Evaluation of tissue oxygen saturation in naturally occurring canine shock patients

Objective To measure tissue oxygen saturation (StO(2)) in a population of dogs with naturally occurring shock and to evaluate the relationship of StO(2) with an established veterinary severity scoring system (Acute Patient Physiologic and Laboratory Evaluation) and patient survival. Design Prospective observational study. Setting University teaching hospital. Animals Twenty-five adult dogs presenting in shock, as determined by the presence of hypotension, the calculated shock index, and hyperlactatemia. Interventions StO(2) was measured prior to any therapeutic interventions. Blood samples were also collected for measurement of plasma lactate, complete blood count, and a serum biochemical profile. Abdominal and thoracic focused assessment with sonography was also performed. Measurements and Main Results Dogs enrolled in this study had lower mean (+/- SD) StO(2) values (65.12 +/- 17.7%) than previously reported in experimental models of canine hemorrhagic shock. There was a moderate correlation between lower StO(2) and increasing Acute Patient Physiologic and Laboratory Evaluation scores. A single StO(2) value, assessed prior to therapeutic intervention, was not a sensitive predictor of mortality in this population. Conclusions Dogs with naturally occurring shock have lower mean StO(2) values than those previously reported in dogs with experimentally induced shock. A lower initial StO(2) was associated with worse disease severity but was not a significant predictor of survival in this population.