Internal Jugular Vein Flow in the Sitting Position

Study Overview
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Brief Summary
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During neurosurgical procedures, patients need to be placed in sitting position for surgical access especially in surgeries in the vertex or posterior fossa. Due gravitational effect of sitting position the flow in IJV may be reduced. Venous air embolism (VAE) is a common complication of sitting position craniotomy and carries high mortality and morbidity. Venous pressure decreases as the head of the patient is raised above the heart. Hence, negative venous pressure in the cerebral venous system promotes entrapment of air in accidental opening of the sinuses. Common methods to prevent VAE in sitting position include increasing the venous pressure by either jugular venous compression and/or increasing the venous pressure by adding positive end expiratory pressure (PEEP). Both these methods can decrease venous return and can lead to brain swelling.. In addition, improper neck position can cause the kinking of the IJV which may lead to decreased venous drainage and increased ICP. This has been shown to be the contributing factor for intraoperative brain swelling and postoperative neck and tongue swelling leading to airway obstruction. Optimal brain perfusion is best in the neutral position of the head, but surgery cannot always be performed with this.

Detailed Description
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Currently, there are no studies that looked into the IJV flow in sitting position and effect of venous outflow obstruction on the IJV flow. Valsalva maneuver (forced inspiration with closed glottis) and /or compression of internal jugular veins (IJV) are the two commonly used physiological methods that can cause venous outflow obstruction. A custom made neck collar can be used for compression of internal jugular vein and previous investigations have used a similar device in a rat model to demonstrate the protective effects on slosh-mediated brain injury by increasing intracranial blood volume . While the collars have not yet been studied on people for their effectiveness at preventing concussions, many studies have looked at the effect of neck collars on both jugular compression and ICP.. The purpose of this study is to measure the venous blood flow of healthy volunteers by the use of an ultrasound and Doppler velocimetry in sitting position. the investigators will measure the IJV flow on both sides in sitting position at rest and at two conditions of venous outflow obstruction- 1. Neck compression using a custom made collar and 2. During 30 seconds Valsalva maneuver. This study will provide information on the cerebral venous drainage. This information will be very useful in planning and positioning of patients undergoing neurosurgical procedures and to prevent complications from the improper patient position.

Official Title
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Measurement of Flow in Internal Jugular Vein in the Sitting Position: an Ultrasound Study on Healthy Volunteers

Conditions
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Jugular Venous Flow

Intervention / Treatment
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* Diagnostic Test: Jugular venous ultrasound


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adult healthy volunteers who are above the age of 18 ASA 1 Body mass index (BMI) less than and equal to 35 Exclusion Criteria: Lack of informed consent Language barrier Medical students and anesthesia residents going through the department as part of their rotation

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: sitting position<br>The volunteers were kept comfortable in the sitting position. The cricoid cartilage (representing the C6 level) was used as a landmark. A horizontal straight line drawn across the volunteer's neck at the cricoid level and intersecting the IJV on both sides of the neck marked the initial scanning points. The second scanning point was along the IJV at the highest accessible point on the neck. Internal jugular vein cross-sectional area and blood velocity were measured using 2D ultrasound and Doppler (Philips CX50, Andover, MA, USA), respectively, with a 12-3 MHz transducer (Philips L12-3, Andover, MA, USA) | Diagnostic Test: Jugular venous ultrasound<br>* All volunteers will be fully awake throughout the study and be kept comfortable. A cross will be marked where the left and right IJV cross the level of C6. This is where all the measurements will be taken in 3 different conditions at rest, jugular occlusion and valsalva maneuver. At each conditions, the left and right IJV will be scanned with an ultrasound measuring the cross sectional area and Doppler velocity of the IJV. The least amount of pressure will be used to press on the ultrasound probe and the measurements will be obtained at end inspiration. The IJV flow is then calculated.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Internal Jugular Venous Flow | Right Internal Jugular Vein Flow in the sitting position. | 1 day | 
| Left Internal Jugular Vein Flow | left internal jugular vein cross-sectional area in the sitting position at rest and with application of the cervical collar. | 1 day | 
| Right Internal Jugular Vein Flow in the Sitting Position | Right internal jugular vein peak velocity in the sitting position at rest and with application of the cervical collar | one day | 
| Right Internal Jugular | Comparisons of right internal jugular vein ﬂow in the sitting position at rest and with application of the cervical collar | one day | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Left Internal Jugular Vein Flow in the Sitting Position | Comparisons of left internal jugular vein peak velocity in the sitting position at rest and with application of the cervical collar | One day | 
| Left Internal ﬂow in the Sitting Position | left internal jugular vein ﬂow in the sitting position at rest and with application of the cervical collar | One day |