The present study will be undertaken to compare the postoperative analgesic effect of 0.25% bupivacaine and 0.5% bupivacaine for unilateral ilioinguinal and Iliohypogastric nerve block after open inguinal hernia repair.

Primary outcome:

The time to first request for rescue analgesia.

Secondary outcome:

1. The post-operative pain in the form of NRS scores at rest & during movement at 0, 2, 4, 8, 12, 18 and 24 hours post-procedure.
2. The total 24 hour opioid consumption.
3. The incidence of complication related to nerve block (urinary retention, hematoma, hypotension and arrhythmia).
4. Patient satisfaction

Postoperative pain is a common complication that may cause a neuroendocrine stress response, which is characterized by increased release of catabolic and immunosuppressive pituitary hormones and activation of the sympathetic nervous system. Excessive postoperative pain and the physiological stress response can influence postoperative outcomes, length of hospital stay and overall costs of hospital care Inguinal herniorrhaphy is a common outpatient surgical procedure with approximately 20 million operations performed worldwide annually.

Patients undergoing this procedure often experience moderate-to-severe pain, which can hinder post anesthesia care unit (PACU) discharge. While pain can be treated with opioid therapy, the literature supports that opioids may cause postoperative nausea, vomiting, hypoxia, and urinary retention. In contrast, analgesia provided by regional block has been shown to decrease the previous complications.

There is an ongoing interest in developing regional anesthetic techniques that may reduce or eliminate the use of opioid analgesics after minor surgical procedures such as hernia repair.

Regional analgesia has found wide acceptance both by the patients and their treating physicians, and therefore, it is now an important part of multimodal analgesia techniques. Ilioinguinal/iliohypogastric nerve block(IINB),transversus abdominis plane (TAP) block, paravertebral and rectus sheath, have all been used for providing analgesia following abdominal surgeries .

The combined ilioinguinal and iliohypogastric nerve block (IINB) is a commonly used technique for blockade of the ilioinguinal/iliohypogastric (IIIH) nerves and has been shown to decrease pain after OIH as well as reduce opioid requirements.

Bupivacaine belongs to the amide family, and its structure is similar to that of lidocaine. Bupivacaine is a potent agent capable of producing prolonged anesthesia. Its long duration of action plus its tendency to provide more sensory than motor block has made it a popular drug for providing prolonged analgesia during the postoperative period.

We assume that the use of higher concentration of bupivacaine in ilioinguinal and iliohypogastric nerve block (IINB) might increase the efficacy of post-operative analgesia and patient satisfaction.

Inclusion Criteria:

• Patients between 21 and 60 years age with the American Society of Anesthesiologists' status I or II scheduled for elective primary open inguinal hernia repair

Exclusion Criteria:

1. Patient refusal.
2. Body mass index (BMI) >40 kg m2.
3. The presence of skin infection at the injection site.
4. Allergy to local anesthetic drugs.