it is about the use of local anesthesia

1. COMPLICATIONS OF LOCAL ANAESTHESIA

2. CONTENTS
 Introduction
 Definition
 History
 Properties
 Classification
• Chemical structure
• Duration of action
• Potency
• Mode of application
 Mechanism of action
 Factors affecting onset and duration of action of local
anesthetics
 Composition

3.  Complications
• Local
 Needle breakage
 Prolonged anesthesia or paresthesia
 Facial nerve paralysis
 Trismus
 Soft tissue injury
 Hematoma
 Pain on injection
 Burning on injection
 Infection
 Edema
 Sloughing of tissue
 Postanesthetic intraoral lesions
• Systemic
 Toxicity
 Adverse drug reactions
 Allergies
 Idiosyncrasy
 Fainting /syncope
 Methemoglobenemia

4.  Local anesthetics agents in medically compromised patients
 Cardiovascular diseases
 Hypertension
 Asthma
 Diabetes mellitus
 Pheochromocytoma
 Hyperthyroidism
 Hypothyroidism
 Bleeding disorders
 Pregnancy
 Universal safety guidelines
 Conclusion
 References

5. INTRODUCTION
 The local anesthetic drugs have been used as a mode of pain
control in dentistry and medicine for over 85 years.
 These are the drugs which upon topical application or local
injection cause reversible loss of sensory perception, especially of
pain, in a restricted area of the body.
 Many types of drugs have local anesthetic actions (eg.β-blockers
and antihistamines), but all those known and used as local
anesthetics have originated from cocaine.

6. WHAT IS LOCAL ANESTHESIA
 A loss of sensation in a circumscribed area of the body
caused by a depression of excitation in nerve endings or
an inhibition of the conduction process in peripheral
nerves.
STANLEY F. MALAMED
 Local anesthesia is defined as a reversible, temporary
cessation of painful impulses from a particular region of
the body
KOCH

7. HISTORY
 COCAINE -first local anesthetic agent isolated by NIEMAN -
1860 from the leaves of the coca tree.
 Its anesthetic action was demonstrated by KARL KOLLER in
1884.
 First effective and widely used synthetic local anesthetic -
PROCAINE -produced by EINHORN in1905 from benzoic acid
& diethyl amino ethanol.
 Its anesthetic properties were identified by BIBERFIELD and the
agent was introduced into clinical practice by BRAUN.
 LIDOCAINE- LOFGREN in 1948.
 The discovery of its anesthetic properties was followed in 1949 by
its clinical use by T. GORDH.
 Thereafter, series of potent anesthetic soon followed with a wide
spectrum of clinical properties.

8. Cocaine
structure

9. PROPERTIES OF LOCAL ANESTHESIA
 It should not be irritating to tissue to which it is applied
 It should not cause any permanent alteration of nerve structure .
 Its systemic toxicity should be low .
 Time of onset of anesthesia should be short .
 It should be effective regardless of whether it is injected into the
tissue or applied locally to mucous membrane.
 The duration of action should be long enough to permit the
completion of procedure.(yet not so long as to require an extended
recovery)

10. In addition to these qualities, BENNET lists other desirable
properties of ideal L.A :-
• It should have the potency sufficient to give complete anesthesia
without the use of harmful concentration solutions.
• It should be free from producing allergic reactions.
• It should be stable in solution and relatively undergo
biotransformation in the body.
• It should be either sterile or be capable of being sterilized by heat
with out deterioration.

11. CLASSIFICATION OF LOCAL
ANESTHESIA

12. Based on chemical structure

16. MECHANISM OF ACTION

21. Local anesthetic action. An injected local anesthetic exists in equilibrium as a quaternary
salt (BH+) and tertiary base (B). The proportion of each is determined by the pKa of the
anesthetic and the pH of the tissue. The lipid-soluble base (B) is essential for
penetration of both the epineurium and neuronal membrane. Once the molecule reaches
the axoplasm of the neuron, the amine gains a hydrogen ion, and this ionized,
quaternary form (BH+) is responsible for the actual blockade of the sodium channel. The
equilibrium between (BH+) and (B) is determined by the pH of the tissues and the pKa of
the anesthetic (pH/pKa).
Anesth Prog. 2012 Summer;59(2):90-101

22. FACTORS AFFECTING ONSET AND DURATION
OF ACTION OF LOCAL ANESTHETICS
 pH of tissue
 pKa of drug
 Time of diffusion from needle tip to nerve
 Time of diffusion away from nerve
 Nerve morphology
 Concentration of drug
 Lipid solubility of drug
J Can Dent Assoc 2002; 68(9):546-51

23. pKa:
Local anesthetics have two forms, ionized and nonionized. The
nonionized form can cross the nerve membranes and block the sodium
channels.
pH influence:
Usually at range 7.6 – 8.9
Decrease in pH shifts equilibrium toward the ionized form, delaying
the onset action.
Lipid solubility:
All local anesthetics have weak bases. Increasing the lipid solubility
leads to faster nerve penetration, block sodium channels, and speed up
the onset of action.

