Anaesthesia and Analgesia Flashcards
Local anaesthetics reversibly interrupt propagation of nerve impulses by interfering with sodium ion influx into peripheral nerve cells.
T
Topical anaesthesia is generally less effective for mucosal surfaces.
F
Very effective dt enhanced absorption.
Intradermal infiltration of anaesthesia causes less pain thn subcutaneous infiltration
F
Other way around
Intradermal infiltration of anaesthesia is more immediate in onset and more prolonged than subcutaneous infiltration
T
The chemical structure of most local anaesthetic agents consists of an aromatic portion, an intermediate chain, and an amine portion.
T
The amine portion of the local anaesthetic compound provides most of its lipophilic properties.
F
Aromatic end.
The aromatic end of the local anaesthetic compound facilitates the diffusion of the anaesthetic through membranes, which correlates to the potency of the anaesthetic.
T
The hydrophilic end of the local anaesthetic compound is involved in binding within the sodium channel.
T
This is usually a tertiary amine.
The intermediate chain of the local anaesthetic compound consists of either an ester or an amide.
T
Amide-type compounds tend to have a shorter duration of action because they are rapidly hydrolyzed by plasma pseudocholinesterases to form metabolites excreted by the kidneys. .
F
This is true for esters. Pts with decreased levels of pseudocholinesterase may be prone to their toxic effects
PABA is the major metabolite product of the ester-type anaesthetics and is responsible for their higher incidence of allergies.
T
related to PPD - cross reacts with ester anaesthetics
suphonylureas and thiazides alos cross react with this group
Ester derivatives are metabolised by microsomal enzymes in the liver and excreted by the kidneys.
F
This is true for amides.
Individuals with compromised liver function are more susceptible to the toxic effects of ester anaesthetics.
F
This is true for amides.
Highly protein-bound anaesthetics, such as bupivacaine, are tightly associated with the neural membrane, leading to a longer duration of action.
T
Shorter-acting anaesthetics tend to have a longer action of onset and more toxicity.
F
Shorter onset of action, less toxicity.
Local anaesthetics are weak bases, with a pKa between 7.7 and 9.1.
T
Prepared with hydrochloride salts though so become acidic.
A lower pKa correlates to a higher concentration of base and a faster onset of action.
T
Tissue pH does not affect the action of local anaesthetics.
F
Eg. infected tissue more acidic
Local anaesthetics can cross the placenta.
T
Local anaesthetics can be excreted in breast milk.
T
Procaine, tetracaine, benzocaine, chloroprocaine, and cocaine are types of amide anaesthetics.
F
Esters
Lignocaine, bupivacaine, mupivacaine and prilocaine are types of ester anaesthetics.
F
Amides
Procaine has a faster onset of action than lignocaine.
F
Procaine 5 mins, lignocaine
Procaine lasts longer than lignocaine.
F
Procaine 15-30mins, ligno 30-120 mins.