Diaphragmatic Tissue Doppler During Weaning From Mechanical Ventilation

Study Overview
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Brief Summary
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Weaning from mechanical ventilation is a critical issue and the diaphragmatic disfunction has been demonstrated to play an important role in extubation failure. the aim of present investigation is to evaluate diaphragmatic excursion velocity during in patients undergoing spontaneous breathing trial through tissue Doppler analysis in both inspiration and expiration.

Detailed Description
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Tobin Index (RSBI), which is the ratio between respiratory rate (RR) and tidal volume (VT), is one of the most used indices to predict weaning outcome. The diaphragm plays a key role in generating VT and, in the case of diaphragmatic dysfunction, inspiratory accessory muscles may contribute to support ventilation. If this occurs during a spontaneous breathing trial (SBT), it will probably result in delayed weaning, since the accessory muscles are more fatigable than the diaphragm. The diaphragmatic tissue Doppler imaging (TDI) is an ultrasonographic technique derived from ultrasound evaluation of heart's motility. Being a muscle doppler assessment, it can be easily used on the diaphragm to calculate the speed of muscles displacement that could be associated with patient's respiratory drive, as well as other derived index of muscle function. The aim of the study is to measure the variations of diaphragmatic displacement velocities before and during the spontaneous breathing trial, useful to check if the patient is ready to breathe spontaneously. An observational study will be performed. Patients who are ready to be weaned will be subjected to a spontaneous breathing test (Cpap 5), that consists of applying a positive end-expiratory pressure of 5 cm H2O for 20 minutes. A tissue Doppler evaluation will then be performed by analyzing the diaphragmatic displacement velocity during inspiration and expiration in the modality of ventilation which precedes the trial and during the SBT. Vital parameters will be monitored during the study. Mechanical ventilation length, incidence of tracheostomies, ICU and hospital recovery duration and hospital mortality will also be acquired.

Official Title
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Diaphragmatic Tissue Doppler During Weaning From Mechanical Ventilation

Conditions
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Weaning From Mechanical Ventilation

Intervention / Treatment
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* Other: Weaning TDI


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: mechanical invasive ventilation ≥ 24 h readiness for extubation Exclusion Criteria: refusal to grant consent pregnancy hemodynamic instability difficult management of secretions request for inotropy and/or vasoactive drugs at high doses

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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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Interventional Model Description: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Weaning TDI<br>A tissue doppler evaluation, using a sector transducer, will be performed by analyzing the diaphragmatic displacement velocity during inspiration and expiration in the modality of ventilation which precedes the trial, during the SBT and after extubation. | Other: Weaning TDI<br>* Patients will be subjected to a spontaneous breathing test (Cpap 5), that consists in applying a positive end-expiratory pressure of 5 cm H2O for 20 minutes. A tissue doppler evaluation will then be performed by analyzing the diaphragmatic displacement velocity during inspiration and expiration and calculating the speed of muscles displacement and other derived index of muscle function in the modality of ventilation which precedes the trial, during the SBT and after extubation.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Primary Outcome Measure - Change in diaphragmatic displacement velocity | Inspiratory and expiratory diaphragmatic displacement velocity evaluated with tissue doppler during the assisted ventilation modality which preceded the trial, during the spontaneous breathing trial ( CPAP 5 ) and in spontaneous breathing. | through each trial completion, an average of 20 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Diaphragmatic acceleration and deceleration | Diaphragmatic acceleration and deceleration evaluated with tissue doppler during the assisted ventilation modality which preceded the trial, during the spontaneous breathing trial ( CPAP 5 ) and in spontaneous breathing. | through each trial completion, an average of 20 minutes | 
| Gas exchange - arterial carbon dioxide tension | Arterial blood gases sample | through each trial completion, an average of 20 minutes | 
| Gas exchange - pH | Arterial blood gases sample | through each trial completion, an average of 20 minutes | 
| Gas exchange - arterial oxygen tension | Arterial blood gases sample | through each trial completion, an average of 20 min | 
| Dyspnea level | Dyspnea level will be evaluated through visual analogical scale ( VAS dyspnea). The dyspnea visual analog scale is represented by a 20 cm horizontal line. The ends are defined as the extreme limits of dyspnea from the left-lower end best, not at all breathless-to the right-upper end worst, extremely breathless. Subjects will be instructed to indicate on the line the point corresponding to their breathlessness perception. | through each trial completion, an average of 20 minutes | 
| Heart rate | Heart Rate (HR) averages during each of the 3 ventilatory modes | through each trial completion, an average of 20 minutes | 
| Number of patients who experienced weaning failure | the need for non invasive ventilation or re-intubation due to any cause | over 48 hours following extubation | 
| Blood Pressure | Mean arterial Blood Pressure (BP) averages during each of the 3 ventilatory modes | through each trial completion, an average of 20 minutes | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Diaphragmatic Tissue Doppler, Weaning, Mechanical ventilation