24. Protein binding:
The more tightly local anesthetics bind to the protein, the longer the
duration of onset action.
Vasodilation:
Vasodilator activity of a local anesthetic leads to a faster absorption
and slower duration of action
Vasoconstrictor is used to keep the anesthetic solution in place at a
longer period and prolongs the action of the drug

25. COMPOSITION
 LOCALANESTHETIC AGENT(DRUG) (xylocaine, lignocaine 2%)
Blockade of nerve conduction. 24.64 mg
 VASOCONSTRICTOR (adrenaline 1: 80,000)
Increase depth and increase duration of anesthesia; decreases aborption of local
anesthetic. 0.0125 mg
 SODIUM METABISULPHITE
reducing agent (antioxidant)
 METHYLPARABEN,CAPRYL HYDROCUPRIENOTOXIN
Bacteriostatic agent
 THYMOL Fungicide
 VEHICLE (DISTILLED WATER and NACL)
Volume and Isotonicity of solution

26. Dent Clin N Am 54 (2010) 587–599

27. Local Reg Anesth. 2018; 11: 35–44.

28. COMPLICATIONS OF LOCAL
ANESTHESIA

29.  There are mainly 2 types of complications present
after administration of local anesthesia:
1. Local
2. Systemic

30. LOCAL COMPLICATIONS
The following complications are:
• Needle breakage
• Prolonged anesthesia or paresthesia
• Facial nerve paralysis
• Trismus
• Soft tissue injury
• Hematoma
• Pain on injection
• Burning on injection
• Infection
• Edema
• Sloughing of tissue
• Postanesthetic intraoral lesions

31. NEEDLE BREAKAGE
 Rare complication in dental LA injection.
 CAUSES:
Sudden unexpected movement of the patient
Small needle size
Bent needles
Defective needles
Forceful contact with bone
 Needle fracture mainly occurred at the hub, never along the shaft of the
needle
 Broken needle fragments may cause pain, limit the opening of the
mouth, and lead to infection and it could migrate to other parts of the
body through muscle movement, causing damage to vital structures like
vessels or nerves.

32. Prevention
 Use long needles for deep injection (>18mm), i.e for inferior alveolar
nerve block in adults or older children.
 Avoid using 30-gauge needles for IAN block in adults or children.
 Do not bend needles when inserting them into soft tissue .
 Do not insert the needles till its hub.
 Redirect only when adequately withdrawn.

33. Management
 Remain calm
 Don't explore
 Have the patient keep opening wide
 Remove needle if it is visible with help of a small haemostat or Magill
forceps.
 If not visible take radiographs of the region .
 If needle is lost into the tissue spaces ,e.g. pterygomandibular space,
infratemporal space, assure the patient and review regularly.
 3D CT scanning recommended.
 Refer to an Oral Surgeon

34. Preoperative radiographic
images showing the broken
needle in (A) panoramic view,
(B) computed tomography
(CT) axial view, and (C) as a
3D-CT image.
The broken needle was
removed using a hemostat
forcep.

35.  thinner needles are prone to cause more pain because
the pressure applied on the syringe is much greater
with a small gauge needle, so it is advisable to use of a
27-gauge 21 mm needle, instead of a 30-gauge 21 mm
needle, for young patients who have a low pain
threshold.
 young patients can move abruptly and unexpectedly, so
the use of a mouth gag is advisable to avoid sudden
mouth closure during the administration of LA.
J Dent Anesth Pain Med. 2017 Sep; Sep;17(3):225-229

37. PROLONGED ANESTHESIA OR PARESTHESIA
 Persistent anesthesia or altered sensation well beyond the expected
duration of anesthesia .
 In addition it includes hyperesthesia, dysesthesia in which patient
experiences both pain and numbness.
 The patient reports feeling NUMB [frozen] many hours or days
after LA injection.
 Clinical response: sensation , swelling, tingling, itching, oral
dysfunction, tongue biting ,drooling, loss of taste ,speech
impediment.

38. Cause
 Trauma to any nerve
 Neurolytic agents: Injection of LA solution with alcohol or cold
sterilizing solution near a nerve produces irritation and edema of the
tissue and subsequent pressure on the nerve.
 Intraneural injection
 Hematoma : Hemorrhage around the neural sheath also causes
pressure on the nerve, leading to paresthesia.
 Articaine and prilocaine are more likely than other anesthetics to be
associated with paresthesia and have most commonly affected the
lingual nerve
 Many patients report the sensation of an electric shock throughout the
distribution of the involved nerve.

39.  the needle can penetrate the nerve sheath and
consequently could cause
(1) direct damage of nerve fibres
(2) damage of small blood vessels located within the nerve,
leading to intraneural haemorrhage
(3) damage of connective tissues within the nerve,
producing oedema within the nerve sheath.
Basic Clin Pharmacol Toxicol. 2015 Jul; 117(1):52-6

40. Problem:
 Persistent anesthesia, rarely total, in most cases partial, can lead to
self-inflicted soft tissue injury.
 Biting or thermal or chemical insult can occur without a patient’s
awareness
 When the lingual nerve is involved sense of taste may also be
impaired
PREVENTION
Strict adherence to injection protocol
proper care and handling of dental
cartridges

41. Management
 Most case resolve within 8 weeks
 Reassurance to the patient
 Reschedule the patient for examination every 2 months for as long
as the sensory deficit persist.
 Dental treatment may continue, but avoid re administering LA into
region of the previously traumatized nerve. Use alternate LA
techniques if possible.

42. FACIAL NERVE PARALYSIS
 Usually occurs in inferior alveolar nerve block
 Loss of the motor action of the muscle of facial
expression produced by LA
 lasts for one to seven hours.
 The patient suffers unilateral paralysis of the facial
muscles

43. Cause
 Caused by the induction of local anesthetic into the capsule of the
parotid gland which is located at the posterior border of
mandibular ramus clothed by medial pterygoid and masseter
muscles.
 Needle positioned inadvertently in the posterior direction, may
place the tip of needle within the body of the parotid gland.

44.  Paralysis of the muscles of facial expression, causing a
unilateral Bell palsy.
 The mouth will deviate to the affected side and the
individual will be unable to close the eye on the affected
side

45. Problem
 Lasts no longer than several hours depending on the LA
formulation used
 Primary problem is cosmetic; the person’s face appears lopsided
 Second problem is patient is unable to voluntarily close one eye.
 Protective lid reflex of the eye is abolished
 Winking and blinking become impossible
 Corneal reflex is intact and tears lubricate the eye.

