Echocardiographic assessment of pulmonary artery occlusion pressure in ventilated patients: a transoesophageal study

Abstract

Background: Non-invasive evaluation of left ventricular filling pressure has been scarcely studied in critically ill patients. Accordingly, we prospectively assessed the ability of transoesophageal echocardiography (TEE) Doppler to predict an invasive pulmonary artery occlusion pressure (PAOP) < or = 18 mmHg in ventilated patients.

Methods: During two consecutive 3-year periods, TEE Doppler parameters were compared to right heart catheterisation derived PAOP used as reference in 88 ventilated patients, haemodynamically stable and in sinus rhythm (age: 63 +/- 14 years; simplified acute physiologic score (SAPS) II: 45 +/- 12). During the initial period (protocol A), threshold values of pulsed-wave Doppler parameters to predict an invasive PAOP < or = 18 mmHg were determined in 56 patients. Derived Doppler values were prospectively tested during the subsequent period (protocol B) in 32 patients.

Results: In protocol A, Doppler parameters had similar area under the receiver operating characteristic (ROC) curve. In protocol B, mitral E/A < or = 1.4, pulmonary vein S/D > 0.65 and systolic fraction > 44% best predicted an invasive PAOP < or = 18 mmHg. Lateral E/E' < or = 8.0 or E/Vp < or = 1.7 predicted a PAOP < or = 18 mmHg with a sensitivity of 83% and 80%, and a specificity of 88% and 100%, respectively. Areas under ROC curves of lateral E/E' and E/Vp were similar (0.91 +/- 0.07 vs 0.92 +/- 0.07: p = 0.53), and not significantly different from those of pulsed-wave Doppler indices.

Conclusion: TEE accurately predicts invasive PAOP < or = 18 mmHg in ventilated patients. This further increases its diagnostic value in patients with suspected acute lung injury/acute respiratory distress syndrome.

Figure 1

Receiver operating characteristic (ROC) curves of transoesophageal echocardiography (TEE) Doppler parameters to predict an invasive pulmonary artery occlusion pressure (PAOP) ≤ 18 mmHg in protocol A. Left panel: area under the curves (AUC) with standard error and 95% confidence intervals (CI) and p values (comparison of the actual AUC with the 0.50 AUC) of mitral Doppler parameters were as follows: E/A, 0.83 ± 0.09 (95% CI: 0.70–0.92; p = 0.0002); mitral E wave deceleration time, 0.81 ± 0.07 (95% CI: 0.67–0.90; p < 0.0001); atrial filling fraction: 0.82 ± 0.07 (95% CI: 0.68–0.91; p < 0.0001). Right panel: AUC with standard error and 95% CI of pulmonary vein Doppler parameters were the followings: S/D, 0.78 ± 0.07 (95% CI: 0.65–0.88; p = 0.0001); systolic fraction, 0.84 ± 0.06 (95% CI: 0.72–0.93; p < 0.0001). Abbreviations: AFF, atrial filling fraction; DT_E, deceleration time of early diastolic mitral E wave; SF, systolic fraction.

Figure 2

Examples of transoesophageal echocardiography (TEE) Doppler findings obtained in a patient with a low invasive pulmonary artery occlusion pressure (PAOP) (left panels) and in a patient with elevated left ventricle (LV) filling pressures (right panels) who were both enrolled in protocol B. Values of studied Doppler indices are noted on each corresponding TEE view. Abbreviations: DTI, Doppler tissue imaging; DT_E, deceleration time of early diastolic mitral E wave; SF, systolic fraction.