Do we have our FACTTs straight about cor pulmonale in acute respiratory distress syndrome?

The incidence of cor pulmonale in acute respiratory distress syndrome is roughly 20-25% and is associated with nearly 50% increase in mortality risk. Our primary aim was to quantify the association of traditional cor pulmonale risk factors {pH, PaO2:FiO2 ratio, PaCO2, and driving pressure [plateau pressure minus the positive end-expiratory pressure (PEEP)]} and PEEP with the mentioned cor pulmonale parameters.

Using data from the FACTT trial, we examined four cor pulmonale parameters. In addition to pulmonary arterial compliance (Cpa) and pulmonary vascular resistance index (PVRi), we assessed pulmonary artery pulsatility index (PAPi) and effective arterial elastance (Ea) of the pulmonary circulation. Median [interquartile range (IQR)] Cpa on study day 1 was 4.28 mL/mmHg (3.14, 6.08). Increasing pH and P:F were associated with an increase in Cpa. Median (IQR) Ea on Day 1 was 0.48 mmHg/mL (0.36, 0.66). Increase of pH, PaCO2, and P:F were associated with a decrease in Ea, while an increase in PEEP was associated with an increase in Ea. Median (IQR) PAPi on Day 1 was 1.58 (1.13, 2.38). Increase in pH was associated with an increase in PAPi, while increase in PEEP was associated with a decrease in PAPi. Median (IQR) PVRi on Day 1 was 3.86 WU*m2 (2.45, 4.79). Increases in PaCO2 and P:F were associated with a decrease in PVRi, while increasing driving pressure and PEEP were associated with an increase in PVRi.

While the FACTT data demonstrate neither a clear nor a consistent relationship between right ventricular-pulmonary arterial function and traditional risk factors, this does not indicate their unimportance.