46. Prevention
 BONE CONTACT when injecting
 If bone is not contacted, the needle should be withdrawn almost
entirely from the soft tissues and direct the tip of the needle
anteriorly and readvanced it till contacts bone
 Avoid over penetration
 Avoid arbitrary injection

47. Management
 Defer dental treatment
 Reassure patient( transient; no residual effect)
 contact lenses these should be removed, as the lenses may cause
damage to the cornea
 Cornea care(an eye patch should be applied until muscle tone
return)

48. OPHTHALMIC COMPLICATIONS
 include diplopia (double vision), ptosis (drooping of
upper eyelid), and mydriasis (dilatation of pupil),
amaurosis, blindness, anophthalmia, loss of
accommodation and strabismus.
 Alamanos et al reported that 8% of ocular complications
were permanent.
 Among the documented ocular complications, diplopia
(39.8%) is the most common followed by ptosis
(16.7%), mydriasis (14.8%), and amaurosis (13.0%)

49.  These complications are most commonly associated with
inferior alveolar nerve anesthesia (45.8%) or posterior
superior alveolar nerve anesthesia (40.3%) injected in
possible risk zones
 Amaurosis results from an intravascular administration
of local anesthetic agent into the maxillary artery.
 Accidental injection into the inferior alveolar artery
under pressure forces the anesthetic solution into the
maxillary artery and middle meningeal artery via
retrograde flow.

50.  The following steps can be taken to avoid such
complications, including aspiration before injection,
slow injection of small quantities (if possible without
epinephrine), and moving the needle during injection to
avoid injecting a large bolus of epinephrine in one
location

52.  This type of complication is best understood by
pathophysiological hypotheses that include intra-arterial injection,
intravenous injection, autonomic dysregulation, or deep injection
and diffusion.
 Management:
• the patient should be reassured.
• In the case of diplopia, the eye should be covered with a gauze
dressing, and the patient should be instructed about associated
safety risks.
• If symptoms persist or when vision deteriorates, referral to an
ophthalmologist is advisable.
Ned Tijdschr Tandheelkd. 2017 Mar; 124(3):149-153

54. TRISMUS
 Defined as a prolonged tetanic spasm of the jaw muscle
by which the normal opening of the mouth is restricted
 A motor disturbance of the trigeminal nerve precipitating
or resulting in spasm of the muscles of mastication
 Postinjection trismus can and does occur after the
administration of local anesthesia for inferior alveolar
blocks.

55. CAUSES :
 Trauma to muscles or blood vessels : caused by repeated needle
insertion especially into medial pterygoid in inferior alveolar
nerve block.
 Contaminated anesthetic solutions
 Hemorrhage- large volumes of extravascular blood can produce
tissue irritation, leading to muscle dysfunction as the blood is
slowly resorbed
 Infection
 Excessive anesthetic volume
 Injection of local anesthetic directly into muscle may cause a
mild myotoxic response, which can lead to necrosis. The
symptoms of trismus, often associated with pain, arise
anywhere from 1 to 6 days following an injection.
 Infection may produce hypomobility through increase pain,
increase tissue reaction and scarring

56. Prevention
 Sharp, sterile and disposable needles
 Proper care and handling of cartridges
 Use aseptic technique and clean injection site
 Atraumatic insertion
 Avoid repeated insertion
 Minimal injections and volume
Trismus is not always preventable

57. Management:
 With mild pain and dysfunction-
• Heat therapy- applying hot, moist towels to the affected area for
approx. 20 minevery hour
• Warm saline rinses- teaspoon of salt added to 12 ounce glass of
warm water; rinse held on the involved site
• Analgesics- aspirin
• Muscle relaxants
• Diazepam or benzodaizepine
• Physiotherapy- opening and closing of mouth and lateral
excursions of mandible for 5 min every 3-4 hr
• Use chewing gum for lateral mvements
• Avoid further dental treatment
• Antibiotics- continued for 7 full days

58.  Severe pain or dysfunction:
• Refer to oral surgeon
• Use of ultrasound or appliances

59. SOFT TISSUE INJURY
 Self inflicted trauma to lips and tongue is frequently
caused by the patients inadvertently biting or chewing
these tissues while still anesthetized
 Cause:
• Mostly in young children, mentally or physically
disabled children or adults and in older patients.
• Trauma to these anesthetized tissue lead to swelling and
pain

60.  Prevention:
• Place cotton rolls between lips and teeth
• Warn patient and guardian against eating, drinking hot fluids
and biting on lips or tongue
 Management:
• Analgesics
• Antibiotics, as necessary
• Lukewarm saline rinses
• Petroleum jelly or other
lubricants

62. Design 1 (A, B)
consisted of an anterior
extension with
numerous perforations,
design 2 (C, D) had a
buccal flap extension,
and design 3 (E, F)
comprised of serrated
borders.

63. HEMATOMA
 Defined as effusion into the extravascular space by inadvertent
nicking of blood vessels during administration o f LA.
 Rare in palatal region due to close adherence of mucoperiosteum
to the bone
 Tissue density surrounding the injured vessel is a determining
factor
 Denser the surrounding tissues less likely a hematoma is
developed

64. CAUSE:
 Damage to blood vessels by the needle during penetration into soft
tissue
 Most commonly involved vessels are pterygoid plexus of veins
,PSA vessels.
 Inferior alveolar nerve hematomas are visible intraorally whereas
PSA hematomas are visible extra orally.

65. Problem
• Causes inconvenience to the patient.
• Possible complication include trismus and pain.
• Swelling and discoloration of the region subside gradually over 7- 14
days
Prevention:
• Knowledge of normal antomy
• Modify the injection technique
• Use short needle for PSA block
• Minimize number of needle penetration
• Never use needle as a probe in tissues

66. Management:
 If hematoma is visible immediately following the injection, apply
direct pressure for not less than 2 min, if possible. Once bleeding
has stopped, discharge patient with instructions to :
 Apply ice intermittently to the site for the first 6 hours.
 Do not apply heat for at least 6 hours and may start from next day.
It should moist warm heat
 Use analgesics as required (aspirin or NSAIDs)
 Expect discolouration.
 If difficulty in opening occurs, treat as with trismus, described
above

67. PAIN ON INJECTION
 CAUSES:
• Careless injection technique and a callous attitude
• Dull needles
• Rapid deposition of LA solution (may cause tissue damage)
• Needle with barbs produce pain during withdrawal
• pressure from the spread of the anesthetic solution
• temperature of anesthetic solution
• low pH of anesthetic solution
• pain from the characteristics of the drug.

