Stable Small Animal Ventilation for Dynamic Lung Imaging to Support Computational Fluid Dynamics Models

Pulmonary computational fluid dynamics models require that three-dimensional images be acquired over multiple points in the dynamic breathing cycle without breath holds or changes in ventilatory mechanics. With small animals, these requirements can result in long imaging times (∼90 minutes), over which lung mechanics, such as compliance, may gradually change if not carefully monitored and controlled. These changes, caused by derecruitment of parenchymal tissue, are manifested as an upward drift in peak inspiratory pressure (PIP) or by changes in the pressure waveform and/or lung volume over the course of the experiment. We demonstrate highly repeatable mechanical ventilation in anesthetized rats over a long duration for dynamic lung x-ray computed tomography (CT) imaging. We describe significant updates to a basic commercial ventilator that was acquired for these experiments. Key to achieving consistent results was the implementation of periodic deep breaths, or sighs, of extended duration to maintain lung recruitment. In addition, continuous monitoring of breath-to-breath pressure and volume waveforms and long-term trends in PIP and flow provide diagnostics of changes in breathing mechanics

Geochemical and Geomechanical Effects on Wellbore Cement Fractures: Data Information for Wellbore Reduced Order Model

The primary objective of the National Risk Assessment Partnership (NRAP) program is to develop a defensible, generalized, and science-based methodology and platform for quantifying risk profiles at CO2 injection and storage sites. The methodology must incorporate and define the scientific basis for assessing residual risks associated with long-term stewardship and help guide site operational decision-making and risk management. Development of an integrated and risk-based protocol will help minimize uncertainty in the predicted long-term behavior of the CO2 storage site and thereby increase confidence in storage integrity. The risk profile concept has proven useful in conveying the qualitative evolution of risks for CO2 injection and storage site. However, qualitative risk profiles are not sufficient for specifying long-term liability for CO2 storage sites. Because there has been no science-based defensible and robust methodology developed for quantification of risk profiles for CO2 injection and storage, NRAP has been focused on developing a science-based methodology for quantifying risk profiles for various risk proxies