Medial Versus Traditional Approach to US-guided TAP Blocks for Open Inguinal Hernia Repair

This study is a prospective, open, randomized trial. Subjects will be randomized using a
computer-generated table of random numbers into 2 groups to receive pre-incisional
ipsilateral ultrasound-guided TAP block using classic or medial approach. Group assignments
will be sealed in sequentially numbered, opaque envelopes that would be opened by an
anesthesiologist performing the block. The research nurse, not involved with patient care
after the subject signed written informed consent, will provide postoperative data
collection. Study subjects and other anesthesia care providers will also be blinded to group
allocation.

All patients will be premedicated with 1-2mg IV midazolam and 50-150 mcg IV fentanyl. In the
OR, propofol infusion will be started at 75mcg/kg/hr and titrated for patient comfort. After
patient is adequately sedated, ultrasound guided TAP block will be performed in all subjects
using a linear 6-15MHz ultrasound probe on a portable ultrasound machine (SonoSite, Bothell,
WA). Classic approach group will receive a TAP block as previously described (Hebbard P,
2007). For the medial approach, once the external oblique abdominal, the internal oblique
abdominal, and the transversus abdominal muscles were visualized using the ultrasound
transducer between the costal margin and the iliac crest at the level of the anterior
axillary line (classic approach), the transducer would be moved medially to the point where
internal oblique muscle disappears. The injection target area will be within 1 inch lateral
to that point.

The place of needle insertion will be prepped with Chlorhexidine gluconate 2% antiseptic
solution, and 21G 90-mm StimuQuik needle (Arrow International, Reading, PA) will be used to
inject 20ml of Ropivacaine 0.5% in the proper place once it is identified. Each subject will
receive local infiltration with 20ml of Lidocaine1% : Bupivacaine 0.25% 1:1 mix prior to the
incision by the surgeon as well as 1000 mg of IV acetaminophen and 8 mg IV dexamethasone
intraoperatively.

In the postanesthesia care unit (PACU), the patient will be asked to rate their pain at rest
upon arrival and at regular intervals on a 0 to 10 numeric rating scale (NRS), where 0 means
no pain and 10 is the worst pain imaginable. Hydromorphone 0.5 mg IV will be administered
every 5 minutes to maintain an NRS pain score <4 of 10. In cases of postoperative nausea or
vomiting, subjects will receive 4mg IV ondansetron, followed by 12.5 mg IV Diphenhydramine
if necessary. The Aldrete Recovery Score will be used to transfer the patients from Phase I
of recovery, which focuses on providing a transition from a totally anesthetized state to
one requiring less intervention. Aldrete Scoring System assesses respiration, oxygen
saturation, consciousness, circulation and activity. Each item is scored on a 0 to 2 scale
with higher score representing more advanced recovery. Once the score of 9 or higher is
reached, the subjects will be transferred to Phase II recovery, which focuses on preparing
the patient for dicharge. At discharge, subjects will be instructed to take a combination of
oxycodone 5mg and acetaminophen 325mg orally every 4-6 hours for NRS pain score>4 of 10.
Postoperative opioid consumption for the 48 hours will be converted to an equivalent dose of
oral hydromorphone.

Subjects will be contacted by telephone by a research nurse or one of the investigators not
involved in their care, and will be asked about their pain and amount of pain medication
they consumed since discharge or since the last phone call respectively. In case of a
potential problem, the matter will be referred to a physician.

Inclusion Criteria:

- Patients age 18 - 75 years of age undergoing open inguinal hernia repair.

- 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