Shock index utility to predict mortality in pediatric patients with septic shock or severe sepsis

Background: Pediatric sepsis is considered the main cause of hospital death around the world. Many groups have tried to create tools that facilitate its early identification, as the shock index (SI) defined as the ratio between cardiac frequency and systolic blood pressure. The objective of this study was to determine the utility of SI to predict mortality in pediatric patients with severe sepsis and septic shock. Methods: Retrospective cohort with 165 pediatric patients with severe sepsis or septic shock in the Pediatric Intensive Care Unit. SI was calculated at diagnosis, 2, 4 and 6 hours after (SI2, SI4 and SI6). We divided the population in two groups depending their outcome: survivors and non-survivors. The statistical analysis was performed with U Mann-Whitney and chi squared tests. The risk factors were compared between the survivors and the dead, and we calculated the odds ratio (OR). Results: The median value of SI was compared between groups; in the group of septic shock, SI showed a tendency to remain high in SI4 and SI6 (p = 0.010 and p = 0.005, respectively). Among the survivors and the non-survivors, we found that in the latter, SI was progressively increased in SI4 and SI6 (p < 0.05). High values of SI4 and SI6 increased the risk of death in patients (SI4: OR: 442.1; CI 95% [confidence interval 95%]: 54.2-3,601.7; p < 0.001 and SI6: OR: 81,951.3; CI 95%: 427.1-15,700,000]; p < 0.001). Conclusions: High values of SI are associated with increased mortality. The IS6 value is the most useful to predict mortality.