Perioperative Fluid Therapy

A 58-year-old man with hypertension and type 2 diabetes mellitus is scheduled for elective open cholecystectomy. Preoperative labs: Na⁺ 138 mEq/L, K⁺ 4.2 mEq/L, Cl⁻ 102 mEq/L, HCO₃⁻ 24 mEq/L, Cr 1.1 mg/dL. He has been fasting for 8 hours. Intraoperatively, 2 L of normal saline (0.9% NaCl) is infused over 2 hours. At the end of surgery (3 hours total), his urine output is 180 mL, and postoperative labs show Na⁺ 135 mEq/L, Cl⁻ 108 mEq/L, HCO₃⁻ 20 mEq/L. Which of the following best explains the electrolyte abnormality observed?

Which of the following crystalloid solutions has the most similar electrolyte composition to plasma and is considered a 'balanced' solution?

A 72-year-old woman with chronic kidney disease (eGFR 35 mL/min/1.73 m²) and heart failure (EF 40%) undergoes emergency repair of a perforated peptic ulcer. She arrives hypovolemic: BP 88/54 mmHg, HR 118 bpm, JVP not visible, urine output 0.2 mL/kg/hr. Intraoperatively, she receives 1.5 L of Lactated Ringer's over 1.5 hours. Postoperatively, her BP improves to 105/65 mmHg, HR 92 bpm, but urine output remains 0.3 mL/kg/hr. Postoperative labs: Na⁺ 136 mEq/L, K⁺ 5.8 mEq/L, Cr 1.8 mg/dL (baseline 1.4 mg/dL). What is the most appropriate next step in fluid management?

According to the 4-2-1 rule for perioperative fluid maintenance in children, what is the hourly maintenance fluid requirement for a 25 kg child?