Effectiveness of Low Volume and Low Pressure in Severe Hypoxemic Patients

Assessing the Effectiveness of Low Tidal Volume and Low Driving Pressure in Mechanically Ventilated Severe Hypoxemic Patients: a Multicenter Emulated Target Trial

The present study set up to answer two questions: (a) "how low tidal volume must be to provide protective ventilatory settings able to minimize the risk of death due to Ventilator-Induced Lung Injury (VILI)?"; (b) "if protection from VILI is better achieved by targeting the driving pressure instead of the tidal volume, what is the optimal target for the driving pressure?". Solving these questions is pivotal for clinicians to personalized and precise mechanical ventilation practices to reduce the risk of VILI and avoid unnecessary risks associated to protective ventilatory settings.

Two multicenter emulated target trials will be performed using data collected with the Electronic Health Record MargheritaTre, to investigate the effect of low tidal volumes (6.0 to 8.0 ml/kg PBW vs 8.0 to 10.0 ml/kg PBW) and low driving pressures (7.0-12.0 cmH2O vs 12.0-18.0 cmH2O), respectively. Data will be used to obtain the dose-response curve of lower VT and lower ∆P in mechanically ventilated patients with acute severe hypoxemia.

Inclusion Criteria:

all the following conditions present continuously for 24 hours commencing within 36 hours of ICU admission, while the patient is undergoing invasive mechanical ventilation in either flow or pressure- regulated assist/controlled modes:

1. arterial oxygen tension (PaO2) to inspiratory oxygen fraction (FiO2) ratio P/F ≤ 300 mmHg
2. hypoxemia developed within one week of a known clinical insult
3. hypoxemia not fully explained by cardiac failure or fluid overload*

Exclusion Criteria:

1. pregnancy
2. expected duration of mechanical ventilation < 48h
3. severe or moderate COPD
4. chronic liver disease
5. acute brain injury
6. patient admitted for palliative sedation
7. tumor with metastases
8. prior cardiac arrest
9. New York Heart Association Class IV
10. acute coronary syndrome
11. patients transferred from other ICUs
12. patients transferred to the ICU from the Emergency Department after a duration exceeding 24 hours in the Emergency Department
13. patients on Pressure Support Ventilation and/or patients in whom end-inspiratory plateau pressure was not measured