Assessment of shock index in healthy dogs and dogs in hemorrhagic shock.

Abstract

OBJECTIVE: To compare the shock index (SI) in a population of healthy dogs to a population of dogs with confirmed hemorrhagic shock. DESIGN: Retrospective analysis of data collected prospectively from 2 previous studies. SETTING: University teaching hospital. ANIMALS: Seventy-eight healthy control dogs enrolled in a study to establish a reference interval for a tissue oxygen monitor; 38 dogs with confirmed hemorrhagic shock enrolled in a study to evaluate the tissue oxygen monitor in hemorrhagic shock. The heart rate and systolic blood pressure obtained during the respective studies were used to calculate the SI. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Shock index was significantly higher in the hemorrhage group (median 1.37, range 0.78-4.35) than the control group (median 0.91, range 0.57-1.53); 92% of the dogs in hemorrhagic shock had an SI of >0.91. Compared with controls, dogs in hemorrhagic shock had significantly lower body temperatures (median 38.3°C, range 35.6-39.9°C versus median 38.7°C, range 37.5-39.9°C), higher heart rates (median 150/min, range 120-220/min versus median 110/min range 80-150/min), lower systolic blood pressures (mean 112 mm Hg, SD ±35.8 mm Hg versus mean 125 mm Hg, SD ±21.5 mm Hg), higher lactate concentrations (median 0.51 mmol/L, range 0.078-1.41 mmol/L versus median 0.11 mmol/L, range 0.033-0.33 mmol/L), and lower hemoglobin concentrations (median 81 g/L, range 56-183 g/L versus median 162.5 g/L, range 133-198 g/L). CONCLUSIONS: Shock index is a simple and easy calculation that can be used as an additional triage tool and should prompt further investigation for hemorrhage if the values are >0.9.