PVB With vs. Without Clonidine for Ventral Hernia Repair

Introduction

Paravertebral block (PVB) showed to be successful in both children and adults. It has been reported to be an excellent pain reliever and it reduces post-operative nausea and vomiting, in patients undergoing breast surgery. PVB has proven to be very useful as a regional anesthetic technique when it comes to surgeries involving lumbar and thoracic dermatome. It was shown that the PVB combined with light intravenous sedation was associated with a short hospital stay, less post-operative nausea and vomiting (PONV) and reduced analgesic consumption compared to general anesthesia for ventral hernia repair. Given the effectiveness of PVB in the ventral hernia repair, it would be beneficial to study the effect of PVB with versus without clonidine in elderly patients.

Objectives:

The primary objective of this study is to compare the hemodynamic stability in a ventral hernia repair using paravertebral block with clonidine versus the PVB without clonidine.

The secondary objectives include a comparison of PONV and postoperative analgesic consumption.

Materials and Methods

Study design and sampling This is a prospective study with a randomized double- blinded design that will be conducted between August 2015 and August 2016.

Patients scheduled for ventral hernia repair whose age is 65 years and older with American Society of Anesthesiologists (ASA) greater or equal to 2 will be included. Exclusion criteria comprised history of allergic reactions to local anesthetics, bleeding diatheses and spinal abnormality.

Patients will be randomly allocated to one of 2 groups with 30 patients in each, using the sealed envelope technique. Group one will receive PVB with clonidine while group 2 will receive PVB with placebo.

Anesthetic techniques Since this trial is double-blinded, a specialized nurse will prepare the syringes for each patient.

Paravertebral nerve block techniques Bilateral nerve-stimulator PVB will be performed at the levels of T9-T10 or T9-T11 according to the type of ventral hernia and the planned incision type. The patient will be anesthetized in the lateral decubitus position. Supplemental oxygen will be given by facemask and regular anesthetic monitors will be attached.

Each local anesthetic mixture will contain:

For group 1, the syringes will contain: lidocaine 2% 6 mL, lidocaine 2% 6 mL with epinephrine 5µg.mL-1, bupivacaine 0.5% 5 mL, fentanyl 1 mL (50µg) and clonidine 2 mL.

As for the group 2, the same anesthetic mixture will be administrated however the clonidine will be substituted with 2 mL saline.

Data collection

Demographic data, ASA score, type and duration of surgery will be recorded. Haemodynamics will be registered such as the mean arterial blood pressure, heart rate and oxygen saturation, preoperatively (baseline), intra-operatively (incision of skin, dissection of hernia, traction over the sac and closure of incision) and postoperatively.

As for postoperative analgesia consumption, patients with a VAS score between three and four are given Tramadol Hydrochloride 50-100 mg every 4- 6 hours. If the VAS score is greater or equal to five, patients receive 1 mg/kg Dolosal.

Post-operative nausea and vomiting will be recorded in the recovery room and in the regular ward. Pain assessment will be taken from patients by a verbal statement using Numeric Rating Scale.