Applicability of Fluid Responsiveness Indices in Circulatory Failure (AFRIC Study) Study Project

Study Overview
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Brief Summary
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Fluid administration is one of the main strategies for patients with acute circulatory failure. However, about half of the patients could not benefit from the fluid administration after the ICU admission. Thus predict the effect of fluid responsiveness is essential. There are sevral indices or tests can be used, such as pulse pressure variation (PPV), end-expiratory occulsion test (EEOT), passive leg raising (PLR), etc. Question of the prevalence of cases in which the different predictive indices of fluid responsiveness in intensive care unit (ICU) are not applicable.

Detailed Description
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Fluid administration is one of the first-line therapies for most patients with acute circulatory failure. And it was supposed to increase cardiac preload and thus output significantly. However, it only has this effect if cardiac output is dependent on cardiac preload, that is if both ventricles work on the ascending part of the Frank-Starling curve. Our group had already shown that, in half of the critically ill patients admitted in ICU, fluid administration is likely to exert only deleterious effects without any hemodynamic benefit. To predict whether it will exert beneficial effects or not before administering the fluid therapy, a dynamic approach has been developed. It consists of observing the effects of changes of preload induced by various tests on cardiac output. 1) Pulse pressure variation: mechanical ventilation induces cyclical changes in cyclical changes in cardiac preload and right ventricular afterload due to cardiopulmonary interactions. If both ventricles are in a preload-dependent state, these variations will induce a cyclical variation in stroke volume. The latter being physiologically related to the pulsed arterial pressure (systolic - diastolic), the respiratory variation of the pulsed arterial pressure (PPV) indicates the existence of a preload-dependence of the two ventricles. 2) The End-expiratory occlusion test (EEOT): this is another method that takes advantage of heart-lung interactions to predict fluid responsiveness in ventilated patients. During mechanical ventilation, each insufflation increases intrathoracic pressure, which hinders systemic venous return. Thus, interrupting the respiratory cycle at the end of expiration inhibits this cyclic hindrance to venous return, increases cardiac preload and cardiac output if both ventricles are preload dependent. The duration of the EEOT must be at least 15 seconds. 3): Passive leg raising (PLR): when a patient is in a recumbent position, the elevation of the lower extremities and the horizontalization of the trunk passively transfers a significant volume of blood from the lower part of the body to the heart chambers and mimics volume expansion. Numerous studies have reported that the increased cardiac output induced by PLR predicts fluid responsiveness. There is always the question of the prevalence of cases in which the different predictive indices of fluid responsiveness are not applicable and data on this issue are scarce, incomplete, and unsatisfactory. Few studies have systematically investigated the number of patients in whom PPV cannot be used in the ICU settings. Some studies have reported a very low prevalence of cases where PPV was usable but they included the entire ICU population on a given day, including many patients who did not have an acute circulatory failure, which had no sense since PPV is only used in patients in whom the question of fluid therapy arises. Other studies have reported a higher prevalence of cases where PPV is usable, but they have only looked at the first 24 hours of hospitalization or have focused on patients with an unstable hemodynamic event. Finally, no study has ever studied the prevalence of cases where the respiratory variation of the PLR, or the EEOT are not applicable.

Official Title
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Applicability of Fluid Responsiveness Indices in Patients With Acute Circulatory Failure (AFRIC Study)

Conditions
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Shock, Acute Circulatory Failure

Intervention / Treatment
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* Other: Passive leg raising


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age ≥ 18 The presence of acute circulatory insufficiency defined by the following pragmatic criteria: Prior administration of at least 1000 mL of crystalloid or colloid solute during a volemic expansion in the previous 12 hours Norepinephrine administration/lactate ≥ 1.5 mmol/L Exclusion Criteria: No strict exclusion criterion only if the refusal of the patient.

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

| Intervention/Treatment |
| --- |
|Other: Passive leg raising|We perform the PLR test by adjusting the bed and not by manually raising the patient's legs. Bronchial secretions must be carefully aspirated before PLR. If awake, the patient should be informed of what the test involves. And measure the cardiac output by using certain devices at the bedside. The end-expiratory occlusion consists in interrupting the ventilator at end-expiration for 15-30 s and assessing the resulting changes in cardiac output.|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The prevalence of cases and reasons in which the conditions that the PPV cannot be correctly interpreted. | By using one arterial line, the scope at the bedside could have a PPV value that automatly calculated on the screen. | One minute at the bedside | 
| The prevalence of cases and reasons in which the conditions that the EEOT cannot be correctly interpreted. |  | 15 seconds for EEOT | 
| The prevalence of cases and reasons in which the conditions that the PLR cannot be correctly interpreted. |  | One minute fot the passive leg raising | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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pulse pressure variation, passive leg raising, end-expiratory occulsion test