Assessment of the effectiveness of lung recruitment and PEEP setting by vibration response imaging

Introduction

Vibration response imaging (VRI) is a novel technology that measures vibration energy generated from airflow to create a real-time structural and functional image of the respiration process. Since this new imaging technique can be performed quickly and non-invasively at the bedside, it offers potential as a real time noninvasive method of adjusting ventilatory therapy.

Case

A 75-year-old male patient was admitted to the ICU with acute lung injury due to acute pancreatitis and was mechanically ventilated with a PEEP setting of 5 mmHg and FiO₂ 1.0. VRI recordings were obtained before and after a recruitment maneuver (40 cmH₂O PEEP for 40 s) and increasing PEEP to 10 cmH₂O. Images were taken during 20-s periods of respiration and respiratory cycles for analysis selected based on predefined selection rules. Mechanical ventilator settings were the same before and after recruitment. The total areas were measured by using the Image-J program (Table 1). Arterial blood gases were obtained immediately before and after recruitment and in close proximity (within 1 min) of VRI (Table 2). Statistical analysis was performed using a t test. Figures 1 and 2 show representative images before and after recruitment and PEEP elevation.

Figure 1

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Figure 2

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Table 1 abstract P15

Table 2 abstract P15

Discussion

This case demonstrates a significant increase in the geographical area of vibration response images at peak inspiration after recruitment maneuver and a PEEP increase in early ARDS. This increase in VRI area correlates with improvement in oxygenation.

Conclusion

Increased spatial distribution of ventilation following effective recruitment has previously been demonstrated using computerized tomography. VRI may provide a rapid bedside assessment of the effectiveness of lung recruitment and PEEP setting as an alternative to computerized tomography