形成单侧硬膜外阻滞的原因.doc

1、Topic of the Day I(for Interns and CA-2s)Oct 26 - Discuss unilateral epidural block - explain this result形成单侧硬膜外阻滞的原因Discussion point.A unilateral anesthetic block may result from the administration of local anesthetic in the epidural space secondary to the plica mediana dorsalis, a connective tissu

2、e band in the epidural space that extends in a vertical direction between the ligamentum flavum and dura mater dividing the epidural space in half. 由于背正中皱襞的存在，在硬膜外腔注入局部麻醉药后可造成单侧阻滞。背正中皱襞作为连接黄韧带和硬膜的带状结缔组织在硬膜外腔垂直延伸，并把其一分为二。Oct 27 - Compare sympathetic, motor p. 182, 183; Miller RD: Anesthesia, 5th ed.

3、Philadelphia, Churchill Livingstone, 2000; p. 1513-1514, 1497.Spinal Anesthetic SEs脊髓麻醉的并发症Some side effects associated with spinal anesthesia include hypotension, bradycardia, postdural puncture headache, total spinal, nausea, urinary retention, backache, neurologic sequelae, and hypoventilation.脊髓

4、麻醉的并发症包括低血压，心动过缓，硬膜穿破后头痛，全脊麻，恶心，尿潴留，腰背痛，神经病学结局和低通气。References. Stoelting RK, Miller RD: Basics of Anesthesia, 4th ed. Philadelphia, Churchill Livingstone, p. 176. Miller RD: Anesthesia, 5th ed. Philadelphia, Churchill Livingstone, 2000; pp. 1506-1507. Oct 29 - Discuss the dx and management of an acc

5、idental dural puncture意外穿破硬膜的诊断与处理Discussion point.Accidental puncture of the dura mater during attempted localization of the epidural space can be recognized by the anesthesiologist by the appearance of cerebrospinal fluid in the hub of the epidural needle. The flow of cerebrospinal fluid from the

6、large-bore needle is rapid and continuous. Cerebrospinal fluid is wann, distinguishing it from saline used for the loss of resistance technique for localization of the epidural space. Cerebrospinal fluid will also dipstick test positive for glucose. Once accidental dural puncture during attempted ep

7、idural anesthesia has occurred, the anesthesiologist may convert to a spinal anesthetic. Alternatively, the needle may be removed and reattempt an epidural anesthetic at another interspace. The development of a postdural puncture headache after accidental dural puncture with an 18-gauge epidural nee

8、dle is likely, given the size of the hole in the dura mater produced by the relatively large needle. For this reason the patient should be informed about the possibility of a postdural puncture headache and should be instructed as to whom to contact for evaluation and treatment should a postdural pu

9、ncture headache occur.（前面重复，不作叙述）一旦意外穿破硬膜，麻醉医生可改行脊髓麻醉。另外一种方法是拔出穿刺针后在另一个间隙试行硬膜外麻醉。假如硬膜破口正是 18G 硬膜外穿刺针所造成的，意外穿破硬膜就极有可能发生硬膜穿破后头痛。因此应该告知病人发生硬膜穿破后头痛的可能性，而且应说明一旦出现硬膜穿破后头痛病人可联系哪位医生进行评估和治疗。References. Stoelting RK, Miller RD: Basics of Anesthesia, 4th ed. Philadelphia, Churchill Livingstone, 2000; p. 182; M

10、iller RD: Anesthesia, 5th ed. Philadelphia, Churchill Livingstone, 2000; p. 1513-1514. Oct 30 - Discuss caudal anesthesia - anatomy, technique, etc.骶管麻醉相关的解剖、技术及其他Discussion points.To facilitate the administration of a caudal anesthetic the adult patient should be in the prone position, whereas the

11、pediatric patient may be in the lateral decubitus position.The sacral hiatus is located between the sacral cornua approximately 5 cm from the tip of the coccyx.For the administration of a caudal anesthetic the needle is first introduced through the sacrococcygeal ligament perpendicular to the skin.

12、After contact with the sacrum, the needle is withdrawn slightly and redirected at a slightly reduced angle about 2 cm into the caudal canal. The needle is then appropriately placed for the administration of the local anesthetic for caudal epidural anesthesia.Confirmation that the needle tip is appro

13、priately placed in the caudal canal for the administration of local anesthetic can be made by injecting about 5 mL of saline or air. If the needle is subcutaneously placed, subcutaneous air or a subcutaneous bulge will appear overlying the tip of the needle. Aspiration on the needle before injection

14、 would result in the appearance of cerebrospinal fluid in the syringe if the needle were erroneously placed in the subarachnoid space.为了有助于骶管麻醉的实施，成年人应该采取俯卧位，而小儿则可采取侧卧位。骶管裂孔位于距尾骨尖端约 5 cm 的两侧骶角之间。实施骶管麻醉时，穿刺针首先垂直刺过皮肤和骶尾韧带，触及骶骨后，针回退少许后稍放低，重新推进 2 cm 进入骶管腔，然后适当固定穿刺针以注射局麻药。为了确认针尖是否位于骶管腔，可注射 5ml 生理盐水或空气。如果

