LAUSR

Abstract Purpose/Background Subanesthetic dosing of intravenous ketamine has shown to be an effective treatment for patients with major depressive disorder. It is unknown whether sympathetic response is related to treatment outcomes. The purpose of this study is to evaluate sympathetic response to ketamine infusions as it relates to treatment outcomes. Methods/Procedures This retrospective study examines an outpatient population diagnosed with major depressive disorder or bipolar depression treated with ketamine infusions. Patient characteristics, depressive symptoms measured with the Patient Health Questionnaire (PHQ-9), and vital signs were retrieved by chart review. Patients (n = 145) were categorized as responders (50% reduction in PHQ-9 or less than 10 on final PHQ-9) or nonresponders. Changes in vital signs were recorded during each infusion for the initiation series. Findings/Results Ketamine responders (51.7%) showed a significant greater increase in systolic blood pressure response during the first infusion when compared with nonresponders. There was no difference seen in diastolic pressure, heart rate, or rate pressure product. Changes in vital signs for subsequent infusions also did not approach significance. Implications/Conclusions Physiologic sensitivity to the effects of ketamine may predict treatment responsiveness. Blood pressure and heart rate did not always increase. Further work should examine possible influences on physiologic responses.