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Acute renal failure, fluid management and renal replacement therapy

Acute renal failure, fluid management and renal replacement therapy. Nephrologist 鄭昌錡 2007-1-26. 急性腎衰竭 Acute renal failure. 正常腎臟的作用. 排除代謝廢物 排除水分 維持電解質 , 酸鹼平衡  透過 濾過作用 , 再吸收 , 分泌作用 達成 分泌 EPO 活化 Vitamin D. 腎臟的構造. 怎麼看 濾過 的功能好不好 ?. 1. 驗 Cr, 用公式估計

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Acute renal failure, fluid management and renal replacement therapy

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  1. Acute renal failure, fluid management and renal replacement therapy Nephrologist 鄭昌錡 2007-1-26

  2. 急性腎衰竭Acute renal failure

  3. 正常腎臟的作用 • 排除代謝廢物 • 排除水分 • 維持電解質, 酸鹼平衡  透過濾過作用,再吸收,分泌作用達成 • 分泌 EPO • 活化 Vitamin D

  4. 腎臟的構造

  5. 怎麼看濾過的功能好不好? • 1.驗Cr,用公式估計 Estimated Glomerular filtration rate (GFR): (140-age) x BW (女性再乘0.85) Cr x 72 eg(1).20 y/o male, BW 72 kg, Cr:1mg/dl,請問estimated GFR多少? Ans: (140-20)x72 / 1x72 = 120ml/min eg(2).100 y/o female, BW 40 Kg, Cr:1mg/dl,請問estimated GFR多少? Ans: (140-100)x40 / 1x72 x 0.85 =18.7ml/min

  6. 怎麼看濾過的功能好不好? • 2. 驗24小時尿量,尿中的Cr,血中的Cr,算出Creatinine clearance (CCr)來表示GFR. 算法: ㄧ天尿量 x 尿中Cr濃度 血中Cr濃度 x 1440 eg. 100y/o female, 24小時尿量1000cc. 尿中Cr濃度 25 mg/dl, 血中Cr 1 mg/dl,試問CCr? Ans: 1000 x 25 1 x 1440 = 17.36 ml/min

  7. 怎麼看再吸收的功能好不好? • Fractional excretion rate (排泄分率) • 計算通過腎絲球的東西有多少百分比被排泄掉, • 我們把這個百分比叫做 FeXX eg. FeNa, FeK, FeWater…… 怎麼算? 以Na為例FeNa(正常<1%,即99%被再吸收) (1)先算出每天通過腎絲球的鈉離子有幾個? 通過腎絲球的總血量*血中Na濃度 = (Ucr*總尿量/血中Cr)*血中Na濃度

  8. 怎麼看再吸收的功能好不好? • (2)再算尿裡面有幾個Na被排掉? 尿Na濃度*總尿量 = U Na * Total urine amount (3)算算看排在尿裡的Na是通過腎臟的Na 總量的幾分之幾,就是FeNa (2)/(1)就是答案! 公式簡化得 Urine Na x Blood Cr Blood Na x Urine Cr

  9. 怎麼看再吸收的功能好不好? • Eg. 100y/o female, 尿Cr 10mg/dl, 血Cr 1 mg/dl,尿Na 100 meq/L,血Na 140 meq/L, 總尿量1000ml/day,請問FeNa正常嗎? Ans: 100 meq/L x 1 mg/dL 140 meq/L x 10mg/dL = 0.0714 再乘100換算為百分比就是7%!  不正常,太多Na離子流失  腎臟只有再吸收93%, 所以再吸收不良!

  10. 急性腎衰竭的定義 • Acute renal failure (ARF) is a syndrome characterized by • rapid decline in glomerular filtration rate (hours to days), • retention of nitrogenous waste products, and • perturbation of extracellular fluid volume and electrolyte and acid-base homeostasis. • Oliguria (urine output < 500 mL/d) is a frequent but not invariable clinical feature (~50%). ~From Harrison 15th ed.

  11. 幾個小時或幾天內腎臟排除毒素的功能下降到使BUN或Cr上升的地步,體內水分電解質酸鹼度的平衡亦受影響幾個小時或幾天內腎臟排除毒素的功能下降到使BUN或Cr上升的地步,體內水分電解質酸鹼度的平衡亦受影響 • 急性腎衰竭也可能尿量正常,寡尿也未必是急性腎衰竭 • oliguria ( < 500 ml/day ); anuria ( < 100 ml/day )

  12. 腎衰竭的臨床表現

  13. 急性腎衰竭的臨床表現 • Clinical findings: 1. decreased urine amount ( not specific ) 2. uremic manifestation ( later stage ) 3. recovery phase: days to months ( median 10~ 14 days ) increase urine amount  decrease BUN and Cr  restoration of concentration ability 4. 5~10% of ATN will not recover

  14. 急性腎衰竭的臨床表現 • Biochemical and hematological changes * elevated plasma BUN and Cr * hyperkalemia, metabolic acidosis, hypocalcemia, hyperphosphatemia * anemia ( due to EPO deficiency, toxic effects of uremia on bone marrow ) * urinary biochemical indices

  15. Diagnosis of the cause of acute renal failure Q1: 腎衰竭真的是急性的嗎? Q2: 腎衰竭的原因為何?

  16. Q1: 腎衰竭真的是急性的嗎? • Clinical features: • history of vague ill health of some months duration, of nocturia, of pruritus; skin pigmentation • Anemia • Long-standing hypertension orneuropathy. • Measurement of renal size

  17. Q2: Causes of ARF 1. Prerenal failure 2. Intrinsic renal failure 3. Postrenal failure

  18. 下診斷需要哪些資訊?

