Ventilation area measured with eit in order to optimize peep settings in mechanically ventilated patients.

Abstract

INTRODUCTION. Electrical Impedance Tomography (EIT) is a non-invasive imaging technique, which can be used to visualize ventilation. Ventilation will be measured by impedance changes due to ventilation. OBJECTIVES. The aim of this study was to optimize PEEP settings based on the ventilation area of EIT images during a decremental PEEP trial. METHODS. After a recruitment maneuver, a decremental PEEP trial was performed in 10 mechanically ventilated post cardiac surgery patients. Ventilation area, blood gases, FRC and compliance were measured at each PEEP level. The ventilation area was defined as the surface of ventilation at one lung slice measured with EIT and was expressed as percentage of its maximum obtained during a recruitment maneuver (RM). RESULTS. The amount of ventilated pixels during the RM is set as 100 %. Figure 1 shows the amount of ventilated pixels as percentage compared to its maximum during the RM. The ventilation area was significantly smaller at 5 and 0 PEEP compared to its maximum at both the dependent and non-dependent lung. Also PaO2/FiO2 and FRC were significantly lower at these PEEP levels. (Figure presented) Bars represent the mean + SD. Black = dependent lung region, White = non-dependent lung region. * p<0.05 compared to RM. CONCLUSIONS. Changes in ventilation area based on EIT images can be used to set the PEEP level in mechanically ventilated patients.