Measurement of gas transport kinetics in high‐frequency oscillatory ventilation (HFOV) of the lung using hyperpolarized ³He magnetic resonance imaging

Abstract

Purpose: To protect the patient with acute respiratory distress syndrome from ventilator associated lung injury (VALI) high-frequency oscillatory ventilation (HFOV) is used. Clinical experience has proven that HFOV is an efficient therapy when conventional artificial ventilation is insufficient. However, the optimal settings of HFOV parameters, eg, tidal volumes, pressure amplitudes and frequency for maximal lung protection, and efficient gas exchange are not established unambiguously. Methods: In this work magnetic resonance imaging (MRI) with hyperpolarized 3He was employed to visualize the redistribution of gas within the cadaver pig lung during HFOV. The saturated slice method was used to characterize fast gas kinetics.Results: The strong differences in kinetics were observed for HFOV-driven gas exchange in comparison with diffusive gas transport (apnea). The significant regional and HFOV frequency dependence was detected for washout and gas exchange within the lungs. Gas redistribution was much faster in posterior than in anterior parts of the lungs during HFOV, in contrast to minor differences with an opposite trend observed in apnea. Conclusion:The method shows significant potential for visualization and quantification of gas redistribution under HFOV and may help in optimization of the parameters to improve the clinical effect of HFOV for patients.

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