68.  Problem
• It increases patient anxiety and may lead to
sudden unexpected movement, increases risk of
needle breakage
• traumatic soft tissue injury to the patient or
needle stick injury to the administrator.

69. Prevention:
 Use the correct technique and equipment
 Stretch the mucosa with finger
 Distract the patient at the moment when the mucosa is
pierced
 Position the needle supraperiosteally
 Direct the bevel toward the bone
 Use sharp and small gauge needles.
 Use topical anesthetics properly.
 Room temperature solutions
 Rate of injection: faster injection is painful …Inject LA
slowly
 Slow removal of the needle

70.  swabbing anesthesia is often performed on the injection
point
 infiltration anesthesia, should be used rather than
subperiosteal or intraosseous injections that can cause
pain.
 the anesthetic ampoule must be used administered at a
temperature similar to body temperature
 sterile local anesthesia should be used
J Dent Anesth Pain Med. 2016 Jun; 16(2): 81–

71. Various painless anesthetic devices are
• Computer-controlled local anesthetic delivery (CCLAD)
devices.
 It slow and maintain the injection speed, but also
maintain a constant speed while taking into account
the anatomical characteristics of the tissues being
injected.
• Wand® (Milestone Scientific, Livingstone, NJ)
• Comfort Control Syringe (CCS; Dentsply, USA)
• QuickSleeper (Dental HiTec, France)
• iCT (Dentium, Seoul, Korea)
J Dent Anesth Pain Med. 2016 Jun; 16(2): 81–

75. BURNING ON INJECTION
 A burning sensation on injection may occur for two
reasons:
• First, local anaesthetics with a vasoconstrictor are
acidic(pH approx. 3.5) because of the preservative
required for the vasoconstrictor. This acidity can cause
the anaesthetic to burn when it is injected into tissues.
• As the cartridge ages and approaches the expiry date, the
vasoconstrictor begins to break down, resulting in even a
lower pH and therefore even more burning on injection

76. • Second, if cartridges are immersed in sterilizing solution
and the solution seeps into the cartridge, the sterilizing
solution can cause a burning sensation upon injection.
CAUSES:
 pH of solution
 Rapid injection
 Contamination
 Warmed solutions

77. By using fresh anaesthetics with little or no vasoconstrictor .
By buffering the LA solution to a pH of 7.4 immediately before
injection(using sodium bicarbonate)…dilution factor 10:1
By injecting slowly (ideal rate 1ml/min) and not exceeding the
recommended rate of 1.8ml/min.
Storing at room temperature.
Prevention:

78. INFECTION
CAUSES:
 Needle contamination
 Improper handling of armamentarium
 Infection at injection site
 Improper handling of tissue

79. Prevention
 Disposable needles
 Aseptic technique
 Proper care of equipments and dental cartridges
• Use cartridges only once
• Store it aspetically
• Clean diaphragm with sterile disposable alcohol ipes
 Prepare tissue before penetration
MANAGEMENT
 Usual sign is trismus (1-3 days resolution)
 Antibiotics- penicillin or erythromycin

80. EDEMA
 Swelling of the tissue is not a syndrome but a clinical
sign of the presence of some disorder.
 Causes:
• Trauma during injection
• Infection
• Allergy
• Hemorrhage
• Injection of irritating solution

81. Problem
 Edema result in pain and dysfunction of the region and
embarrassment for the patient.
 Angioneurotic edema produced by topical anesthetic in
the allergic individual although exceedingly rare can
compromise the airway.
 Edema of the tongue, Pharynx or Larynx may develop
and represents life threatening situation that requires
vigorous management.

82. Prevention:
 Properly care for and handle the LA
 Use atraumatic injection technique
 Medical evaluation of patient before drug administration
Management:
 Traumatic oedema resulting from inflammation resolves
in one to three days with antiinflammatory drugs.
 Allergic oedema: requires immediate assessment to
avoid the risk of anaphylaxis : treated with epinephrine
,antihistaminics and steroidal antiinflammatory drugs

83.  If edema occurs in any area which compromises
breathing, treatment consists:
• P(position): if unconscious, patient placed in supine
position
• A-B-C(airway, breathing, circulation)
• D (definitive treatment)
• Epinephrine
• Histamine blocker (i.v. or i.m)
• Corticosteroid (i.v. or i.m)
• If total airway obstruction then prepare for
cricothyrotomy

84. SLOUGHING OF TISSUES
 Prolonged irritation or ischemia of the gingival soft
tissues may lead to a number of unpleasant
complications,including epithelial desquamation and
sterile abscess.
Causes:
 Application of topical anesthesia for prolonged period
 Heightened sensitivity to topical or injectable LA
 Secondary to prolonged ischemia;use of LA with
vasoconstrictor (mostly on hard palate)

85. Sloughing of tissues on
palate caused by
prolonged ischemia
secondary to the use of
LA with high
concentration of
epinephrine (1:50,000)

86. Prevention:
 Apply topical anesthesia for 1-2 min to minimize
toxicity
 Avoid using overly concentrated LA solutions when
using vasoconstrictors for hemostasis
Management:
 Reassure the patient
 Symptomatic treatment of pain using NSAIDS and
topically applied ointment is recommended
 Epithelial desquamation resolves within 7-10 days

