Assessing Effects of Lateral Tilt on Cardiac Output Using a Non-invasive Technique

Study Overview
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Brief Summary
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In pregnant term patients, we intent to use a non invasive cardiac output monitor to detect the changes in cardiac output as the patient is being placed in different positions. The patient will be placed on her back, flat, and in left lateral tilt at two different angles. Measurements of cardiac output will be recorded.

Detailed Description
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Aortocaval compression compromising tissue perfusion has always been of a concern in term pregnant women undergoing caesarian delivery or regional anesthesia when placed in the supine position. It is believed that this phenomena happens when the gravid uterus compresses the inferior vena cava (IVC)resulting in decreased venous return and hence cardiac output (CO) leading to low placental perfusion and associated fetal heart rate changes. Hence, due to these concerns, left lateral tilt is currently a common practice in obstetrics and it is believed to relief aortocaval compression and to improve blood flow to the fetus. Supporting evidence for this intervention remains controversial, and shows conflicting results. Some studies suggest that lateral tilt does not affect neonatal outcomes (1) or changes in cardiac output in patients with no regional anesthesia (2). While others suggest it can actually increase the volume of the IVC, especially when the patient is tilted 30 degrees or more (3) and may lead to increases in CO (4). Non-invasive hemodynamic monitoring (NICOM, Cheetah Medical), an FDA approved device, is currently being used to detect changes in CO in the United States. Its use has been validated in different clinical settings (5,6). Our hypothesis is that CO is increased in pregnant women that were placed in the lateral tilt position. We intend to compare CO measurements using the non-invasive hemodynamic monitoring among term pregnant patients in supine vs lateral tilt position.

Official Title
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Assessing Effects of Lateral Tilt on Cardiac Output Using a Non-invasive Technique

Conditions
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Cardiac Output

Intervention / Treatment
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* Other: supine position
* Other: 15 degrees lateral tilt
* Other: 30 degrees lateral tilt


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Pregnant women between the ages of 18-50. Elective repeat cesarean section or induction of labor. Exclusion Criteria: Incarcerated patients Patient unwilling or unable to provide consent Intrauterine fetal demise (no fetal heart beat identified and documented by two physicians).

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 50 Years

Sexes Eligible for Study
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Female

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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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Control arm/pregnant patients at term<br>Control arm where the term pregnant patient will be lying on the bed at 45 degrees. | |
| Experimental/Supine<br>Term pregnant patient will be positioned in supine. Changes in hemodynamics will be measured. | Other: supine position<br>* The patient will be placed in a supine position. Changes in cardiac output will be measured.<br>|
| Experimental/15 degrees lateral tilt<br>Term pregnant patient will be positioned at 15 degrees in lateral tilt. Changes in hemodynamics will be measured. | Other: 15 degrees lateral tilt<br>* The patient will be placed in 15 degrees lateral tilt position. Changes in cardiac output will be measured.<br>|
| Experimental/30 degrees lateral tilt<br>Term pregnant patient will be positioned at 30 degrees in lateral tilt. Changes in hemodynamics will be measured. | Other: 30 degrees lateral tilt<br>* The patient will be placed in 30 degrees lateral tilt position. Changes in cardiac output will be measured.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cardiac output (liters/minute) | Changes in cardiac output while lying on bed at 45 degrees | 20 minutes | 
| Cardiac output (liters/minute) | Changes in cardiac output while patient in placed in supine position | 20 minutes | 
| Cardiac output (liters/minute) | Changes in cardiac output while patient in placed in lateral tilt at 15 degrees | 20 minutes | 
| Cardiac output (liters/minute) | Changes in cardiac output while patient in placed in lateral tilt at 30 degrees | 20 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Blood pressure (mm Hg) | Changes in blood pressure while patient in placed in different positions | 80 minutes | 
| Fetal heart rate abnormalities (beats/minute) | Changes in fetal heart rate tracing while patient is placed in different positions | 80 minutes |