Systemic Anesthetics (toxicity Allergy Hypotension Hyperventilation) – Flashcards
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How would you anesthestize a tooth in the nose?
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(SUPERNUMERARY INTERNASAL TEETH (GET INVERTED) Infiltration into the vestibule and local into the nasal mucosa they come right out and are not anchored in bone
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What is a toxic reaction?
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similar to an overdose it is an exaggerated pharmacological effect of a drug to a high concentration
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When does the toxicity occur?
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It occurs when the drug cannot keep up with the blood concentration
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What increases the likelihood of a toxic reaction?
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the higher the blood level and the longer it remains elevated the greater likelihood of a toxic reaction
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How is toxicity different from an allergic reaction?
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a toxic reaction is a large dose whereas an allergic reaction may give rise to a sever systemic response in a hypersensitive patient
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What is the maximum does of xylocaine?
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300 mg or 8 cartriges in a 160 lb patient (about 2.0mg/lb)
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How many mg in a 2% xylocaine solution?
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20 mg per 1 cc or 36mg per 1.8 cc cartridge or 34 mg per 1.7 cc cartridge
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Which local anesthetic is associated with a disproportionate number of local anesthetic toxicity reports? and why?
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3% mepivicaine plain, because it lacks a vasoconstrictor, allowing rapid systemic absorption Or because its used so much in pediatric patients
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What patient population is mepivicaine typically used in?
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Used more commonly in pediatric patients because its short duration and limits MOUTH BITING
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For a small two year old what is the maximum amount of cartridges given?
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2.2 cartridges
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What is the rule of 25?
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For children, 1 cartridge of any formulation can be administer safely for every 25 lb of the childs body weight
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What are the 4 ways that high blood concentration of local anesthetic for toxic over comes?
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1) Too large of a dose of local anesthetics 2) Unusually rapid absorption of the drug or intravascular injection 3) Unusually slow biotransformation 4) Slow elimination
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What are patient factors that predispose someone to having a toxic reaction to LA?
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1) Age (very young and the very old) 2) Weight (light weight) 3) Presence of Pathology 4) Gender (women are less weight and likely to have worse reactions)
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What are predisposing factors for a drug toxicity reaction that are DRUG factors?
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1) Dose 2) Route of Administration 3) Rate of Administration 4) Vascularity of Injection site 5) Presence of Vasoconstrictors
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How does age predispose a patients for a toxicity reaction?
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geriatric patients show the half life of lidocaine was shown to be increased approximately 70 percent over a control group in their twenties
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Doses of medications be decreased in patients of what ages?
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younger than six and older than 65
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Between, lido, mepiv, bupiv, peril and articaine which one has the shortest half life?
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articaine has the shortest about 30 minutes Bupivicaine has the longest 3.5 hours
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Who are the majority of local anesthetic toxic reaction patients profile?
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young children 2-6 years old who are 15-40Kg, light weight
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What are examples of pathology that predispose for a toxicity?
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1) Patients with CV disease espescially CHF demonstrate blood levels of local anesthetics about 2X those in healthy patients receiving the same day In SEVERE CHF there is decreased LIVER PERFUSION where amide anesthetics are metabolized and it increases the HALF LIFE 2) SEVERE Hepatic and Renal dysfunction impair the bodys ability to break down and excrete local anesthetic
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What are medications pre-disposing factors for a toxicity reaction?
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1) Demerol (opioid analgesic), Dilantin (phenytoin), Quinidine (Class I anti arrhythmic), Desiprimine (TCA), may increase blood levels of local anesthetics because of PROTEIN BINDING COMPETITION 2) Cimetidine (H2 histidine blocker) slows biotransformation of lidocaine by competing for hepatic oxidative enzymes with the local anesthestetic
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What drugs will local anesthetics increase the effects of?
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Cardiac Medications 1) Digoxin 2) Beta blckers 3) Calcium blockers
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What are the main symptoms of a toxicity reaction?
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BIPHASIC CNS response. Most are related to the CNS as it is the most sensitive target tissue. There is usually early CNS stimulation followed by a proportional degree of depression
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What type of effect do local anesthetics have on excitable membranes?
