Comparison of Different Methods to Calculate Pendelluft by Electrical Impedance Tomography in Mechanically Ventilated Patients

University of Sao Paulo General Hospital

Status: Enrolling

Conditions: Respiratory Effort-Related Arousal | Patient | Respiratory Measures and Ventilator Management; Asynchrony, Patient-Ventilator; Respiratory Insufficiency; ARDS

Treatments: Other: Pressure Support Variation and Calculation of Respiratory Mechanics

Study type: Interventional

Funder types: Other

Identifiers

NCT06494215

79317924.0.0000.0068

Details and patient eligibility

About

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.

Full 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.

Enrollment: 15 estimated patients

Sex: All

Ages: 18+ years old

Volunteers: No Healthy Volunteers

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.

Trial design

Primary purpose: Diagnostic

Allocation: N/A

Interventional model: Single Group Assignment

Masking: None (Open label)

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15 participants in 1 patient group

Pressure Support Variation

Other group

Description:

Patients shall be submitted to pressure support variation in a randomly assigned manner. First 30 minutes after plethysmogram stabilization shall be recorded at clinical pressure support. Next, a blood gas sample shall be collected by a nurse or a physician, and three inspiratory pauses of at least 2 seconds shall be performed in between eight respiratory cycles. Next three expiratory pauses shall be performed in between eight respiratory cycles. All data shall be recorded and analysed offline. Subsequently the same sequence of events shall be performed at a 50% higher pressure support and at a 50% lower pressure support. The sequence in which this will happen shall be randomly assigned (first lower PS vs higher PS or first higher PS vs lower PS).

Treatment:

Other: Pressure Support Variation and Calculation of Respiratory Mechanics