每日一题_2022.06.26

A 72-year-old man with a history of chronic obstructive pulmonary disease, hypertension, and colon cancer, who is status post partial colectomy four years ago presents with symptoms of a small bowel obstruction with transition point noted on CT. He undergoes urgent small bowel resection with primary anastamosis. The repair is difficult, and the patient receives 7 liters of crystalloid and 1 liter of albumin, with an estimated blood loss of 300 mL. He produces 700 mL of urine during the repair. He is given ciprofloxacin and metronidazole intraoperatively. The abdomen is closed at the conclusion of the repair. He is brought to the ICU intubated and on nitroprusside for intraoperative hypertension. Over the next 12 hours, he becomes febrile to 39.4°C (103°F) and develops atrial fibrillation with a rate in the 130s beats/min. His blood pressure remains stable at 120/80 mm Hg, and his oxygen saturation is 96% on 70% fraction of inspired oxygen with peak airway pressures of 30 cmH2O (up from 20 cmH2O in the operating room). Urine output for the past hour is 5 mL. On examination, he is sedated, with a distended abdomen, and the exploratory laparotomy incision site appears clean. His laboratory results show the following values: sodium 145 mEq/L, potassium 3.8 mEq/L, chloride 109 mEq/L, bicarbonate 13 mEq/L, blood urea nitrogen: 45 mg/dL, creatinine 2.34 mg/dL (up from baseline of 1.2 mg/dL), albumin 4 g/dL.

Which of the following is the most likely cause of this patient’s renal failure?

A. Intravascular depletion and hypovolemia

B. Ureteral compression by increased abdominal pressure

C. Decreased cardiac output due to increased abdominal pressures

D.Renal vein compression by increased abdominal pressure

答案解析：

腹内高压是指腹内压(IAP)大于10 mmHg。腹腔间隔室综合征(ACS)是长期腹内高压导致的有效终末器官低灌注。IAP高于20～25 mmHg可能引起ACS，并通过这种方式引起各种腹部和腹外器官的急性功能丧失。腹内高压引起的炎症和血流动力学因素可能影响腹部器官旁的骨盆、胸腔、颅骨和肌肉区域。膀胱压力是测量IAP的金标准，IAP高达70 mmHg时仍有效。影响其可靠性的因素包括妊娠，肥胖选项A是不正确的，因为患者在整个住院期间保持正常的血压，我们可以假设在7L晶体液后，他接近血管内补充。此外，考虑到腹压升高的证据，在这种情况下给予IV液体是适当的。少尿进展为无尿，扩容无反应的肾前性氮质血症是ACS肾功能不全的特征。

IAP增加导致的输尿管压迫曾被认为是ACS肾衰竭的原因，但此后已被否定，因为输尿管支架在这种情况下不能预防肾衰竭的发生。1947年，研究检查了接受外部压迫至20 mmHg的受试者。在这些模型中，研究了肾静脉压、下腔静脉压、肾血浆流量和肾小球滤过率的测量值。有效肾血浆流量和肾小球滤过率分别下降24.4%和27.5%。所有患者均出现少尿，压力释放时尿流量无突然增加，提示输尿管压迫不太可能是少尿的原因。相反，发现肾静脉压升高可能是罪魁祸首，使选项D成为正确答案。

腹内高压引起静脉充血和前负荷降低肯定会影响心输出量，尤其是当压力进入引起ACS的范围时；然而，这不是肾衰竭的主要原因，因为在这种情况下用液体和正性肌力药纠正心输出量没有显示出益处。重要的是要注意，当给予液体时，应通过颈内静脉而不是股静脉管路进行，因为膈下静脉回流可能受到阻碍。

正确答案：D