Effect of Airway Pressure Release Ventilation on Right Ventricular Function Assessed by Transthoracic Echocardiography

Heart rate (HR)

HR is a basic element of hemodynamic index

Time frame: HR monitoring was performed before APRV mechanical ventilation and 6 hours, 12 hours, Day 1, Day 2, Day 3 after APRV mechanical ventilation, and 24 hours after APRV ended

Systolic blood pressure (SBP)

SBP is basic element of hemodynamic index

Time frame: SBP monitoring was performed before APRV mechanical ventilation and 6 hours, 12 hours, Day 1, Day 2, Day 3 after APRV mechanical ventilation, and 24 hours after APRV ended

Mean arterial pressure (MAP)

MAP represents peripheral organ perfusion pressure

Time frame: MAP monitoring was performed before APRV mechanical ventilation and 6 hours, 12 hours, Day 1, Day 2, Day 3 after APRV mechanical ventilation, and 24 hours after APRV ended

cardiac output (CO)

CO is an important parameter to reflect the cardiac function of patients

Time frame: CO monitoring was performed before APRV mechanical ventilation and 6 hours, 12 hours, Day 1, Day 2, Day 3 after APRV mechanical ventilation, and 24 hours after APRV ended by ultrasound

Stroke volume (SV)

Stroke volume is the amount of blood that the ventricle shoots out during a single heart beat.

Time frame: SV monitoring was performed before APRV mechanical ventilation and 6 hours, 12 hours, Day 1, Day 2, Day 3 after APRV mechanical ventilation, and 24 hours after APRV ended by ultrasound

28-day mortality

28-day mortality after study entry

Time frame: Day 28 after study entry

The number of days in ICU

The number of days in ICU(up to 90 days)

Time frame: From the day subjects entered ICU to the day left ICU(up to 90 days)

The number of days in hospital

The number of days in hospital(up to 90 days)

Time frame: From the day subjects entered hospital to the day left hospital including death(up to 90 days)

in-hospital mortality

Any death occurred during hospitalization(up to 90 days)

Time frame: From the day patients admitted to hospital to the day death or discharge(up to 90 days)

Sequential Organ Failure Assessment score

The higher the Sequential Organ Failure Assessment(SOFA) score, the higher the disease risk factor and the higher the mortality rate(The highest score is 24, while the lowest score is 0).

Time frame: Within 2 hours admission to ICU and 24 hours after inclusion in the study

Acute Physiology and Chronic Health Evaluation II score

The higher the Acute Physiology and Chronic Health Evaluation II(APACHE II) score, the higher the disease risk factor and the higher the mortality rate(the highest score is 71, while the lowest score is 0).In particular, the accuracy of group patient prediction is high.

Time frame: Within 2 hours admission to ICU and 24 hours after inclusion in the study

the effect of APRV ventilation time on right ventricular area fractional change (RV FAC) in ARDS patients

The RV end-diastolic area (RVEDA) and RV end- systolic area (RVESA) were measured on the apical four-chamber section by two-dimensional ultrasound. RV FAC=(RVEDA- RVESA)/RVEDA\*100%.

Time frame: RV FAC monitoring was performed before APRV mechanical ventilation and 6 hours, 12 hours, Day 1, Day 2, Day 3 after APRV mechanical ventilation, and 24 hours after APRV ended by ultrasound

the effect of APRV ventilation time on tricuspid annular systolic displacement (TAPSE) in ARDS patients.

TAPSE was measured on the four-chamber section of the apex of the heart by M-mode ultrasound. the sampling line was placed at the side wall of the tricuspid valve ring, parallel to the free wall of the right ventricle as far as possible, and the displacement of the tricuspid valve ring was measured from the end of diastole to the end of RV systole.

Time frame: TAPSE monitoring was performed before APRV mechanical ventilation and 6 hours, 12 hours, Day 1, Day 2, Day 3 after APRV mechanical ventilation, and 24 hours after APRV ended by ultrasound

the effect of APRV ventilation time on tricuspid annular systolic S' velocity in ARDS patients.

Tricuspid annular systolic S' velocity is an objective and accurate ultrasound technique for evaluating right ventricular function.Measurement method:The sample volume was applied to the free wall of the RV and the peak velocity of tricuspid annulus motion was measured in the four-chamber section of the apex by tissue doppler imaging (TDI).

Time frame: Tricuspid annular systolic S' velocity monitoring was performed before APRV mechanical ventilation and 6 hours, 12 hours, Day 1, Day 2, Day 3 after APRV mechanical ventilation, and 24 hours after APRV ended by ultrasound

the effect of APRV ventilation time on right ventricular end-diastolic area/left ventricular end-diastolic area (RVEDA/LVEDA) in ARDS patients.

RVEDA/LVEDA：RVEDA/LVEDA a simple and repeatable ultrasound method for evaluating dynamics changes of RV function.Methods: The RV end-diastolic area (RVEDA) and LV end-systolic area (lVEDA) were measured on the apical four-chamber section by two-dimensional ultrasound.

Time frame: RVEDA/LVEDA monitoring was performed before APRV mechanical ventilation and 6 hours, 12 hours, Day 1, Day 2, Day 3 after APRV mechanical ventilation, and 24 hours after APRV ended by ultrasound