Hemodynamic Changes Due to Prone Position

Study Overview
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Brief Summary
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Perioperative prone position may be associated with hemodynamic instability. The causes of instability have not yet been precisely elucidated. The aim of this study is to demonstrate physiological changes during prone positioning in healthy volunteers .

Detailed Description
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The prone position could decrease the cardiac index (CI), mainly due to reduction in stroke volume, with little changes in heart rate. Mean arterial pressure (MAP) could be maintained by increased systemic vascular resistance (SVR) in the majority of patients. The aim of this study is to describe hemodynamic changes in two different surgical prone positions in 10 healthy non-anesthetized volunteers (flat position and using a support system allowing a free abdomen) by non-invasive measurement of hemodynamics (ClearSight, Edwards) and indirectly evaluated intra-abdominal pressure using ultrasound. The ClearSight system provides advanced hemodynamic parameters (cardiac index CI, stroke volume SV, stroke volume variation SVV, systemic vascular resistance SVR, mean arterial pressure MAP) from a finger cuff.

Official Title
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Hemodynamic Changes Due to Prone Position in Healthy Volunteers

Conditions
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Hemodynamics Instability, Prone Position

Intervention / Treatment
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* Procedure: prone position


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: age >18 years, American Society of Anesthesiologists (ASA) Physical Status Classification I agreement with study participation Exclusion Criteria: disagreement with study participation, BMI over 40 pregnancy

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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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Non-anesthetized volunteers<br>Hemodynamic parameters will be measured in supine position. Volunteers will be turned into prone position. After a five-minute stabilization phase will be monitored CI, MAP, heart rate (HR), stroke volume variation SVV, systemic vascular resistance index (SVRI) by non-invasive measurements using a ClearSight (Edwards) in two prone positions (lying on support system allowing a free abdomen and then lying flat without any device). Furthermore, the width of the inferior vena cava and vena jugularis interna, vena saphena and vena cephalica will be measured by ultrasound. The measurement will be performed in inspiration and in expiration phase. | Procedure: prone position<br>* Unsupported prone position with arms along the body in neutral position will be used first without any supportive device except support of heels with a soft cylindrical device, head will be held in a neutral position using prone head rest. After recording of all measered values, the prone position using the prone position support system will be tested. The support system allows free movement of the lower thorax and abdomenal wall, upper arms are elevated and angled in 90 degrees (in shoulders and elbows). Heels will be positioned at the level of the heart using a supportive cylindrical device. Head will be held in a neutral position using prone head rest.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Cardiac Index | after changing supine to prone position | 5 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in vena cava diameter | after changing supine to prone position | 5 minutes | 
| Changes in vena jugularis diameter | after changing supine to prone position | 5 minutes | 
| Changes in vena saphena diameter | after changing supine to prone position | 5 minutes | 
| Changes in vena cephalica diameter | after changing supine to prone position | 5 minutes | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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hemodynamics, prone position, cardiac output