Positive end-expiratory pressure does not influence Doppler-derived ventriculoatrial pressure gradient and Tei index in critically ill p

Abstract

Echocardiographic parameters of left ventricular (LV) systolic and diastolic function usually include LV dimensions, ejection fraction and transmitral inflow patterns. In mechanically ventilated patients, the use of positive end-expiratory pressure (PEEP) reduces LV preload and afterload and thus may confound accurate assessment of these markers, as they are known to be load dependent. The myocardial performance index (Tei index) and the Doppler-derived ventriculoatrial pressure gradients dP/dt and –dP/dt are known to be less load-dependent and may therefore be more accurate markers to characterize LV-function under PEEP conditions. We consecutively studied ten mechanically ventilated, critically ill patients with mild mitral regurgitation. Each patient was examined at two PEEP levels, 5 and 15 mbar. At each PEEP level, transthoracic echocardiography was performed to assess the parameters of LV function. Moreover, blood pressure measurements and respiratory parameters were recorded. Blood pressure and minute ventilation did not change at either PEEP level. Left ventricular dimensions and ejection fraction decreased significantly at increased PEEP, whereas Tei index and dP/dt remained unchanged. Only moderate correlations between ejection fraction and Tei index or dP/dt could be observed. Increased PEEP did not influence transmitral inflow patterns and –dP/dt. Tei index and Doppler-derived dP/dt serve as accurate markers of LV performance independent of loading conditions in mechanically ventilated patients, as they are not influenced by PEEP.