Correlation Between Base Excess in Patients Upon Admission to the ICU and Platelet Count Trend in the Following Days

Overview

Several studies have revealed that a relative platelet count decline in patients after their admission to the intensive care unit (ICU) is a very reliable marker of the severity of their sickness. ICU patients with a greater platelet count decline after their admission to the ICU have generally worse outcome. Investigators assume that a quick appearance of a deep metabolic acidosis, which commonly occurs in critically ill, has an important role in pathogenesis of relative platelet count decline. To evaluate this, correlation of metabolic acidosis severity in participants upon admission to the ICU with platelet count decline in 2 days, following admission, was investigated with a retrospective observational study, analysing all participants, admitted to the ICU in one year period (in 2020). As a measurement of metabolic acidosis severity, investigators took base excess (BE) value (expressed in mmol/L) from arterial blood gas analysis with lowest pH in participants in around admission time (in a period from 24 hours before to 24 hours after their admission to the ICU). To calculate relative platelet count decline in 2 days after admission to the ICU, investigators took platelet count on admission to the ICU (P0) and lowest platelet count on day 2 after the patient's admission (P2). Following formula was used to calculate relative platelet count decline in 2 days after ICU admission (delta P): delta P = (P2-P0)/P0 x 100 (expressed in %). More negative values of delta P represent larger relative platelet count decline. The main interest of the study was if BE value correlates with delta P. Investigators assumed that participants with a more severe metabolic acidosis upon admission to the ICU (represented with more negative BE value) would tend to have a larger relative platelet count decline in 2 days, following admission to the ICU (represented with more negative value of delta P). Pearson correlation was used to evaluate correlation between BE and delta P.

The aim of the study was to answer the question, if metabolic acidosis severity in participants upon admission to the ICU correlatets with platelet count decline in days, following admission. Investigators conducted this study at the Department of Anesthesiology and Surgical Intensive Care at University Medical Centre Ljubljana. The study included all participants, admitted to the ICU in a one-year period (in 2020; from 1st January to 31st December 2020). From the electronic recordings of the department (Hospital Information System BIRPIS21), investigators obtained the following data of each participant: age, gender, lowest pH in arterial blood gas analysis in around admission time with corresponding bicarbonate concentration \[HCO3-\] and BE value, platelet count on admission (P0), and lowest platelet count on second day after ICU admission (P2). As a measurement of metabolic acidosis severity, investigators took the BE value of arterial blood gas analysis with the lowest pH from the range of 24 hours before to 24 hours after ICU admission. To calculate relative platelet count decline in 2 days after ICU admission (delta P), the following formula was used: delta P = (P2-P0)/P0 x 100. Participants who died before the second day after ICU admission or participants whose demanded laboratory findings were for some other reasons lacking (arterial blood gas analysis or platelet count on admission or platelet count on second day after ICU admission), were excluded from final analysis of correlation between BE and delta P. Pearson's correlation coefficient (r) with 95% confidence interval (CI) was used to estimate the association between BE and delta P.