Increasing Levels of Positive End-expiratory Pressure Improve the Left Ventricular Strain

The goal of this study was to evaluate possible changes in the left myocardial performance of patients with cardiogenic shock (CS) during ascending levels of positive end-expiratory pressure (PEEP) using speckle-tracking echocardiography.

This was an interventional clinical study performed on CS patients under mechanical ventilation. These patients underwent echocardiography after 15 to 30 minutes of progressive increases in PEEP zero end-expiratory pressure (ZEEP) (PEEP 5, PEEP 10, PEEP 15 cm H2O). We evaluated the changes caused by these increasing levels of PEEP on the E/E' ratio and the parameters of left ventricular systolic and diastolic functions, including longitudinal strain (S) and strain rate (SR). Analyses of mean values were carried out using analysis of variance.

A total of 65 CS patients were included. Their mean age was 68.58±14.61 years. Progressive increases in PEEP induced a significant decrease in the E/E' ratio (ZEEP=12.87±1.81; PEEP=5, 8.39±3.61; PEEP=10, 6.34±1.73; and PEEP=15, 7.10±0.37; P<0.0001). Although we did not find significant changes in left ventricular ejection fraction, a clear increase in left ventricular S and SR occurred (ZEEP=-13, 15±1.27; PEEP=5, -16.97±4.01; PEEP=10, -16.89±0.46; PEEP=15, -15.39±4.21; and ZEEP=-1.02±0.02; PEEP=5, -1.49±0.13; PEEP=10, -1.57±0.21; PEEP=15, -1.24±0.29, respectively; all values were significant).

Increasing levels of PEEP improve the left ventricular S and SR. PEEP levels could modify the performance of left ventricular fibers.