Mortality Predictors in Shock

INTRODUCTION: Shock is a potentially fatal clinical condition which causes cellular hypoxia and tissue death leading to multiorgan dysfunction. Shock usually progresses through stages and may be reversible initially with appropriate treatment. Mortality in septic shock is reported around 40 to 50%. Various physiological and biochemical markers provide windows to diagnose shock. Prediction of morbidity and mortality among patients with shock through bedside parameters help in timely intervention and prognostication. Among these markers, blood lactate levels, shock index, and the end-tidal CO(2)-arterial CO2 (ETCO2-PaCO2) gradient have individually been studied before. We intended to study these parameters together in prediction of 14-day mortality among mechanically ventilated patients across all etiologies of shock. OBJECTIVES: To study the utility of ETCO2-PaCO2 Gradient, Modified shock index and Blood lactate levels measured at various time points, in predicting mortality at day 14 in mechanically ventilated patients with shock. MATERIALS AND METHODS: This prospective observational study enrolled mechanically ventilated patients diagnosed with shock at a tertiary care hospital. Blood lactate levels, Modified shock index, and the ETCO2-PaCO2 gradient were analysed against primary outcome, i.e, mortality at 14 days. These parameters were compared between survivors and non survivors at inclusion, 6hour, 12hour, 18hour, and 24 hours. Sensitivity and specificity with cut off values were obtained for each of these parameters. Receiver operator characteristics curves were plotted at each time points.(1–4) RESULTS: The study included 115 patients. Septic shock was the most common type of shock. Blood lactate level with cut off of 4.5meq/L at 12 hours(sensitivity of 71.6% and specificity of 66.7% with AUC ROC = 0.705), Modified shock index, with a cut off of 1.7, at 12 hours (sensitivity of 79.1% and specificity of 68.8%, AUC ROC = 0.726), and ETCO2- PaCO2 Gradient, with a cut off of 8mmhg, at 6 hours(sensitivity of 85.1% and specificity of 68.8% AUC ROC = 0.716) predicted mortality at 14 days since admission among mechanically ventilated patients with shock. DISCUSSIONS/CONCLUSIONS: Plasma lactate levels, End tidal-Arterial CO2 tension gradient and modified shock index are useful predictors of mortality amongst patients in shock when used at appropriate time points helping in guiding intervention and prognostication.