NMS. Casos Clínicos

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Part II ♦ Specific Disorders

Figure 8-2: Upright abdominal radiograph showing bowel obstruction. Note the air–fluid levels. Together, Figures 8-1 and 8-2 make up an “obstructive series.” (From McKenney MG, Mangonon PC, Moylan JA, eds. Understanding Surgical Disease: The Miami Manual of Surgery . Philadelphia: Lippincott-Raven; 1998:139.)

Q: What is the patient’s predicted fluid and electrolyte status? A: Dehydration due to vomiting and poor oral intake is expected. In addition, the usual metabolic picture involves a contraction alkalosis with hypokalemia, which develops as a result of a multistep process. When H + is secreted into the stomach, HCO 3 − is secreted into the plasma. To maintain neutrality, Cl − is also secreted into the stomach. With vomiting, there is loss of H + , Na + , Cl − , and water, which leads to alkalosis and volume contraction. In response to this state, the kidney preferentially retains Na + at the expense of H + and K + , which is lost in the urine. Q: How would you correct this metabolic problem? A: Correction of this deficit requires rehydration with sodium- and potassium-containing intravenous (IV) fluids. The alkalosis usually corrects itself after rehydration if renal func- tion is normal. SAMPLE