Postoperative non-invasive assessment of pulmonary vascular resistance using Doppler echocardiography

Non-invasive monitoring of pulmonary vascular resistance (PVR) in postoperative cardiac surgery patients might be useful, particularly for management of pulmonary hypertension. For this purpose, we sought to assess Doppler echocardiography in the intensive care setting. In 73 patients, hemodynamics was measured using both, invasive gold standard (pulmonary artery catheter), and non-invasively by Doppler echocardiography. Four Doppler parameters: (1) tricuspid regurgitant velocity/time-velocity-integral of right ventricular outflow tract (TRV/VTI(RVOT)), (2) tricuspid annular systolic velocity (S'), (3) tricuspid annular strain, and (4) tricuspid annular strain rate, were compared with invasive PVR, using linear regression analysis and receiver-operating-characteristics. Patients without (n = 25, group 1) and patients with elevated left ventricular filling pressure (wedge pressure ≥ 15 mmHg, group 2, n = 48) were compared. Correlations were (1) R = 0.874, P < 0.0001, (2) R = -0.765, P < 0.0001, (3) R = 0.279, P = 0.009, (4) R = 0.378, P = 0.001. TRV/VTI(RVOT) showed prediction of PVR >300 dyn*s*/cm(5) (area-under-curve 0.975, cut-off 0.245, sensitivity 100%, specificity 91%). Strain correlated with PVR in group 2 patients only. TRV/VTI(RVOT) and tricuspid annular systolic velocity (S'), are useful for non-invasive monitoring of PVR in postoperative cardiac surgery patients with or without elevated left ventricular filling pressure. Strain may be used in patients with elevated filling pressure.