每日一题_2022.10.05

A 22-year-old man is admitted to the ICU for severe dehydration due to polydipsia. Vital signs are: heart rate 110 beats/min, blood pressure 92/48 mm Hg, respiratory rate 28 breaths/min, oxygen saturation 98% on 2 L. He is lethargic but follows commands. Initial chemistry panel results are: sodium 128 mEq/dL, potassium 4.7 mEq/dL, chloride 94 mEq/dL, bicarbonate 16 mEq/L, blood urea nitrogen 34 mg/dL, creatinine 1.2 mg/dL, glucose 436 mg/dL. He is volume resuscitated with 0.9% normal saline and started on appropriate medical therapy. His hemodynamic profile improves. Repeat electrolytes after four hours of treatment are: sodium 131 mEq/dL, potassium 4.0 mEq/dL, chloride 100 mEq/dL, bicarbonate 20 mEq/L, blood urea nitrogen 28 mg/dL, creatinine 1.1 mg/dL, glucose 202 mg/dL. His mentation initially improves with treatment, but then he becomes obtunded and unresponsive, and requires intubation for airway protection.

Which of the following is the most likely cause of this clinical picture?

A. Central pontine myelinolysis from rapid sodium correction

B. Cerebral edema from rehydration and rapid correction of glucose

C. Symptomatic hyponatremia

D. Hypoactive delirium

E. Left hemispheric infarct

答案解析：

该患者患有糖尿病酮症酸中毒 (DKA)。主要治疗是使用等渗溶液、电解质替代品（尤其是钾和胰岛素）进行复苏。脑桥中央髓鞘溶解症被描述为脑桥中央基底部的非炎性渗透性脱髓鞘。认为在 120 mEq/L 或更低的重度低钠血症中更常发生，但该患者并非如此。他患有低钠血症；然而，考虑到高血糖症，他的校正钠为133-136 mEq/dL，取决于使用的校正公式。活动减退性谵妄表现为警觉性下降伴动作缓慢、嗜睡、言语稀疏、情感淡漠。他因快速纠正葡萄糖和补液而出现脑水肿，常见于 DKA 治疗后。他的症状已经从木僵变成昏迷。

其机制仍不清楚，但可根据神经元对高渗状态的适应和血液渗透压的快速纠正来解释。在这种情况下，神经元将失去间质游离水，以平衡跨膜渗透压。随着快速纠正，水从脑脊液和血液进入大脑（从而增加间质体积），并被细胞摄取溶质（从而将水拉入细胞并恢复细胞体积）。治疗范围从轻度症状的支持治疗到高渗溶液和袢利尿剂。

正确答案：B