IINB vs. QLB for Elective Open Inguinal Herniorrhaphy

Overview

Open inguinal herniorrhaphy is a common outpatient surgical procedure. Post-operative pain can be a significant hindrance to discharge from the post anesthesia care unit. Pain can be treated with opioid therapy, but the literature supports that these agents are known to create or exacerbate adverse effects and complications, including post-operative nausea and vomiting, hypoxia, and urinary retention. In contrast, analgesia provided by regional anesthesia results in a decreased risk of the aforementioned complications.1 Because of this, various regional anesthetic techniques have been developed to provide analgesia following open herniorrhaphy. One technique is a combined ilioinguinal and iliohypogastric nerve block (IINB), which has been shown to decrease the initial pain after inguinal herniorrhaphy.2 The quadratus lumborum block (QLB) is a newer regional anesthetic technique that we think could be as effective as IINB at providing pain control following open herniorrhaphy. Additionally, because local anesthetic injected during a QLB has the potential to spread cranially into the thoracic paravertebral space following its lumbar deposition it could lead to alleviation of both somatic and visceral pain.3 This might therefore improve the quality and or duration of analgesia as compared to the IINB. To the best of the author's knowledge there has been no investigation comparing the efficacy, with regards to post-operative pain management, between IINB and QLB.

This study will be a double-blinded prospective randomized controlled equivalency trial comparing QLB to IINB. Patients presenting for unilateral open inguinal herniorrhaphy who agree to participate in the study and do not meet exclusion criteria will be randomized to either receiving an IINB or a QLB for post-operative analgesia. After performing a timeout, applying monitors (ECG, capnography, Sp02, non-invasive blood pressure), and confirming all paperwork per the usual pre-procedural check list the study participants will be administered procedural sedation (fentanyl and midazolam) to comfort as well as supplemental oxygen. The anatomy of both block sites will be identified by palpation of landmarks, labeling of structures with a skin marking pen, and visualization under ultrasound guidance. Both sites will be administered a small skin wheal of lidocaine 1% at the site the block needle would be introduced into the skin. Our intent with regards to administering a local anesthetic skin wheal is to increase our success in blinding the patient to which block was actually performed. A regional anesthetic block will only be performed at the randomized block site (IINB vs. QLB). After 15-30 minutes post block or post operatively the block will be assessed for success. Loss of cold sensation in the area of the surgical site would be indicative of block success. The patient will then proceed to the operating room and receive a general anesthetic with the final details of that anesthetic to be determined by the anesthesiologist responsible for the patient in the operating room. We will ask the operating room anesthesiologist and surgeon to avoid administration of medications that would confound our results. Specifically, no additional local anesthetic is to be injected at the incision site, no long acting opioids (hydromorphone, morphine, methadone etc…), dexamethasone or ketamine. After completion of the procedure the patient will recover in the post anesthesia care unit (PACU) where the participant will recover as per the usual process. The patient's discharge disposition will be at the discretion of the surgeon and anesthesiologist responsible for the participant's PACU care. The patient will be provided a diary that the participant will complete at 8hrs and 24hrs post block that will help the participant compile the data pertinent to the investigators primary and secondary outcomes. This diary should take no more than a minute or two for each sampling time. Participants will receive two phone calls at home to obtain this data at 8hrs and 24hrs.