Incidence and Risk Factors of Weaning-induced Cardiac Dysfunction: Results From a Multicenter, Observational Study

Study Overview
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Brief Summary
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During weaning from mechanical ventilation, the shift from positive to negative pressure ventilation may be responsible for a cardiac dysfunction that can lead to the development of pulmonary oedema (weaning-induced pulmonary oedema, WIPO) and to the failure of spontaneous breathing trials. However, the incidence and risk factors for WIPO development are not well defined and have been investigated only by a few studies.

Detailed Description
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During weaning from mechanical ventilation, the shift from positive to negative pressure ventilation may be responsible for a cardiac dysfunction that can lead to the development of pulmonary oedema (weaning-induced pulmonary oedema, WIPO) and to the failure of spontaneous breathing trials. The mechanisms leading to WIPO have been described in many studies. The fact that the intrathoracic pressure becomes negative increases right ventricle preload and afterload, reduces right ventricle compliance and increases left ventricle afterload. Arterial hypertension, which results from adrenergic stress and possibly from hypercapnia, usually worsens this latter mechanism. Myocardial ischemia, resulting from the imbalance between the reduction of oxygen delivery (hypoxemia) and increased oxygen demand (unfavourable loading conditions, increase of inotropic and heart rate) may participate in this phenomenon, even though its incidence seems to be low. The means for detecting WIPO in a patient performing a spontaneous breathing trial (SBT) have been widely investigated. To avoid the insertion of a pulmonary artery catheter, which clinicians nowadays tend to avoid when the patient is ready to be extubated, many alternatives methods have been proposed. The increase of left ventricular filling pressure during an SBT was detected with echocardiography, the increase during the test either of B-type natriuretic peptide levels or of extravascular lung water measured by transpulmonary thermodilution can be used. The investigators have also demonstrated that the detection of haemoconcentration during a weaning test, which is related to the filtration of a significant amount of plasma through the alveolar-capillary barrier, allows the detection of WIPO. Unresolved questions: The incidence of WIPO is not well defined. In the studies where it has been reported, it ranged between 44% and 87% of SBT failures. However, these studies included a small number of patients and/or included a specific population of patients that had already failed one or more weaning tests. In a monocentric study, the investigators recently reported that WIPO occurred in 59% of cases of SBT failures. The risk factors for WIPO development are not well defined and have been investigated only by a few studies. In the above-mentioned one, the investigators have identified the presence of pre-existing cardiopathy, pre-existing chronic respiratory failure and obesity as independent risk factors for developing WIPO. However, these results were obtained only from a monocentric cohort.

Official Title
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Incidence of Weaning-induced Pulmonary Oedema (The WIPO Study)

Conditions
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Weaning Failure, Weaning-induced Pulmonary Edema, Spontaneous Breathing Trial

Intervention / Treatment
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* Procedure: Spontaneous breathing trial


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age ≥ 18 years. Social coverage from health insurance (in France). Decision of the attending physicians to perform an SBT. Exclusion Criteria: Presence of tracheostomy (in this case at the end of the test the patient could be connected to the ventilator, even in case of positivity of the weaning test. Thus, it is not possible to test the absence of reintubation at 48 hours, which is one of the criteria defining the success of weaning). Refusal of the patient or, if the case, one of the relatives to participate to the study.

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 |
| --- |
|Procedure: Spontaneous breathing trial|A spontaneous breathing trial (SBT) is used to identify patients who are likely to fail liberation from mechanical ventilation. The test can be done according to the usual modalities of the participating centre, following the international recommendations, meaning either by disconnecting the endotracheal tube from the ventilator and connecting it to a source of oxygen through the T-tube or by setting pressure support with low positive end-expiratory pressure (PEEP). The choice of the method will not be determined according to the participation in this study but will be done according to the habits of the participating centre.|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The incidence of WIPO | The diagnosis of WIPO will be done a posteriori by a group of experts. They will establish the diagnosis of WIPO, based on the following elements: Failure or success of SBT Clinical examination at the end of SBT Variation during SBT of arterial blood gas variables, plasmatic protein and blood haemoglobin concentration, extravascular lung water (optional), B-type natriuretic peptide (optional), echocardiographic estimation of left ventricular preload (E and A waves of mitral flow, e' wave of the mitral valve annulus), pulmonary arterial occlusion pressure (optional). | 30-120 mins during the Spontaneous Breathing Trial | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Risk factors for developing WIPO |  | The risk factors for WIPO will be done a posteriori by multivaraite analysis |