PURPOSE: Vibration response imaging (VRI) is a novel technology that measures vibration energy generated from airflow to create real-time structural and functional image of the respiration process. The purpose is to assess the differences observed in lung vibration energy waveform in mechanical ventilation compared to spontaneous breathing.
METHODS: Sophisticated surface skin sensors are placed on the back to record and display vibrations as a non-invasive measure of airflow in the lung. In addition to dynamic image, the software in the device also provides a waveform displaying the total vibration intensity from the lungs over time. VRI recordings were taken from healthy individuals during spontaneous breathing and from the mechanical ventilated patients. An inspiratory hold was performed to seperate inspiration from expiration.
RESULTS: In healthy individuals, vibration due to airflow in the lungs, as recorded with the VRI, typically produce two distinctive vibration signals (inspiration and expiration) separated by a return to baseline with the inspiratory signal greater than the expiratory signal (Figure 1). We have noted a distinctive VRI signal in many mechanically ventilated patients in which there is a superimposition of the typical inspiratory and expiratory signals. The occurrence of this was confirmed by performance of inspiratory holds producing a clear separation into traditional inspiratory and expiratory signals. Figure 2 demonstrates separation of inspiratory and expiratory signals produced by application of an inspiratory hold. The top waveform is vibration intensity over time from the VRI and the lower waveform is flow over time from the ventilator.
CONCLUSION: The merging of inspiratory and expiratory peaks in patients on volume control ventilation is likely due to an abrupt transition from high inspiratory flow to high expiratory flow. An inspiratory hold markedly decreases, or curtails, end inspiratory flow allowing a transition of inspiratory to expiratory flow as is seen in spontaneously breathing individuals.
CLINICAL IMPLICATIONS: Analysis of baseline VRI graphic pattern during mechanical ventilation and the effect of inspiratory hold maneuver on that pattern may allow a more physiologic adjustment of ventilator settings.
DISCLOSURE: Ismail Cinel, University grant monies NA; Grant monies (from sources other than industry) Deep Breeze Ltd.; Grant monies (from industry related sources) NA; Shareholder NA; Employee NA; Fiduciary position (of any organization, association, society, etc, other than ACCP NA; Consultant fee, speaker bureau, advisory committee, etc. JE Parrillo, MD, FCCP and RP Dellinger, MD, FCCP; Other NA; Product/procedure/technique that is considered research and is NOT yet approved for any purpose, Vibration Response Imaging.