Positive end-expiratory pressure-induced changes of the vibration response image

Introduction

Vibration response imaging (VRI) is a new modality that reflects the distribution of vibration in the lung during the respiratory process. The VRI dynamic and functional image has been proved to be sensitive to changes in ventilator settings, including changes in mode of mechanical ventilation. In the present study, we assess the changes of the VRI image and quantification data as a function of positive end-expiratory pressure (PEEP) changes.

Methods

Thirty-four ventilated patients were consecutively enrolled in this study. PEEP levels (0–15 cmH₂O) were assigned according to level of oxygenation and blood pressure. A change in vibration distribution of more than 10% in one of the six lung segments was considered major. One hundred and thirteen recordings were performed sequentially in 21 patients at the same level of PEEP in order to assess the reproducibility of the measurement.

Results

One hundred and sixty VRI recordings were completed. Sixty-eight percent showed major changes in the VRI measurement when changing the PEEP. These changes were detectable for a PEEP change of 5 cmH₂O or less in 17 patients and for 10 cmH₂O for six patients. Among most VRI responders, an optimal PEEP range could be detected, in the range 5–10 cmH₂O (Figure 1). Ninety-six percent of the sequential recordings performed on the same patient at a given PEEP level exhibited less than 10% change.

Figure 1

Conclusion

VRI measurements respond rapidly to PEEP changes, and can provide the optimal vibration distribution at different PEEP levels.