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Questions and Answers
Which local anesthetic agent has a contraindication for use in children under the age of 4?
Which local anesthetic agent has a contraindication for use in children under the age of 4?
What is a common caution when administering Articaine?
What is a common caution when administering Articaine?
Which medication should be avoided in patients who have used cocaine within the last 24 hours?
Which medication should be avoided in patients who have used cocaine within the last 24 hours?
Which local anesthetic agent poses a risk of post-operative paraesthesia when administered via an ID block?
Which local anesthetic agent poses a risk of post-operative paraesthesia when administered via an ID block?
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Which of the following cautions is associated with the use of Propanolol?
Which of the following cautions is associated with the use of Propanolol?
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Felypressin poses a theoretical risk during which condition?
Felypressin poses a theoretical risk during which condition?
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What is a recommended limit for local anesthetic cartridges in cases of renal failure?
What is a recommended limit for local anesthetic cartridges in cases of renal failure?
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What is a precaution when using local anesthetics in breastfeeding individuals?
What is a precaution when using local anesthetics in breastfeeding individuals?
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What is the primary mechanism by which local anesthetic agents (LA) exert their systemic effects?
What is the primary mechanism by which local anesthetic agents (LA) exert their systemic effects?
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Which of the following is NOT a factor that influences the rate of systemic absorption of a local anesthetic agent?
Which of the following is NOT a factor that influences the rate of systemic absorption of a local anesthetic agent?
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What is the primary route of metabolism for most commonly used local anesthetic agents?
What is the primary route of metabolism for most commonly used local anesthetic agents?
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Which of the following is a potential sign of systemic toxicity from local anesthetic agents?
Which of the following is a potential sign of systemic toxicity from local anesthetic agents?
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Which of the following is a valid strategy to reduce the risk of systemic toxicity from local anesthetic agents?
Which of the following is a valid strategy to reduce the risk of systemic toxicity from local anesthetic agents?
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Which of the following local anesthetic agents is also metabolized in plasma?
Which of the following local anesthetic agents is also metabolized in plasma?
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Which of the following is a contraindication for the use of lidocaine?
Which of the following is a contraindication for the use of lidocaine?
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What is a reason for using vasoconstrictors in conjunction with local anesthetic agents?
What is a reason for using vasoconstrictors in conjunction with local anesthetic agents?
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Flashcards
Absorption of LA
Absorption of LA
Local anesthetics are not easily absorbed through intact skin but are absorbed when applied to mucous membranes or injected.
Systemic actions of LA
Systemic actions of LA
Local anesthetics cause reversible blockage of nerve conduction and can relax smooth muscles while affecting heart and CNS activity.
Toxicity Signs
Toxicity Signs
Rare but serious signs of systemic toxicity include tingling, sensory disturbances, mood changes, and respiratory issues.
Factors Affecting Absorption
Factors Affecting Absorption
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Metabolism of LA
Metabolism of LA
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Reducing Toxicity
Reducing Toxicity
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Maximum Safe Dose
Maximum Safe Dose
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Contraindications of Lidocaine
Contraindications of Lidocaine
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Propanolol
Propanolol
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Prilocaine
Prilocaine
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Mepivacaine
Mepivacaine
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Articaine
Articaine
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Epinephrine/Adrenaline
Epinephrine/Adrenaline
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Felypressin
Felypressin
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Contraindications
Contraindications
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Cautions
Cautions
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Study Notes
Systemic Effects of Local Anaesthetics (LA)
- Local anaesthetics (LA) are not easily absorbed through intact skin.
- LA are absorbed into the bloodstream when applied to mucous membranes or injected into tissues.
- LA are distributed throughout the body.
- LA are metabolized and eliminated.
- The rate of systemic absorption depends on the type of anaesthetic agent, its dose, the vascularity of the tissues, the presence/absence of vasoconstrictors, and accidental intravascular injections.
