Local and general anaesthetics Flashcards
What is the general structure of local anaesthetics?
Bulky aromatic end - liable ester or more stable amide linker - tertiary nitrogen
When uncharged LA are ______
Hydrophobic
What is the pKa of the tertiary amine group and what effect does this have physiologically?
Have a pKa of 8-9 and at the physiological pKa of 7.2-7.4 most LA will be charged thus acting against their hydrophobic nature.
Why are LA less effective in injured tissues?
Injured tissues are more acidic and the lower pH reduces the efficacy of the drug.
What are surface anaesthesias?
Can be applied via cream of drops to the surface of the skin and common examples of these contain lidocaine, benzocaine, tetracaine.
What is an Infiltration Anaesthesia?
Are most LA that are effectively injected and can have their durations extended by use of adrenaline vasoconstriction that sustains concentration of LA at site of action by reducing blood flow.
What are Intravenous regional Anaesthesia?
Injected distally to blood flow cuff. Mainly used in limb surgery as can be sustained for as long as blood flow is stopped. commonly uses lidocaine and prilocaine.
What are nerve block anaesthetics?
Most LA that are injected into the nerve trunks. this reduces the concentration required.
What are spinal/Epidural anaesthetics?
These are injected into the subarachnoid space or epidural space that act on the spinal cord and roots. Typically used where general cannot be used such as child birth.
What are Cardiac antidysrhythmic (Class 1 drugs)?
are drugs used to prevent abnormal cardiac rhythms such as atrial fibrillation, atrial flutter, ventricular tachycardia, and ventricular fibrillation. These drugs work by blocking sodium, potassium, and calcium channels in the heart muscles.
What are general anaesthetics?
A reversible complete drug induced loss of consciousness.
What are the general class of drugs of General anaesthetics?
They cannot be classed in a drug group! can be gases, simple hydrocarbons, alcohol etc.
General anaesthetics are delivered systemically via the ____
Central nervous system.
What occurs in stage 1 of anaesthesia?
Analgesia where there is a reduction in the pain response. still conscious.
What occurs in stage 2 anaesthesia?
Become unconscious but there is NO reflex depression or delirium.
What occurs in stage 3 anaesthesia?
Unconscious, and reflex depression. This is the stage surgical anaesthesia takes most patients to.
What occurs in stage 4 anaesthesia?
Respiratory paralysis. occurs progressively until complete loss of function.
What occurs in stage 5 anaesthesia?
Total loss of cardiac and respiratory function. DEATH.
What determines the speed of induction/recovery of general anesthetics?
Blood gas partition coefficient. (bloods solubility) , Oil gas partition coefficient (lipid solubility) and the physiological effects such as alveolar ventilation and the cardiac output.
what happens when there is a lower blood solubility?
equilibrium is met quicker.
What is MAC?
minimum alveolar concentration. It is the concentration of vapour in the lungs that is needed to prevent a motor response in 50% of patients using inhalation anaesthetics.
