Dr University of Washington Medical Center, United States
Introduction: Hypophosphatemia has been associated with increased time on mechanical ventilation, longer ICU stays, and a higher mortality. Case reports have described a phenomenon where fluid-resistant lactic acidotic patients have had resolution of lactate levels once their hypophosphatemia was treated. The University of Washington Medical Center implemented an ICU hypophosphatemia replacement protocol which provided standing orders to address low phosphate levels with IV and oral repletion. We hypothesized that vigilant phosphate repletion would lower lactate levels and improve post-operative clinical outcomes.
Methods: We conducted a quasi-experimental pre-post study in a cardiothoracic intensive care unit (CTICU) at an academic medical center. Patients were divided into the “pre-protocol group” or the “post-protocol group”. The primary endpoint was median serum lactate levels post-operatively and at 6, 12, 24, and 48 hours from CTICU admission. Secondary endpoints included median serum phosphate levels at the same time points, amount of insulin infusions, average phosphate repletion, time on mechanical ventilation, hospital and ICU length of stay, and mortality.
Results: Of 1412 patients screened, 709 patients in the pre-protocol group and 255 patients in the post-protocol group were analyzed. Lactate levels were higher in the post-protocol group at 48-hours (median 1.2 mg/dL vs. 1.7 mg/dL; p=0.02) but not at any other time point. Similarly, only phosphate at 12-hours was different between the pre-protocol and post-protocol group respectively (median 3.7 mg/dL vs. 3.5 mg/dL; p=0.02). The post-protocol group had an increased usage of all oral and IV phosphate repletion. Fewer patients in the post-protocol group required insulin infusions (56.1% vs. 47.1%; p=0.04) and had shorter hospital length of stays (11 vs. 10 days; p=0.03).
Conclusions: Although there were no clinically significant differences in lactate and phosphate levels between the pre-protocol and post-protocol groups, the implementation of an electrolyte repletion protocol increased phosphate doses administered. This suggests the need for aggressive monitoring and repletion of phosphate >24 hours post-operative to prevent complications. A protocolized approach can ensure more efficient and standardized correction of hypophosphatemia.
