This document discusses systemic complications that can arise from local anesthesia. It begins by outlining three principles: 1) no drug exerts a single action, 2) no clinically useful drug is devoid of toxicity, and 3) a drug's potential toxicity depends on how it is used by the healthcare provider. It then discusses factors that can lead to overdose, including patient characteristics, drug properties, and inadvertent intravascular injection. Signs and symptoms of overdose are described, as well as ways to prevent overdose through careful administration and use of aspiration.

1. SYSTEMIC COMPLICATIONS OF
LOCAL ANAESTHESIA
PREAPARED BY:PARTH AND SHEFALI

2. SYSTEMIC COMPLICATIONS OF LA
• Drugs have 2 types of effect when administerd.
• 1)Desirable=Actions may be sought ,beneficial.
• 2)Undesirable=Actions may be additional,not sought.
• Basically 3 principles are their..
• 1)NO DRUG EVER EXERTS A SINGLE ACTION.
• 2)NO CLINICALLY USEFUL DRUG IS ENTIRELY DEVOID
OF TOXICITY.
• 3)THE POTENTIAL TOXICITY OF A DRUG RESTS IN THE
HAND OF THE USER.

3. PRINCIPLE-1
• If we follow this route so it helps to produce
the desirable actions.
• The way from starting to till the end is given
below.
• Right drug>Right dose>Right route>Right
patient>Right time>Right reason.
• Because of this clinical requirements the drug
is not suppose to exert the desirable actions in
all the patients.

4. PRINCIPLE-2
• It says that all the drugs have 2 effect.
• 1)TOXIC
• )NON-TOXIC
• If the drug is properly handeled it may produce
non toxic effect.
• If not properly handeled it may harmful or toxic.
• For nontoxic effect=we have to take the
precautions

5. PRINCIPLE-3
• It based on the patient’s health or the past
medical history.
• Because different people have different
reactivity to the drug.
• So must ask questions or about past medical
and drug history before giving to the patient.

6. MAIN TOPIC
• Mainly in this chapter we have to study briefly
about the topic given below.
• 1)OVERDOSE
• 2)ALLERGY
• 3)IDIOSYNCRASY

7. OVERDOSE
• It is a clinical sign and symptom which is responsible
for absolute or relative overadministration of drug.
• All the drugs are poision when its given with
inadequate dose.
• First the drug gain accessin the circulatory system in
quantities to produce adv on the various tissues.
• There is constant absorption of the drug occurs from
site of administration.
• Steady removal is also occurs from the blood.
• This steady state can be alter.

8. La overdose:predisposing factors
Patient factors
• 1)AGE
• 2)SEX
• 3)OTHER DRUGS
• 4)WEIGHT
• 5)PRESENCE OF DISEASE
• 6)GENETICS
• 7)MENTAL ATTIYUDE
Drug factors
• 1)VASOACTIVITY
• 2)CONCENTRATION
• 3)DOSE
• 4)ROUTE OF
ADMINISTRATION
• 5)RATE OF INJECTION
• 6)VASCULARITY OF
INJECTION SITE
• 7)PRESENCE OF
VASOCONSTRICTORS

9. Patient factors
• 1)AGE:
• ADR occurs in any person with any age.
• The functions like absorption distribution and secretion
are not properly devloped and in old age its get
diminshed.
• 2)WEIGHT:
• Greater the body weight:More tolerance power
produce against the overdose.
• Maximum recommended doses can be calculated on
the basis of miligram of drug per kilogram or pound of
body weight.

10. • 3)SEX:
• In humans the only instance of sexual difference affecting a
drug response is pregnancy.
• During pregnancy renal functions are disturbed.
• There is a impaired excretion of certain drugs their
acccumulation in the blood and increased risk of overdose.
• 4)PRESENCE OF DISEASE
• Disease may affect the ability of the body to transform a
drug into inactive product.
• Hepatic and renal dysfunction impair the body’s ability to
breakdown and excrete the local anaesthetic leading to an
increased anaesthetic blood level whereas congestive heart
failure decreases liver perfusion therby increasing the half
lives of amide local anaesthetics and increasing the risk of
overdose.

