Use of Ultrasonography to Determine Fluid-responsiveness for Shock in a Population of Intensive Care Unit Patients

Study Overview
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Brief Summary
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The objective of our study is to determine the correlation of transthoracic ultrasonographic indices of fluid responsiveness to changes in direct measures of cardiac output and to compare them to other established predictors of fluid responsiveness such as central venous pressure variation, systolic arterial pressure variation and pulse pressure variation in a broad population of patients. Hypothesis: There will be a significant difference in the inferior vena cava respiratory variation and subclavian vein respiratory variation between responders and non-responders to intravenous fluid challenge in a broad population of patients with shock.

Detailed Description
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Shock is a common occurrence in the intensive care unit (ICU), and the management of this condition frequently requires the administration of intravenous fluids (IVF). Multiple studies have shown that only about 50% of these patients will respond to fluids. The ability to predict which patients will respond is an important tool for clinicians to treat shock while avoiding unnecessary fluid administration in those who are unlikely to respond. This is essential to avoid the adverse effects of fluid loading that can occur. A number of studies have attempted to determine predictors of volume-responsiveness through various methods, including the use of ultrasonography performed by intensivists, anesthesiologists and emergency medicine physicians. The currently published studies establish predictors of fluid-responsiveness in their populations. However, there has been large variability in the study designs, making it difficult to compare different modalities. The objective of our study is to determine the correlation of transthoracic ultrasonographic indices of fluid responsiveness to changes in direct measures of cardiac output and to compare them to other established predictors of fluid responsiveness such as central venous pressure variation, systolic arterial pressure variation and pulse pressure variation. Furthermore, we wish to include a broad range of patients with different types of shock in order to determine the generalized applicability of these indices. Additionally, reported success of intensivist-obtained echocardiographic images varies widely in the literature, but most studies do not report which views are most accessible. We plan to study prospectively which views are obtainable and correlate them to patient characteristics. This would potentially establish echocardiography by an intensivist as a widely applicable, non-invasive, and easily accessible method for determining fluid-responsiveness in a patient with shock. Achievement of this goal would allow clinicians to quickly identify those patients that would respond to fluids and at the same time minimize the administration of fluids to those in whom it is unlikely to benefit.

Official Title
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Use of Ultrasonography to Determine Fluid-responsiveness for Shock in a Population of Intensive Care Unit Patients

Conditions
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Hypotension

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adult patients (> 18 years old) admitted to the intensive care unit. Decision by clinicians to give intravenous fluids for volume expansion. Decision by clinicians to obtain central venous access. Exclusion Criteria: Patients with known chronic right heart failure syndromes. Patients with terminal conditions in whom aggressive care will not be pursued. Patients with a history of left bundle branch block. Patients will not be excluded on the basis of sex, race, or ethnicity.

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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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Hypotensive patients in shock<br> | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Fluid Responder vs. Non-responder | Patients will be divided into responder and non-responder groups based on an increase in cardiac output of greater than or equal to 15% as measured by thermodilution from a right heart catheter in response to a one liter normal saline fluid bolus. | pre-fluid challenge baseline and post-fluid challenge (approximately 1 hour) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Inferior vena cava diameter and respiratory variation | pre-fluid Inferior vena cava diameter and Inferior vena cava respiratory variations will be correlated to fluid responsiveness | pre-fluid challenge baseline and post-fluid challenge (approximately 1 hour) | 
| subclavian vein diameter and respiratory variation | pre-fluid subclavian diameter and subclavian respiratory variations will be correlated to fluid responsiveness | pre-fluid challenge baseline and post-fluid challenge (approximately 1 hour) | 
| pulse pressure variation | pre-fluid pulse pressure variation will be correlated to fluid responsiveness | pre-fluid challenge baseline and post-fluid challenge (approximately 1 hour) | 
| central venous pressure (CVP) and CVP respiratory variation | pre-fluid CVP and CVP respiratory variations will be correlated to fluid responsiveness | pre-fluid challenge baseline and post-fluid challenge (approximately 1 hour) | 
| pulmonary capillary wedge pressure (PCWP) and respiratory variations of PCWP | pre-fluid PCWP and PCWP respiratory variations will be correlated to fluid responsiveness | pre-fluid challenge baseline and post-fluid challenge (approximately 1 hour) | 
| Possible views of echocardiogram | Determine percentage of which echocardiographic views are obtainable in a broad population of patients with shock and correlate to patient characteristics | pre-fluid challenge baseline and post-fluid challenge (approximately 1 hour) | 
| Concurrence with cardiologist interpretation | Determine the rate at which cardiologist concurs with intensivist interpretation of echocardiographic images. | pre-fluid challenge baseline and post-fluid challenge (approximately 1 hour) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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shock, transthoracic echocardiography, critical care