15、针位于皮下，可在针尖上面覆有一皮下气肿或皮下隆起。如果针误入蛛网膜下腔，注射前可回抽出脑脊液。References. Stoelting RK, Miller RD: Basics of Anesthesia, 4th ed. Philadelphia, Churchill Livingstone, 2000; p. 183; Miller RD: Anesthesia, 5th ed. Philadelphia, Churchill Livingstone, 2000; p. 1508, 1511-1512, 1525. Topic of the Day II(for CA-2s and C

16、A-3s)Oct 26 - Discuss adrenal insufficiency and supplemental periop steroids肾上腺皮质功能不全和围术期替代治疗Discussion points:Adrenocortical insufficiency can be due to the destruction of the adrenal cortex by cancer, tuberculosis, or hemorrhage; to deficiency in adrenocorticotropic hormone; or to the prolonged ex

17、ogenous administration of corticosteroids. The adrenal cortex of the adrenal gland synthesizes glucocorticoids, mineralocorticoids, and androgens. Cortisol, a glucocorticoid, is essential for the maintenance of blood pressure and the conversion of norepinephrine to epinephrine in the adrenal medulla

18、. Indeed, acute adrenocortical insufficiency can be life threatening. Cortisol also plays an important role in gluconeogenesis, sodium retention, and potassium excretion and has anti-inflammatory effects. Surgical stimulation normally results in an increase in the amount of circulating cortisol. Pat

19、ients who are being chronically treated for adrenocortical insufficiency have impaired cortisol secretion and may have cardiovascular compromise because they are unable to respond to the physiologic stress of surgery with the secretion of cortisol. This is the basis for the perioperative administrat

20、ion of supplementary doses of corticosteroids to these patients.造成肾上腺皮质功能不全的原因包括肿瘤、结核或出血引起肾上腺皮质破坏；促肾上腺皮质激素缺乏；长时间应用外源性皮质类固醇。肾上腺皮质可合成糖皮质激素、盐皮质激素和雄激素。皮质醇是一种糖皮质激素，对动脉血压的维持和在肾上腺髓质中去甲肾上腺素向肾上腺素转化相当重要。事实上，急性肾上腺皮质功能不全可危及生命。皮质醇对糖异生、钠潴留和钾排出起着相当重要的作用，同时还具有抗炎作用。外科刺激正常情况下可导致血中皮质醇水平升高。慢性肾上腺皮质功能不全的病人皮质醇分泌受损，由于对外科生理

21、性应激不能反应地引起的皮质醇分泌，病人可出现心血管不良事件。这就是此类病人进行围术期糖皮质激素补充替代治疗的依据。References. Stoelting RK, Miller RD: Basics of Anesthesia, 4th ed. Philadelphia, Churchill Livingstone, 2000; pp. 313-314; Miller RD: Anesthesia, 5th ed. Philadelphia, Churchill Livingstone, 2000; pp. 920-922. Oct 27 - Discuss clinical present

22、ation of acute adrenal insufficiency急性肾上腺皮质功能不全的临床表现Discussion points:Acute adrenal insufficiency, or addisonian crisis, presents as hypovolemia, hyponatremia, and hyperkalemia. Patients may also have hypotension, decreases in systemic vascular resistance, and decreases in left ventricular stroke in

23、dex severe enough to lead to death. 急性肾上腺皮质功能不全，或称为 Addisonian 危象，表现为低血容量，低钠血症，高钾血症。病人也可伴有低血压，外周血管阻力降低和严重至足以引起死亡的左室每搏指数下降。References. Stoelting RK, Miller RD: Basics of Anesthesia, 4th ed. Philadelphia, Churchill Livingstone, 2000; p. 314; Miller RD: Anesthesia, 5th ed. Philadelphia, Churchill Livin

24、gstone, 2000; p. 921-922. Oct 28- Discuss recommendations for preop steriod administration for at risk pts高风险病人术前应用类固醇的建议Discussion points:Patients at risk for adrenal insufficiency typically receive supplementary doses of corticosteroids in the perioperative period given they cannot respond to the

25、increased stress of surgery with the secretion of cortisol. Perioperative acute adrenal insufficiency occurs rarely but can be severe and potentially fatal. In contrast, the administration of perioperative high-dose corticosteroids places the patient at minimal risk. The precise dose of corticostero

26、id supplementation has not been studied. There has been a correlation established between the stress of surgery and the natural response of a healthy adrenal gland. Under peri operative conditions the adrenal gland secretes 120 to 185 mg of cortisol per day. Under maximum stressful conditions the ad

27、renal gland may secrete 200 to 500 mg/d. One method of administering supplementary corticosteroids is to mimic the natural response of the adrenal gland. For more stressful surgical procedures hydrocortisone can be administered at a dose of 200 mg/d, while for minor surgical stresses a hydrocortison

