SYSTEM AND METHODS FOR VENTILATION THROUGH A BODY CAVITY

A system and methods for the delivery of oxygen through a body cavity of a subject using oxygen microbubbles . Through circulation of oxygen microbubbles through the body cavity , oxygen and carbon dioxide exchange may occur . Overall improvement in extending survival rate time during emergency situations caused by pulmonary or similar oxygen - intake restricting injury and / or failure may be achieved through use of the invented system and methods

Evaluation of Peritoneal Microbubble Oxygenation Therapy in a Rabbit Model of Hypoxemia

Alternative extrapulmonary oxygenation technologies are needed to treat patients suffering from severe hypoxemia refractory to mechanical ventilation. We previously demonstrated that peritoneal microbubble oxygenation (PMO), in which phospholipid-coated oxygen microbubbles (OMBs) are delivered into the peritoneal cavity, can successfully oxygenate rats suffering from a right pneumothorax. This study addressed the need to scale up the procedure to a larger animal with a splanchnic cardiac output similar to humans. Our results show that PMO therapy can double the survival time of rabbits experiencing complete tracheal occlusion from6.6 ± 0.6 min for the saline controls to 12.2 ± 3.0 min for the bolus PMO-treated cohort. Additionally, we designed and tested a new peritoneal delivery system to circulate OMBs through the peritoneal cavity. Circulation achieved a similar survival benefit to bolus delivery under these conditions. Overall, these results support the feasibility of the PMO technology to provide extrapulmonary ventilation for rescue of severely hypoxic patients

State-of-the-art of microbubble-assisted blood-brain barrier disruption.

Focused ultrasound with microbubbles promises unprecedented advantages for blood-brain barrier disruption over existing intracranial drug delivery methods, as well as a significant number of tunable parameters that affect its safety and efficacy. This review provides an engineering perspective on the state-of-the-art of the technology, considering the mechanism of action, effects of microbubble properties, ultrasound parameters and physiological variables, as well as safety and potential therapeutic applications. Emphasis is placed on the use of unified parameters, such as microbubble volume dose

Methods of Generating Submicrometer Phase-Shift Perfluorocarbon Droplets for Applications in Medical Ultrasonography

Continued advances in the field of ultrasound and ultrasound contrast agents have created new approaches to imaging and medical intervention. Phase-shift perfluorocarbon droplets, which can be vaporized by ultrasound energy to transition from the liquid to the vapor state, are one of the most highly researched alternatives to clinical ultrasound contrast agents (i.e., microbubbles). In this paper, part of a special issue on methods in biomedical ultrasonics, we survey current techniques to prepare ultrasound-activated nanoscale phase-shift perfluorocarbon droplets, including sonication, extrusion, homogenization, microfluidics, and microbubble condensation. We provide example protocols and discuss advantages and limitations of each approach. Finally, we discuss best practice in characterization of this class of contrast agents with respect to size distribution and ultrasound activation

Theranostic Oxygen Delivery Using Ultrasound and Microbubbles

Means to overcome tumor hypoxia have been the subject of clinical investigations since the 1960's; however these studies have yet to find a treatment which is widely accepted. It has been known for nearly a century that hypoxic cells are more resistant to radiotherapy than aerobic cells, and tumor hypoxia is a major factor leading to the resistance of tumors to radiation treatment as well as several cytotoxic agents. In this manuscript, the application of ultrasound combined with oxygen-carrier microbubbles is demonstrated as a method to locally increase dissolved oxygen. Microbubbles can also be imaged by ultrasound, thus providing the opportunity for image-guided oxygen delivery. Simulations of gas diffusion and microbubble gas exchange show that small amounts (down to 5 vol%) of a low-solubility osmotic gas can substantially increase microbubble persistence and therefore production rates and stability of oxygen-carrier microbubbles. Simulations also indicate that the lipid shell can be engineered with long-chain lipids to increase oxygen payload during in vivo transit. Experimental results demonstrate that the application of ultrasound to destroy the microbubbles significantly enhances the local oxygen release. We propose this technology as an application for ultrasound image-guided release of oxygen directly to hypoxic tissue, such as tumor sites to enhance radiotherapy

Effect of anesthesia carrier gas on in vivo circulation times of ultrasound microbubble contrast agents in rats

Microbubble contrast agents are currently implemented in a variety of both clinical and preclinical ultrasound imaging studies. The therapeutic and diagnostic capabilities of these contrast agents are limited by their short in-vivo lifetimes, and research to lengthen their circulation times is ongoing. In this manuscript, observations are presented from a controlled experiment performed to evaluate differences in circulation times for lipid shelled perfluorocarbon-filled contrast agents circulating within rodents as a function of inhaled anesthesia carrier gas

