Association between baseline sodium level, fluid therapy and outcomes in patients with coronavirus disease 2019

This study aimed to determine a correlation between baseline sodium levels, laboratory test results, and clinical condition as well as the association between sodium level changes during treatment and prognosis of patients with COVID-19.

Our retrospective analysis included 1673 patients hospitalized due to COVID-19 at the Temporary Hospital in Pyrzowice. The patients were treated in accordance with the hospital's treatment protocol, including standard fluid therapy regimen adjusted to oxygen support. The analysis considered data on comorbidities, laboratory tests results, blood gas analysis and computed tomography. The endpoints were the need for treatment in the intensive care unit, length of hospital stay, in-hospital mortality, and long-term mortality.

Abnormal sodium levels were found in 35.7% (597) of patients. This correlated with comorbidities and abnormal laboratory test results. Baseline sodium imbalance correlated with longer hospitalization and increased in-hospital and long-term mortality rates. Significant sodium level changes (≥6 mmol/L) were observed in 148 patients which correlated with higher in-hospital and long-term mortality rates.

Baseline sodium imbalances and significant sodium level changes during treatment are associated with worse prognosis of COVID-19. According to our best knowledge there are no prospective randomized studies which would compare different fluid strategies in COVID-19 patients. Further prospective studies comparing different fluid therapy strategies and different compositions of fluids should be conducted.