Systemic Actions of Local Anaesthetics
- Local anaesthetics cause a reversible blockage of conduction within nerve endings and nerve trunks.
- Local anaesthetics directly relax smooth muscle.
- Local anaesthetics cause myocardial depression (decreased conduction rate, decreased force of contraction, decreased electrical excitability).
- Local anaesthetics cause central nervous system depression (initial signs are excitatory).
Absorption of Local Anaesthetic Agents into the Circulation
- Systemic absorption of LA causes the action of the LA to cease.
- Systemic absorption can lead to toxicity.
- Factors affecting Systemic Absorption:
- Anaesthetic agent and concentration
- Vessel density of the affected tissue
- Presence or absence of vasoconstrictor
- Accidental intravascular injection
Metabolism and Elimination of Local Anaesthetics
- Elimination of LA depends on patient physiology.
- Most commonly used LA agents are metabolised in the liver to inactive metabolites.
- Articaine is also metabolised in plasma.
- LA metabolites are then excreted in the urine.
- Liver and kidney function impact LA elimination. If impaired, the patient may require a lower dose for safety.
Signs of Systemic Toxicity
- Perioral signs (e.g. tingling, numbness of lips)
- Visual/hearing problems (e.g. tinnitus)
- Mood changes (irritability, agitation, anxiety, restlessness)
- Light-headed/dizziness
- Increased rate and depth of respiration
- Drowsiness
- Coma and convulsions
- Respiratory arrest
- Cardiac arrest
Reducing Systemic Toxicity
- Avoid intravascular injections. Always aspirate first.
- Inject slowly.
- Use safe doses.
- Choose less toxic drugs (e.g., 3% prilocaine with felypressin).
- Use vasoconstrictors (to reduce systemic toxicity).
Maximum Safe Dose
- Information on maximum safe doses(mg/kg) for different types of LA agents, including lidocaine, prilocaine, mepivacaine, and articaine.
- Maximum cartridge volumes (mL) for different patient groups are also included.
Contraindications and Cautions of LA Agents
- Lidocaine: Contraindicated in hypersensitivity. Cautions with beta-blockers.
- Prilocaine: Contraindicated in hypersensitivity. Cautions with sulphonamides and beta-blockers.
- Mepivacaine: Contraindicated in hypersensitivity, children under 4 years old. Cautions in pregnancy, breastfeeding, and with beta-blockers
- Articaine: Contraindicated in hypersensitivity, children under 4 years old, and those with plasma cholinesterase deficiency.. Cautions in pregnancy (only if benefit > risk), avoid breast feeding for 48 hours after administering, cautious use with beta-blockers , and ID block (risk of post-op paraesthesia)
- Epinephrine/Adrenaline: Contraindicated in cocaine use within last 24 hours, and have cautions with tricyclic antidepressants, Mono-amine oxidase inhibitors, Beta-blockers, Calcium-channel blockers, Diuretics, Cardiac conditions, Hypertension, and Circulatory problems (including previous strokes)
- Felypressin: Caution in late stages of pregnancy (theoretical risk of inducing labour)
LA Equipment
- Cartridges: Different types of cartridges are available (e.g., Lignospan Special, Septanest).
- Plunger (handle): Used for delivering LA.
- Safety plus needles: Different lengths and gauges are available.
- Bevel indicator: Used for proper needle insertion.
- Traditional LA system: Includes syringe, cartridge, and cone.
General notes
- Patients with renal or liver failure may require reduced dosages.
- Limit LA usage to 2 x 2.2ml cartridges per day, or 1 cartridge per day, respectively, for patients with renal/liver failure according to the cautions specified.
- Consult with the patient's physician regarding safe dosages when necessary.
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Description
Explore the systemic effects and actions of local anaesthetics in this quiz. Learn about their absorption, metabolism, and how they impact nerve conduction and smooth muscle. Test your understanding of their physiological effects on both the cardiovascular and central nervous systems.
