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งานนำเสนอกำลังจะดาวน์โหลด โปรดรอ

LOCAL ANESTHETIC AGENTS. History of local anesthesia 1500’s Accounts referring to Peruvian Indians chewing on leaves of the coco plant are found 1884.

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งานนำเสนอเรื่อง: "LOCAL ANESTHETIC AGENTS. History of local anesthesia 1500’s Accounts referring to Peruvian Indians chewing on leaves of the coco plant are found 1884."— ใบสำเนางานนำเสนอ:

1 LOCAL ANESTHETIC AGENTS

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3 History of local anesthesia 1500’s Accounts referring to Peruvian Indians chewing on leaves of the coco plant are found 1884 Cark Koller demonstrated the usefulness of the extract from these leaves[cocaine]as a topical anesthetic for the eyes, and earned distinction as the “father of local anesthesia 1884 Willium Halsted used cocaine in the first nerve block [ Inferior alveolar nerve block]. The use of cocaine for anesthesia produced several unwanted side effects including cardiac problem and addiction 1885 James Corning demonstrated the use of a tourniquet to slow absorption of cocaine

4 1901 Heinrich Braun demonstrated the use of epinephrine to retard local anesthetic absorption from the site of injection 1904 Alfred Einhorn introduced procaine. Epinephrine was needed to constrict the vessels in the area of administration to lengthen the duration of anesthesia. It was common to see a 1:50,000 concentration for many years 1943 Nils Lofgren introduced lidocaine 1947 Novocol company made the dental aspirating syringe available 1959 Disposable sterile needles made available by Cook- Waite, Roehr Company History of local anesthesia

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6 Physiology of nerve conduction

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8 Sodium-potassium Pump

9 Channel Entry

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13 Local anesthetics: amides vs. esters

14 Classification of local anesthetics AmidesEster BupivacaineBenzocaine LidocaineCocaine MepivacaineProcaine Prilocaine

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16 Absorption Site of injection The dose of local anesthetic Physicochemical properties of local anesthetic The addition of epinephrine

17 Distribution Site of injection Systemic absorption brain Skeletal muscle heart

18 Biotransformation and Elimination Aminoester Aminoamide Plasma esterase Hepatic enzyme Renal excretion

19 สภาพของผู้ป่วยกับการขับถ่ายยา อายุ – ผู้ป่วยสูงอายุขับถ่ายยาได้ช้าลง โรคตับ – ทำให้ half life ของยานานขึ้น cardiac output – ถ้ามี cardiac output ต่ำ จะ ขับถ่ายยาได้ช้าลง

20 Potency: lipid solubility Onset : pKa, concentration of local anesthetic

21 What is pKa? pKa = pH + log[ RNH + ] [RN] (modified Henderson- Hasselbalch equation) pKa is the dissociation constant, represents the pH at which the concentration of the ionized base(RNH + ) and the non-ionized base (RN) are equal.

22 RNH + RN + H + Outside membrane RNH + RN + H + Inside membrane

23 AnestheticpKa%RN at pH 7.4Onset [min] Mepivacaine Etidocaine Articaine Lidocaine Prilocaine Bupivacaine Procaine

24 Example at physiologic pH (7.4) LidocaineProcaine pKa 7.9 3:1 ionized to non-ionized :1, ionized to non-ionized onset 2 to 3 minutes6 to 12 minutes if lidocaine (pKa 7.9) is administered into an area of infection (pH 4.9) resulting 1,000:1 ionized to non- ionized indicates a poorer penetration into the nerve tissue and therefore a less effective nerve block

25 Quinn and Malamed (1990) and Haegerstam (1990) suggested of administer L.A. AWAY from the area of inflammation (nerve block) especially in the area of EXTENSIVE CELLULITIS Malamed. Handbook of LOCAL ANESTHESIA Haegerstam, Introduction to Dental Local anesthesia 1990.

26 Duration of action Differential sensory/ motor blockade Adverse reaction

27 Clinical use of local anesthesia Topical anesthesia Infiltration Peripheral nerve block Epidural block Spinal block Intravenous regional anesthesia

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29 Clinical sign and symptom LA toxicity

30 CNS toxicity Potency The rate of intravenus administration Acid base status and PaCO 2

31 Cardiovascular toxicity

32 CC/CNS Ratio i.e. the ratio of the LA dosage required for irreversible cardiovascular collapse and the dosage that produces CNS toxicity (convulsions) the higher the CC/CNS ratio the better the safety margin

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35 Prevention Aspiration before injection Inject slowly Use smallest quantity of solution and lowest concentration of vasoconstrictor Observe the patient after injection Choose another anesthetic if the patient has tendency for allergic reaction

36 The signs and symptoms of allergic reaction include: generalized body rash or skin redness itching, urticaria (hives) bronchospasm (difficulty breathing) swelling of the throat asthma abdominal cramping irregular heartbeat hypotension (low blood pressure) swelling of the face and lips (angioneurotic edema)

37 Adverse reactions of commonly used local anesthetics Methemoglobinemia associated with prilocaine, articaine, benzocaine Local tissue toxicity

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39 Receptor Response Alpha stimulationVasoconstriction Peripheral resistance Beta 1 stimulation Heart rate Force of cardiac contraction Cardiac output Beta 2 stimulationVasodilatation Bronchodilation Coronary blood flow

40 Adverse reactions of vasopressor drugs Signs Elevated BP, HR Symptoms Fear Anxiety Restlessness Throbbing headache Tremor Dizziness Pallor Respiratory difficulty Palpitations

41 Contraindication for Epinephrine Blood pressure over 200 torr systolic or 115 torr diastolic Uncontrolled hypertension Severe cardiovascular disease including less than 6 months after a myocardial infarction or cerebrovascular accident Daily episodes of angina pectoris or unstable angina Cardiac dysrhythmias despite appropriate therapy Medicated with beta blocker,monoamine oxidase inhibitor, or tricyclic antidepressant; or general anesthesia with a halogenated anesthetic like halothane

42 New York Heart Association : แนะนำว่าควรใช้ epinephrine ใน ขนาด 3 ug. / kg. Body weight แต่ ไม่ควรเกิน 0.2 mg. (200 µg) หากผู้ป่วยมีปัญหาเกี่ยวกับ โรค ความดันโลหิตสูง โรคหัวใจ ให้ใช้ Epinephrine ในขนาด 40 ug และ สูงสุด ไม่ควรเกิน 54 µg ต่อการฉีดยา ครั้งหนึ่ง

43 วิธีคำนวณปริมาณของ Epinephrine Epinephrine ขนาด 1 : 200,000 1 gm / 200,000 ml 1,000 mg / 200,000 ml 1 mg / 200 ml mg / 1 ml

44 ผู้ป่วยเด็กอายุ 2 ปี หนัก 12 กิโลกรัม หกล้มมีแผลฉีกขาดที่นิ้ว ต้องเย็บแผล ควรใช้ยา ชาชนิดใด ปริมาณและความเข้มข้น เท่าไร

45 ผู้ป่วยชายอายุ 25 ปี น้ำหนัก 60 กิโลกรัม ไม่มีโรคประจำตัว บอกวิธีการให้ยาชาและ ปริมาณยาที่ใช้กับผู้ป่วย


ดาวน์โหลด ppt LOCAL ANESTHETIC AGENTS. History of local anesthesia 1500’s Accounts referring to Peruvian Indians chewing on leaves of the coco plant are found 1884.

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