Impact of the Transpulmonary Pressure on Right Ventricle Function in Acute Respiratory Distress Syndrome (VD-SDRA)

Impact of the Transpulmonary Pressure on Right Ventricle Function in Acute Respiratory Distress Syndrome

Impact of the Transpulmonary Pressure on Right Ventricle Function in Acute Respiratory Distress Syndrome

Pulmonary distension induced by mechanical ventilation physiologically alters right ventricle pre and after-load, hence might lead to right ventricle failure. The hypothesis is that in Acute Respiratory Distress Syndrome, the occurence of a right ventricle failure under lung protective ventilation might : i) be correlated to the transpulmonary pressure level, ii) lead to global heart failure, iii) and extremely result in poor outcome and death. The primary objective is to test the impact of transpulmonary pressure on right ventricular function in Acute Respiratory Distress Syndrome in adults and children. Secondary objectives are : i) to compare thresholds of transpulmonary pressure associated with right ventricle failure between children and adults. ii) to assess if there is an association between transpulmonary pressure and morbidity and mortality. - For pediatric patients, a specific monitoring with electrical impedance tomography (EIT) will allow: To assess if the transpulmonary pressure is associated with the level of regional pulmonary overdistention (or collapse) on electrical impedance tomography.(EIT) To assess if there is an association between the occurrence of right ventricular failure, and distribution of ventilation on EIT.

Acute Respiratory Distress Syndrome (ARDS) is an acute inflammatory lung injury associated with a high pulmonary vascular permeability, leading to acute respiratory failure. Positive pressure mechanical ventilation,improves survival but might lead to ventilator-induced lung injury (VILI) and right ventricular failure. This hemodynamic effect is more important when compliance is decreased, especially in ARDS. The use of long protective ventilation (with low tidal volumes and low plateau pressures) has improved prognosis of ARDS in adult patients. However, tidal volume and plateau pressures do not always reflect the lung deformation and the stress induced by the ventilation; these variables depend on the characteristics of the patient's respiratory system. Therefore, management focuses on ventilation strategies according to these characteristics. Among tools used to evaluate respiratory physiological parameters, the esophageal pressure measurement is easily feasible at the bedside, and well estimates pleural pressure and pulmonary distension. During invasive ventilation, transpulmonary pressure (PL) can be obtained with the difference between the airway pressure and the esophageal pressure. Calculation of transpulmonary pressure in ARDS allows optimal ventilator management of adult and children treated for ARDS. Although individualized ventilation techniques have shown some benefits in ARDS, studies have failed to show that survival could be improved by such strategies. This lack of efficacy could be partly explained by the hemodynamic impact of ventilation-induced pulmonary distension. It therefore seems essential to combine a robust assessment of right ventricular function with measurements of transpulmonary pressure in order to know the real hemodynamic impact of positive pressure ventilation in ARDS in adults and children. The primary objective is to test the impact of transpulmonary pressure on right ventricular functionin ARDS adults and children. Secondary objectives are : i) to compare thresholds of transpulmonary pressure associated to right ventricle failure between children and adults ii) to assess if there is an association between transpulmonary pressure and morbidity and mortality. - For pediatric patients, a specific monitoring with electrical impedance tomography (EIT) will allow: To assess if the transpulmonary pressure is associated with the level of regional pulmonary overdistention (or collapse) on electrical impedance tomography.(EIT) To assess if there is an association between the occurrence of right ventricular failure, and distribution of ventilation on EIT.

Acute Respiratory Distress Syndrome, Mechanical ventilation, Transpulmonary pressure, Right ventricle failure

Children of more than one month of age and adults hospitalized in Intensive Care Unit for Acute Respiratory Distress Syndrome.

Measurements will be performed during the first three days of Acute Respiratory Distress Syndrome management : The first measurement will be performed 5 minutes after the initial ventilator settings. Measurements will be repeated systematically at 24 hours, 48 hours and 72 hours of evolution. An additional measure will be performed at each positive end-expiratory pressure modification (maximum 5 measures).

