Magnesium for Shivering in Epidural Lidocaine Deliveries

Study Overview
=================
Brief Summary
-----------------
Magnesium has been shown to decrease the shivering experienced from neuraxial anesthesia. This study aims to investigate whether magnesium decreases the shivering experienced in parturients undergoing labor epidural anesthesia for Cesarean delivery.

Detailed Description
-----------------
Women who have epidurals in place and go on to require a Cesarean delivery typically have their epidurals 'topped-up' with a fast onset local anesthetic to ensure the lower body is fully numb for surgery. This is called an epidural 'top-up'. However, a side effect of epidural top-ups is shivering, which is uncomfortable for the mother and interferes with patient monitoring. Magnesium administration has been shown to decrease shivering in the non-pregnant population. Therefore, in this study the investigators aim to determine if magnesium given prior to an epidural top-up decreases the incidence and severity of shivering in the pregnant population.

Official Title
-----------------
Intravenous Magnesium Sulfate for the Prevention of Intraoperative Shivering in Parturients Undergoing Cesarean Delivery Under Lidocaine Top-up Via a Pre-existing Epidural Catheter Inserted for Labor Analgesia - A Randomized Double-blind, Placebo-controlled Trial

Conditions
-----------------
Anesthesia

Intervention / Treatment
-----------------
* Drug: Magnesium Sulfate
* Other: Normal Saline


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Gestational age of ≥37 weeks Women who are ≥ 19 years old Women undergoing Cesarean delivery under lidocaine top-up via a preexisting epidural catheter inserted for labor analgesia American Society of Anesthesiologist (ASA) Physical Status class 1 or 2 Exclusion Criteria: Emergency Cesarean delivery with limited time for informed consent Women who have received MgSO4 prior to study enrollment Indication for alternative mode of anesthesia for Cesarean delivery (e.g., general anesthesia) Medical conditions or medications that could lead to tremor or shivering. (e.g., movement disorder, untreated thyroid disease) or mask tremor or shivering (e.g., beta-blocker, benzodiazepine, anticonvulsants) Active shivering at time of recruitment Inability to read and understand English for the purpose of informed consent Contraindications to receiving MgSO4 (hypersensitivity reactions, respiratory rate <16breaths/min, absent reflexes, urine output <100 mL during the previous 4 hours, renal failure, or hypocalcemia) History of previous postpartum hemorrhage

Ages Eligible for Study
-----------------
Minimum Age: 19 Years

Sexes Eligible for Study
-----------------
Female

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Magnesium sulfate<br>Magnesium sulfate (MgSO4) infusion will be commenced prior to epidural top-up. | Drug: Magnesium Sulfate<br>* Bolus infusion: 100mL normal saline with 4g MgSO4 over 30 minutes Maintenance infusion: 25mL normal saline per hour with 1g MgSO4<br>|
| Placebo Comparator: Normal saline<br>Normal saline infusion will be commenced prior to epidural top-up. | Other: Normal Saline<br>* Bolus infusion: 100mL normal saline over 30 minutes Maintenance infusion: 25mL normal saline per hour<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of intraoperative shivering | Incidence measured as shivering present or absent | Through completion of cesarean surgical procedure (maximum 2 hours) | 
| Severity of intraoperative shivering | Severity measured subjectively by anesthesiologist and patient | Through completion of cesarean surgical procedure (maximum 2 hours) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of hypothermia | Number of patients whose tympanic membrane temperature decreases below 36 degrees Celsius. | Through study completion (maximum 2.5 hours) | 
| Incidence of hypotension | Number of patients who experience a greater than or equal to 20% reduction in systolic blood pressure. | Through study completion (maximum 2.5 hours) | 
| Total vasopressor(s) dose |  | Through study completion (maximum 2.5 hours) | 
| Total utertonic(s) dose |  | Through completion of cesarean surgical procedure (maximum 2 hours) | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
Epidural top-up, Shivering, Magnesium