it can cause decrease in contractility hypotension decrease in conduction rate

It can cause decrease in contractility hypotension

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" it can cause: *decrease in contractility *hypotension *decrease in conduction rate *vasodilation " central nervous system toxicity is can also occur is the LA is absorbed systemically " depending on the concentration of the LA absorbed, different effects can occur: *at LOW doses ! CNS excitement "leads to light headedness, nervousness, dizziness, drowsiness, muscle twitches/tremours *at HIGH doses ! CAN depression " leads to respiratory depression and respiratory arrest (at extremely highly doses) " other adverse effects caused by LAs include: *loss of visceral and skeletal muscle tone ! therefore LAs must be used with caution when it is known that the patient as myasthenia gravis (an autoimmune disorder that leads to muscle weakness – caused by antibodies attacking acetylcholine receptors) " signs from early to late stages of toxicity is as follows: * (early) circum"oral and tongue numbness lightheadedness, tinnitus, visual disturbances muscular twitching, convulsions *(late) unconsciousness, coma, respiratory arrest, cardiovascular collapse Indications of Local Anesthetics " the different types of LAs include: o topical anaesthesia (surface anaesthesia) o infiltration anaesthesia o I.V regional anaesthesia o Nerve block anaesthesia o Spinal anaesthesia " of all the different kinds, only infiltration and nerve block anaesthesia is used in dentistry *and sometimes Surface anaesthesia [ Surface anaesthesia ] " the LAs include: lidocaine, Benzocaine, Tetracaine, Procaine " A topical block is accomplished by applying the anaesthetic agent to skin, mucous membrane, or cornea *Only superficial layer is anesthetized [ Infiltration anaesthesia ] "Direct injection into subcutaneous tissues to reach nerve branches and terminals *Used in minor surgery, e.g. suturing of wound or removal of foreign bodies * Dental procedures " Most of the LAs can be used ! *Epinephrine is usually added except in fingers and toes
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[ Nerve Block Anaesthesia ] " LA is injected close to nerve trunk to produce a loss of sensation peripherally. " it can be ssed for surgery, dentistry , analgesia " most types of LAs can be used (although the most popular is still lidocaine) " this technique requires less LA Vasoconstrictors "sometimes vasoconstrictors can be used in conjunction with LAs to increase duration *the duration of the anesthetic agent is prolonged by ! decreasing the blood flow in the immediate area of the injection. " the vasoconstrictors can also decrease bleeding in the area where the surgical procedure is occurring " the different types of vasoconstrictors that can be used include: * adrenaline *noradrenaline *levonordefrin " the advantages and disadvantages of using vasoconstrictors include: Advantages Disadvantages < increase in duration of action " decrease in dose of LA needed " decrease risk of bleeding " increase intensity of nerve block < increase risk of local tissue injury and tissue necrosis " delay in wound healing " increase in cardiovascular risk in susceptible patients " contraindications for LA usage include: *Unstable angina *Recent myocardial infarction
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