Effects of Intraoperative Magnesium Sulfate on Perioperative Pain Relief After Spine Surgery

Effects of Intraoperative Magnesium Sulfate on Pain Relief, Hemodynamics and Quality of Recovery After Spine Surgery

The treatment of postoperative pain is increasingly based on a multimodal approach and although opioids remain the drug of choice, they are often used in combination with other analgesics (paracetamol, cyclooxygenase inhibitors or non-steroidal anti-inflammatory drugs) and co-analgesic agents (clonidine and anti- NMDA such as ketamine or MgSO4). The rationale for combined analgesia is to achieve additive or synergistic analgesic properties while decreasing the incidence of side effects by reducing the dose of each agent. Nociceptive stimuli are known to activate the release of the excitatory amino acid glutamate in the dorsal horn of the spinal cord. The resultant activation of NMDA receptors causes calcium entry into the cell and triggers central sensitisation. This mechanism is involved in the perception of pain and mainly accounts for its persistence during the postoperative period.

Although magnesium is not a primary analgesic in itself, it enhances the analgesic actions of more established analgesics as an adjuvant agent. Magnesium produces a voltage-dependent block of NMDA receptors and has been reported to have analgesic properties that might be related to this inhibiting property. Magnesium sulfate has been reported to be effective in perioperative pain treatment and in blunting somatic, autonomic and endocrine reflexes provoked by noxious stimuli.

When magnesium was used intraoperatively, many researchers reported that it reduced the requirement for anesthetics and/or muscle relaxants.

Intraoperative use of magnesium sulfate can also be associated with decreased incidences of nausea and vomiting after surgery, which could have been due to the lower consumption of anesthetics (i.e. volatile agents), rather than any antiemetic effect of magnesium sulfate. In addition, perioperative i.v. administration of magnesium sulfate has another advantageous effect, as it decreases the incidence of shivering by up to 70-90%. Previous studies investigating the analgesic efficacy of MgSO4 in general, gynaecological, ophthalmic and orthopaedic surgery have shown conflicting results, while reports regarding spine surgery are extremely limited.

Our study was designed to investigate the effects of MgSO4 on perioperative pain relief and postoperative quality of recovery after lumbar laminectomy surgery.

Study Overview

• Status: Completed
• Conditions: Pain, Postoperative; Analgesia; Spine Disease
• Intervention / Treatment: Drug: Magnesium Sulfate; Drug: Isotonic saline 0.9%

Detailed Description

Each participant will receive standard monitoring (ECG, SpO2, capnography, SBP, oesophageal temperature, accelerography) and an intravenous access will be established. The level of anaesthesia will be monitored with the bispectral index (BIS), targeting to a BIS level 40-50.

Group M patients will receive intravenous magnesium sulfate 20 mg/kg over a 15-min period before induction of anaesthesia and 20 mg/kg/h by continuous i.v. infusion during the operation. Group C will be given isotonic solution of 0.9% in the same volume as the study drug.

A standard anesthesia protocol will be applied involving propofol 2mg/kg (iv) and fendanyl 2 μg/kg (iv). Cis-atracurium 0.2 mg/kg (iv) will be given to facilitate endotracheal intubation. Anaesthesia will be maintained with air 50% and oxygen 50%, and desflurane adjusted to achieve a target BIS between 40 and 50. Remifentanil will be added to the anesthesia regimen as needed.

Hemodynamic parameters will be recorded upon

• Baseline: Before the administration of the tested drug
• T5: 5 minutes after the administration of the tested drug
• T10: 10 minutes after the administration of the tested drug
• T15: 15 minutes after the administration of the tested drug
• Ts: surgical incision
• T30: 30 minutes after the administration of the tested drug
• T45: 45 minutes after the administration of the tested drug
• T60: 60 minutes after the administration of the tested drug
• T90: 90 minutes after the administration of the tested drug
• T120: 120 minutes after the administration of the tested drug
• T180: 180 minutes after the administration of the tested drug

Low arterial blood pressure during surgery defined as a mean blood pressure value < 50 mmHg will be treated by a bolus of 5 mg ephedrine administered intravenously or phenylephirne civ for persistent hypotension.

Also, time to accelerography recording indicating the appropriateness of neuromuscular block for intubation, mean expired desflurane concentration (from 30 min after skin incision to the end of surgery), boluses of ephedrine and total intraoperative remifentanil consumption will be recorded.

Postoperative analgesic protocol will involve paracetamol 1 mg (iv), lornoxicam 8mg (iv) and morphine 3 mg (upon request).

Postoperatively pain assessment will be performed by Visual Analogue Scale (VAS), Verbal Rating Scale (VRS) and Numerical Rating Scale (NRS) at emergence from anesthesia and 2, 4, 6, and 24 h in the study period. Time to first analgesic request and total analgesics consumption postoperatively (morphine equivalents) will be recorded. Episodes of shivering, as well as episodes of nausea and vomiting (PONV), will be recorded at emergence and thereafter, throughout the study period. Finally, patients' global satisfaction will be assessed the first day after surgery using a 5-grade scale (1= worst discomfort ever experienced in their life and 5= totally satisfied during the immediate postoperative period).