Vaporizable endoskeletal droplets via tunable interfacial melting transitions. Science Advances

Liquid emulsion droplet evaporation is of importance for various sensing and imaging applications. The liquid-to-gas phase transformation is typically triggered thermally or acoustically by low-boiling point liquids, or by inclusion of solid structures that pin the vapor/liquid contact line to facilitate heterogeneous nucleation. However, these approaches lack precise tunability in vaporization behavior. Here, we describe a previously unused approach to control vaporization behavior through an endoskeleton that can melt and blend into the liquid core to either enhance or disrupt cohesive intermolecular forces. This effect is demonstrated using perfluoropentane (C F ) droplets encapsulating a fluorocarbon (FC) or hydrocarbon (HC) endoskeleton. FC skeletons inhibit vaporization, whereas HC skeletons trigger vaporization near the rotator melting transition. Our findings highlight the importance of skeletal interfacial mixing for initiating droplet vaporization. Tuning molecular interactions between the endoskeleton and droplet phase is generalizable for achieving emulsion or other secondary phase transitions, in emulsions.</p

Testing oxygenated microbubbles via intraperitoneal and intrathoracic routes on a large pig model of LPS-induced acute respiratory distress syndrome

With a mortality rate of 46% before the onset of COVID-19, acute respiratory distress syndrome (ARDS) affected 200,000 people in the US, causing 75,000 deaths. Mortality rates in COVID-19 ARDS patients are currently at 39%. Extrapulmonary support for ARDS aims to supplement mechanical ventilation by providing life-sustaining oxygen to the patient. A new rapid-onset, human-sized pig ARDS model in a porcine intensive care unit (ICU) was developed. The pigs were nebulized intratracheally with a high dose (4 mg/kg) of the endotoxin lipopolysaccharide (LPS) over a 2 h duration to induce rapid-onset moderate-to- severe ARDS. They were then catheterized to monitor vitals and to evaluate the therapeutic effect of oxygenated microbubble (OMB) therapy delivered by intrathoracic (IT) or intraperitoneal (IP) administration. Post-LPS administration, the PaO2 value dropped below 70 mmHg, the PaO2/FiO2 ratio dropped below 200 mmHg, and the heart rate increased, indicating rapidly developing (within 4 h) moderate-to- severe ARDS with tachycardia. The SpO2 and PaO2 of these LPS-injured pigs did not show significant improvement after OMB administration, as they did in our previous studies of the therapy on small animal models of ARDS injury. Furthermore, pigs receiving OMB or saline infusions had slightly lower survival than their ARDS counterparts. The OMB administration did not induce a statistically significant or clinically relevant therapeutic effect in this model; instead, both saline and OMB infusion appeared to lower survival rates slightly. This result is significant because it contradicts positive results from our previous small animal studies and places a limit on the efficacy of such treatments for larger animals under more severe respiratory distress. While OMB did not prove efficacious in this rapid-onset ARDS pig model, it may retain potential as a novel therapy for the usual presentation of ARDS in humans, which develops and progresses over days to weeks

Oxygen Microbubbles Improve Radiotherapy Tumor Control in a Rat Fibrosarcoma Model – A Preliminary Study

Cancer affects 39.6% of Americans at some point during their lifetime. Solid tumor microenvironments are characterized by a disorganized, leaky vasculature that promotes regions of low oxygenation (hypoxia). Tumor hypoxia is a key predictor of poor treatment outcome for all radiotherapy (RT), chemotherapy and surgery procedures, and is a hallmark of metastatic potential. In particular, the radiation therapy dose needed to achieve the same tumor control probability in hypoxic tissue as in normoxic tissue can be up to 3 times higher. Even very small tumors (<2–3 mm3) comprise 10–30% of hypoxic regions in the form of chronic and/or transient hypoxia fluctuating over the course of seconds to days. We investigate the potential of recently developed lipid-stabilized oxygen microbubbles (OMBs) to improve the therapeutic ratio of RT. OMBs, but not nitrogen microbubbles (NMBs), are shown to significantly increase dissolved oxygen content when added to water in vitro and increase tumor oxygen levels in vivo in a rat fibrosarcoma model. Tumor control is significantly improved with OMB but not NMB intra-tumoral injections immediately prior to RT treatment and effect size is shown to depend on initial tumor volume on RT treatment day, as expected