p.1
Mechanisms of Local Anaesthetics
What is an important feature of local anesthesia?
It produces loss of sensation without inducing a loss of consciousness.
p.6
Intradermal Injections
What is an indication that the intradermal injection was administered correctly?
A blister should be raised.
p.4
Central Nervous System Effects of Local Anaesthetics
What are the central nervous system (CNS) effects of local anaesthetic toxicity?
1. Drowsiness, 2. Numbness of the tongue and perioral region, 3. Restlessness, 4. Paraesthesia (including sensations of hot and cold).
p.5
Central Nervous System Effects of Local Anaesthetics
What are some central nervous system effects of local anesthetics at higher concentrations?
Muscle twitching, tremors, and convulsions.
p.5
Central Nervous System Effects of Local Anaesthetics
What are severe central nervous system effects of local anesthetics?
Respiratory failure, unconsciousness, and coma.
p.1
Mechanisms of Local Anaesthetics
What is local anesthesia defined as?
A loss of sensation in a circumscribed area of the body caused by depression of excitation in nerve endings or inhibition of the conduction process in peripheral nerves.
p.4
Toxicity and Side Effects of Local Anaesthetics
What systems are mainly involved in the systemic toxicity of local anaesthetics?
The central nervous and cardiovascular systems.
p.3
Use of Vasoconstrictors in Anaesthesia
Why should solutions containing adrenaline not be used for anaesthesia in appendages?
Because it may produce ischaemic necrosis.
p.2
Lidocaine as a Local Anaesthetic
Why is Lidocaine the most widely used local anaesthetic drug?
It acts more rapidly, is more stable than most other local anaesthetics, and is effectively absorbed from mucous membranes.
p.3
Use of Vasoconstrictors in Anaesthesia
Why is care necessary when using adrenaline?
Because, in excess, it may produce ischaemic necrosis.
p.2
Use of Vasoconstrictors in Anaesthesia
What effect do most local anaesthetics, except cocaine, have on blood vessels?
They cause dilation of blood vessels.
p.4
Toxicity and Side Effects of Local Anaesthetics
How does injection into inflamed or infected tissues affect the absorption of local anaesthetics?
It increases absorption into the blood, leading to higher plasma concentrations and potential toxicity.
p.4
Toxicity and Side Effects of Local Anaesthetics
Does a single application of a topical lidocaine preparation generally cause systemic side effects?
No, it does not generally cause systemic side effects.
p.3
Cautions and Contraindications for Local Anaesthetics
How should adrenaline be administered in cases of severe renal or liver disease?
Avoid or reduce the dose.
p.5
Central Nervous System Effects of Local Anaesthetics
What are some central nervous system effects of local anesthetics at lower concentrations?
Dizziness, blurred vision, nausea, and vomiting.
p.6
Intradermal Injections
What position should the subject be in for an intradermal injection?
Seated in a chair with arms (not on a stool).
p.2
Use of Vasoconstrictors in Anaesthesia
Why are vasoconstrictors like adrenaline added to local anaesthetics?
To diminish local blood flow, slow the rate of absorption of the local anaesthetic, and prolong its local effect.
p.4
Toxicity and Side Effects of Local Anaesthetics
What are the main causes of toxic effects after the administration of local anaesthetics?
1. Inadvertent intravascular injection, 2. Too rapid injection, 3. Repeated dosages due to accumulation of the drug, 4. Injection into inflamed or infected tissues.
p.5
Mechanism of Action of Lidocaine
How does lidocaine work as a local anesthetic?
Lidocaine blocks fast voltage-gated sodium channels in the cell membrane of neurons, preventing depolarization and inhibiting the generation and propagation of nerve impulses.
p.6
Intradermal Injections
Where should the intradermal injections be administered on the body?
On the forearm, at positions well spaced over the forearm.
p.6
Intradermal Injections
At what angle should the needle be inserted for an intradermal injection?
At a very horizontal angle, between 10-15 degrees.
p.3
Cautions and Contraindications for Local Anaesthetics
What are the contraindications for using adrenaline?
Hypovolaemia, sino-atrial disorders, all grades of atrioventricular block, severe myocardial depression, respiratory depression, acute porphyria.
p.5
Mechanism of Action of Lidocaine
What happens when lidocaine is present at higher blood concentrations?
The effects become generalized.
p.1
Mechanisms of Local Anaesthetics
Does local anesthesia cause structural damage to neurons?
No, it does not cause structural damage to neurons.
p.4
Toxicity and Side Effects of Local Anaesthetics
Why should reduced doses of local anaesthetics be given in some cases?
To avoid accumulation of the drug and subsequent toxicity.
p.5
Cardiovascular Effects of Local Anaesthetics
What are some cardiovascular effects of local anesthetics?
Myocardial depression and bradycardia, peripheral vasodilatation, hypotension, arrhythmias, and cardiac arrest.
p.6
Intradermal Injections
What should you do if no blister is raised after an intradermal injection?
Repeat the injection at a different site, as the initial injection was probably too deep.
p.3
Use of Vasoconstrictors in Anaesthesia
Why should adrenaline not be added to injections used in digits and appendages?
Because it may produce ischaemic necrosis.