87. POST ANESTHETIC INTRAORAL LESIONS
 Approx. 2 days after intraoral injection of LA, ulcerations
developed in their mouth, mainly at site of injection
 Initial symptom is pain of intense nature
Cause:
 Recurrent aphthous stomatitis or herpes simplex occur
intraorally after a local anesthetic injection
 Recurrent aphthous stomatitis is more common than
herpes simplex intraorally

88. Problem:
 Acute sensitivity in ulcerated area
Management:
 Primary management- symptomatic
 Reassure the patient
 Topical anesthetic solutions, mixture of
diphenhydramine and milk of magnesia, orabase helps in
relieving pain
 Ulceration lasts for 7-10 days

89. SYSTEMIC COMPLICATIONS
 Toxicity
 Adverse drug reactions
 Allergies
 Idiosyncrasy
 Fainting /syncope
 Methemoglobenemia

90. Adverse reactions of commonly used local anesthetics
J Can Dent Assoc 2002; 68(9):546-51

91. TOXICITY
 Occurs due to systemic absorption of an excessive
amount of the drug.
 Because local anesthetics block conduction in many
tissues in addition to the peripheral nerve, toxicity could
result if sufficient amounts of the anaesthetic reach these
other tissues, such as the heart or brain.
 High blood levels of the drug may be secondary to
repeated injections or could be a result of a single
intravascular administration.
 This risk is one reason why aspiration prior to every
injection is so important.

92. Manifestaion of LA toxicity
Aesthetic Surgery Journal 2014, Vol. 34

93. Risk factors for LA toxicity

94. Pathophysiology
Local anesthetics cross the blood-brain barrier, producing CNS
depression as the blood level rises eg. LIDOCAINE
Blood Level Action Produced
• no adverse CNS effects< .5 ug/ml
0.5-4 ug/ml
• agitation, irritability4.5-7.5 ug/ml
• tonic-clonic seizures> 7.5 ug/ml
anticonvulsant

95. 1.8-5 ug/ml
• treat tachycardia
5-10 ug/ml
• cardiac depression
>10 ug/ml
• severe depression,
• bradycardia, vasodilatation, arrest
Local anesthetics exert a lesser effect on the cardiovascular system
e.g. LIDOCAINE
Blood
Level Action Produced

96. Prevention:
 Prevention should be the priority for reducing the frequency and
severity of LAST.
 No single intervention eliminates the risk, and therefore,
prevention is a multifactorial process.
1. Ultrasound-guided nerve blockade
 Ultrasound has been shown to reduce the risk of LAST by 60%–
65% as compared to peripheral nervous stimulation alone
2. Drug and injection
 Restricting the drug dosage may contribute to LAST riskreduction.
Local and Regional Anesthesia 2018:11 35–44

97. Management:
 Stop administration of LA
 Monitor vital signs
 Place in supine position
 Observe in office for 1hr

98. Severe toxicity: seizure, cardiac dysrhythmia or arrest.
 MANAGEMENT
• Place in supine position
• If seizure, protect from nearby objects and suction oral cavity if
vomiting occurs
• Have someone summon medical assistance
• Monitor vital signs
• Establish airway , administer oxygen
• Start IV
• Administer diazepam 5-10 mg slowly or midazolam 2-5 mg slowly
• Institute BLS if necessary
• Transport to emergency care facility

99. Management
of toxicity
Aesthetic Surgery
Journal
2014, Vol. 34(7) 1111–
1119

100. Preparation:
 In clinics should have oxygen, standard monitoring, and
intravenous access
 Monitoring should continue for at least 30 minutes
 all medications and resuscitation equipment required
should be immediately available, preferably in the form
of a “LAST Rescue Kit”.
Immediate management:
 Maintain airway, oxygenation, and ventilation
Intravenous lipid emulsion therapy:
 Early administration of 20% intravenous lipid emulsion
therapy should, therefore, be an immediate priority after
airway management in any LAST event
Local and Regional Anesthesia 2018:11 35–

101. Seizure management
 benzodiazepines are the first-line therapy.
 Propofol should be avoided where there are signs of
cardiovascular compromise
 If seizures persist despite all efforts, low-dose neuromuscular
blockade can be administered
Cardiovascular support
 Advanced Cardiac Life Support algorithms for
cardiopulmonary resuscitation must be followed
Post-event management
 CVS features, patients should be monitored for at least 6 hours
 CNS features require patient monitoring for a minimum of 2
hours

102. Lipid emulsion therapy
 Lipid emulsion therapy reduced the median lethal dose
(LD50) of bupivacaine and, more important, showed
potential as a therapy for LAST
 Current recommendations call for a bolus injection of 1.5
mL/kg followed by an infusion at 0.25 mL/kg/min
 improve the cardiac output and blood pressure (hence
further facilitating the shuttling effect), while
postconditioning myocardial protection may also occur
Local and Regional Anesthesia 2018:11 35–

104. ALLERGY
 Reports of allergic reactions to local anesthetics are somewhat
common, but investigation finds most of these reactions to be of
psychogenic origin.
 A confirmed allergy to an amide is rare; the ester procaine is
somewhat more allergenic.
 An allergy to one ester rules out using another ester, as the
allergenic component is the breakdown product para-
aminobenzoic acid (PABA), and all esters are metabolized to this
product.
 Conversely, an allergy to one amide does not rule out using
another amide.
 Epinephrine has not been shown to have any allergenic potential.

