Abbreviations, acronyms & symbols
CABG	= Coronary artery bypass graft
CTS	= Cardiothoracic surgeries
DEX	= Dexmedetomidine
FDA	= Food and Drug Administration
ICU	= Intensive care unit
NRS	= Numerical rating scales
PCIA	= Patient controlled intravenous analgesia
POP	= Postoperative pain
RCTs	= Randomized controlled trials
SUF	= Sufentanil
VAS	= Visual analogue scale
VRS	= Verbal rating scales