Dexmedetomidine vs Ketamine as Adjuvants to Bupivacaine in Transversus Abdominus Plane Block in Inguinal Hernioplasty

Preoperative Assessment:

Patients scheduled for unilateral inguinal hernioplasty will be assessed preoperatively by evaluating their medical history, laboratory investigations, and fulfillment of the above inclusion criteria. The patient's preparation will be done by IV cannulation with an 18G cannula, and infusion of 500 ml of Ringer's solution will be started, and about 20 minutes before anesthesia induction, midazolam (0.05 mg/kg) will be received as a sedative premedication.

Intraoperative Procedures and Assessments:

After reaching the operating room, standard monitoring will be applied, which includes electrocardiography (ECG), non-invasive blood pressure, and pulse oximetry for peripheral oxygen saturation (SPO2). After preoxygenation, induction of general anesthesia will be done by IV injection of propofol (2 mg/kg), fentanyl (2 mcg/kg), atracurium (0.5 mg/kg), and inhalational isoflurane 1.2%, followed by endotracheal intubation and controlled mechanical ventilation with tidal volume 7-8 ml/kg, respiratory rate 12/min, and FIO₂ 100%. Then anesthesia will be maintained by inhalational isoflurane, atracurium 0.1 mg/kg every 20 minutes, and intraoperative fluid (Ringer's solution), which was calculated to cover the maintenance, deficit, and 3rd space requirement.

At the end of surgery an ipsilateral US-guided TAP block will be given to all the patients by placing a linear US probe (high-frequency probe 10-12 MHz) connected to a portable US unit initially in the mid-axillary plane midway between the lower costal margin and the highest point of iliac crest, then it was moved posteriorly till a scan reveals the transversus abdominis muscle tailing off into the aponeurosis, near the Quadratus lumborum muscle. The injection site was superficial to the aponeurosis near quadratus lumborum. while the patient in supine position with slight lateralization After skin disinfection, a 22-G needle with an injection line will be inserted in plane with the probe. Once the tip of the needle is placed in place, and after negative suction, 5 ml of 0.9% saline will be injected to verify the right place, then one of the three study solutions will be injected.

Group A (Dexmedetomidine Group): patients received 20 ml solution containing 1 mg/kg bupivacaine + 1 mcg/kg dexmedetomidine + normal saline.

Group B (Ketamine Group): patients received 20 ml solution containing 1 mg/kg bupivacaine + 0.5 mg/kg ketamine + normal saline.

Group C (Control Group): Patients received 20 ml of solution containing 1 mg/kg bupivacaine + normal saline.

Then discontinuation of inhalational isoflurane and reversal of muscle blockade by a neostigmine 0.05 mg/kg and atropine (0.01-0.02 mg/kg) mixture, and after fulfillment of extubation criteria, extubation was done.

Postoperative analgesic regimen:

When NRS >3: Nalbuphine (0.1 mg/kg) will be given.

Inclusion criteria

• Patients undergoing unilateral inguinal hernioplasty of ASA I or II.
• Age group: 18-60 years old.

Exclusion criteria

• Patient refusal.
• known allergy to any of the used drugs
• ASA III or above
• Coagulation disorders and thrombocytopenia
• Body mass index (BMI) >30
• Infection at needle insertion site
• Patients undergoing bilateral inguinal hernioplasty