Anaesthesia Flashcards
What is potency?
A measure of drug activity expressed in terms of the amount required to produce an effect of a given intensity.
What is MAC?
MAC describes potency of inhaled drugs, it is the minimum alveolar concentration to make an effect.
What factors cause the potency to be increased/decreased?
Increased in: infancy, hyperthermia, pregnancy, alcoholism, central stimulants
Decreased in: elderly, hypothermia (cold), other anaesthetics and sedatives, opioids.
What are some sites of target for anaesthetics?
GABA receptors, these are chloride ion channels, so when something binds then the chloride ions flow into the cell and cause hyperpolarisatiin, so it more harder to excite, inhibitory.
NDMA receptors are another probable site- these are responsible for excitation.
The balance between binding to NDMA and GABAa is really important as it is the balance between sleep and consciousness…
GABA a = sleep
NDMA= consciousness
What is a local anaesthetic?
An anaesthetic which affects the restricted portion of the body.
Examples include: lidocaine, bupivacajnw, procaine, ropivicaine
Is a lower potency better or worst?
Worst! It only evokes a response at a higher concentration.
How does lidocaine work?
Inhibits the ionic fluxes which are required for the initiation and conduction of impulses, thereby effecting the local anaesthetic action. Lidocaine alters signal conduction in neurones by blocking the fast voltage gated sodium channels in the neuronal cell membrane which are responsible for signal propagation, with sufficient blockage the membrane of the postsynaptic neurone will not depolarise and therefore will fail to transmit an action potential.
