Reliability of PVI Changes During Tidal Volume Challenge in ICU Patients

Study Overview
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Brief Summary
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The aim of this study is to assess whether changes in the plethysmography variability index, during a tidal volume challenge, can reliably detect simultaneous changes in arterial blood pressure pulsatility, in patients hospitalized in intensive care unit. If results will be positive, this will allow the test to be performed even in the absence of an invasive arterial catheter.

Detailed Description
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Among patients in a state of shock one of the first treatments is volume expansion, consisting in a fast intravenous injection of crystalloid or colloid solutions in order to increase cardiac preload and consequently cardiac output. However, this augmentation of the cardiac output happens only in half of the patients.To avoid ineffective fluid administration several tests have been developed. One of these tests is called the tidal volume challenge (TVC). It consists of transiently increasing for 1 minute the volume of air inhaled with each breath, in mechanically ventilated patients, and then evaluating whether this change impacts the pulsatility of the arterial blood pressure, detected by an arterial catheter. This test seems reliable, but it requires an arterial catheter to be in place. It has been suggested in previous studies that pulsatility of blood pressure can be estimated by the pulsatility of the plethysmography signal (plethysmography variability index), obtained from the oxygen saturation signal that's measured in all intensive care patients. The advantage is that this measurement only requires a sensor placed at the end of a finger, on the earlobe or on the forehead. The aim of the study is to assess whether changes in the plethysmography variability index (PVI) during a TVC can reliably detect simultaneous changes in blood pressure pulsatility. This study will include patients hospitalized in intensive care unit, mechanically ventilated, in whom physicians have decided to perform a TVC as common practice. Changes, occurred during this test, in arterial blood pressure pulsatility and in plethysmography pulsatility index will be measured and compared. If results will show that changes in PVI during TVC are reliable for measuring blood pressure pulsatility changes during this test, this will allow the test to be used even in the absence of an arterial catheter.

Official Title
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Assessment of the Reliability of Changes in Plethysmography Variability Index During Tidal Volume Challenge for Predicting Fluid Responsiveness in Intensive Care Unit Patients

Conditions
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Shock, Septic Shock, Sepsis, Hemodynamic Instability

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: patients hospitalized in intensive care unit physicians' decision to perform a tidal volume challenge hemodynamic monitoring with a calibrated pulse contour analysis device (PICCO2) in place monitoring of oxygen saturation with Masimo SET mechanical ventilation with tidal volume of 6 ml/kg on ideal body weight Exclusion Criteria: thoracic drainage patient under judicial protection

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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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Reliability of PVI changes in diagnosing preload responsiveness during TVC | The primary objective is to assess the reliability of PVI changes induced by a tidal volume challenge test in diagnosing a preload responsiveness state in adult ICU patients. | TVC is performed in 1 minute | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Reliability of PVI absolute values to diagnose preload responsiveness | Secondary objective is to test the reliability of absolute values of PVI to diagnose a preload responsiveness state in adult intensive care patients. | TVC is performed in 1 minute | 
| Evaluation of PVI changes during TVC according to sensor position | Third objective is to compare the value of changes in PVI induced by a tidal volume challenge test to diagnose a preload responsiveness state according to the location of the plethysmographic measurement (finger, earlobe, forehead). | TVC is performed in 1 minute | 
| Comparison of PPV and PVI changes during PLR test or volume expansion | Forth objective is to compare the changes in pulse pressure variation (PPV) and PVI during a passive leg raising test (PLR) and a volume expansion, if applicable. | PLR is performed in 1 minute | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Tidal volume challenge, Pleth variability index