Ventilatory Variables in Subjects With Acute Respiratory Distress Syndrome Due to COVID-19

Primary Objective:

• To evaluate the association between the ventilatory variables of mechanical power and the outcome of the subjects in terms of mortality, days on MV and days free of MV at 28 days (both in survivors).

Secondary Objectives:

• Evaluate the association of demographic and gas exchange variables with the outcome of the subjects.

METHODOLOGY

Study design: retrospective and observational, analytical.

Operational definition of variables

Ventilatory variables:

• Global mechanical power: 0.098 × Tidal Volume × Respiratory Rate × (Peak Pressure - ½ Distension Pressure)
• Dynamic elastic mechanical power: 0.098 × Tidal Volume × Respiratory Rate × 0.5 × Distension Pressure
• Static elastic mechanical power: 0.098 × Tidal Volume × Respiratory Rate × PEEP
• Resistive mechanical power: 0.098 × Tidal Volume × Respiratory Rate × (Peak Pressure - Plateau Pressure)
• Cyclic Strain: DP x 4 + Respiratory Rate.
• Driving Pressure adjusted to predicted body weight: Driving Pressure / Tidal Volume (in ml / kg of predicted weight).

Demographic Variables:

• Age: in years.
• Sex: female / male.
• ARDS Classification:

• Mild (PaO2 / FIO2 ≤ 300 mm Hg and > 200 mm Hg)
• Moderate (PaO2 / FIO2 ≤ 200 mm Hg and > 100 mm Hg)
• Severe (PaO2 / FIO2 ≤ 100 mm Hg)
• Body mass index: weight in kilograms divided by height in meters squared.

Gas Exchange Variables:

• Ventilatory quotient: (Respiratory Rate x Tidal Volume x PCO2) / (Predicted Weight x 100 ml x 37.5)
• Pa/FiO2: Arterial oxygen pressure/ Fraction of inspired oxygen Outcome Variables
• Mortality
• MV-free days at 28 days
• MV days Population and scope of study: Subjects registered in the ICU 2 database of the Francisco Santojanni Donation Hospital of the Autonomous City of Buenos Aires, who have received MV for ARDS with a confirmed diagnosis of COVID-19 pneumonia by polymerase chain reaction.

Study period: Data from subjects admitted from April 2020 to August 2021 will be analyzed.

Results analysis plan: A descriptive analysis of the clinical variables will be performed using the mean and standard deviation (SD), if the distribution is normal, or the median and interquartile range (IQR) otherwise.

Categorical variables will be presented as absolute number of presentation and percentage.

A value of p<0.05 will be considered as statistically significant.

SPSS software will be used for data analysis.

Inclusion criteria

• Confirmed diagnosis of pneumonia due to COVID-19.
• Need of mechanical ventilation in intensive care unit.

Exclusion criteria

• Patients with data loses