Chapter 56 Renal Failure vol.1

Chapter 56 今日のメモ☆

Acute Renal Failure

acute renal failure[急性腎不全：ARF] is sudden, potentially reversible interruption of kidney function, resulting in retention[滞留] of nitrogenous waste products in body fuluids.

 - Prerenal ARF[腎前性腎不全]
  腎臓の前にある血管（流れる血液が減るなど）、心臓が原因で起こるものもある
    * arterial blood volume↓
    * urinary losses
    * cardiac output↓
    * renal vascular obstruction
    * severe hypotension

 - Intrarenal ARF[腎性腎不全]
 急性腎不全の場合はこれをさす。薬剤によって起こるものがある。（アミノグリコシド系抗生物質　代謝性アシドーシス　（Na上昇による高血圧）
    * Acute tubular necrosis[急性腎尿細管壊死：ATN]（leading cause of ARF）
      ･ aminoglycosides, anethetics, pesticides, organic metal, radiopaque contrast materials[放射線造影剤]
      ･ ischemic injury[虚血性障害]
      ･ heme pigment[ヘム色素]－hemolysis[溶血], myoglobinuria[ミオグロビン尿]
    * Acute glomerulonephritis[急性糸球体腎炎]
    * Tubular obstruction[尿細管閉塞]
    * Acute inflammation
    * renal vasculitis
    * malignant hypertension[悪性高血圧]
    * radiation nephritis

 - Postrenal ARF[腎後性腎不全]
 腎臓のあとの尿管等が原因で起こり尿量が低下するもの。尿路の閉塞等。尿管の圧迫。尿道の閉塞。GFRの低下。
    * ureteral obstruction[尿管閉塞]
    * bladder obstruction[膀胱閉塞]
    * urethral obstruction[尿道閉塞]
    * extrinsic obstruction[外因性閉塞]

Pathophysiology
 -1. Intiating phase
  may not be well-defined clinically
    * Urine output↓ － >400mL/day : oliguria[欠尿症], >100mL/day : anuria[無尿症]
    ※ 40-50% of ARF patients are not oliguric or anuric.
    * Nitrogen waste products ↑
    － azotemia[尿毒症] : glomerular filtration↓& concentrating capacity↓
    － creatinine concentration↑, sulfate↑, phosphate↑, organic acid level↑
    * Na concentration↓ : due to dilution[希釈]
    * Hyperkalemia[高K血漿] : due to organic acids↑(metabolic acidosis)
    ※ without treatment, neuromuscular paralysis, respiratory muscle paralysis, cardiac arrest, arrhythmias and ultimately death.

 -2. Maintenance phase
  when urine output >500mL/day
  urinary output↑ does NOT signal recovery of renal function
    * Urine out put↑ － >300~500mL/day then double day by day
    * Azotemia may persist until urine output >1000~2000mL/day
    * carries risk of electrolyte abnormalities, GI bleeding, infection, respiratory failure

 -3. Recovery phase
  recovery of renal function may continue for a year.
  residual[後遺症] may persist indefinitely[永久的に]

Clinical Evaluation

Order of physical finindings
 1. Azotemia
 2. oliguria (50-60%)
 3. electrolyte abnormalities
 4. other severe systemic effects

 - Urine output : low (200~500mL/day), complete anuria is rare
 - hyperkalemia[高K血症](metabolilc acidosis)
    * neuromuscular depression (paralysis)
    * diarrhea and abdominal distention[腹部膨満]
    * slow / irregular pulse
    * electrocardiographic[心電図] change
 - uremia[尿毒症]
    * excessive nitrogen waste product retention
    * vomiting, diarrhea, edema, fatigue[疲労], coma
 - metabolic acidosis
    * mental status ↓, lethargy[倦怠感], coma
    * hypotension, pulmonary edema, ventricular fibrillation[心室細動]
    * nausea
    * respiratory abnormalities
 - hyperphosphatemia[高ホスファターゼ血症] : phosphate[リン酸塩] ↑
    * cause hypocalcemia[低Ca血症] : P-Ca（リン酸カルシウム複合体）形成のため
        * neuromuscular irritability, spasm, tetany[手足のけいれん]
        * hypotension
        * soft-tissue calcification[石灰化]
        * mental status change
 - hyponatremia[低Na血症] in the diuretic phase[利尿期（維持期）]
    * lethargy, weakness, unconsciousness
    * seizures[発作]
    * cognitive impairment[認知低下]
 - intravascular volume depletion[血管内容量低下] : prerenal failure[前腎性不全]
    * flat jugular venous[頸静脈] pulses
    * dry mucus membranes

Diagnostic test result
 - Urinalysis[検尿]
    * urinary sediment[沈殿物] examination
        ATN : renal tubular epithelial cells[尿細管上皮細胞]
        inflammatory dissease : red blood cell & white blood cell casts
        chronic renal failure : large number of white cell casts
    * hematuria[血尿] / proteinuria[タンパク尿] : （renal dysfunction[腎不全]）
    * urine-specific gravity[比重] : ranges 1.010~1.016
    * urine osmolality[浸透圧] ↑ （prerenal ARF）
 - urine Na & creatinine levels
    prerenal ARF : creatinne ↑↑ / Na ↓↓
    intrarenal ARF, ATN : creatinine ↓↓ / Na ↑↑
 - creatinine clearance : index of the glomerular filtration rate(GFR)
    renal dysfunction : cratinin clearance ↓↓
 - Blood chemistry[血液化学] : index of renal excretory function
    * blood ure nitrogen(BUN) ↑
    * creatinin concentration ↑
    * hemoglobin & hematocrit values ↑ : due to dehydration
    * abnormal serum elctrolyte values
      K > 5mEq/L, P > 2.6mEq/L(4.8mEq/L), Ca < 4mEq/L (8.5mg/dL), Na < 135mEq/L
      ※ Ca level must be correlated[相関がある] with the serum albumin level
    * abnormal arterial blood gas value (pH < 7.35) : metabolic acidosis
 - Renal failure index (RFI) : ratio of Na/creatinine
    prerenal ARF > 1, intrarenal ARF < 2
 - electrocardiography (ECG)[心電図] : evidence of hyperkalemia
    テント状T波、P波の消失、QRS幅延長
 - radiographic findings[放射線（X線写真）]
    * ultrasound[超音波] : upper urinary tract obstruction
    * radiography
      urinary tract calculi[尿管結石]
      enlarged kidney[腎臓肥大] : ATNによるものの疑い
      asymmetrical kidneys : renal artery disease, ureteral abstruction, chronic pyelonephritis[腎毒腎炎]
    * radionuclide scan[放射性核種スキャン]
      ATN : diffuse, slow, dense uptake
      acute glomerulonephritis : patchy or absent uptake
      ※正常な腎臓ほど吸収率が良い
    * Computed tomography(CT) scan
      better visualization of an obstruction
 - Renal biopsy[生検] : when otehr test results are inconclusive.