Flow Controlled Ventilation in ARDS Associated With COVID-19

The pandemic of a newly upcoming viral disease which is associated with COVID-19 puts the
whole world's health system under pressure.

Patients suffering from this disease mainly develop respiratory symptoms, which can lead to
severe acute respiratory distress syndrome (ARDS) necessitating ICU admission in 10-20% of
the cases admitted to hospital. In addition to these symptoms, patients show lymphopenia,
cardiac symptoms and altered coagulation profiles. Although those patients are treated in the
ICU the mortality there is up to 20% due to multiorgan failure. Currently, there is no proven
therapeutic strategy next to symptomatic treatment.

Although the severely ill patients will need intubation and invasive ventilation according to
ARDS treatment strategies including low tidal volumes and low end-expiratory pressures, not
all patients recover their pulmonary function.

Flow control ventilation (FCV) is a recently developed ventilation strategy which allows to
keep the intrapulmonary pressures low while achieving optimal gas exchange. It had been
proven in animal models to improve pulmonary function and oxygenation and in cases with ARDS.

Flow Controlled Ventilation mode is a unique ventilation technique in which inspiration as
well as expiration are controlled i.e. actively performed. This is achieved by generating a
continuous flow into the patient's lungs during inspiration or a continuous (negative) flow,
sucking gasses out of the patient's lungs.

The continuous flow without ventilation pauses, results in linear increases and decreases in
intratracheal pressures. As a result, the mean airway pressure will be higher compared to
conventional large bore Volume Controlled Ventilation or Pressure Controlled Ventilation
(PCV). Therefore, the bronchiole and alveoli will be kept open during ventilation
facilitating oxygen uptake to the blood. Moreover, the continuous gas flow enhances gas
mixture in the lungs also improving gas exchange. Altogether, FCV results in more efficient
ventilation as compared to conventional ventilation techniques.

Evone® is the only commercially available ventilator applying FCV ventilation mode, thus
directing the inspiration as well as the expiration. Evone's FCV® ventilation mode is based
on a controlled inspiration and expiration flow from a set PEEP to a set peak pressure and
vice versa. The inspiratory flow is continuously controlled by advanced mass flow regulators;
the expiratory flow is controlled by regulated suctioning.

Aim of the study This study aims to demonstrate the positive effects on oxygenation of
flow-controlled ventilation compared to conventionally ventilated patients (pressure control
ventilation) in patients suffering from ARDS associated with COVID-19.