Abstract
Background: Bedside vital signs and routine laboratory tests are available within minutes of intensive care unit (ICU) admission, but their comparative value in tracking severity and mortality in acute respiratory distress syndrome (ARDS) is not well characterised in Indian cohorts. Methods: In this prospective observational study in the medical ICU of a tertiary care hospital, 100 patients fulfilling the Berlin definition of ARDS were enrolled. Admission vital signs and haematological, biochemical and arterial blood gas parameters were compared across Berlin severity strata by analysis of variance and between survivors and non-survivors by independent-samples testing. Results: Forty-six patients had mild, 31 moderate and 23 severe ARDS; in-hospital mortality was 27.0%. Every clinical parameter deteriorated across severity strata (p≤0.018): heart rate rose from 115.4 to 132.1/min and SpO₂ fell from 75.8% to 50.6%. By outcome, heart rate, SpO₂ and Glasgow Coma Scale differed but respiratory rate (p=0.052) and mean arterial pressure (p=0.153) did not. Haemoglobin, platelet count, haematocrit and INR were deranged with both endpoints (p≤0.023), while leucocyte count was associated with neither (p=0.186 and 0.475). All six biochemical parameters differed significantly by both endpoints. PaO₂/FiO₂ showed the widest gradient of any parameter, falling from 236.2 to 88.2 mmHg across strata and from 193.6 to 125.4 mmHg between survivors and non-survivors (p<0.001 for both); PaCO₂ was associated with neither. Derived fractional inspired oxygen rose from 0.35 to 0.71 across strata. Conclusion: Almost every routinely available parameter tracked both severity and mortality, the consistent exceptions being leucocyte count and PaCO₂. All comparisons are univariate.
Keywords: ARDS, haematological parameters, biochemical parameters, arterial blood gas, PaO2/FiO2, Mortality