• Study Type: Interventional
• Enrollment (Actual): 74
• Phase: Phase 4

Contacts and Locations

Study Locations

• Greece
  • Thessaloniki, Greece, 54636
    • Ahepa University Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 80 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Adult patients aged between 18 and 80 years
• ASA Physical status 1 to 3
• Elective or semi-elective lumbar laminectomy surgery
• Signed informed consent

Exclusion Criteria:

• Under medication with calcium channel blockers or magnesium
• Drugs or alcohol abuse
• Neurological disorders
• Myopathy
• Intracardiac block
• Hepatic failure
• Renal failure
• Pregnancy

Study Plan

How is the study designed?

Design Details

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

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Magnesium sulfate; Magnesium sulfate 20 mg/kg intravenous over a 15-min period before induction of anesthesia and 20 mg/kg/h by continuous i.v. infusion until surgery completion.	Drug: Magnesium Sulfate; Intravenous magnesium sulfate 20 mg/kg in 100ml isotonic saline 0.9% over a 15-min period before induction of anesthesia and 20 mg/kg/h by continuous i.v. infusion until surgery completion.; Drug: Isotonic saline 0.9%; Isotonic saline 0.9% 100ml over a 15-min period before induction of anesthesia and thereafter continuous i.v. infusion until surgery completion in dosage identical to magnesium sulfate group.
Placebo Comparator: Isotonic solution 0.9%; Isotonic solution 0.9% in the same volume as the study drug using identical pattern of administration.	Drug: Magnesium Sulfate; Intravenous magnesium sulfate 20 mg/kg in 100ml isotonic saline 0.9% over a 15-min period before induction of anesthesia and 20 mg/kg/h by continuous i.v. infusion until surgery completion.; Drug: Isotonic saline 0.9%; Isotonic saline 0.9% 100ml over a 15-min period before induction of anesthesia and thereafter continuous i.v. infusion until surgery completion in dosage identical to magnesium sulfate group.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Analgesics consumption postoperatively in morphine equivalents	The difference in analgesic consumption (assessed as mg of morphine equivalents) postoperatively after intravenous infusion of magnesium sulfate or isotonic saline 0.9%	24 hours after the emergence from anesthesia

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Analgesics consumption intraoperatively	The difference in analgesics consumption (μg of remifentanil) intraoperatively after /during intravenous infusion of magnesium sulfate or isotonic saline 0.9%	180 minutes intraoperatively
Pain intensity	The difference in pain intensity postoperatively assessed by Visual Analogue Scale, Numerical Pain Scale or Verbal Pain Scale after intravenous infusion of magnesium sulfate or isotonic saline 0.9%	10 minutes after emergence from anesthesia, 2, 4 and 6 hours after the emergence from anesthesia
Time to first analgesic request in minutes	The difference in the time frame (minutes) for analgesia request after emergence from anesthesia after intravenous infusion of magnesium sulfate or isotonic saline 0.9%	24 hours after the emergence from anesthesia

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Heart rate changes intraoperatively	The changes in heart rate (beats per minute) intraoperatively after /during intravenous infusion of magnesium sulfate or isotonic saline 0.9%	180 minutes intraoperatively
Systemic blood pressure changes intraoperatively	The changes in systemic blood pressure (mmHg) intraoperatively after /during intravenous infusion of magnesium sulfate or isotonic saline 0.9%	180 minutes intraoperatively
Postoperative adverse effects	The incidence of shivering and nausea /vomiting after emergence from anesthesia after intravenous infusion of magnesium sulfate or isotonic saline 0.9%	24 hours after the emergence from anesthesia
Patients' satisfaction	The patients' global satisfaction assessed the day after surgery using a 5-grade scale (1= worst and 5= totally satisfied) after intravenous infusion of magnesium sulfate or isotonic saline 0.9%	24 hours after surgery

Collaborators and Investigators

• Sponsor: Aristotle University Of Thessaloniki
• Investigators: Principal Investigator: Georgia Tsaousi, Aristotle University of Thessaloniki

Study record dates

Study Major Dates

• Study Start (Actual): January 28, 2020
• Primary Completion (Actual): May 3, 2020
• Study Completion (Actual): May 5, 2020

Study Registration Dates

• First Submitted: November 3, 2019
• First Submitted That Met QC Criteria: November 12, 2019
• First Posted (Actual): November 13, 2019

Study Record Updates

• Last Update Posted (Actual): May 14, 2020
• Last Update Submitted That Met QC Criteria: May 13, 2020
• Last Verified: May 1, 2020

More Information

Terms related to this study

• Keywords: analgesia; magnesium; spine surgery; pain score; opioid consumption
• Additional Relevant MeSH Terms: Pathologic Processes; Postoperative Complications; Pain; Neurologic Manifestations; Musculoskeletal Diseases; Bone Diseases; Pain, Postoperative; Spinal Diseases; Physiological Effects of Drugs; Molecular Mechanisms of Pharmacological Action; Anti-Arrhythmia Agents; Central Nervous System Depressants; Peripheral Nervous System Agents; Analgesics; Sensory System Agents; Anesthetics; Membrane Transport Modulators; Anticonvulsants; Calcium-Regulating Hormones and Agents; Reproductive Control Agents; Calcium Channel Blockers; Tocolytic Agents; Magnesium Sulfate
• Other Study ID Numbers: SpiMag

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No

Drug and device information, study documents

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