comparison of tap, anterior ql, or esp block for elective cesarean section

Conditions: Pain, Postoperative; Cesarean Section

Summary: the purpose of this prospective single center, randomized study is to determine if ultrasound guided transversus abdominis plane (tap), quadratus lumborum (ql), and erector spinae plane (esp) blocks decrease opioid consumption in subjects undergoing elective cesarean section.

the typical anesthetic for cesarean section at duke university hospital includes a spinal or combined spinal epidural anesthetic with intrathecal dosing of 1.4-1.6 ml bupivacaine hcl 0.75%, 15 mcg fentanyl, and 150 mcg morphine. if the epidural component of a combined spinal epidural anesthetic is used, the subject will be withdrawn from the study. patients also receive rectal acetaminophen 975 mg prior to incision; intravenous (iv) ondansetron 4 mg, iv metoclopramide 10 mg, iv famotidine 20 mg and iv dexamethasone 4 mg intraoperatively; and iv ketorolac 15 mg prior to skin closure. there will be no change to this typical practice. patients who consent to be in this study will be randomized to receive one of three truncal nerve blocks using an online randomization program by the study pi (ak/eg): (1) ultrasound-guided bilateral classic tap block; (2) ultrasound-guided bilateral anterior ql (also known as transmuscular or ql type 3) block; (3) ultrasound-guided bilateral esp block at the level of t9. these nerve blocks will be performed after delivery and within one hour of skin closure with 25 ml of 0.2% ropivacaine with epinephrine 1:400,000 per side. nerve blocks will be performed by a dedicated and trained group of regional anesthesiologists. this non-blinded regional anesthesiologist will save an ultrasound image after local anesthetic administration while the needle is still in position on each side. the study team will review these images to ensure a high quality of block performance. patients will have standard postoperative pain medication orders, including acetaminophen 975 mg po q6h for 4 days (scheduled, starting 6 hours after intraoperative rectal dose), ketorolac 15 mg iv q6h for 24 hours (scheduled, starting 6 hours after intraoperative dose), ibuprofen 600 mg po q6h for 3 days (scheduled, starting 24 hours after first dose of ketorolac) and oxycodone 5-10mg po q3-4h prn for 4 days. if patients are unable to tolerate oral medication or oxycodone is insufficient, rescue medications may be ordered: iv morphine 1-2 mg or iv hydromorphone 0.3-0.5 mg q4h as needed. there is no change from the standard postoperative order sets used for patients after cesarean section. subjects' verbal pain scores at rest and with movement as well as opioid consumption will be recorded at 2, 6, 24, and 48 hours postoperatively. additionally, the amount of antiemetics and antipruritics used will also be recorded at the above time points. these scores will be entered into a duke university hospital redcap database. subjects will also be sent a survey assessing their satisfaction with pain control one week after discharge via email or telephone. this information will be collected via duke university hospital redcap.

Eligibility criteria:
inclusion criteria: 1. american society of anesthesiologists (asa) physical status 1-3 2. age greater than or equal to 18 years 3. scheduled for elective cesarean section 4. english speaking exclusion criteria: 1. asa physical status 4-5 2. diagnosis of chronic pain 3. chronic opioid use (opioid use in the past 3 months) 4. preoperative use of ssris (celexa, lexapro, prozac, paxil), snris (cymbalta, effexor), gabapentin, or pregabalin (lyrica) 5. inability to cooperate with or understand protocol 6. inability to communicate pain scores or need for analgesia 7. infection at the site of block placement 8. intolerance or allergy to local anesthetics 9. neurologic deficit or disorder 10. blood thinning disorder or taking anticoagulant medication 11. bmi \> 50 kg/m2 12. suspected or known addiction to or abuse of illicit drug(s), prescription medicine(s), or alcohol within the past 2 years 13. uncontrolled anxiety, schizophrenia, or other psychiatric disorder that, in the opinion of the investigator, may interfere with study assessments or compliance 14. current or historical evidence of any clinically significant disease or condition that, in the opinion of the investigator, may increase the risk of surgery or complicate the subject's postoperative course