Optic Nerve Sheath Diameter in Pre-Eclamptic Parturient Receiving Magnesium Sulfate Combined With Dexmedetomidine

Study Overview
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Brief Summary
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Dexmedetomidine was reported to effectively reduce cerebral metabolism and ICP by decreasing cerebrospinal fluid pressure in patients with cerebral tumors or head injuries that require craniotomy. However, it was also reported to exhibit no effect on ICP. the effect of MgSO4 associated with dexmedetomidine on ONSD in severely pre-eclamptic parturient has been understudied . Though this study aims to evaluate the effect of dexmedetomidine infusion on raised ICP in severely pre-eclamptic parturients using ocular ultrasonography to determine ONSD as a measure of ICP.

Detailed Description
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Dexmedetomidine, a highly selective α-2-receptor agonist, is a first-line sedative medication in ICU and has been increasingly used for obstetric anesthesia. Dexmedetomidine, which provides light sedation, possesses analgesic, sympatholytic, anxiolytic properties and attenuates the stress response without significant respiratory depression. In addition, dexmedetomidine-induced stimulation of postsynaptic alpha-2 adrenergic receptor on the cerebral blood vessels can cause cerebral vasoconstriction and decrease cerebral blood flow. However, the effects of dexmedetomidine on ICP are controversial. Clinical signs of raised ICP are not specific and often difficult to interpret, especially during pregnancy and pre-eclampsia. Though the use of invasive devices is considered a gold standard in the measurement of ICP, Ocular sonography is a promising bedside tool, which serves as a noninvasive, readily available, and cost-effective means for indirectly measuring ICP. Bedside ultrasound can be used as a point-of-care tool for rapidly measuring the optic nerve sheath diameter (ONSD), which is a validated indirect means for measuring ICP. An increase in ICP reflects as a raised ONSD since the optic nerve is surrounded by Dural sheath and cerebrospinal fluid (CSF) containing subarachnoid space, which is distensible in the retrobulbar segment, particularly when CSF pressures rise.

Official Title
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Using Optic Nerve Sheath Diameter to Monitor Intracranial Tension in Pre-Eclamptic Parturient Receiving Magnesium Sulfate in Combination With Dexmedetomidine

Conditions
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Preeclampsia Severe, Optic Nerve Sheath Diameter

Intervention / Treatment
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* Drug: Dexmedetomidine
* Drug: Saline


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: aged18 to 40 years with at least 36 weeks gestation admitted with diagnosis of severe pre-eclampsia and scheduled to receive Magnesium Sulphate therapy before delivery Exclusion Criteria: Presence of ocular wound or Prior ocular surgery emergency cases, and evidence of fetal compromise HELLP syndrome (hemolysis, elevated liver enzymes, and low platelet levels) Chronic hypertension Hyperthyroidism, and diabetes mellitus Presence of pre-existing chronic lung and/or cardiac diseases Presence of pre-existing chronic renal and/or hepatic diseases Presence of any chronic diseases of central nervous system. known allergies to the tested drug.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

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


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Group (D)<br>Patients will receive a loading dose of iv dexmedetomidine followed by a maintenance infusion. | Drug: Dexmedetomidine<br>* pre-eclamptic Patients will receive a loading dose of iv dexmedetomidine (0.5 ug/kg) diluted in 50 ml saline and given over 10 min, followed by a maintenance infusion of (0.2 ug/kg/h) diluted in 200 ml saline till The sedation scores on the Richmond Agitation and Sedation Scale was -2 to +1 (lightly sedated to restless).<br>|
| Placebo Comparator: Group (C)<br>patients will receive saline loading and infusion | Drug: Saline<br>* pre-eclamptic patients will receive 50 ml saline loading for 10 min followed by 200 ml saline infusion<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Optic nerve sheath diameter (ONSD) measurments following Drug administration |  | Baseline (before starting MgSO4 therapy) then at 1, 6, 12 and 24 hours postoperative | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The incidence of raised ICP in severe pre-eclampsia | ONSD >5.0 mm | Baseline (before starting MgSO4 therapy), and during 24 hours postoperative. | 
| Sedation Score | the Richmond Agitation and Sedation Scale (RASS), on which scores range from -5 [unresponsive] to +4 [combative]. | every 2 hours after drug infusion, till 24 postoperative hours | 
| Heart Rate (HR) |  | Baseline (before starting MgSO4 therapy) then every 2 hours till 24 postoperative hours | 
| mean arterial pressure (MAP) changes. |  | Baseline (before starting MgSO4 therapy) then every 2 hours till 24 postoperative hours | 
| The duration of hospital stay | defined as time from the day of operation to the day of discharge | one month after delivery |