105.  Methylparabens are preservatives used for multi-dose vials.
 In the past, methylparabens were often found to be the source
of allergy.
 Today they are no longer included in dental cartridges.
 Alternative to methylparaben: CAPRYL HYDRO-
CUPRIENOTOXIN
 If patient is allergic to esters LA AMIDES
 If patient is allergic to both amide and esters, then either
CENTBUCRIDINE or DIPHENHYDRAMINE
 Allergies to local anesthetic may be type I or type IV
hypersensitivity reactions, with the type I response more
commonly reported

106. Testing for LA allergy
 different tests that can be used by the allergist to document an
allergy to local anesthesia, such as
• skin prick test, the
• interdermal or subcutaneous placements test,
• drug provocative challenge test.
 Most allergists consider the drug provocative test to be the gold
standard in the diagnosis of drug allergy
 The local anesthesia to be tested should be free of all additives
(plain LA)
 Intradermal injection is performed by inserting the needle tip,
bevel up, just underneath the surface of the skin and injecting 0.1
ml of the agent.
 A “bleb” should be formed if injection is properly performed.

109. Signs and symptoms:
 Respiratory:
Laryngeal edema
Bronchospasm, wheezing
Use of accessory muscles
Distress
Dyspnea
Anxiety
Cyanosis or flushing
Tachycardia
 Dermatologic:
Urticaria - wheals, pruritis
Angioedema
Minor rash

110. Management of allergy
 Delayed skin reaction
• Benadryl(Diphenhydramine) - 50 mg stat & Q6H X 3-4 days
 Immediate skin reaction
• Epinephrine 0.3 mg IM , Benadryl - 50 mg IM
• Observation, medical consultation
• Benadryl - 50 mg Q6H X 3-4 days
 Bronchial constriction
• Semi-erect position, O2 - 6 L/min
• Epinephrine 0.3 mg IM
• Benadryl - 50 mg IM
• Observation, medical consultation
• Benadryl - 50 mg Q6H X 3-4 days

111.  Laryngeal edema
• Place supine, O2 - 6 L/min
• Epinephrine 0.3 mg IM
• Maintain airway
• Benadryl - 50 mg IV or IM
• Hydrocortisone - 100 mg IV or IM
• Perform Cricothyrotomy

112. ANAPHYLAXIS (TYPE I REACTIONS)
 Mediated by antibodies derived from immunoglobulin
IgE.
 Typical progression (may occur rapidly, with
considerable overlap)
• Skin reactions
• Smooth muscle spasms (GI,respiratory)
• Respiratory distress
• Cardiovascular collapse

113.  It is a immediate hypersensitivity reaction which is
mediated by IgE antibodies
 In clinical presentation, skin reactions, such as urticaria,
severe pruritus and angioedema, are prevalent.
 They can be accompanied by symptoms from airways,
the gastrointestinal tract and the cardiovascular system,
leading to anaphylactic shock
International Journal of Occupational
Medicine and Environmental Health
2019;32(3):333 – 339

114. Grade of severity for quantification of immediate
hypersensitivity reactions

116.  The commonest diagnostic test for drug allergy is SPT
(skin prick test)
 IgE mediated reaction can be demonstrated by a positive
skin prick test and/or intradermal test.
 SPT and intradermal tests should be performed 4-6
weeks after the reaction, in a specialist environment with
intensive care facilities, since the tests themselves can
induce anaphylaxis
Tropical Biomedicine 22(2): 179–183 (2005)

117.  Intradermal test are usually carried out when the SPT is
negative.
 Intradermal test is performed initially at the lowest dose
dilution with progressive increasing dose later

118. Management:
 Anaphylaxis is a dramatic, major medical emergency and required
immediate management.
 Treatment of anaphylaxis should begin with a high degree of
suspicion and appropriate maintenance of the ABCs of basic life
support (airway, breathing, and circulation).
 early use of epinephrine, and oxygen and fluid resuscitation are
crucial for successful treatment.
 Corticosteroids and antihistamines may reduce or prevent the late-
phase reactions over the next several hours and days.
 All fatal symptoms are usually reversible by early administration
of epinephrine and appropriate measures, administered
subcutaneously or intramuscularly every 15 to 30 minutes.
Pediatr Emerg Care. 2004 Mar;20(3):178-80.

119. HYPERSENSITIVITY REACTION
 Type IV response is induced most frequently by the
contact of the skin with a local anaesthetic, but localized
edema can also be caused by an injection.
 In clinical presentation, delayed reactions are usually
visible after 24–48 h, but in the case of local
anaesthetics, they can appear even after 2 h from
administering the drug
Delayed-type hypersensitivity reaction 4
days after superficial subcutaneous
provocation with prilocaine (1 ml)

120. SYNCOPE
 Syncope is a temporary loss of consciousness usually
related to insufficient blood flow to the brain. It's also
called fainting or "passing out." It most often occurs
when blood pressure is too low (hypotension) and the
heart doesn't pump enough oxygen to the brain.
 the most common emergency seen in dental offices (50%
to 60% of all emergencies). Although it occurs
predominately in adults

121. Predisposing factor:
• Fright
• Anxiety (due to the anticipation of discomfort or the fee)
• Stress
• Sudden and unanticipated pain (injection or during
treatment)
• The sight of blood (gauze, dental instruments)

122. Signs and symptoms
 In the early stage the patient:
• Expresses feeling warm
• Exhibits loss of color with an ashen-gray skin tone
• Perspires heavily
• Reports "feeling bad" or "feeling faint"
• Reports feeling nauseous
• Exhibits slightly lower blood pressure and tachycardia
 In the late stage the patient exhibits:
• Pupillary dilation
• Yawning
• Hyperpnea
• Cold extremities
• Hypotension
• Bradycardia
• Visual disturbances
• Dizziness
• Loss of consciousness

123. Management:
• Discontinue treatment
• Assess the level of consciousness: Evaluate the patient’s lack of
response to sensory stimulation.
• Activate the office emergency system: Call for help and have
oxygen
• Position the patient: The patient should be in a supine position
with the feet elevated slightly.
• Assess airway and circulation: Assess the patient’s breathing and
airway patency and adjust the head and jaw position accordingly;
monitor the pulse and blood pressure.
• Provide definitive care:
• Administer oxygen
• Monitor vital signs
• Administer aromatic ammonia ampoules.

