The Impact of a Preoperative Nerve Block on the Consumption of Sevoflurane in Total Shoulder Arthroplasty

Total arthroplasty surgery of the shoulder is performed under general anesthesia. Pain control for after the surgery can be achieved purely with intravenous and oral pain medication or in combination with freezing of the nerves. Nerve freezing (nerve block) placed before surgery has the potential to substantially reduce the amount of inhaled anesthetic given to the patient during surgery. This can benefit the patient by minimizing the opioid usage after surgery and also reduce cost to the system in terms of duration of hospital stay. The purpose of the study is to investigate whether the inclusion of a nerve block to the general anesthetic for total shoulder arthroplasty surgery will also reduce the amount of inhaled anesthetic and thereby lowering the environmental footprint from the anesthetic.

The investigators of the proposed study plan to quantify the amount of inhaled anesthetic used for each case and will compare how the consumption is affected by whether the nerve block is applied before or after surgery. Patients will have a nerve block catheter (interscalene catheter) placed under ultrasound-guidance prior to the induction of general anesthetic by an experienced regional anesthesiologist. The nerve block catheter will be bolused with a solution to which the anesthesiologist is blinded which will either be local anesthetic or normal saline (sham). The general anesthetic will be conducted according to a the protocol with the aim of maintaining a standard anesthetic depth monitored by patient state index (PSI). Measurements of the MAC-Value (minimum alveolar concentration) of inhaled anesthetic will be recorded every five minutes and the total amount of volatile anesthetic (in ml and ml/kg) will be noted down by a blinded observer. At the end of the case the anesthesiologist blinded to the solution will inject another solution (now a saline (sham) or local anesthetic before the patient is woken up.

Study Overview

• Status: Recruiting
• Conditions: Rotator Cuff Injuries; Anesthesia; Functional
• Intervention / Treatment: Drug: Ropivacaine; Drug: Dextrose

Detailed Description

Following ethics approval, eligible patients meeting the inclusion/exclusion criteria will be consented in pre-assessment unit or day surgery ward at least 2 hours prior to their surgery. Patients will then be randomized into two groups:

Interscalene nerve block catheter insertion with 10 mL 1% ropivacaine injection (Treatment group) Interscalene nerve block catheter insertion with 10 mL 5% dextrose injection (Sham group)

The patient, anesthesia provider, data recorder, OR staff and Post Anaesthetic Care Unit (PACU) nurses, will be blinded at the beginning of the case. The patients consenting for the study and meeting the eligibility criteria for the study will be randomized to either group-1 (PRE-GA) or group-2 (POST-GA) . Prior to induction of general anesthesia, all patients will receive an interscalene nerve block catheter (Pajunk e-cath) inserted under ultrasound guidance using the catheter-over-needle technique by an acute pain physician who has been performing interscalene blocks under ultrasound guidance for at least 5 years. Successful catheter placement will be verified by ultrasound visualization of the injectate spread. Based on the randomization, each patient will receive a clear 10 mL syringe containing either the Treatment or the Sham solution. Patients in group PRE-GA will receive 10 ml of 1% ropivacaine through the catheter before the start of surgery and 10 ml of 5% dextrose at the end of surgery. The patients in group POST-GA will receive 10 ml of 5% dextrose before the start of surgery and 10 ml of1% ropivacaine at the end of surgery. All study medications will be prepared by the principal investigator who will be unblinded to the patient allocation. All other team members will be blinded to the group allocation.

Following the interscalene nerve block catheter insertion, all patients will receive general anesthesia with a standardized protocol using intravenous administration of fentanyl (2 mcg/kg), propofol (2 mg/kg), and rocuronium (0.6 mg/kg). General anesthesia will initially be maintained with sevoflurane at 1.0 age-adjusted Minimal Alveolar Concentration (MAC). Subsequently, the age-adjusted MAC will be titrated to achieve an intraoperative PSI target of 25-50 (Sedline, Masimo®), and intraoperative heart rate (HR) and mean blood pressure (MBP) target of +/-20% baseline values. The anaesthesiologist will have the ability to administer IV boluses of analgesic (remifentanil 0.5mcg/kg) if the Patient State Index (PSI) is >50 and/or the MBP or HR is above 20% of baseline. Vasopressors such as phenylephrine (100 mcg IV bolus) and ephedrine (5 mg IV bolus) can be used as last-line therapy to treat hypotension that is unresponsive to MAC adjustments. The age-adjusted MAC value will be recorded every 5 minutes starting at the time of skin incision until the time of skin closure. In addition, intraoperative analgesic and vasopressor usage are recorded. After the conclusion of MAC recording and prior to emergence from general anesthesia, the anaesthesiologist will be unblinded to the randomized groups, and the patients who received Sham solution will be given 10 mL of the treatment solution via the interscalene catheter to ensure patients receive adequate analgesia postoperatively.

Postoperatively, patients will be transferred to recovery area where the distribution of the sensory or motor block will then be checked and recorded 30 minutes after arriving in PACU to document the success of the block in both groups by the nurses blinded to the group allocation. The Visual Analogue Pain Scale for pain will also be recorded in PACU at 0, 15, 30 and 45 minutes. Postoperative opioid consumption, nausea and vomiting scores and pain scores over the first 24 postoperative hours will also be collected for comparison.

