3.2. A 60-kg 17-year-old man presents for open reduction and internal fixation of an ankle fracture. You discuss a general anesthetic for intraoperative management with a sciatic block via the popliteal approach. You decide to use 20 mL of 0.5% bupivacaine with 1:200,000 of epinephrine. How many mL of 1:1000 epinephrine should you add to your bupivacaine to reach the appropriate concentration?
A. 0.05 mL
B. 0.1 mL
C. 0.02 mL
D. 0.2 mL
E. 0.04 mL
1. open reduction and internal fixation of ankle fracture 踝关节骨折切开复位内固定
“Open reduction” means a surgeon makes an incision to re-align ([ ,ri:ə'lain ] v.align anew or better) the bone. “Internal fixation” means the bones are held together with hardware like metal pins (金属钉), plates (金属板) , rods (棒), or screws (螺丝). After the bone heals, this hardware isn’t removed. Generally, ORIF is an urgent surgery.
ankle ['æŋk(ə)l] n.踝；踝关节
fracture [ˈfræktʃə(r)] n.断裂；裂缝；【医学】挫伤
2. sciatic block via the popliteal approach 腘窝入路坐骨神经阻滞
sciatic [saɪ'ætɪk] adj.坐骨的；坐骨神经的of the hip or of the nerve which goes from the pelvis to the thigh (= the sciatic nerve) → ischium ['ɪskɪəm] n.【解】坐骨；
A sciatic nerve block is a nerve block that uses local anesthetic to achieve analgesia in the leg. The block works by affecting the sciatic nerve and is used for surgeries at or below the knee. The sciatic nerve is located in the gluteus maximus muscle ([ˈɡluːtiəs] ['mæksɪməs] 臀大肌), where the block is performed. The sciatic nerve can be blocked at different locations. At the popliteal fossa ([pɒp'lɪtɪəl] ['fɒsə] 腘窝), the sciatic nerve divides into its two branches: The tibial (['tɪbɪəl] adj.胫骨的) and the common peroneal ([ˌperə'niːəl] adj.腓骨的) nerve. If surgery is performed on the ankle, achilles tendon ([əˌkɪliːz ˈtendən] n.【解】跟腱)_ or foot a popliteal block can be performed, affecting the two branches of the sciatic nerve. It is done above the knee on the posterior leg where the sciatic nerve starts splitting into the common peroneal and tibial nerves.
popliteal [pɒp'lɪtɪəl] adj.【解】腿弯部的，腘的
3. bupivacaine [bjʊpɪvə'keɪn] n. 布比卡因
4. epinephrine [ˌepɪ'nefrɪn] n.【生化】肾上腺素
3.1. A 48-year-old woman presents for laparoscopic cholecystectomy. Her past medical history is significant only for prior tonsillectomy and adenoidectomy as a child. She states that she has an allergy to local anesthetics. Upon further questioning, she states that she received Novocain (procaine) at the dentist and her “heart began to race and she became light-headed.” Which of the following conditions most likey explains this patient’s reaction?
A. A true allergic reaction to the amide local anesthetic procaine
B. An allergic reaction to a breakdown product of procaine
C. A side effect of epinephrine, which was added to the Novocain preparation
D. A somatization of the patient’s apprehension toward dental procedures
E. A side effect of phenylephrine, which was added to the Novocain preparation
ANSWERS
C. The patient’s reaction is most likely a representation of the side effects of epinephrine that is often added to local anesthetic preparations in order to increase duration of action and reduce systemic absorption of the local anesthetic. The patient’s symptoms of tachycardia are more consistent with the sympathetic sequelae from epinephrine injection rather than a true allergic reaction (bronchospasm and urticaria). Procaine is an ester local anesthetic, which is more likely to cause an allergic reaction than amide local anesthetics, although the incidence of ester-mediated allergic reaction is very rare. Ester local anesthetics are broken down to para-aminobenzoic acid (PABA), a known allergen. Further, certain preservatives in local anesthetics such as methylparaben and sulfites can cause an allergic response.
1. sequela [sɪ'kwelə] n.【医】后遗症,后续 plural sequelae [sɪ'kweli] n.【医】后遗症
2. urticaria [ˌɜ:tɪ'keəriə] n.荨麻疹，风团 red spots on the skin that itch (= make you want to scratch) , caused by an allergic reaction, for example to certain foods
3. procaine ['prəʊkeɪn] n.普鲁卡因
4. Ester local anesthetic 酯类局麻药 Metabolized in the blood plasma and has a high incidence of allergy. Allergies to this drug stem from an atypical pseudocholinesterase (['sjuːdəʊˌkɒlɪ'nestəreɪs] n.假胆碱酯酶) which is a protein needed to metabolize these drugs. They tend to have a cross allergy meaning that if you are allergic to one ester drug you are likely going to be allergic to other esters
Amide local anesthetic 酰胺类局麻药 Metabolized in the liver like most other drugs, very low incidence of allergy. Individuals with liver disease or low liver function will have a hard time metabolizing the drug and more drug free in the body increasing its toxicity
5. para-aminobenzoic acid (PABA) 对氨基苯甲酸
para-[pærə] pref. 【化】对(位)；
amino- [ə'mi:nəʊ] adj.【化】氨基的
benzoic[ben'zəʊɪk] adj. 苯甲酸的
6. allergen [ˈælə(r)ˌdʒen] n.过敏原（能引起变态反应或过敏的物质）a substance that causes an allergy
7. preservative [prɪˈzɜː(r)vətɪv] n.防腐剂；预防法
8. methylparaben [meθɪl'pærəben] n.对羟基苯甲酸甲酯
methyl ['meθɪl] n.【化】甲基
9. sulfite ['sʌlfaɪt] n.亚硫酸盐
Case Files: Anesthesiology 学习笔记 Q&A3.1 / 电子书分享！Case Files: Anesthesiology 学习笔记 Q&A 2.3 / Case Files: Anesthesiology 学习笔记 Q&A 2.2 / Case Files: Anesthesiology 学习笔记 Q&A 2.1
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