Value of Shock Index in prognosticating the short-term outcome of death for patients presenting with severe sepsis and septic shock in the emergency department

Abstract

Introduction: The importance of early recognition and treatment of sepsis and its effects on short-term survival outcome have long been recognized. Having reliable indicators and markers that would help prognosticate the survival of these patients is invaluable and would subsequently assist in the course of effective dynamic triaging and goal directed management.

Study objectives: To determine the prognosticative value of Shock Index (SI), taken upon arrival to the emergency department and after 2 hours of resuscitation on the shortterm outcome of severe sepsis and septic shock patients.

Methodology: This is a retrospective observational study involving 50 patients admitted to the University of Malaya Medical Centre between June 2009 and June 2010 who have been diagnosed with either severe sepsis or septic shock. Patients were identified retrospectively from the details recorded in the registration book of the resuscitation room. 50 patients were selected for this pilot study. The population comprised 19 males (38%) and 31 females (62%). The median (min, max) age was 54.5 (17.0, 84.0) years. The number of severe sepsis and septic shock cases were 31 (62%), and 19 (38%) respectively. There were 17 (34%) cases of pneumonias, 13 (26%) cases of urological sepsis, 8 (16%) cases of gastro intestinal tract related infections and 12 (24%) cases of other infections. There were a total of 23 (46%) survivors and 27 (54%) deaths. The value of the shock index is defined as systolic blood pressure divided by heart rate was calculated. Shock Index on presentation to ED (SI 1) and after 2 hours of resuscitation in the ED (SI 2). The median, minimum and maximum variables were tested using Mann-Whitney U and Chi square analysis. The significant parameters were re-evaluated for sensitivity, specificity and cut-off points. ROC curves and AUC values were generated among these variables to assess prognostic utility for outcome.

Results: Amongst all 7 variables tested, 2 were tested to be significant (p: < 0.05). From the sensitivity, specificity and ROC analysis, the best predictor for death was (SI 2) with a sensitivity of 80.8%, specificity of 79.2%, AUC value of 0.8894 [CI 95 0.8052, 0.9736] at a cut-off point of > or = 1.0.

Conclusion: (SI 2) may potentially be utilized as a reliable predictor for death in patients presenting with septic shock and severe sepsis in an emergency department. This parameters should be further analyzed in a larger scale prospective study to determine its validity.