Shock Index
Sepsis is a leading cause of morbidity and mortality in children, and often hard to diagnose given physiologic variability of children (they "hang on" as long as they can, and then fall off the proverbial cliff). Additionally, early recognition and treatment improves survival. Recent changes to the diagnosis of sepsis (the Phoenix criteria) focus more on organ dysfunction. But before we get to diagnosing organ dysfunction, which kids should we be concerned about? The shock index is a quick and easy way to determine who you may want to be more concerned about. Shock index is simply HR/SBP. Given different vital sign norms in children, these authors set out to see how the pediatric age-adjusted shock index performed in identifying severe sepsis/septic shock compared to non-adjusted shock index, laboratory markers, and the combination of these values.
What did they do? They retrospectively looked at 1 year's worth of children presenting to the PED that met SIRS criteria and divided this group into those that were found to have severe sepsis/septic shock, and those that didn't. They then looked at their shock index, their pediatric age-adjusted shock index, and their lab values to see how they performed in the identification of severe sepsis/septic shock.
What did they find? Shock index with a cut off of 1.81, immature granulocyte percentage with a cutoff of 0.85, lactic over 2.25, and creatinine over 0.5 all performed pretty well. But not awesome. These values really maximized the Negative Predictive Value, and showed pretty mediocre sensitivity and specificity. Combining shock index and lab values improved performance.
Bottom Line: Vital signs are vital for a reason. The shock index works well as a screening tool, but you have to remember that it's not a "one-size-fits-all" situation. Younger kids have higher HR and lower SBP already, therefore they have a higher shock index at baseline. That being said, pay attention to these high heart rates in kids that already give you pause. This is how they compensate, and we want to catch them before the cliff.
What did they do? They retrospectively looked at 1 year's worth of children presenting to the PED that met SIRS criteria and divided this group into those that were found to have severe sepsis/septic shock, and those that didn't. They then looked at their shock index, their pediatric age-adjusted shock index, and their lab values to see how they performed in the identification of severe sepsis/septic shock.
What did they find? Shock index with a cut off of 1.81, immature granulocyte percentage with a cutoff of 0.85, lactic over 2.25, and creatinine over 0.5 all performed pretty well. But not awesome. These values really maximized the Negative Predictive Value, and showed pretty mediocre sensitivity and specificity. Combining shock index and lab values improved performance.
Bottom Line: Vital signs are vital for a reason. The shock index works well as a screening tool, but you have to remember that it's not a "one-size-fits-all" situation. Younger kids have higher HR and lower SBP already, therefore they have a higher shock index at baseline. That being said, pay attention to these high heart rates in kids that already give you pause. This is how they compensate, and we want to catch them before the cliff.