124. IDIOSYNCRASY

125.  Etiology:
• Unknown
• Enzymopathy
o Congenital
o Acquired
• Psychogenic
 Clinical features:
• Pallor
• Tachycardia
• Hypotension
• Decreased heart rate
• collapse

127. METHEMOGLOBINEMIA
 It is a reaction that can occur after administration of
amide local anesthetics, nitrates, and aniline dyes.
 Prilocaine and benzocaine are used in dentistry and may
induce methemoglobinemia.
 Methemoglobinemia occurs when the iron atom within
the hemoglobin molecule is oxidized.
 The iron atom goes from a ferrous state to a ferric state.
Once the hemoglobin molecule is in the ferric state, it is
referred to as methemoglobin.
Oral Maxillofacial Surg Clin N Am 23 (2011) 369–

128. Sign and symptoms:
 usually do not appear for 3 to 4 hours after the
administration of large doses of local anesthesia.
 Clinical signs of cyanosis are observed when blood
levels of methemoglobin reach 10% to 20%
 Dyspnea and tachycardia are observed when
methemoglobin levels reach 35% to 40%.
Diagnosis:
 blood sample and a co-oximetry test.

129. Management:
 Methylene blue 1 to 2 mg/kg intravenously

130. SAFETY DENTAL SYRINGES
• minimizes the risk of accidental needle-stick injury
occurring to a dental health provider with a contaminated
needle after the administration of LA.
• These syringes possess a sheath that ‘locks’ over the
needle when it is removed from the patient's tissues
preventing accidental needle stick.
• Various syringes available are:
 Ultra Safety Plus XL syringe
 UltraSafe Syringe
 HypoSafety Syringe
 SafetyWand™
 RevVac™ safety syringe
Natl J Maxillofac Surg. 2013 Jan-Jun; 4(1): 19–

131. LOCAL ANESTHETIC AGENTS IN MEDICALLY
COMPROMISED PATIENTS

132. It include are:
Cardiovascular diseases
Hypertension
Asthma
Diabetes mellitus
Pheochromocytoma
Hyperthyroidism
Hypothyroidism
Bleeding disorders
Pregnancy

134. CARDIOVASCULAR DISEASES
 In the presence of ischaemic heart disease,
elective dental treatment is contraindicated in
the following situations: patients with
unstable angina, recent myocardial infarction
(less than six months), recent coronary artery
bypass surgery (less than three months).

135. ANGINA PECTORIS
 The dosage of the vasoconstrictor should be limited to
that contained in one to two 1.8 ml cartridges of
vasoconstrictor-containing anesthetic in stable angina
patients
 For patients with unstable angina elective dental
treatment should be postponed.
 If emergency dental treatment is necessary, medical
consultation is required and adrenaline dosages should
be limited to one to two cartridges of 1:100000 solution
(0.018 to 0.036 mg of adrenaline

136. MYOCARDIAL INFARCTION
 In stable patients, doses of epinephrine should be limited
to less than 0.036 mg during administering LA for dental
treatment
 recent myocardial infarction is to postpone dental
treatment for at least 3 to 6 months.
 epinephrine and other vasoconstrictors are strictly
contraindicated for patients recovering from myocardial
infarction

137. CARDIAC DYSRHYTHMIA
 Patients with coronary atherosclerotic heart disease, ischemic
heart disease, or congestive heart failure are susceptible to stress-
induced cardiac dysrhythmias.
 Elective dentistry should be avoided in patients with severe or
refractory dysrhythmias until their physician can get the problem
under control
 it is reasonable and safe to limit the total dose of local anesthetic
to no more than two 1.8 ml cartridges per appointment.
 The use of periodontal ligament or intraosseous injections using a
vasoconstrictor-containing local anesthetic is not recommended in
these patients.

138. HYPERTENSION
 There is no contraindication to use of a LA associated with
adrenaline when a prolonged and deep local anaesthesia is needed
in hypertensive subjects, provided the hypertension is stabilized by
an antihypertensive treatment.
 The current maximum recommended dose of local anesthetic
solution for a patient with hypertension is two 1.8-ml cartridges
with 1:100,000 epinephrine per appointment (0.018 to 0.036 mg of
epinephrine)
 In patients with blood pressure of 160-179/100-109 (Stage II
hypertension), epinephrine should be limited to three cartridges
(0.054 mg)
J Oral Maxillofac Surg 64:111-121, 2006

139. ASTHMA
 Dental management of asthmatic patients is primarily
aimed at prevention of an acute asthma attack.
 Sodium metabisulfite, which is used as an antioxidant
agent in dental local anesthetic solutions containing
vasoconstrictors to prevent the breakdown of the
vasoconstrictor, may induce allergic, or extrinsic, asthma
attacks
 Local anesthetic with vasoconstrictor can be used safely
for nonsteroid-dependent asthma patients.
 Avoiding local anesthetic with vasoconstrictors in
corticosteroid-dependent asthma patients on account of a
higher risk of sulfite allergy

140. DIABETES MELLITUS
 Patients with either Type I insulin-dependent diabetes mellitus
or Type II non-insulin-dependent diabetes mellitus, can
generally receive local anesthetics without special precautions
if control of their disease is well-managed
 Special caution should be used for patients with Type I diabetes
who are being treated with large doses of insulin.
 Local anesthesia with vasoconstrictors at the minimal amount is
safe to use in patients with controlled blood glucose level.
 Epinephrine increases gluconeogenesis and glycogen
breakdown in the liver, leading to hyperglycemia.
 it is unsafe to use the anaesthetic solution in those patients who
are not taken their medication.
2000 JOURNAL OF THE CALIFORNIA DENTAL

