ARDS, Asynchrony, Patient-Ventilator, Respiratory Effort-Related Arousal | Patient | Respiratory Measures and Ventilator Management, Respiratory Insufficiency
Conditions
Keywords
Pendelluft, Ventilator-patient asynchrony, Patient self-induced lung injury, ARDS, Respiratory failure, Electrical Impedance Tomography
Brief summary
The Pendelluft phenomenon is an important cause of lung damage in spontaneously breathing mechanically ventilated patients since it considerably increases the stress on the lung parenchyma in the dependent areas. It can result in a local driving pressure up to three times higher than the global driving pressure. The measurement of Pendelluft is still uncertain in the literature, and although various methods have been proposed, not all have the same meaning in terms of pulmonary overstress and overstrain. This study proposes a comparative analysis of different ways to calculate and estimate the stress imposed on the lung parenchyma by Pendelluft in terms of regional volume and local driving pressure through electrical impedance tomography.
Detailed description
Respiratory mechanics and regional ventilation will be monitored by electrical impedance tomography (Enlight 1800 and 2100, Timpel). Esophageal and gastric pressures will be obtained by placing an esophageal/gastric balloon cathether (Nutrivent ®), validation concerning position will be done through modified Baydur maneuver (delta esophageal/delta airway pressure = 0.8-1.2). The hardware Pneumodrive will be used to inflate the balloon and store the airway, gastric and esophageal pressures. Initially the patients will be monitored with EIT for aproximately 30 minutes after pletismography stabilization. Then, an arterial blood-gas sample shall be collected for analysis. Next, three expiratory and three inspiratory pauses of at least two seconds will be realized with intervals of eight respiratory cycles between them, allowing plateau pressure to be recorded and global and regional driving pressure to be estimated. All this data will be stored for later analysis. The same procedures and measurements shall be made sequentially with a 50% higher pressure support and with a 50% lower pressure support.
Interventions
OTHERPressure Support Variation and Calculation of Respiratory Mechanics
Patients will be submitted to different levels of pressure support (PS) in a randomly assigned order. First 30 minutes shall be recorded at the clinical PS. Next, blood gas samples shall be collected. Subsequently, three inspiratory pauses of at least 2 seconds shall be performed with an interval of at least 8 respiratory cycles between them. The same shall be performed with three expiratory pauses. Next, the PS shall be varied to 50% less or 50% more than clinical PS (based on randomization) and the same procedures shall be performed after 30 minutes of data recording (blood gas sample collection, inspiratory and expiratory pauses). All data shall be analyzed offline using a software that will be able to compare three different methods to calculate Pendelluft magnitude based on the literature. After completion of the protocol, ventilatory parameters shall be returned to the original settings. If the patient becomes tachypneic during lower PS, the protocol shall be interrupted.
Sponsors
University of Sao Paulo General Hospital
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
DIAGNOSTIC
Masking
NONE
Masking description
None (Open Label)
Intervention model description
All the participants shall be exposed to the same situations (variation of pressure support and inspiratory/expiratory pauses)
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Patients under invasive mechanical ventilation intubated due to respiratory failure in pressure support mode (weaning phase)
Exclusion criteria
* Age less than 18 years; sedation or neuromuscular blockade; absence of respiratory effort; contraindications to esophageal balloon cathether positioning or electrical impedance tomography belt positioning; presence of pneumothorax or active air leaks; hemodynamic instability; absence of informed consent.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| 1. Magnitude of Pendelluft | During 30 minutes after plethysmogram stabilization at clinical PS, during 30 minutes at 50% lower PS, and during 30 minutes at 50% higher PS | Three differents methods of estimating magnitude of Pendelluft shall be compared using a software based on electrical impedance tomography monitoring (Enlight 2100, Timpel Medical®, Brazil) |
| 2. Magnitude of Pendelluft during inspiratory pause | During 30 minutes after plethysmogram stabilization at clinical PS, during 30 minutes at 50% lower PS, and during 30 minutes at 50% higher PS | One of the methods of Pendelluft measurement shall be performed during an inspiratory pause for comparison with a normal cycle (without pause). |
| 3. Magnitude of respiratory effort | During 30 minutes after plethysmogram stabilization at clinical PS, during 30 minutes at 50% lower PS, and during 30 minutes at 50% higher PS | Respiratory effort shall be estimated through expiratory pauses and though recording of esophageal pressure at different pressure support levels. These data shall be compared to Pendelluft magnitude according to the different methods of calculation |
Countries
Brazil
Contacts
Primary ContactMarcelo BP Amato, MD PhD
Backup ContactEmily Sofia Ceron
Outcome results
None listed