Effects of Transverse Abdominis Plane Block Guided by Ultrasound on the Postoperative Analgesia and Quality of Lives Among the Patients Undergo Inguinal Hernia Repair

The incidence of post-operative pain after open inguinal hernia repair is high and impair the quality of lives of the patients.The purpose of this study is to determine whether transverse abdominis plane block combined with intravenous patient controlled analgesia is superior to intravenous patient controlled analgesia in improving the quality of life and reducing the incidence of chronic post-surgical pain

The incidence of post-operative pain after open inguinal hernia repair is high according to a a larger-sample epidemic research. Meanwhile, the investigators also found the incidence of CPSP of herniorrhaphy was 37.8% among the patients with PCA, and the incidence of neuropathic pain was 37.5% in these patients with CPSP. European hernia society has proposed that local infiltration anesthesia was suggested to all patients without any contraindications who undergo inguinal hernia repair. Transverse abdominis plane block(TABP),which injecting local anesthetics into the interval between obliquus internus abdominis muscle and transverse abdominal muscle could block the abdominal nerve and could alleviate the pain postoperatively. TABP can block the two mainly nerve (iliohypogastric nerve, ilioinguinal nerve) for inguinal hernia repair and so it seems to have a good effects to relieve the pain of inguinal hernia repair. So the investigators conduct the randomized controlled trial to investigate whether transversus abdominis plane block combined with intravenous patient controlled analgesia is superior to intravenous patient controlled analgesia in improving the quality of life and reducing the incidence of chronic post-surgical pain.

This study was approved by the Medical Ethics Committee of the First Affiliated Hospital of Chongqing Medical University. All potentially eligible participants will be asked to give written informed consent before they are enrolled in this study. This study is a prospective, randomized, controlled clinical trial guided by the standard of good clinical practice (GCP), and eligible participants are divided into two groups: group TAPB and group PCIA, and assess the outcomes of the incidence of acute and chronic postoperative pain and the effects of the two methods on the quality of lives of patients undergo inguinal hernia repair.

Participants in group TAPB will receive transversus abdominis plane block guided by ultrasound at the end of the surgery and also receive intravenous patient controlled analgesia after surgery.

Participants in group PCIA will only receive intravenous patient controlled analgesia after surgery.

The primary outcome of the study is VAS scores at rest and in motion at 3 months postoperatively. The secondary outcomes of this study are chronic post-surgical pain at 6 and 12 months postoperatively, acute post-operative pain, rescue medication and the incidence of neuropathic pain at 3, 6,12 months postoperatively, also the quality of life measured by EQ-5D questionnaire, adverse events associated with postoperative analgesia.

This study will be conducted under the supervision of an independent auditor. Every week, the auditor checked the data of the participants the day after the surgery was conducted. Assessment of pain intensity and prognostic outcomes must be confirmed by the auditor in sample population. When there is disagreement between surgeon and anesthesiologists in evaluating the prognosis of patients, the auditor must solve this disagreement by discussion with evaluators. Data will be double-entered by two statisticians with limitation of access and locked during statistical analysis

Eligibility Criteria:
Inclusion Criteria:

* clinical diagnosis of inguinal hernia and will receive open inguinal hernia repair (UHS mesh)
* men or woman and 18 \~ 80 years old

Exclusion Criteria:

* body mass index≤18 or≥35
* American Society of Anesthesiology (ASA) classification of anesthesia risk IV and V grade
* allergic to local anesthetics
* hepatic or renal failure
* being pregnant
* skin infection at the puncture site
* pre-operative opioid or non-steroidal anti-inflammatory drugs treatment for chronic pain
* addicted to drugs or alcohol
* uncontrolled general infection
* femoral hernia, incisional hernia or other special types of hernia