Fig. 1

Experimental design. The experimental design and flow for the two groups (NBP normal blood pressure group, LBP low blood pressure group). Key time points are marked with arrows and vertical bars. Solid vertical bars show pre- or post-intervention baselines, where the red arrows indicate supplemental blood gas readings. Open vertical bars show vasopressor challenges. Yellow horizontal bar indicates period with propofol–remifentanil TIVA, green horizontal bar indicates period with propofol–remifentanil–dexmedetomidine, and blue horizontal bar indicates period with induced hypotension. PCB pre-caval block, PR-1 baseline during propofol–remifentanil, NE-1 norepinephrine during propofol–remifentanil, PR-intvas after norepinephrine and wash-out period during propofol–remifentanil, PE-1 phenylephrine during propofol–remifentanil, PR-2 after phenylephrine wash-out period/pre-dexmedetomidine during propofol–remifentanil, PRD propofol–remifentanil–dexmedetomidine, NE-2 norepinephrine during propofol–remifentanil, PRD-intvas after norepinephrine and wash-out period during propofol–remifentanil–dexmedetomidine, PE-2 phenylephrine during propofol–remifentanil–dexmedetomidine, PRD-end after phenylephrine and wash-out period during propofol–remifentanil–dexmedetomidine (end of experiment)