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.

Dissolved oxygen technologies as a novel strategy for non-healing wounds: A critical review

Non-healing wounds are steadily becoming a global-health issue. Prolonged hypoxia propagates wound chronicity; yet, oxygenating treatments are considered inadequate to date. Dissolved oxygen (DO) in aqueous solutions introduces a novel approach to enhanced wound oxygenation, and is robustly evaluated for clinical applications. A systematic literature search was conducted, whereby experimental and clinical studies of DO technologies were categorized per engineering approach. Technical principles, methodology, endpoints and outcomes were analysed for both oxygenating and healing effects. Forty articles meeting our inclusion criteria were grouped as follows: DO solutions (17), oxygen (O₂ ) dressings (9), O₂ hydrogels (11) and O₂ emulsions (3). All technologies improved wound oxygenation, each to a variable degree. They also achieved at least one statistically significant outcome related to wound healing, mainly in epithelialization, angiogenesis and collagen synthesis. Scarcity in clinical data and methodological variability precluded quantitative comparisons among the biotechnologies studied. DO technologies warrantee further evaluation for wound oxygenation in the clinical setting. Standardised methodologies and targeted research questions are pivotal to facilitate global integration in healthcare.

Treatment of a Rat Model of LPS-Induced ARDS via Peritoneal Perfusion of Oxygen Microbubbles

Acute respiratory distress syndrome (ARDS) is a serious respiratory condition that occurs in approximately 10% of patients entering intensive care units around the world, affecting nearly 190,000 patients annually in the United States. Owing to the severity of the condition, conventional methods of oxygenation are often insufficient. However, current alternate methods of oxygenation are associated with contraindications and a mortality rate near 50%. Therefore, a need exists for a safer and more effective method of oxygenation for patients with ARDS. In this work, the feasibility of using intraperitoneal perfusions of oxygen microbubbles-peritoneal microbubble oxygenation (PMO)-to treat lipopolysaccharide-induced ARDS was explored with the objective of showing restoration of normoxic conditions after a single bolus infusion of oxygen microbubbles. Male Wistar rats induced with ARDS via lipopolysaccharide inhalation were treated with PMO at 12-h intervals over a period of 48 h. Their physiological responses were monitored throughout the study, after which necropsy was performed. Response data were then compared with saline control and untreated groups. We conclude that rats experiencing moderate to severe ARDS that were treated with PMO experienced a survival rate 37% higher than animals not given treatment and exhibited increased peripheral blood oxygen saturation when compared with untreated and saline-treated groups. Moreover, those treated with PMO experienced a lower lung wet/dry ratio and less severe lung pathology, indicating a surprising improvement in lung health. Overall, this study demonstrates the ability of PMO to deliver life-sustaining supplemental oxygen to rats suffering from ARDS and warrants further work toward clinical translation.