SUPraclavicular Regional Anaesthesia affecting Bispectral Index as Level Of Consciousness monitor (SUPRABLOC): a pilot randomised controlled trial

ABSTRACT

Background: Recent renewed interest in regional anaesthesia during the COVID-19 pandemic has inspired the application of neuraxial anaesthesia for previously unconventional indications, such as awake abdominal surgeries. These patients needed little sedation, since studies demonstrate that neuraxial anaesthesia causes sedation as measured by Bispectral Index (BIS). In contrast, no studies have investigated the possible sedative effects of non-neuraxial regional anaesthesia. Aim: This pilot randomised controlled trial (RCT) was designed as a template for, and to test the feasibility of performing a definitive RCT to establish if non-neuraxial regional anaesthesia has any sedative effect. Methods: Forty patients presenting for forearm surgery were randomly allocated to two treatment arms (supraclavicular block and control). Their level of sedation was quantitatively monitored before surgery for 60 minutes. Specific feasibility outcomes were planned and data collected according to CONSORT 2010 recommendations. Results: Out of 48 patients screened, 41 (85.42%) were invited to participate, 40 (97.56%) consented and 100% completed the study. Four (10.00%) BIS electrodes needed replacement, inadequate contact was shown in three patients (7.50%), data collection and form completion were deemed “easy”, and block success rate was 100%. Differences in mean BIS between groups were < 5, and a difference of 10% between groups in the incidence of BIS < 80 (85% block group, 75% control group) was shown. Conclusion: We propose that progression to formal RCT is feasible with modifications. Decrease in BIS value from baseline should be measured per patient, and clinically significant decrease should be estimated (we suggest a decrease of 10 or more), exclusion of emergency patients (starved for longer, more anxious, may affect BIS), the sample size should be 500 patients and multi-site involvement implemented.