Shock index is positively correlated with acute blood loss and negatively correlated with cardiac output in a canine hemorrhagic shock model

Abstract

OBJECTIVE To determine whether shock index (SI) positively correlates with percentage blood loss and negatively correlates with cardiac output (CO) in a canine hemorrhagic shock model and whether SI and metabolic markers may be used as end point targets for resuscitation. ANIMALS 8 healthy Beagles. PROCEDURES Between September and December 2021, dogs underwent general anesthesia for experimental induction of hypotensive shock, with the total volume of blood removed, CO, heart rate, systolic blood pressure, base excess, blood pH, and concentrations of hemoglobin, lactate, ionized calcium recorded, and SI calculated at 4 time points (TPs): after anesthetic induction when the dog had been stable for 10 minutes (TP1), 10 minutes after the mean arterial pressure stabilized to a target of 40 mm Hg following jugular removal of up to 60% blood volume to induce hemorrhagic shock (TP2), 10 minutes after autotransfusion of 50% of the removed blood (TP3), and 10 minutes after autotransfusion of the remaining 50% of the removed blood (TP4). RESULTS Mean SI increased between TP1 (1.08 ± 0.35) and TP2 (1.90 ± 0.73) and did not return to the prehemorrhage values for TP3 or TP4. SI correlated positively with percentage blood loss (r = 0.583) and negatively with CO (r = –0.543). CLINICAL RELEVANCE An increase in SI may support diagnosis of hemorrhagic shock; however, SI cannot be used as the sole end point of resuscitation. Significant differences in blood pH, base excess, and lactate concentration suggested they may be useful markers of hemorrhagic shock and need for blood transfusion.

Thromboelastometry for assessment of hemostasis and disease severity in 42 dogs with naturally‐occurring heatstroke

“…Higher scores were reported among nonsurvivors than among survivors in dogs with heatstroke. 21 The case fatality rate in this cohort was 31%, which is lower than previously reported (50% and 40%). 5,8 While the studies were performed in different years, warranting statistical comparison irrelevant, these differences possibly result from variations in enrollment criteria, treatment regimens, stricter monitoring and earlier intervention in face of secondary complications.…”

“…Acute kidney injury was a common secondary complication herein, occurring in nearly 80% of all dogs, and in all nonsurvivors 53 . Its frequency herein is higher than previously reported in dogs and humans with heatstroke, 8,21,54 possibly because of differences in the diagnostic criteria of AKI, or higher disease severity in this cohort. Hypocoagulable INTEM phenotype at 12 to 24 hours PP was associated with occurrence of AKI.…”

“…The heatstroke severity score previously described in dogs, based on multiple laboratory and clinical variables and heatstroke‐related secondary complications, 20 was a powerful assessment and predictive tool in this cohort. Higher scores were reported among nonsurvivors than among survivors in dogs with heatstroke 21 …”

“…20 The shock index (SI) was calculated for each dog (heart rate\systolic BP). 21 Acute kidney injury was diagnosed when serum creatinine concentration (sCr) was >140 μmol/L (1.6 mg/dL) at presentation, or when sCr increased by ≥26.4 μmol/L (0.3 mg/dL) within 48 hours PP, compared to baseline sCr, despite aggressive intravenous fluid therapy. 22 Disseminated intravascular coagulation was diagnosed based on ≥1 of the following: (1) presence of ≥4 abnormal hemostatic test results (Table 1) concurrently; (2) presence of ≥1 abnormal hemostatic test in each of the 3 following categories: coagulation activation (ie, thrombocytopenia, prolonged PT or aPTT and hypofibrinogenemia), anticoagulant consumption (ie, hypoantithrombinemia) and excessive fibrinolysis (ie, increased D-dimer concentration).…”

Is the shock index a useful prognostic indicator for dogs experiencing shock?

“…Paper 9 : Shock index is positively correlated with acute blood loss and negatively correlated with cardiac output in a canine hemorrhagic shock model 9 …”