.
 Cauda equina injury.
 Cardiac arrest.
 Hypothermia.
 Broken needle.
 Bleeding resulting in hematoma, with or without subsequent neurological
sequelae due to compression of the spinal nerves.

78.  Infection: immediate within six hours of the spinal anesthetic
manifesting as meningism or meningitis or late, at the site of
injection, in the form of pus discharge, due to improper
sterilization of the LP set.
 PDPH: Post dural puncture head ache or post spinal head ache.

80. Epidural anesthesia

81. Mechanism
 Direct action on nerve
roots and spinal cord
following local anesthetic
diffusion across the dura.
 Diffusion of local
anesthetic into
paravertebral region.

82.  Onset of action:15-30
minute delay .
 Choice of local anesthetics:
 Lidocaine (Xylocaine):
frequently used; diffuses
well for tissues.
 Bupivacaine (Marcaine)
& Ropivacaine (Naropin)
(0.5%-0.75%).

83. Epidural anathesia Spinal anathesia
Site of injection In the epidural space Subarachnoid space
Onset and duration Slow onset and continous duration Rapid onset and limited
(use catheter) duration
advantages Can be used in analgesia Not used
Needle Curved,longand blunt (touhy) Small and sharp
dose 10_30ml 1_4ml
space Any space usually lumber lumber
Quality of sensory less More liable
and motor nerve
block
toxicity Hypotention gradual Sudden
total spinal +++ +
systemic toxicity +++ +

84.  Indications:
1-Pain relief:
a)Post operative
b)Labour pain
c)Cancer
2-Operations in perineum lower limb
lower abdomen.
3-Expected difficult intubation.
 An epidural injection may be
performed anywhere along the
vertebral column (cervical, thoracic,
lumbar, or sacral).

85. Contra indications:
A)absolute:
1-Hypovolemia.
2-Refusal of patient.
3-Coagulopathy.
4-Local and systemic sepsis.
B)relative:
- Increase intra cranial pressure deformity of vertebral
column.

86. Complications
A)during operation:
1)Hypotension
2)Bradycardia
3)Cardiac arrest
4)Nausea ,vomiting
5)Failed spinal
6)Total spinal
7)Broken needle
8)Hypothermia

87.  B)Post operative:
1)Post dural puncture
headache.
2)Back pain.
3)Meningitis and
neurological sequalae.
4)Haematoma.
5)Urine retention.