11. • 5)Genetics:
• It may alter the patient’s response to certain
drugs.
• A genetic deficiency in the enzymw serum
pseudocolinstearase is an imp.ex.
• This enzyme produced in liver>circulates in
blood>responsible for the biotransformation of
the ester local anaesthetics.
• A deficiency in this enzyme either quantitative or
qualitative can prolong the half life of an ester
local anaesthetic and increase its blood level.

12. • MENTAL ATTITUDE AND ENVIROMENT:
• A patient’s psycological attitude influence the
ultimate effect of a drug.
• It affects the patient’s response to various stimuli.
• The apprehensive patient who overreacts to
stimulation is more likely to receive a larger dose of
local anaesthetic.
• Local anaesthetic seizure threshold is lower in
patients who are fearful and apprehensive than in
nonfearful patients.

13. DRUG FACTORS
• 1)VASOACTIVITY:
• All the LA have vasodialating properties.
• INJ in to soft tissues increases perfusion in the
area, so greater absorption occurs in from the
site of inj in to cvs.
• 2 undesirable effects are their.
• 1)short duration of clinical LA.
• 2)increased blood level of local anaesthetic.

14. 2)CONCENTRATION:
• Greater the concentration of the local anaesthetics
administered ,greater the number of mg/ml of
solutions and greater the circulating blood volume
of the drug in the patient.
• 3)DOSE:
• Larger the volume of a local anaesthetic ,the greater
number of mg is injected and the higher the
resulting circulating blood level.
• High blood levels of the local anaesthetic can be
achieved in dental situations because of the greater
vascularity of the intraoral injections site or
intravascular injection.

15. • 4)ROUTE OF ADMINISTRATION:
• LA used to control pain.
• Drug should not enter in the cvs and reach to the
minimum therapeutic blood level.
• LA administered for anti-dys-rhydhmic purposes
must reach a therapeutic blood level to be effective .
• One factor involved in pain control by a LA is
diffusion of the drug out of the nerve tissues ,absorb
into the cvs and removal from the area of injection.
• Absorption of LA by OMM is dangerous because of
the rate at which some topically applied
anaesthetics enter the circulatory system.
• Example:lidocaine,tetracaine.

16. • 5)RATE OF INJECTION:
• Very important factor in the causation or
prevention of overdose reactions.
• Acc to author rate of injection is the single most
factor.
• IV injection may or may not produce signs and
symptoms of overdose.
• The rate is most imp factor which determine that
the effect of the drug which will be clinically safe or
hazardous.

17. • 6)VASCULARITY OF THE INJECTION SITE:
• Greater the vascularity of the inj site ,more rapid the
absorption of the drug from that area in to the
circulation.
• Oral cavity is the highly vascular in entire body.
• Some areas within the oral cavity that are less well
perfused ,these areas are more recommended than any
other more well perfused areas.
• 7)PRESENCE OF VASOCONSTRICTORS.
• The addition of vasoconstriction to a local anaesthetic
produces a decrease in the perfusion of an area and a
decreased rate of systemic absorption of the drug.

18. CAUSES
• 1)BIOTRANSFORMATION OF THE DRUG IS UNUSUALLY SLOW.
• 2)THE UNBIOTRANSFORMED DRUG IS TOO SLOWLY ELMINATED
FROM THE BODY THROUGH THE KIDNEYS.
• 3)TOO LARGE A TOTAL DOSE IS ADMINISTERED.
• 4)ABSORPTION FROM THE INJECTION SITE IS UNUSUALLY RAPID.
• 5)INADVERTENT INTRAVASCULAR ADMINISTRATION OCCURS.

