(1738) Efficacy of Phosphorus Replacement Protocol in Trauma and Surgical Critical Care Patients

Introduction: Hypophosphatemia occurs frequently in critically ill patients and can be associated with increased mortality, length of stay, and duration of mechanical ventilation. Patients admitted to the trauma/surgical intensive care unit (ICU) may have increased needs and decreased responsiveness to electrolyte replacement when compared to medical ICU patients. The goal of this study was to determine the efficacy of the institutional non-weight based, sliding scale electrolyte replacement protocol in replacing phosphorus in critically ill trauma and surgical patients.

Methods: A retrospective analysis of adult patients admitted to the Trauma/Surgical ICU was performed. The primary endpoint was the efficacy of the protocol-recommended dose of phosphorus replacement, defined as a normal phosphorus level ( > 2.5 mg/dL). Patients were analyzed at 24 and 72 hours after the first phosphorus replacement dose. Secondary endpoints included total cumulative phosphorus replacement required to achieve successful replacement; overall protocol compliance; excess intravenous volume administration; ICU length of stay; length of mechanical ventilation; and risk factors for unsuccessful phosphorous normalization at 24 hours.

Results: One hundred and eighty patients were analyzed (68.3% were admitted for trauma-related reasons). Overall, 44.4% of patients achieved phosphorus normalization within 24 hours. This incidence increased to 75% at 72 hours post-replacement dose. Non-compliance to the protocol was 34.4%, largely attributed to patients receiving higher doses than the replacement protocol. Patients who did not achieve phosphorus normalization by 24 hours had a lower median age (49 years vs 58 years, p = 0.022), had lower baseline phosphorus levels (1.9 mg/dL vs 2.3 mg/dL, p < 0.001), and received more cumulative phosphorus (0.710 vs 0.375 mmol/kg IBW/day, p < 0.001). There were no differences in length of mechanical ventilation, intravenous fluid administration, or ICU and hospital length of stay.

Conclusions: Additional phosphorus replacement was required to a non-weight based, sliding scale protocol for successful phosphorus replacement in critically ill trauma and surgical patients. Future studies should explore weight based phosphorous replacements strategies.