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Local anesthetics exert a DEPRESSANT effect on all excitable membranes
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After an intraoral injection of 40-160 mg of lidocaine, blood concentration rises to what range?
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.5-2ug/ml
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What are considered non-overdose levels of lidocaine?
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=<4.5ug/ml
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What is the first phase of stimulation in a toxic reaction?
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1) Cerebral Cortical Stimulation 2) Medullary Stimulation 3) Cardiac Ectopic Cardiac Rhythms this is followed by cortical depression, medullary depression
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What are the signs of Cerebral Cortical Stimulation?
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talkativeness, restlessness, apprehension, excitement, muscle twitching, shivering, tremors, tonic-clonic seizures
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What is Medullary stimulation?
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HTN, tachycardia, tachypnea, nause and vomitting
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What are signs of cerebral cortical depression?
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lethargy, sleepiness, unconsciousness (coma)
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What are signs of medullary depression?
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hypotension, bradycardia, bradypnea, or apnea
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What is the treatment for a toxic reaction local that is mildly stimulated?
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1) Mildly stimulated patients require no treatment
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What is the treatment for a toxic reaction local that is moderately stimulated?
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2) Moderately stimulated should be given 100 percent oxygen
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What is the treatment for a toxic reaction local that is convulsive?
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3) Convulsive patients should be restrained to prevent injury and assure adequate ventilation, administer 100 percent oxygen
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What is the treatment for a toxic reaction local that is CNS depressed??
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4) Treatment of CNS depression should be directed toward supporting respiration with 100 percent oxygen, maintaining adequate CV function through positional changes and IV fluids, and vasopressors if required
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What is the reversal agent?
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phentoalamine, and it dilates the blood vessels and taken away rapidly
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What is the lipid rescue kit?
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intravascular infusion of lipid emulsion to treat sever local anesthetic toxicity treats severe cardiotoxicity secondary to local anesthetic overdose The amount of local anesthetic to produce toxicity tends to parallel the lipid solubility and potency of the drug
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Which local anesthetics have high cardiac toxicity?
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Local anesthetics with low solubility (prilocaine, lidocaine, mepivicaine) are less toxic than highly soluble BUPIVACAINE
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How many mg is 1:100000 epinephrine?
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.01mg/cc of fluid so in a cartridge its .018mg per cartridge
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Where is epinephrine overdose most common?
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more common after its use in gingival retraction cord
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Administration of 7 cartridges of 4 percent articaine with 1:100,000 Epi has been found to increase the heart rate on an average of how many beats per minute? Increases systolic blood pressure by how much?
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9 beats per minute 6 mmHg
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What should you about epinephrine in a medically compromised patient?
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If you use Epi 1:100,000; the maximum recommended for a compromised patient = 40mcg = 2.2 cartridges) Epi 1:200,000 the maximum dose for medically compromised patient is 40mcg = 4.4 cartridges
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What are toxicity reactions to epineprhine symptoms?
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Palpitations, HR, BP increase, Nausea Sweating, Premature Ventricular Contractions, Arrythmias
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Is epinephrine metabolized quickly?
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Yes very quickly within 10 minutes, toxic symptoms are resolved
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What are the contraindications for vasoconstrictors?
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1) Hyperthyroidism 2) Sulfite Sensitivity (metabisulfite is used as preservative for epinephrine) 3) Uncontrolled diabetes (action of epic opposes insulin and produces hyperglycemia) 4) Corticosteroid dependent asthmatics 5) Unstable angina 6) Refractory Arrhythmias 7) Untreated or uncontrolled HTN 8) Catecholamine tumors 9) Do not use retraction cord in patients with CV disease (cords contain 225.ug of racemic epinephrine/inch of cord)
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What patients should you not used epinephrine cord in? How much epinephrine is in the cord?
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CV patients should not be used in. 225 ug of racemic mixture per inch
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How do you manage an epinephrine overdose?
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USUALLY its SHORT duration and little management is necessary 1) terminate the procedure 2) position the patient in a semi sitting comfortable position 3) Reassure the patient 4) monitor their vitals 5) Administer oxygen
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Most reports related to local anesthesia are what type of local?
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Esters yielding PABA which is the allergen
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How many reported cases of anaphylaxis to lidocaine in the past 50 years?
