Electrolyte supplementation patterns and evaluation in perioperative parenteral nutrition for patients undergoing major thoracoabdominal surgery

For patients undergoing major thoracoabdominal surgery, perioperative nutritional management is essential. Although enteral nutrition is preferred, parenteral nutrition (PN) is needed when oral or enteral intake is inadequate or contraindicated and serves as a key electrolyte source. Electrolytes are crucial for fluid balance, acid–base stability, and metabolic function, and inappropriate supplementation may cause serious disturbances. Real-world evidence on perioperative PN electrolyte use in China remains limited. This multicenter retrospective study included 2018 patients who underwent major thoracoabdominal surgery and received PN between January 1 and December 31, 2024, across 10 medical centers in 8 provinces in China. Daily sodium, potassium, calcium, magnesium, and phosphorus intake and related clinical outcomes were collected from 2 days before to 5 days after surgery. Adequacy was assessed according to current guideline recommendations. Among the 2018 patients included, perioperative electrolyte supplementation showed substantial deviations from guideline recommendations. On the day of surgery, excessive sodium supplementation (>150 mmol) was observed in 73.7% of patients, while insufficient supplementation of potassium, magnesium, and phosphorus occurred in 56.2%, 91.0%, and 94.7%, respectively. Overall, 48.9% of patients experienced at least 1 electrolyte disturbance, with hypocalcemia (30.4%), hypophosphatemia (18.2%), and hyponatremia (17.8%) being the most common abnormalities. Potential PN compatibility risks were identified in 40.4% of prescriptions on the day of surgery and were associated with longer hospital stay. Multivariable analyses showed that supplementation routes were not independently associated with clinical outcomes. In contrast, higher PN volume was independently associated with increased risks of electrolyte disturbances, major complications, and prolonged hospitalization. Phosphate insufficiency was associated with prolonged hospital stay and increased risks of electrolyte disturbance and major complications, particularly on postoperative day 1. Surgical complexity also influenced outcomes, with pancreaticoduodenectomy associated with substantially higher risks of electrolyte disturbances and major complications. Perioperative PN is characterized by sodium overload and multi-electrolyte deficiency. Beyond supplementation routes, PN volume, phosphate insufficiency, and surgical complexity are key independent determinants of adverse clinical outcomes. Optimization of PN dosing strategies and targeted correction of phosphate imbalance may improve postoperative recovery and safety.