Background and Aims Propofol and dexmedetomidineare commonly used forsedation during regional anaesthesia. Although there are many studies comparing these two agents, none of the studies have compare the effect of these agents on diaphragmatic activity. Hence this trial was done after institutional ethics committee approval to evaluate whether dexmedetomidine sedation during regional anaesthesia preserves diaphragmatic thickness fraction compared to propofol sedation.

Methods One hundred and twenty-six patients scheduled for elective surgery undergoing regional anesthesia were randomized into either dexmedetomidine (Group D) or propofol (Group P) sedation during surgery. For both the groups diaphragmatic ultrasound was done at baseline (T1), 20 minutes after the block (T2), after achieving a target bispectral index score (BIS) of 70–80 & Observer’s assessment of alertness/sedation (OAA/S) score of 3 (T3) & at the end of surgery after sedation has been stopped (T4). The primary objective was to compare diaphragmatic thickness fraction (DTF) at (T3) during surgery. The diaphragmatic excursion (DE) and velocity were compared as secondary outcomes.

Results Significant difference was seen in percentage change in thickness fraction at T3 between group P and D (p value <.05). Mean of percentage increase in thickness fraction at T3 in group D was significantly higher as compared to group P. DE was also found to be significantly decreased in the Group P.

Conclusions Dexmedetomidine sedation preserves the baseline diaphragmatic thickness in comparison to propofol.