每日一题_2022.3.15

A 70-year-old woman with a history of a prior ventral hernia repair with mesh is admitted to the ICU for a small bowel obstruction requiring serial examinations, nasogastic tube decompression, IV hydration, and correction of electrolyte abnormalities. During the next 24 hours, her pain worsens and there is significant bilious drainage from the nasogastric tube. Laboratory results reveal: sodium 149 mEq/L, potassium 3.3 mEq/L, chloride 105 mEq/L, bicarbonate 17 mEq/L, blood urea nitrogen 55 mg/dL, creatinine 2.3 mg/dL, calcium 8.0 mg/dL, albumin 4.0 g/dL, white blood cell count 18,000/μL, hematocrit 30%. Arterial blood gas analysis shows a pH of 7.50, partial pressure of carbon dioxide 24 mm Hg, partial pressure of oxygen of 90 mm Hg and bicarbonate of 17 mEq/L.

Which of the following acid-base disorder is most likely?

A. Acute respiratory alkalosis with elevated anion gap metabolic acidosis and metabolic alkalosis

B. Metabolic alkalosis and elevated anion gap metabolic acidosis

C. Acute respiratory alkalos is with elevated anion gap acidosis

D. Acute respiratory alkalos is with elevated anion gap acidosis and anon-anion gap acidosis

E. Metabolic alkalosis and non-anion gap metabolic acidosis

答案解析：

该患者患有混合性酸碱失衡。她因缺血性小肠梗阻导致败血症恶化，从而导致代谢性乳酸酸中毒。存在呕吐和鼻胃管引流引起的潜在代谢性碱中毒。呼吸性碱中毒随着她的腹痛而发展，她变得呼吸急促。识别酸碱问题需要系统的方法。下面是可以使用的几种方法之一。第1步：观察pH值，导致偏移至7.40两侧的过程是主要异常。该患者的pH值为7.50，二氧化碳分压为24 mmHg，符合急性呼吸性碱中毒。第2步：计算阴离子间隙。身体永远不会产生大的阴离子间隙来补偿原发性疾病。在这种情况下，阴离子间隙为27 mEq/L。值得注意的是，白蛋白水平正常，但如果低于4.0 g/dL，阴离子间隙需要每低于4.0 g/dL 1次校正2.5 mEq/L。第3步：计算δ-δ间隙，以观察除阴离子间隙酸中毒外，是否存在潜在的非阴离子间隙酸中毒或代谢性碱中毒。在这种情况下，δ间隙大于2.0，表明并发代谢性碱中毒。

正确答案：A

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