Measurements will be performed during the first three days of Acute Respiratory Distress Syndrome management The first measurement will be performed 5 minutes after the initial ventilator settings. Measurements will be repeated systematically at 24 hours, 48 hours and 72 hours of evolution. An additional measure will be performed at each positive end-expiratory pressure modification (maximum 5 measures).

The right ventricle systolic function will be assessed thanks to a transthoracic cardiac ultrasound in children, and a transthoracic of a transesophageal cardiac ultrasound in adults : Measurements will be performed during the first three days of Acute Respiratory Distress Syndrome management : The first measurement will be performed 5 minutes after the initial ventilator settings. Measurements will be repeated systematically at 24 hours, 48 hours and 72 hours of evolution. An additional measure will be performed at each positive end-expiratory pressure modification (maximum 5 measures).

For pediatric patients: measurements will be performed during the first three days of Acute Respiratory Distress Syndrome management.

Right ventricle failure is defined, by ultrasound, as a composite criteria associating : end-diastolic right ventricle/left ventricle area ratio > 0.6 and/or Acute Cor Pulmonale (assocation with a septal dyskinesia), and/or a tricuspid annular plane systolic excursion < 1,6 cm (adults), z-score < -2 (children), and/or a doppler-derived tricuspid lateral annular systolic velocity (S wave) < 10 cm/s, and/or a two-dimensional Fractional Area Change (defined as end-diastolic area - end-systolic area)/end-diastolic area x100) < 35%, and/or a peak right ventricle free wall 2D strain < -30% (adults), z-score < 2 (children).

Airways pressure (Paw) will be measured in cmH2O thanks to a pneumotachograph connected to the ventilator.

Esophageal pressure (Pes) will be measured in cmH2O thanks to an oesophageal balloon catheter introduced in the mid-esophagus of the patient and connected to a manometer.

Measurements will be performed at different moments during the respiratory cycle: after an inspiratory pause to evaluate the tele-inspiratory transpulmonary pressure (PL-insp), and after an expiratory pause to evaluate the tele-expiratory transpulmonary pressure (PL-PEP ). The PL-insp will be calculated using the ratio between the elastance of the chest wall (Ecw) and of the respiratory system (Ers) thanks to this formula PL = Paw - Paw x (Ecw/Ers). The PL-exp will be calculated using the ratio between Paw et Pes (PL = Paw - Pes). Transpulmonary pressure will be expressed in cmH2O.

Correlation between transpulmonary pressure and morbidity. Vaso-Active Inotrope Score is a hemodynamic score taking into account the cumulative doses of inotropic or vassopressive drugs. It is obtained thanks this calculation : VIS = dopamine dose (µg/kg/min) + dobutamine dose (µg/kg/min) + 100 x epinephrine dose (µg/kg/min) + 10 x milrinone dose (µg/kg/min) + 10000 x vasopressin dose (µg/kg/min) + 100 x norepinephrine dose (µg/kg/min). Its value ranges from zero, which is associated to a better outcome, to the maximum cumulative dose without any limit.

Pediatric logistic organ dysfunction score is a specific pediatric multiple organ dysfunction score that includes 10 variables corresponding to 5 organ dysfunctions. Values extend from 0 (best outcome) to 33 (worst outcome).

Sepsis-related Organ Function Assessement score is a multiple organ dysfunction score that includes several variables corresponding to 6 organ dysfunctions. Values extend from 0 (best outcome) to 24 (worst outcome).

Lung and chest wall compliances (in mL/cmH2O) will be calculated thanks to the respective ratios tidal volume/(PL-insp - PL-PEP) and tidal volume/(Pes insp - Pes-PEP).

Electrical impedance tomography will be monitored only in children. Several methods will be used and compared, based on e.g. pixel information of lung aeration, to assess end-expiratory lung volume (ELLV, in mL) and the distribution of ventilation

Inclusion Criteria: Patients over one month Patients with mild to severe ARDS (onset within 48 hours). ARDS definition will follow Berlin guidelines for adults, and Pediatric Acute Lung Injury Consensus Conference (PALICC) guidelines for children Signed consent Exclusion Criteria : Neonates less than 28 days-old Pregnancy or breastfeeding Any contra-indication to esophageal manometry (less than one month esophagus surgery, bronchopleural or esotracheal fistula, latex allergy) No social care