Flow Controlled Ventilation in Cardiac Surgery

Study Overview
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Brief Summary
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This trial investigates effects of individualized (by compliance guided pressure settings) flow-controlled ventilation compared to best clinical practice pressure controlled ventilation in cardiac surgery requiring cardiopulmonary bypass.

Detailed Description
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The aim of the study is to investigate flow-controlled ventilation (FCV) during cardiac surgery requiring cardiopulmonary bypass. Previous preclinical trials have already shown improved oxygenation and CO2 removal within a significantly reduced respiratory minute volume as an expression of more efficient gas exchange with FCV compared to volume controlled ventilation (VCV). Preliminary data of our own animal study comparing individualized FCV by compliance guided pressure settings with state-of-the-art low tidal volume pressure controlled ventilation (PCV) confirmed previous findings with a significantly improved oxygenation by 20% while reducing respiratory minute volume. We therefore assume that FCV may be a more lung protective ventilation method. Open heart surgery requires bridging of the heart and lung function with a cardiopulmonary bypass (CPB) performed by a heart-lung machine. During this time the lung is most frequently not ventilated at all and lies collapsed in the chest for several hours. After weaning from CPB, the lungs must be recruited and ensure sufficient gas exchange of the blood. Not surprisingly, the incidence of postoperative pulmonary complications (PPC) at 20-30% is comparatively high after cardiac surgery and is the leading cause of perioperative mortality. Based on previous trials we expect improved oxygenation and thus arterial partial pressure of oxygen (pO2) is the main primary outcome parameter of this study. Furthermore, we expect improved recruitment of lung tissue due to controlled expiratory flow in FCV without the need of recruitment maneuvers, which may cause deleterious effects on lung tissue. Thus, lung tissue aeration assessed by Hounsfield units analyses of a postoperative computed tomography will be a secondary outcome parameter.

Official Title
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Flow Controlled Ventilation Versus Pressure Controlled Ventilation in Cardiac Surgery After Cardiopulmonary Bypass Without Ventilation - a Prospective, Randomized Clinical Study

Conditions
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Respiration; Artificial, Positive-Pressure Respiration

Intervention / Treatment
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* Device: Evone
* Device: Primus


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Male and female subjects >18 years Body weight >40 kg Elective cardiac surgery with CPB and without ventilation during CPB American Society of Anaesthesiologists (ASA) risc classification I-IV Written informed consent Exclusion Criteria: Emergency surgery Female subjects known to be pregnant Known participation in another interventional clinical trial High risk cardiac surgery such as double valve surgery, re-cardiac surgery, intraoperative cardiac arrest or pre-existing high grade cardiomyopathy (ejection fraction <30%) Closing operation field without chest closure due to hemodynamic instability Acute endocarditis under antibiotic treatment Minimal invasive valve surgery via thoracotomy (MIC)

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 99 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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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: controlled, prospective
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: FCV<br>Artificial ventilation will be performed with individualized flow-controlled ventilation (Evone, Ventinova Medical B.V., Eindhoven, the Netherlands) during cardiac surgery until admission to postoperative ICU. Individualisation will be established by compliance guided end-expiratory and peak pressure setting, flow setting will be adjusted to secure normocapnia and I:E Ratio set to 1:1. | Device: Evone<br>* Airway ventilation device<br>|
| Active Comparator: PCV<br>Artificial ventilation will be performed with low tidal volume pressure-controlled ventilation (Primus, Dräger, Lübeck, Germany) during cardiac surgery until admission to postoperative ICU. Peak pressure will be set to achieve a tidal volume of 7ml/kg predicted body weight at a compliance titrated positive end-expiratory pressure. Respiratory rate will be set to maintain normocapnia and I:E ratio set to 1:1.5 except extension of expiration is necessary in order to avoid air trapping. | Device: Primus<br>* Airway ventilation device<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Horowitz Index | arterial partial pressure of Oxygen (paO2) / fraction of inspired Oxygen (FiO2) | 15 minutes after chest closure | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| lung tissue aeration | Lung tissue aeration assessed by Hounsfield units analysis of computed tomography | immediately postoperative | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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flow controlled ventilation, pressure controlled ventilation, cardiac surgery