19. • 1)Biotransformation and elmination.
• Ester local anaesthetics as a group undergo more rapid
biotransformation in the liver and blood than the
amides.
• Plasma pseudocolinstearase is primarily responsible for
their hydrolysis to PABA.
• Atypical colinstearase represent a relative
contraindication to the administration of ester local
anaesthetics .
• Amide local anasthetics may be used without increased
risk of the overdose in patient with pseudocolinstearase.
• A low average dose is also causes the problem of
overdose if the liver functions are comprised.

20. • Excessive total dose:in excessive dose all drugs are
capable to produce overdose reactions.
• Biological variability has a great influence on the
manner in which persons respond to drug.
• The maximum recommended dose of parenterally
administered drugs is commonly calculated after
consideration of a number of factors including,
• 1-patient’s age: age increases the tolerance to the
drug is decreased.
• 2-patient’s physical status:for medically
compromised patients the calculated MRD is low.
• 3-patient’s weight:The larger the person the greater
is the distribution of the drug.

21. RAPID ABSORPTION IN TO THE
CIRCULATION
• Vasoconstricting drugs are considered an integral component of all local
anaesthetics whenever depth and duration of anaesthesia are important.
• Vasoconstrictor increases the duration of anaesthesia and reduce systemic
toxicity of most local anaesthetics by delaying their absorption in to the
cvs.
• The ADA and AHA summerised thid as follows:
• “vasoconstrictor agents should be used in local anaesthetic solutions
during dental practice only when it is clear that the procedure will be
shortened or the analgesia rendered more profound.
• When vasoconstrictor is indicated extreme care should be taken to avoid
IV INJECTION.
• Serious overdose reaction have been reported after topical application of
amide local anaesthetic.
• The area of application of a topical anaesthetic should be limited.

22. INTRAVASCULAR INJECTION
• IV INJECTION may occur with any type of intraoral
nerve block but is more likely with following:
• Nerve block: positive aspiration
• Inferior alveolar: 11.7%
• Mental or incisive 5.7%
• Posterior sup alveolar 3.1%
• Ant sup alveolar 0.7%
• Buccal 0.5%

23. • Both IV and interratical injections are capable of
producing overdose.
• IA injection can cause retrograde blood flow in
the artery as the anaesthetic drug is deposited.
• IV injections within the usual practice of
dentistry should not occur.
• With care and knowledge of the anatomy of the
area to be anaesthetised and proper technique
of aspiration before injecting the anaesthetic
solution overdose as a result of inadvertent
intravascular injection is minimized.

24. PREVENTION
• To prevent intravascular injection use an aspirating
syringe.
• Use a needle no smaller than 25 guage when the risk of
aspiration is high.
• Althought aspiration of blood is possible smaller gauge
needles ,there is an increase in resistance to the return
of blood into lumen of smaller gauge needles,leading
to an increased likelihood of an unreliable aspiration
test.
• Therefor injection technique with a greater likelihood
of positive aspiration dictate the use of a 25 gauge
needle.

25. CLINICAL MANIFESTATIONS
• Clinical signs and symptoms of LA overdose
appear whenever the anaesthetic blood level in
an organ becomes overly high for that individual.
• The rate of onset of signs and symptoms and to
an extent their severity correspond to this level.
• First clinical manifestation may be drowsiness
which leads up to unconsciousness and
respiratory arrest.This is occurs due to lidocaine
therapy.

26. PATHOPHYSIOLOGY
• The blood or plasma level of a drug is the amount absorbed
into circulatory system and transported in plasma
throughout the body.
• Levels are measured in micrograms/ml.
• LA exert a depressant effect on all excitable membranes.
• In clinical use LA is applied in particular area of the body
where it produces its primary effect :a reversible
depression of peripheral nerve conduction;other effects are
related to its absorption into the circulation and its
subsequent actions on excitable membranes,including
smooth muscle, the myocardium, and the CNS.