Impact of the Depth of Neuromuscular Blockade on Respiratory Mechanics in Moderate to Severe ARDS Patients

Study Overview
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Brief Summary
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Neuromuscular blockade (NMB) is proposed in patients with moderate to severe acute respiratory distress syndrome (ARDS). The supposed benefit of these muscle relaxants could be partly linked to their effects on respiratory mechanics by reducing ventilator induced lung injuries (VILI), especially the so called atelectrauma. Although its monitoring is recommended in clinical practice, data about the depth of NMB necessary for an effective relaxation of the thoracic and diaphragmatic muscles and, therefore, the reduction of the chest wall elastance, are scarce. The investigators hypothesised that complete versus partial NMB can modify respiratory mechanics and its partitioning.

Detailed Description
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The investigators conducted a prospective study to compare the respiratory mechanics of patients with moderate to severe ARDS according to the NMB depth, using an oesophageal pressure catheter (NutriVent®, Sidam) for transpulmonary pressure (PL) assessment, and facial train of four (TOF) for neuromuscular blockade monitoring. The oesophageal balloon was calibrated according to the method recently described to estimate the individual target volume which is assumed to be more adequate. Each patient was analysed at two different times: deep NMB (TOF = 0) and intermediate to light NMB (TOF > 0). The mechanical ventilation parameters were identical for these two measurements. The primary endpoint was the proportion of patients with expiratory transpulmonary pressure (PLexp) greater than or equal to 0 according to the NMB level, in order to assess the risk of region-dependent atelectasis and alveolar opening/closing injury (atelectrauma). Secondary endpoints included: the impact of the depth of NMB on other partition parameters of respiratory mechanics, and the variability of results according to the type of oesophageal balloon calibration.

Official Title
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The Depth of Neuromuscular Blockade is Not Related to Expiratory Transpulmonary Pressure and Respiratory Mechanics in Moderate to Severe ARDS Patients. A Prospective Cohort Study

Conditions
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Acute Respiratory Distress Syndrome, Ventilator-Induced Lung Injury

Intervention / Treatment
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* Other: Modulation of the depth of the neuromuscular blockade


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Moderate to severe ARDS patients with PaO2/FiO2 ratio < 150 mmHg Mechanical ventilation, deep sedation and neuromuscular blockade with continuous infusion of cisatracurium for more than 24 hours Presence of an oesophageal catheter Written informed consent Exclusion Criteria: contraindication of oesophageal catheter

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

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Moderate to severe ARDS adult patients under mechanical ventilation and neuromuscular blockade<br>no intervention | Other: Modulation of the depth of the neuromuscular blockade<br>* Analysis of the respiratory mechanics at two times: Facial train of four = 0, indicating a deep neuromuscular blockade Facial train of four > 0, indicating a intermediate to light neuromuscular blockade<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Proportion of patients with expiratory transpulmonary pressure greater than or equal to 0 | Proportion of patients with expiratory transpulmonary pressure greater than or equal to 0 according to the level of neuromuscular blockade (%) | one day | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Inspiratory transpulmonary pressure | Inspiratory transpulmonary pressure according to the level of neuromuscular blockade (cmH20) | one day | 
| Respiratory system compliance | Respiratory system compliance according to the level of neuromuscular blockade (ml/cmH20) | one day | 
| Chest wall elastance | Chest wall elastance according to the level of neuromuscular blockade (cmH2O/l) | one day | 
| Pulmonary elastance | Pulmonary elastance according to the level of neuromuscular blockade (cmH2O/l) | one day | 
| Driving pressure | Driving pressure according to the level of neuromuscular blockade (cmH20) | one day | 
| Transpulmonary driving pressure | Transpulmonary driving pressure according to the level of neuromuscular blockade (cmH20) | one day | 
| Plateau pressure | Plateau pressure according to the level of neuromuscular blockade (cmH20) | one day | 
| Oesophageal balloon calibration | Proportion of patients with expiratory transpulmonary pressure greater than or equal to 0 according to the oesophageal balloon calibration volume (%) | one day | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Oesophageal pressure, Transpulmonary pressure, Train of four, Neuromuscular blockade