Subtenon Block Combined With General Anesthesia for Vitreoretinal Surgery

To evaluate the effects of subtenon block (SB) as an adjunct to general anaesthesia on postoperative pain, oculocardiac reflex and postoperative nausea and vomiting for vitreoretinal surgery.

Study Overview

• Status: Completed
• Conditions: Subtenon Anesthesia
• Intervention / Treatment: Drug: 2% lidocaine and 0.5% bupivacaine; Drug: Sham subtenon block

• Study Type: Interventional
• Enrollment (Actual): 80
• Phase: Phase 3

Contacts and Locations

Study Locations

• Saudi Arabia
  • Riyadh, Saudi Arabia, 11411
    • King Abdulaziz University Hospital at King Saud University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 40 years to 90 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Patient undergoing elective retinal surgery under general anesthesia

Exclusion Criteria:

• ASA physical status > Grade II,
• psychiatric conditions,
• neurological impairment,
• deafness with whom communication would be difficult in the postoperative period,
• clotting abnormalities,
• contraindications for regional anesthesia,
• drug abuse,
• history of allergy to the study drugs,
• previous vitreoretinal or strabismus surgery,
• endophthalmitis, or inflammatory eye pathology
• taking analgesics, antiemetics or drugs that might affect hemodynamics

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Supportive Care
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: SB; receive subtenon block of 4mL of 2% lidocaine and 0.5% bupivacaine (50:50) mixture	Drug: 2% lidocaine and 0.5% bupivacaine; Under general anesthesia and the operating microscope, a Lieberman lid speculum was placed and the conjunctiva was cleaned with 4% povidone iodine solution. The surgeon then created a fornix-based incision through conjunctiva and tenon's tissue inferonasally midway between the insertions of the medial and inferior rectus muscles, with blunt Wescott scissors to expose the scleral surface before tunneling posteriorly with curved Stevens scissors to create a small channel to the posterior subtenon space. A blunt-tipped subtenon cannula was then inserted into the posterior subtenon space, 4mL of 2% lidocaine and 0.5% bupivacaine (50:50) mixture versus saline was introduced and the drug solution was injected slowly into the subtenon space. After administration of local anesthetic mixture, the eyelid was gently taped down, and no ocular massage was performed
Sham Comparator: C; receive subtenon block of 4mL saline	Drug: Sham subtenon block

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
the time to first postoperative analgesic dose	Pain was evaluated using a VNS chart (0-no pain at all, 10-the worst pain imaginable) at 30 min, 1, 2, 4, 6, 12,18 and 24 hours postoperatively. During PACU stay, if the patient complain of pain postoperatively (VNS ≥ 4), morphine boluses of 25 µg /kg (injected at 10-min intervals) was administered intravenously if requested until the pain subsided for a maximum dose of 10 mg. At the end of 2 h, the patients were transferred from the PACU to the ward where the pain was assessed, paracetamol 15 mg/kg was given intravenously and was repeated every 4 hours if needed in the ward by a nurse who is blinded to the study group as paracetamol is the standard post-operative pain medication for patients undergoing ophthalmic surgery at our institute. Time to first post-operative analgesic, which is the time, elapsed between end of the surgical procedure and first administration of an analgesic was noted	24 hrs

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
postoperative pain scores	Pain was evaluated using a VNS chart (0-no pain at all, 10-the worst pain imaginable) at 30 min, 1, 2, 4, 6, 12,18 and 24 hours postoperatively. During PACU stay, if the patient complain of pain postoperatively (VNS ≥ 4), morphine boluses of 25 µg /kg (injected at 10-min intervals) was administered intravenously if requested until the pain subsided for a maximum dose of 10 mg. At the end of 2 h, the patients were transferred from the PACU to the ward where the pain was assessed, paracetamol 15 mg/kg was given intravenously and was repeated every 4 hours if needed in the ward by a nurse who is blinded to the study group as paracetamol is the standard post-operative pain medication for patients undergoing ophthalmic surgery at our institute. Time to first post-operative analgesic, which is the time, elapsed between end of the surgical procedure and first administration of an analgesic was noted.	First 24 hrs after surgery
number of patients requiring rescue analgesics during the 24-h study period		during the whole study (6 months)
consumption of rescue analgesics	The total number of patients receiving rescue analgesia is recorded	during the whole study (6 months)
incidence of oculocardiac reflex		during time of surgery
incidence of postoperative nausea/vomiting	The incidence of postoperative nausea and vomiting (PONV) was assessed by a nurse (who was blinded to the study drug) for the first 2 h in the PACU and subsequently in the ward at 6, 12 and 24 h and Only 2 possible answers was accepted (yes) or (no). Nausea was defined as subjective sensation of discomfort associated with the awareness of the urge to vomit. Vomiting was defined as a forceful expulsion of gastric contents through the mouth. Rescue antiemetic (Ondansetron 0.15 mg/kg) was given if the patient had persistent nausea or more than a single episode of vomiting or whenever patients request medication and number of patients required rescue anti-emetic postoperatively were recorded	First 24 hrs after surgery

Collaborators and Investigators

• Sponsor: King Saud University
• Investigators: Principal Investigator: Marwan Abouammoh, MD, King Saud University

Study record dates

Study Major Dates

• Study Start: December 1, 2013
• Primary Completion (Actual): June 1, 2014

Study Registration Dates

• First Submitted: October 31, 2014
• First Submitted That Met QC Criteria: November 3, 2014
• First Posted (Estimate): November 4, 2014

Study Record Updates

• Last Update Posted (Estimate): November 4, 2014
• Last Update Submitted That Met QC Criteria: November 3, 2014
• Last Verified: October 1, 2014

More Information

Terms related to this study

• Keywords: Vitreoretinal surgery
• Additional Relevant MeSH Terms: Physiological Effects of Drugs; Molecular Mechanisms of Pharmacological Action; Anti-Arrhythmia Agents; Central Nervous System Depressants; Peripheral Nervous System Agents; Sensory System Agents; Anesthetics; Membrane Transport Modulators; Anesthetics, Local; Voltage-Gated Sodium Channel Blockers; Sodium Channel Blockers; Lidocaine; Bupivacaine
• Other Study ID Numbers: E-13-968