TAP Using Dexmedetomidine and Ropivacaine for Cesarean Section Analgesia

To evaluate the effect of dexmedetomidine as an adjuvant of ropivacaine in the TAP block on cesarean section parturients under multimodal analgesia, optimize the multimodal analgesia program for cesarean section, and guide perioperative analgesia managemen。This is a single center, double-blind, randomized clinical trial.

Inclusion Criteria:1) 37-42 weeks of gestation2) Plan cesarean section3) Receiving patient controlled intravenous analgesia4) Age>18 years5) ASA（American Society of Anesthesiologists) grade I-III6) Voluntary participation and informed consentExclusion Criteria:1)The anesthesia method for cesarean section is general anesthesia or intraspinal anesthesia, and epidural administration is used2) Combined with other opioids during operation3) High risk pregnancy (multiple pregnancy, in vitro pregnancy, etc.) or pregnancy related complications (hypertension, preeclampsia, chorioamnionitis, etc.)4) Times of previous cesarean section ≥ 35) BMI ≥ 50kg/m2 is not suitable for TAP block6) Allergies or contraindications to the drugs involved in the study7) Combined with operations other than tubal ligation and ovariectomy8) Severe renal function impairment (SCR>176 µ mol/L and/or blood urea nitrogen>17.9 mmol/L), severe liver function impairment (ALT and/or aspartate aminotransferase exceed 3 times the upper limit of normal value)9) Increased risk of coagulation dysfunction or bleeding (PLT<80 × 109/L or international normalized ratio> 1.5)10) History of chronic pain or opiate abuse11) Other clinical trials in the last three months