Acute cor pulmonale in acute respiratory distress syndrome: a dreaded complication of the past?

Early detection of right ventricular dysfunction using transthoracic echocardiography in ARDS: a more objective approach

PURPOSE

Right ventricular (RV) dysfunction is an independent predictor of morbidity and mortality in acute respiratory distress syndrome (ARDS). Our goal was to describe morphologic changes in the RV using objective measures on transthoracic echocardiography (TTE) that occur following ARDS.

METHODS

We retrospectively measured changes in the following RV parameters from a pre-ARDS TTE to an ARDS TTE: tricuspid annular plane systolic excursion (TAPSE), myocardial performance index (MPI), fractional area change (FAC), systolic pulmonary artery pressure (SPAP), peak tricuspid regurgitant (TR) velocity, and septal shift.

RESULTS

Over 24 months, 14 patients met inclusion/exclusion criteria. Mean TAPSE decreased from 22.4 mm pre-ARDS to 16.3 mm during ARDS, P<.001. Mean MPI increased from 0.19 to 0.38, P=.001. Mean FAC decreased from 60.8% to 41.2%, P=.003. Peak TR velocity increased from 2.67 m/s pre-ARDS to 3.31 m/s during ARDS, P=.02. SPAP and septal shift demonstrated trends but not statistically different between pre-ARDS and ARDS states. TAPSE correlated with ARDS severity (PaO₂ /FiO₂ ratios), P=.004, and was lower among 30-day nonsurvivors compared with survivors, P=.002.

CONCLUSIONS

Mild RV dysfunction is common after ARDS onset. RV morphologic changes coupled with dysfunction can be detected noninvasively through TTE changes with TAPSE, MPI, and FAC. Mild RV dysfunction by TAPSE is associated with ARDS severity and mortality.

Prone positioning unloads the right ventricle in severe ARDS

BACKGROUND

Despite airway pressure limitation, acute cor pulmonale persists in a minority of ARDS patients. Insufficient airway pressure limitation, hypercapnia, or both may be responsible. Because prone positioning (PP) has been shown to be a safe way to reduce airway pressure and to improve alveolar ventilation, we decided to assess its effect on right ventricular (RV) pressure overload in ARDS patients.

METHODS

Between January 1998 and December 2006, we studied 42 ARDS patients treated by PP to correct severe oxygenation impairment (Pao2/fraction of inspired oxygen ratio, <100 mm Hg). RV function was evaluated by bedside transesophageal echocardiography, before and after 18 h of prone-position ventilation. RV enlargement was measured by RV/left ventricular (LV) end-diastolic area ratio in the long axis. Septal dyskinesia was quantified by measuring short-axis systolic eccentricity of the LV.

RESULTS

Before PP, 21 patients (50%) had acute cor pulmonale, defined by RV enlargement associated with septal dyskinesia (group 1), whereas 21 patients had a normal RV (group 2). PP was accompanied by a significant decrease in airway pressure and Paco2. In group 1, this produced a significant decrease in mean (+/-SD) RV enlargement (from 0.91+/-0.22 to 0.61+/-0.21) after 18 h of PP (p=0.000) and a significant reduction in mean septal dyskinesia (from 1.5+/-0.2 to 1.1+/-0.1) after 18 h of PP (p=0.000).

CONCLUSION

In the most severe forms of ARDS, PP was an efficient means of controlling RV pressure overload.