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

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.

Inclusion Criteria:

1. Adult patients (> 18 years old) admitted to the intensive care unit.

2. Decision by clinicians to give intravenous fluids for volume expansion.

3. Decision by clinicians to obtain central venous access.

Exclusion Criteria:

1. Patients with known chronic right heart failure syndromes.

2. Patients with terminal conditions in whom aggressive care will not be pursued.

3. Patients with a history of left bundle branch block.

4. Patients will not be excluded on the basis of sex, race, or ethnicity.