• Study Type: Interventional
• Enrollment (Anticipated): 50
• Phase: Phase 2; Phase 3

Contacts and Locations

• Study Contact: Name: Timur JP Özelsel, MD, DESA; Phone Number: 780-407-8861; Email: ozelsel@ualberta.ca
• Study Contact Backup: Name: Rakesh V Sondekoppam, MD; Phone Number: 780-407-8861; Email: rakesh6282@gmail.com

Study Locations

• Canada
  • Alberta
    • Edmonton, Alberta, Canada, T6G2G3
      • Recruiting
      • University of Alberta Hospital
      • Contact: Rakesh V Sondekoppam, MD; Phone Number: 780-407-8861; Email: rakesh6282@gmail.com
      • Contact: Timur JP Özelsel, MD; Phone Number: 780-407-8861; Email: ozelsel@ualberta.ca
      • Principal Investigator: Timur JP Özelsel, MD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Patients undergoing elective shoulder arthroscopy
• Patients eligible for interscalene brachial plexus block
• All adults 18 years of age or older
• Capable to give consent

Exclusion Criteria:

• Patients who are unable to give consent
• Local anaesthetic allergy
• Hemidiaphragm paresis on the contralateral side to the block/surgery site
• Bleeding diathesis
• Coagulopathy
• Pre-existing neurological deficits
• Patients with a Body Mass Index >35
• Patients with significant comorbidities, physiological limitations, and allergies that are unable to tolerate the protocolized induction and maintenance of anesthesia.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: PRE-GA; 10 mL of 1% ropivacaine injection before the start of surgery and 10 ml of 5% dextrose injection at the end of surgery through the interscalene catheter	Drug: Ropivacaine; Local anesthetic injection; Drug: Dextrose; Sham injection
Sham Comparator: POST-GA; 10 ml of 5% dextrose injection before the start of surgery and 1% ropivacaine injection at the end of surgery through the interscalene catheter	Drug: Ropivacaine; Local anesthetic injection; Drug: Dextrose; Sham injection

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Average age-adjusted MAC of sevoflurane	The average age-adjusted end- tidal minimum alveolar concentration (MAC) will be calculated by averaging the end tidal MAC required to maintain the depth of anesthesia as measured by PSI between 25-50 intra-operatively. This will be compared between the two groups.	Intraoperative measurement done at the end of anesthetic

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The sedation score in PACU	Sedation scores will be recorded at 15 minute intervals based on Ramsay sedation scale (1-6) and will be compared between the two groups	1st postoperative hour
Intraoperative vasopressor usage	Amount and frequency of the intraoperative usage of vasopressor (phenylephrine in micrograms) will be documented and compared between the two groups	Intraoperative period
Postoperative opioid use in PACU	Total amount of opioids (in mg of morphine equivalents) in the PACU and over the first 24 postoperative hours will be recorded and compared between the two groups	Up to 24 postoperative hours
Maximum pain scores in the first 24 post-operative hours	Maximum pain scores will be recorded using numerical rating scale (NRS) of 0-10 (where 0=no pain and 10= maximum pain) on arrival to PACU and at 0,15,30, 45 minutes and at 24 postoperative hours and compared between the two groups	Up to 24 postoperative hours
Intraoperative heart rate	Intraoperative heart rate (in beats/minute) will be documented at 5 minute interval and compared between the two groups	Intraoperative measurement
Intraoperative opioid use	Intraoperative use of short acting opioid (in microgram/Kg) as per the study protocol will be recorded and compared between the two groups	Intraoperative measurement
Nausea and vomiting in the first 24 post-operative hours	Nausea scores (on a Likert scale of 1-4 where 1 = no nausea, 2= mild nausea, 3= moderate nausea and 4= severe nausea) and incidence of vomiting will be recorded on arrival to PACU and at 0,15,30, 45 minutes and at 24 postoperative hours and will be compared between the two groups	Up to 24 postoperative hours
24 hour opioid consumption	Frequency and total consumption of opioids (in morphine equivalents) over the first 24 postoperative hours will be recorded and compared between the two groups	Up to 24 postoperative hours
Sensory testing of nerves in the distribution of the nerve block ("Cold test")	Sensory testing of the C5 and C6 dermatomes will be performed in the PACU at 30 minutes of arrival to PACU to document the success of the block	1st postoperative hour
Intraoperative mean blood pressure	Intraoperative mean blood pressure (in mm Hg) will be documented at 5 minute interval and compared between the two groups	Intraoperative period

Collaborators and Investigators

• Sponsor: University of Alberta
• Investigators: Study Director: Vivian HY Ip, MD, University of Alberta; Study Chair: Rakesh V Sondekoppam, MD, University of Alberta; Study Director: Lora Pencheva, MD, University of Alberta; Principal Investigator: Timur JP Özelsel, MD, DESA, University of Alberta

Study record dates

Study Major Dates

• Study Start (Actual): August 1, 2019
• Primary Completion (Anticipated): August 1, 2026
• Study Completion (Anticipated): August 1, 2026

Study Registration Dates

• First Submitted: July 10, 2019
• First Submitted That Met QC Criteria: July 12, 2019
• First Posted (Actual): July 16, 2019

Study Record Updates

• Last Update Posted (Actual): May 24, 2023
• Last Update Submitted That Met QC Criteria: May 23, 2023
• Last Verified: May 1, 2023

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Wounds and Injuries; Rupture; Shoulder Injuries; Tendon Injuries; Rotator Cuff Injuries; Physiological Effects of Drugs; Central Nervous System Depressants; Peripheral Nervous System Agents; Sensory System Agents; Anesthetics; Anesthetics, Local; Ropivacaine
• Other Study ID Numbers: Pro00092897

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No