Splenic Doppler Resistance Index for Detection of Circulatory Shock in Dogs.

Objective: To assess the splenic flow resistance index (RI) and its response to a fluid bolus in dogs showing circulatory abnormalities upon hospital admission.

Design: Prospective clinical study.

Setting: Veterinary referral hospital.

Animals: Nine dogs with circulatory shock and nine dogs without circulatory abnormalities.

Interventions: Dogs with circulatory abnormalities received an IV bolus of 30 mL/kg of balanced isotonic crystalloid fluid.

Measurements And Main Results: The splenic flow RI and the baseline aortic velocity-time integral of both groups of dogs were evaluated upon hospital admission. Measurements were repeated after the fluid bolus in dogs with circulatory shock. The Mann-Whitney U-test or the Wilcoxon rank sign test was used as appropriate. The median RI in dogs with circulatory shock was higher than that in dogs without hemodynamic disorders (median [interquartile range]: 0.64 [0.62-0.77] vs. 0.54 [0.51-0.54], P < 0.001). The best cutoff value to discriminate between the two groups was 0.61, with an area under the receiver operating characteristic curve of 1.00 (95% confidence interval [CI]: 1.00-1.00), a sensitivity of 100% (95% CI: 66.4-100), a specificity of 100% (95% CI: 66.4-100), a positive predictive value of 100% (95% CI: 66.4-100), and a negative predictive value of 100% (95% CI: 66.4-100). After fluid expansion, a significant decrease in the median splenic flow RI was observed (0.57 [0.54-0.71], P = 0.007 vs. basal).

Conclusions: The splenic flow RI may be a dependable tool for identifying circulatory shock in dogs and assessing their response to fluid therapy. Additional studies are required to evaluate the use of this index for the monitoring of organ perfusion, changes in cardiac output, and fluid responsiveness in critically ill dogs.