141.  the hypoglycaemic agents, prevent the glucose levels from rising
even if the glucose levels had increased due to the epinephrine. It
masking the actual effect of the epinephrine in the local
anaesthetic solution on the blood glucose levels.
 the amounts of epinephrine contained in one to three cartridges of
local anaesthetic (0.018 to 0.054mg) may significantly increase
the risk of a complications like ketoacidosis in patients with
unstable diabetes, and so should be avoided until their condition is
brought under glycaemic control.
 The amount of local anesthetic with epinephrine 1:l00,000 should
be the smallest doses compatible with profound anesthesia of
sufficient duration and should be administered slowly after
negative aspiration has been ensured
International Dental Journal (2007) Vol.
57/No.2

142. PHEOCHROMOCYTOMA
 Pheochromocytoma is a tumour of the
adrenal medulla or paravertebral sympathetic
ganglion which causes severe hypertension
because of endogenous hypersecretion of
adrenaline leading to severe risk of
cardiovascular disorders.
 Local anaesthesia with vasoconstrictors are
strictly contraindicated in the patients
suffering from pheochromocytoma

143. HYPERTHYROIDISM
 The well-managed or euthyroid patient presents no
problem and may be given normal concentrations of
vasoconstrictors
 The use of epinephrine or other vasoconstrictors in local
anesthetics should be avoided, or at least minimized to
one to two cartridges, in the untreated or poorly
controlled hyperthyroid patient.
 Hypertension and cardiac abnormalities, especially
dysrhythmias, are common in the presence of excessive
thyroid hormones.

144. HYPOTHYROIDISM
 In general, the patient with mild symptoms of untreated
hypothyroidism is not in danger when receiving dental treatment.
 However, patients with mild to severe hypothyroidism may have
exaggerated responses to local anesthetics due to the central
nervous system depressant effects.
 Dosage should be kept to a minimum in mild hypothyroid patients
 Dental treatment is best deferred in severe hypothyroidism until
the patient’s condition can be corrected by his or her physician.

145. BLEEDING DISORDERS
 Oral injections of local anaesthetic pose varying
degrees of risk for patients with inherited bleeding
disorders.
 Typically, infiltrations can be used without systemic
haemostatic cover but nerve blocks should be
avoided
 Slow injection will allow time for the local anaesthetic
solution to diffuse through the tissues and minimize
bruising.
 A local anaesthetic with a vasoconstrictor should be
used where possible because these provide
additional local haemostasis
 The risk of haematoma is now thought to be low with
modern fine-gauge single-use needles.
Australian Dental Journal 2011; 56: 221–226

146. PREGNANCY
 Administration of local anesthesia during 1st trimester of
pregnancy should be avoided
 administration of local anesthetics such as benzocaine,
procaine, tetracaine, and lidocaine did not increase the
incidence of complications in the fetus
 The proportion of free lidocaine is relatively high, so the
amount of lidocaine transferred from the mother to the fetus is
also relatively high.
 Vasoconstrictors are added to lidocaine to reduce the absorption
of the local anesthetic, reduce toxicity, and increase the
analgesic effects.
 Epinephrine is commonly added to lidocaine as a
vasoconstrictor. It delays the absorption of local anesthetics by
the mother, therefore transferred to the fetus slowly, and its
margin of safety is also increased.
J Dent Anesth Pain Med. 2017 Jun; 17(2): 81–90

147.  The doses of local anesthetics must be maintained below the
maximal permissible dose, as it may lead to toxicity include
mainly seizures and reduced consciousness and negative aspiration
is monitored to make sure the local anesthetics are not injected in
blood vessels.
 Large doses of prilocaine are known to cause methemoglobinemia
which could cause maternal & fetal hypoxia
 The American Academy of Pediatrics considers lidocaine to be
safe during lactation .
 Vasconstrictors necessitate the use of preservatives in local
anesthetics. During lactation, the neonate can have idiosyncratic
reactions to these preservatives, thus local anesthetics without
vasoconstrictors may be associated with a lower incidence of
adverse side effects.
Dent Clin N Am 54 (2010) 697–713

148. UNIVERSAL SAFETY GUIDELINES FOR
ADMINISTRATION OF LA TO ALL PATIENTS:
 Aspirate carefully before injecting
 To reduce the risk of unintentional intravascular
 injection
• Inject slowly:A maximum rate of 1 min/ capsule
• Monitor the patient both during and after the injection
for unusual reactions
• Select the anesthetic agent with or without a
vasoconstrictor based upon the duration of anesthesia
appropriate for the planned procedure

149. • Use the minimum amount of anesthetic solution
 To achieve an adequate level of anesthesia
 To keep the patient comfortable throughout the dental
procedure.
• Adherence to these simple guidelines will reduce the risk
of adverse reactions to the local anesthetic agents
themselves or to the vasoconstrictors contained in local
anesthetics.

150. CONCLUSION
 Adapting local anaesthetic technique can overcome
difficulties in access and limit soft tissue anaesthesia
 Local anaesthetic doses must be controlled.
 Vasoconstrictors produce systemic effects.
 Dental epinephrine has drug interactions.
 Local anesthesia remains the backbone of pain control in
dentistry.

151.  the appropriate use of local anesthetics in certain
situations (patient allergies), calculating dosages to help
prevent toxicity, and aspirating while giving local
anesthesia to help prevent local and/or systemic
complications.
 These techniques are important for any dentist to
minimize adverse outcomes when administering local
anesthesia.
 Research has been continued in both medicine and
dentistry to seek new and better means of managing pain
associated with many surgical treatments.

152. REFERENCES
 Handbook of local anesthesia – Stanley F Malamed – 6th edition
 Local analgesia in dentistry – by d .h.roberts& j. h.sowray
 Monehim”s local anesthesia and pain control, Benett
 Moodley DS Local anaesthetics in dentistry - Part 3: Vasoconstrictors in local
anaestheticsSADJ May 2017, Vol 72 no 4 p176 - p178
 BALAKRISHNAN & EBENEZER, Contraindications of Vasoconstrictors in
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