Comparison of the patient state index and bispectral index in patients with complex regional pain syndrome undergoing ketamine infusion therapy: Case series

Abstract

It is important for clinicians to perform a continuous comprehensive assessment of the depth of sedation, including the use of processed electroencephalographic monitors and the review of clinical signs. Ketamine is a safe anesthetic and sedative traditionally used in the clinical practice. It possesses analgesic, anti-inflammatory, and antidepressant activities and is used as a therapeutic agent in intractable pain. In this case series, we present a comparison between patient state index (PSI) and bispectral index (BIS) in a sample of eight patients with complex regional pain syndrome undergoing ketamine infusion therapy. Blood pressure, heart rate, respiratory rate, end-tidal carbon dioxide, and oxygen saturation were all noted, as well as the PSI and BIS values. The PSI and BIS readings were not recorded when the artifact was larger than 50%. Four patients (50%) received intravenous midazolam 5 mg when their agitation or movement could not be managed by the clinicians’ verbal instructions. In five patients (62%), 20 min after the ketamine infusion began, deep drowsiness was attained. There are fewer research studies on PSI than there are on BIS. We found that PSI values did not match BIS values. This case series could help clinicians select an appropriate course of action for ketamine sedation in individual patients.