  19. I.先排除腎後因素 History taking– hematuria, passed urinary stone, renal colic, prostatic symptom, retroperitoneal or pelvic surgery, pain in the loin or back Anuria or alternating polyuria & oliguria Renal image : renal ultrasonography, computed tomography, cystoscope + RP, antegrade nephrostomy 診斷思路

  20. II. 再排除血管問題 • Elderly , hypertension, uneven kidney size • Risk factors: ACEI, reduction in B.P., instrumentation of the aorta • Clinical s/s: flank pain, macroscopic hematuria, complete anuria • Best diagnostic method: angiogram

  21. III. 排除有沒有用過會傷害腎臟的藥物?

  22. IV.分辨是腎前還是腎臟本身的問題 如果是腎前性的ARF…… 最常見的ARF 因為腎臟的灌流不足: 可能因為腎血管損傷或收縮 身體的水(血)量不足 重建足夠的灌流可以讓還沒壞死的腎臟功能恢復 如果時間太久還是沒有足夠的灌流 Acute tubular necrosis:需要更長時間恢復,再久一點可能造成永久性的傷害 # 常見原因: Hypotension (sepsis), aminoglycosides

  23. 其實,不管哪一種原因引起的腎衰竭,最後都會造成腎小管壞死其實,不管哪一種原因引起的腎衰竭,最後都會造成腎小管壞死

  24. V. 腎小管壞死 • Pathophysiology of acute tubular necrosis: • ischemic insults • hypotheses 1 : • arteriovenous shunting of oxygen • hypotheses 2 : • intense constriction of renal vessels during shock • 細胞重建後,需要一段時間才會恢復功能.(days or weeks)

  25. 腎小管壞死 • 如何減少腎小管壞死? 1. 維持足夠的intravascular volume 2. 避免使用有腎毒性的藥物

  26. 維持足夠的volume

  27. 避免使用有腎毒性的藥物 • 記得調整劑量 • 最常見造成急性腎衰竭的藥物: aminoglycoside • 臨床特徵: • relative mild, non-oliguric renal failure • recovery may be slow , delayed or incomplete. • risk factors: duration, plasma conc., aged, liver disease, pre-existing renal impairment, female

  28. Strategies for all acute ill patients • 矯正腎前及腎後因素 • 想辦法移除體內廢物 • 想辦法移除多餘水分 - 肺水腫 • 想辦法維持電解質及酸鹼平衡 - 高鉀,嚴重酸中毒

  29. 先用保守性療法 • 尿變少的時候先看是不是缺水:  沒尿不代表水排不出來!! 尤其是prerenal failure,灌水常常就恢復! 如果已經acute tubular necrosis, 尿在水灌夠了之後還很少  用利尿劑

  30. 治療酸中毒 • Metabolic acidosis: • mild ( HCO3 16 meq/L ) • not require therapy • more marked acidosis • sodium bicarbonate 650~ 1300 mg p.o. tid or parenteral Jusomin * 藥物治療無效才血液透析

  31. 治療鉀離子異常 1.腎臟是鉀離子排出的最主要途徑，故腎衰竭病患易有高血鉀症 2.有hypercatabolism,GI bleeding, sepsis, hemolysis, hematoma,crush syndrome更易有大量鉀離子釋出。可能在數小時內血鉀上升1-2 mEq/L 。 3.高血鉀症對肌肉神經系統和心臟的毒性作用更可因下列合併異常而增加：hypocalcemia, hyponatremia,acidosis,hypermagnesemia 4. 而高血鉀症多無症狀直至嚴重心律不整發生  一定要先做EKG

  32. 鉀離子異常 1. 給CaCl2,灌水,給loop利尿劑 2. 給 Glucose + Insulin 3. 給 bicarbonate 4. 給鉀離子結合劑(口服,灌腸) 5. 束手無策時血液透析

  33. 尿毒性出血 • 血小板功能性障礙 • Prostacyclin 抑制血小板凝集 • 不正常的 Factor VIII, Von Willebrand factor • 血色素過低  Bleeding time 延長 !!

  34. 尿毒性出血 • 治療 : • 保持Hematocrit > 30% : • 輸血 • 使用EPO • DDAVP • Cryoprecipitate (冷凝血漿) • Conjugated estrogen • 避免使用 Heparin

  35. 控制飲食=控制一部分代謝 • Dietary modification: • total caloric intake: 35~50 kcal/kg/day  to avoid catabolism • Salt restriction: 2~4 g/day • Potassium intake: 40 meq/day • phosphorus intake: 800 mg/day

  36. 急性腎衰竭之診斷與治療總結 1. 急性腎衰竭指腎臟功能快速變壞,造成 水和代謝問題 2. 診斷需分腎前,腎臟,腎後三大問題,因 為處理的方式完全不同 3. 已經有急性腎衰竭,要盡量減少腎小管壞 死灌足夠的水,避免腎毒藥物 4. 所有的急性腎衰竭都要先處理水和電解 　　質不平衡以免威脅生命 5. 所有的方法都不能重現平衡 　　透析治療

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