Datas are lacking concerning weaning from mechanical ventilation for tracheostomized patients. In particular, the effect of different modalities of spontaneous breathing trials on respiratory effort has not been extensively described. This crossover physiology study will include 18 tracheostomized patients ventilated for more than 72 hours. The objective of this study is to compare the effect of three different modalities of SBTs on respiratory effort in tracheostomized patients. The modalities tested are : Pressure Support Ventilation (PSV level 5 cmH2O, PEEP 5 cmH2O), T-piece test and high-flow Oxygen. Each modality is applied in a randomized order, during 30 minutes. During every modality tested, esophageal and gastric pressure, expired CO2, and comfort will be monitored, in addition to standard monitoring. Based on esophageal pressure monitoring, patient's respiratory efforts can be calculated either by esophageal pressure-time product and work of breathing. Pressure generated by inspiratory muscles will also be assessed.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
NONE
Enrollment
18
Pressure support ventilation (PSV) modality
T-Piece modality
High-flow oxygen
Lausanne University Hospitals
Lausanne, Canton of Vaud, Switzerland
RECRUITINGEvolution of pressure-time product of esophageal pressure
Quantification of inspiratory effort of the patient
Time frame: Recorded every 5 minutes during each sequence and washout period, 180 minutes
Evolution of work of breathing (WOB)
Total area of a Campbell diagram for esophageal pressure and volume during one respiratory cycle
Time frame: Recorded every 5 minutes during each sequence and washout period, 180 minutes
Evolution of esophageal pressure drop
Maximum variation of esophageal pressure during respiratory cycles
Time frame: Recorded every 5 minutes during each sequence and washout period, 180 minutes
Evolution of inspiratory muscle pressure (Pmus)
Pressure generated by patients' respiratory muscles
Time frame: Recorded every 5 minutes during each sequence and washout period, 180 minutes
Evolution of transdiaphragmatic pressure (Ptransdiaph)
Difference between gastric and esophageal pressure. Reflect of pressure generated by diaphragm during inspiration
Time frame: Recorded every 5 minutes during each sequence and washout period, 180 minutes
Evolution of tidal volume (VT)
Time frame: Recorded every 5 minutes during each sequence and washout period, 180 minutes
Evolution of respiratory rate (RR)
Time frame: Recorded every 5 minutes during each sequence and washout period, 180 minutes
Evolution of inspiratory airway flow
Time frame: Recorded every 5 minutes during each sequence and washout period, 180 minutes
Evolution of ratio of inspiratory time over total duration of a breathing cycle (ti/ttot)
Time frame: Recorded every 5 minutes during each sequence and washout period, 180 minutes
Evolution of Rapid Shallow Breathing Index (RSBI)
RR/VT - predictor during ventilation weaning of intolerance of SBT
Time frame: Recorded every 5 minutes during each sequence and washout period, 180 minutes
Evolution of respiratory system compliance (Crs)
Capacity of total respiratory system to gain volume for a given pressure
Time frame: Recorded every 5 minutes during each sequence and washout period, 180 minutes
Evolution of lungs compliance (CL)
Capacity of lungs to gain volume for a given pressure
Time frame: Recorded every 5 minutes during each sequence and washout period, 180 minutes
Evolution of chest wall compliance (Ccw)
Capacity of lungs to gain volume for a given pressure
Time frame: Recorded every 5 minutes during each sequence and washout period, 180 minutes
Evolution of transpulmonary pressure (Ptranspulm)
Alveolar pressure minus pleural pressure
Time frame: Recorded every 5 minutes during each sequence and washout period, 180 minutes
Evolution of ratio of total dead space volume over tidal volume
Calculated by means of expired CO2 and arterial blood gas CO2
Time frame: Recorded every 5 minutes during each sequence and washout period, 180 minutes
Evolution of total dead space volume
Calculated by means of expired CO2
Time frame: Recorded every 5 minutes during each sequence and washout period, 180 minutes
Evolution of total Positive End-Expiratory Pressure (PEEPtot)
Airway pressure during end-expiratory ventilator occlusion
Time frame: Recorded every 5 minutes during each sequence and washout period, 180 minutes
Evolution of heart rate
Standard monitoring
Time frame: Recorded every 5 minutes during each sequence and washout period, 180 minutes
Evolution of blood pressure
Standard monitoring
Time frame: Recorded every 5 minutes during each sequence and washout period, 180 minutes
Evolution of Plateau pressure (Pplat)
Airway pressure during end-inspiratory ventilator occlusion (corresponds to alveolar pressure)
Time frame: Recorded at minute 1 and minute 30 of each three spontaneous Breathing Trial, 90 minutes
Evolution of intrinsic Positive End-Expiratory Pressure (PEEPi)
PEEPi minus PEEP set on ventilator
Time frame: Recorded at minute 1 and minute 30 of each three spontaneous Breathing Trial, 90 minutes
Pulmonary strain
Measured as the ratio of tidal volume over functionnal residual capacity (FRV)
Time frame: Recorded every 5 minutes during each sequence and washout period, 180 minutes
Evolution of Diaphragmatic excursion (DE)
Ultrasound measurement of diaphragm movement during inspiration
Time frame: Recorded at minute 1 and minute 30 of each three spontaneous Breathing Trial, 90 minutes
Evolution of Diaphragmatic thickening fraction (DTF)
Ultrasound measurement of diaphragm thickening during inspiration
Time frame: Recorded at minute 1 and minute 30 of each three spontaneous Breathing Trial, 90 minutes
Evolution of hematocrits
Mesured by arterial blood
Time frame: Recorded at minute 30 of each three spontaneous Breathing Trial, 90 minutes
Evolution of Richmond Agitation/Sedation scale (RASS) score
Used in ICU to monitor neurologic changes in patients. Scale from -5 (unarousable) to +4 (combative). 0 is a calm and responsive patient.
Time frame: Recorded at minute 1 and minute 30 of each three spontaneous Breathing Trial, 90 minutes
Evolution of Borg dyspnea scale score
Numeric scale to quantify dyspnea from 0 to 10. 0 mean patient does not feel that breathing is difficult and 10 is a maximal dyspnea. Measured twice during each Spontaneous Breathing Trial
Time frame: Recorded at minute 1 and minute 30 of each three spontaneous Breathing Trial, 90 minutes
Evolution of Multidimensionnal dyspnea scale (MDP) score
Score to quantify comfort, dyspnea and assess respiratory effort as perceived by patient. This scale contains multiple items, divided in two dimensions : sensory and affective. Sensory dimension contains : intensity on a scale of 0 to 10 of five sensory qualities (physical breathing effort, air hunger, tightness, mental breathing effort, hyperpnoea) Affective dimension contains : a breathing discomfort scale (scale of 0 to 10) Measured once during each Spontaneous Breathing Trial
Time frame: Recorded at minute 30 of each three spontaneous Breathing Trial, 90 minutes
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