The effect of ultrasound-guided ilioinguinal/iliohypogastric nerve block for elective open inguinal herniorrhaphy under local anesthesia: two randomized controlled trials

Abstract Background We aimed to evaluate the efficacy of ultrasound-guided ilioinguinal/iliohypogastric nerve (IIN/IHN) block for peri-operative analgesia in open inguinal herniorrhaphy (OIH) under local infiltration anesthesia (LIA) compared with no block (IIN/IHN 1 trial) and transmuscular quadratus lumborum block (QLB) (IIN/IHN 2 trial). Methods In the IIN/IHN 1 study, 88 subjects were randomized to receive an IIN/IHN block or no block before surgery. In the IIN/IHN 2 study, IIN/IHN block or transmuscular QLB were given to 108 subjects before surgery. All blocks used 30 ml of 0.33% ropivacaine, and patients received LIA during surgery in both studies. The primary outcome was the pain score at the dissociation of the preperitoneal space during surgery, which was assessed using a Numerical Rating Scale (NRS) in both studies. Results In the IIN/IHN 1 study, compared to the no-block group, the IIN/IHN group exhibited clinically reduced NRS scores at dissociation of the preperitoneal space (P = 0.004), clinically lower dynamic NRS scores at 6 h postoperatively, greater surgeon satisfaction, greater patient satisfaction and a lower incidence of postoperative nausea and vomiting (P<0.05). In the IIN/IHN 2 study, the NRS scores at the dissociation of the preperitoneal space were equivalent between the two groups (P = 0.517). Subjects in the IIN/IHN group had a shorter duration of surgery and a faster onset time of block than did those in the QLB group (P<0.05). There were no differences between the groups for the other endpoints. Conclusions Compared to no block, ultrasound-guided IIN/IHN block can provide better peri-operative analgesia for OIH patients underwent LIA. Moreover, the IIN/IHN block and transmuscular QLB are equivalent in providing peri-operative analgesia in OIH patients with LIA. Trial registration: http://www.chictr.org.cn , ChiCTR 2200056670, Date: February 10, 2022 for IIN/IHN trials.