Participants
infection, allergy, opioid abuse, cognitive dysfunction
INFECTION, ALLERGY
Inclusion criteria included 1) elective cardiac surgery with a median sternotomy; 2) American Society of Anesthesiologists (ASA) II ~ III; and 3) adult patients (18 to 75 years of age). Exclusion criteria included 1) known allergy to ropivacaine; 2) platelet count < 100*10^9/L; 3) infection at the puncture site; 4) a history of opioid abuse; and 5) cognitive dysfunction and communication difficulties. Written informed consent was obtained from all participants.