Epidural Block vs. Rectus Sheath Block on Postoperative Pulmonary Function

Overview

Pulmonary complications are among the most important postoperative complications after midline incisions, for which different analgesic modalities have been tried. Epidural analgesia is the recommended technique to relieve pain after major abdominal surgery owing to the proved superior analgesia, reduction of opioid related side effects as nausea, vomiting, pruritis and sedation, earlier recovery of bowel function and earlier ability for postoperative mobility However, it is not without complications. Rectus sheath block provides several advantages over epidural anesthesia. It lessens the potential risks associated with neuraxial techniques, so it may represent a novel alternative approach for somatic analgesia after major abdominal surgeries. Although patients with rectus sheath block may experience some visceral pain, it is usually minimal by 24 hours after surgery.

The aim of this study is to compare the effects of thoracic epidural analgesia and rectus sheath blockade on postoperative pulmonary functions, pain scores, duration of analgesia, sedation scores, patients' satisfaction and adverse effects. FEV1, FEV1/FVC ratio will be measured by a bed side spirometer. * Induction of anesthesia: propofol 1.5-2.5 mg kg-1. * Muscle Relaxants: rocuronium 0.6 mg kg-1 for induction. * Maintenance: Sevoflurane 0.7-1.5 MAC vaporized in air-oxygen (40% inspired fraction). Radial artery catheterization: under complete aseptic conditions 20G cannula will be inserted into the radial artery of non-dominant hand after performing modified Allen's test and local infiltration of 0.5ml xylocaine 2% . Thoracic epidural catheter will be inserted before induction of general anaesthesia under aseptic insertion conditions and using loss of resistance to air technique with the patient in the sitting position at T9- T11 interspaces. The Rectus sheath catheters will be inserted bilaterally using ultrasound (SonoSite M-Turbo®, Sonosite , USA) guidance as described by Webster after induction of general anaesthesia.