tap catheters versus intrathecal morphine for cesarean section

Conditions: Abdominal Muscles/Ultrasonography; Adult; Anesthetics, Local/Administration & Dosage; Ropivacaine/Administration & Dosage; Ropivacaine/Analogs & Derivatives; Cesarean Section; Humans; Nerve Block/Methods; Pain Measurement/Methods; Pain, Postoperative/Prevention & Control; Ultrasonography, Interventional

Summary: morphine, when given as part of spinal anesthesia, is associated high incidence of nausea and pruritus, which may affect quality of recovery. the investigators hypothesize that long-acting local anesthetic infusions via tap catheter can provide better quality of recovery after cesarean section than spinal morphine.

this study is a prospective, open, randomized study. subjects will be randomized using a computer-generated table of random numbers into 2 groups. the first group will receive intrathecal morphine as part of a spinal anesthetic. the second group will receive an ultrasound-guided bilateral tap catheter at the end of the procedure, while the subject is still under the effect of spinal anesthetic. group assignments will be sealed in sequentially numbered, opaque envelopes that would be opened by an anesthesiologist performing the cesarean section. the research nurse or one of the investigators, not involved with patient care after the subject signed written informed consent, will provide postoperative data collection. all patients will be pre-hydrated with 1000ml of lactated ringer's solution. they will then be brought to the or and without premedication receive a spinal anesthetic in a sitting position. the spinal anesthetic will be administered at either l3-4 or l4-5 level with 24g sprotte needle and contain 1.4ml of 0.75% hyperbaric bupivacaine. as per protocol, the first group would receive 0.3mg of preservative-free morphine, mixed in the same syringe. all the subjects then will be immediately placed in supine position with left uterine displacement, and supplemental oxygen 4l/min will be administered via nasal cannula for the duration of procedure. after a successful spinal anesthetic is confirmed by loss of sensation to pinprick, cesarean section will be performed. intraoperative hypotension will be treated with iv fluids, as well as intermittent boluses of iv ephedrine or iv neosynephrine as needed to keep sbp\>100mm hg. intraoperative nausea will be treated with iv ondansetron as needed. at the end of the procedure, the second group will receive ultrasound guided tap catheter using a linear 6-15mhz ultrasound probe on a portable ultrasound machine (sonosite, bothell, wa) as previously described (hebbard p, 2007). each catheter will be dosed with 20ml of ropivacaine 0.5% at that time. double lumen onq c-block pump (i-flow, llc, lake forest, ca) containing 700 ml of the ropivacaine 0.2% will be attached to the tap catheters in the recovery room. the time that this occurs will be recorded in the emar. the catheters will run at 7cc/hr/side for 50 hrs. in the recovery area, the patient will be asked to rate their pain at rest, nausea, and pruritus upon arrival and at regular intervals as per routine care. the pain will be rated on a 0 to 10 numeric rating scale (nrs), where 0 means no pain and 10 is the worst pain imaginable. fentanyl 50 mg iv will be administered every 5 minutes to maintain an nrs pain score \ 7) every 4 hours as requested and 30mg iv ketorolac every 6 hours until subjects start eating. once the subject tolerate diet, their pain will be treated with 800 mg po ibuprofen every 6 hours and a combination of oxycodone 5mg and acetaminophen 325mg po every 4 hours as requested (1 tab for nrs pain 4-7, 2 tabs for nrs pain \>7).

Eligibility criteria:
inclusion criteria: * patients age 18 - 45 years of age undergoing cesarean section under spinal anesthesia. * ability to read and write english exclusion criteria: * patients undergoing other concomitant procedure * patients with history of diabetes or chronic steroid use * patients with chronic or recent (within 1 week prior to procedure) opioid use. * patients without the mental capacity to consent for the procedure/study. * patients requiring a translator in order to sign the consent for the procedure/study. * patients with a history of allergic reactions to local anesthetics

Keywords: anesthesia regional anesthetic techniques: transversus abdominis plane block, pain, postoperative surgery, cesarean section quality of recovery