Local Anaesthetic Systemic Toxicity PDF

Building SCHEMATA with Local Anaesthetic Systemic Toxicit… Building SCHEMATA with Local Anaesthetic Systemic Toxicity sli… Page 1 of 6 This preview may have altered the layout of this file. You can still download the original file. Building...

Building SCHEMATA with Local Anaesthetic Systemic Toxicit… Building SCHEMATA with Local Anaesthetic Systemic Toxicity sli… Page 1 of 6 This preview may have altered the layout of this file. You can still download the original file. Building SCHEMATA with LA Toxicity slides Local Anaesthetic Systemic Toxicity Life Threatening adverse event which takes place after the administration of a local anaesthetic through a variety of routes. Symptoms usually occur within the first 10-minutes but could take place within an hour. Why Local anaesthetic drugs? What are they made of? Water soluble salts (Na+) of lipid (fats) soluble alkaloids (This means they contain salts which dissolve in water (like sodium) of alkaloids (this is the part of the drug which serves the purpose of whatever its being given for) that dissolve in fat)-in other words local anaesthetics have chemicals which can easily dissolve in water and fats. That’s why they are called lipophilic. This structure allow local anaesthetics to cross the cell membrane in their unionized form with ease. Think about why local anaesthetics are given?? Usually to numb an area so the patient does not feel pain. In essence-the drug spreads around that area because its ‘lipophilic’ and blocks Na+ channels so message of pain doesn’t reach brain and kick-start a load of physiological responses like HR going up etc. Something to remember: different local anaesthetics have different abilities of dissolving in lipids-so it will be easier to remove ones that are more lipid soluble (dissolve in fat more easily-like bupivacaine-but these ones can cause fast toxicity too). All local anaesthetics target the voltage-gated Na+ channel and carry the risk of toxicity. They block sodium channels which interferes with signals to the brain. But wasn’t sodium also important for cardiac conduction?? Well exactly! they also prevent the rapid early depolarization stage of an action potential from occurring (so a big problem for the heart-which needs to contract) What is sodium? Sodium is a mineral that carries an electrical charge, known as an electrolyte. Electrolytes facilitate muscle contraction and nerve cell transmission. :