28、e dose of 100 mg/d should be adequate in the average-sized adult patient. The dose can be decreased by 25% each postoperative day until the patient is able to take the normal oral dose. 如果对额外的外科应激无法反应性地引起的皮质醇分泌，肾上腺皮质功能不全的高风险病人围术期常需接受皮质类固醇替代治疗。围术期很少出现急性肾上腺皮质功能不全，一旦发生，症状严重甚至可能危及生命。反过来说，围术期使用大剂量的皮质类固醇可

29、使风险降至最低。尚未有人研究出皮质类固醇替代治疗的精确剂量。外科应激和正常肾上腺反应之间关联性已经明确。围术期肾上腺每天可分泌 120185mg 皮质醇。最大应激情况下肾上腺每天可分泌200500mg 皮质醇。皮质类固醇替代治疗的另一个方法是模拟肾上腺的正常反应。对一个标准身型的成年人来说，更大的外科应激情况下可一天使用氢化可的松 200mg,但较小的外科应激情况下一天氢化可的松 100mg 即已足够。References. Stoelting RK, Miller RD: Basics of Anesthesia, 4th ed. Philadelphia, Churchill Living

30、stone, 2000; p. 314; Miller RD: Anesthesia, 5th ed. Philadelphia, Churchill Livingstone, 2000; p. 921-922. Oct 29 - Discuss the potential risks of periop steriods administration围术期使用类固醇的潜在风险Discussion points:The potential risks of the administration of supplementary doses of corticosteroids to patie

31、nts in the peri operative period are few. In theory, patients may have aggravation of hypertension, fluid retention, stress ulcers, and psychiatric disturbances. Of concern are impaired wound healing and an increased rate of infections, because these have been seen to occur clinically. These events

32、still occur rarely, however. It is generally recommended that supplementary corticosteroids are administered to patients at risk in the perioperative period because the potential risks are minimal and rare and are outweighed by its potential benefit. 围术期使用替代治疗剂量的类固醇的潜在风险很小。理论上，可加剧血压升高、液体潴留、应激性溃疡和精神障

33、碍。实际临床工作中更值得关注的是出现伤口愈合不良和增加感染的发生率。但这些现象的发生率也极低。由于潜在的风险极小，发生率低，使用后利大弊，建议常规对高危病人进行皮质类固醇的替代治疗。References. Stoelting RK, Miller RD: Basics of Anesthesia, 4th ed. Philadelphia, Churchill Livingstone, 2000; p. 314; Miller RD: Anesthesia, 5th ed. Philadelphia, Churchill Livingstone, 2000; p. 922-923. Oct 3

34、0 - Discuss pheochromocytoma; etiology, signs, symptoms嗜铬细胞瘤的病因、体征和症状Discussion points:Pheochromocytoma is a tumor derived from chromaffin tissue that produces, stores, and secretes catecholamines. A pheochromocytoma is most often derived from the adrenal medulla but can develop anywhere. The hallma

35、rk sign of pheochromocytoma is paroxysmal or sustained hypertension. Signs and symptoms of pheochromocytoma include paroxysmal hypertension, diaphoresis, tachycardia, headache, tremulousness, weight loss, decreased intravascular fluid volume, orthostatic hypotension, a hematocrit greater than 45%, c

36、ardiomyopathy, and an intracerebral hemorrhage. The triad of diaphoresis, tachycardia, and headache in a hypertensive patient is highly suggestive for pheochromocytoma. The most common cause of pheochromocytoma is a unilateral solitary lesion. In approximately 5% of cases of pheochromocytoma it can

37、be inherited as an autosomal dominant trait either alone or in combination with other abnormalities. When combined with other abnormalities it is often designated as multiple endocrine neoplasia, of which medullary thyroid carcinoma is often present. Bilateral pheochromocytomas are common in the fam

38、ilial syndromes. 嗜铬细胞瘤是一种起源于嗜铬组织，可合成、储存和分泌儿茶酚胺的肿瘤。绝大多数嗜铬细胞瘤位于肾上腺髓质，但也可发生在其他任何地方。阵发性或持续性高血压是嗜铬细胞瘤的标志性体征。嗜铬细胞瘤的体征和症状包括阵发性高血压、多汗、心动过速、头痛、寒战、体重减轻、血管内容量降低、直立性低血压、高血球压积（45% ）、心肌病和脑出血。高血压病人伴有多汗、心动过速和头痛三联征时高度提示嗜铬细胞瘤。最常见嗜铬细胞瘤的为单侧病变。大约 5% 嗜铬细胞瘤为常染色体显性遗传，可单独或与其他并存病一起发生。当合并有其他畸形时，常被定义为多发性内分泌瘤病，其中又以甲状腺髓样癌最为常见。双侧嗜铬细胞瘤则常见于家庭性综合征。References. Stoelting RK, Miller RD: Basics of Anesthesia, 4th ed. Philadelphia, Churchill Livingstone, 2000; p. 314; Miller RD: Anesthesia, 5th ed. Philadelphia, Churchill Livingstone, 2000; p. 924.