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only 20 reported cases
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If the reaction is strongly suggestive to allergic response what should you do?
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refer to an allergist to be tested
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What are the signs of an allergic response?
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Skin manifestations, ERYTHEMA, PRURITIS< URTICARIA and can progress to bronchial constriction and laryngeal edema
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What does a true allergy diagnosis require?
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requires the formation of an antibody to an antigenic substance
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Is there cross -reactivity among the amide family of local anesthetics?
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YES
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What was removed due to allergies in 1984?
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methyl paraben was removed (the preservative)
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Besides Methyl Paraben what preservative can also produce hypersensitivity?
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METABISULFITES (used to stabilize EPI) cause non-Ig# mediated reactions such as RHINITIS, RASH, HEADACHE, DYSPNEA, CRAMPING
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How many americans have allergic reactions to sulfite containing drugs?
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500,000; most reactions occur in those with asthma
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What part of the dental cartridge themselves contain allergens?
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the latex stopper and diaphragmns can serve as potential antigens which can be released into pharmaceutical sollutions
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What is the most likely cause of transient unconsciousness in the dental office?
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Vasodepressor Syncope Followed by Orthostatic Hypotension
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Why is there is an increase in orthostatic hypotension?
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There is an excess fall in BP (greater than 20/10mm Hg) when the patient goes from a lying position to the upright position
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What is orthostatic hypotension?
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not a disease but a manifestation of abnormal blood pressure regulation due to various causes In patients 65 and over 20 percent of people will have a decrease in BP of 20mm Hg up standing and may develop light headedness
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What are the main etiologies of orthostatic hypotension?
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1) Hypovolemia 2) Drugs 3) Sodium depleting diueretics, tranquilizers, L-dopa 4) Pregnancy 5) Varicose Veins 6) Diabetic Autonomic Neuropathy
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How do you treat orthostatic hypotension?
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1) Put them in supine or TRENDELENBURG position which allows increase CO and venous return 2) Open airway and administer 100 percent Oxygen via a full face mask 3) Monitor Respiration, BP, and pulse 4) Record Vital Signs 5) check levels of consciousness 6) When stable have patient sit up gradually and slowly 7) If a patient does not recover activate EMS or consider other causes
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What is hyperventilation syndrome?
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Deeper more rapid, more prolong respiration than normal, mostly caused by anxiety Breathing pattern varies from frequent deep or sighing Patients may be unaware of breathing pattern
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Besides anxiety what are some other causes of hyperventilation?
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Pain, fever, salicylism (too much aspirin), DKA, Pulmonary Embolism
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What organ systems will hyperventilation syndrome effect?
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1) Resipiratory --> rapid breathing chest tightness and pain with dry mouth 2) CNS --> dizziness, light headedness impaired consciousness, numbness (parenthesis) of the extremities and circumoral tissues 3) Cardiovascular palpitations tachycardia, precordial pain 4) GI --> epigastric pain 5) Musculoskeletal --> muscle pain, cramps, tremors, stiffness CARPOPEDAL TETANY (flexion of ankle wrists, joints and twitching with convulsions) 6) Psychological anxiety agitation and tension
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What is the pathophysiology of hyperventilation?
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1) Anxiety induces catecholamines --> increased respiratory rate and depth 2) Develop respiratory alkalosis due to increase exchange of CO2 and oxygen in the lowing resulting in blowing off carbon dioxide and increasing pH of the blood. 4) This causes a DECREASE in the IONIZABLE CALCIUM and increase neuromuscular irritabilty (tetanus) 5) Respiratory alkalosis also causes CEREBRAL VASOCONSTRICTION leading to light headedness and dizziness
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What is the treatment of hyperventilation?
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Correct breathing pattern and reduce anxiety 1) Terminate the Procedure 2) Reassure patient 3) Have patient breath slowly (6-10 times/minute) breath and into a paper bag and headrest cover to BUILD UP CO2. DO not do this if it is due to other organic issues 4) If it consists Valium 5-10mg IV
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What causes oxygen saturation to remain high during a hyperventilation episode?
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Alkalosis causes an increase in hemoglobin oxygen affinity thereby limiting oxygen release at the tissue level Inhalations of low dose oxygen (.5L/min) may be beneficial
