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Abstract #0823

Effect of Pulmonary Hysteresis on Airspace Dimensions During Positive End Expiratory Pressure Trials in Mechanically Ventilated Rats Using Hyperpolarized Gas Diffusion MRI

Maurizio Cereda1, Yi Xin2, Kiarash Emami2, Jessie Huang2, Jennia Rajaei2, Harrilla Profka2, Biao Han2, Puttisarn Mongkolwisetwara2, Stephen J. Kadlececk2, Nicholas N. Kuzma2, Stephen B. Pickup2, Brian Kavanagh3, Clifford Deutschman1, Rahim Rizi2

1Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, United States; 2Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States; 3Departments of Critical Care Medicine and Anesthesia, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada

Using hyperpolarized gas MRI, we provide evidence supporting the role of airspace recruitment, rather than expansion, in ventilated healthy rats without atelectasis. Our results showed that hysteresis was associated with a decrease in the size of ventilated airspaces. These results, obtained through imaging, are relevant because they contribute to the clarification of a controversial physiological mechanism. Furthermore, this study provides an additional rationale for investigating strategies that may minimize pulmonary stress.

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Keywords

absence acquisition advantageously airspace airspaces alto alveolar anatomical anesthesia anesthetized animals apparent applied ascending attenuate care cell characterized children compliance computed confirm confirmed conflicting confounding content continue contribution critical decades decrease decreased deflation density descending despite diffusion dimensional dimensions dissipation documented dynamic encoding energy evidence explain fashion finding five gradient healthy heart history holds hysteresis improvement in vivo increments inflation initial injury insight intubated larger likely lung male maneuver maneuvers maps measured mechanical mechanically mechanics mechanisms medicine minimize mixture model monotonically necessary newly open others overall oxygen peak peep performance period phenomenon physiological pickup poorly position positive presence pressure pressures previous prior procedures propensity protocol pulmonary pulse quantify quantitative radiological radiology ramp ramps rats reconstructions recruited recruitment regarding remained reopening representative response returned role room scanner separate settings sick slice smaller standardize stress studies subjects successful suggested suggesting suggests supine timing tomography transverse trials undergoing underwent ventilated ventilation ventilator volume volumes white whole