Peritoneal perfusion with oxygenated perfluorocarbon augments systemic oxygenation

Perfluorocarbons in Research and Clinical Practice: A Narrative Review

Perfluorocarbons (PFCs) are organic liquids derived from hydrocarbons in which some of the hydrogen atoms have been replaced by fluorine atoms. They are chemically and biologically inert substances with a good safety profile. They are stable at room temperature, easy to store, and immiscible in water. Perfluorocarbons have been studied in biomedical research since 1960 for their unique properties as oxygen carriers. In particular, PFCs have been used for liquid ventilation in unusual environments such as deep-sea diving and simulations of zero gravity, and more recently for drug delivery and diagnostic imaging. Additionally, when delivered as emulsions, PFCs have been used as red blood cell substitutes. This narrative review will discuss the multifaceted utilization of PFCs in therapeutics, diagnostics, and research. We will specifically emphasize the potential role of PFCs as red blood cell substitutes, as airway mechanotransducers during artificial placenta procedures, as a means to improve donor organ perfusion during the ex vivo assessment, and as an adjunct in cancer therapies because of their ability to reduce local tissue hypoxia.

Enteral liquid ventilation oxygenates a hypoxic pig model

The potential of extrapulmonary ventilation pathways remains largely unexplored. Here, we assessed the enteral ventilation approach in hypoxic porcine models under controlled mechanical ventilation. 20 mL/kg of oxygenated perfluorodecalin (O₂-PFD) was intra-anally delivered by a rectal tube. We simultaneously monitored arterial and pulmonary arterial blood gases every 2 min up to 30 min to determine the gut-mediated systemic and venous oxygenation kinetics. Intrarectal O₂-PFD administration significantly increased the partial pressure of oxygen in arterial blood from 54.5 ± 6.4 to 61.1 ± 6.2 mmHg (mean ± SD) and reduced the partial pressure of carbon dioxide from 38.0 ± 5.6 to 34.4 ± 5.9 mmHg. Early oxygen transfer dynamics inversely correlate with baseline oxygenation status. SvO₂ dynamic monitoring data indicated that oxygenation likely originated from the venous outflow of the broad segment of large intestine including the inferior mesenteric vein route. Enteral ventilation pathway offers an effective means for systemic oxygenation, thus warranting further clinical development.

Peritoneal Oxygenation as a Novel Technique for Extrapulmonary Ventilation; A Review and Discussion of the Literature

The COVID-19 crisis has highlighted the difficulties that might occur when attempting to oxygenate patients who have suffered a severe pulmonary insult, including in the development of acute respiratory distress syndrome (ARDS). Traditional mechanical ventilation (MV) is effective; however, in severe cases of hypoxia, the use of rescue therapy, such as extracorporeal membrane oxygenation (ECMO), may be required but is also associated with significant complexity and complications. In this review, we describe peritoneal oxygenation; a method of oxygenation that exploits the peritoneum's gas exchange properties in a fashion that is similar to peritoneal dialysis and has shown considerable promise in animal models. We have conducted a review of the available literature and techniques, including intraperitoneal perfluorocarbons, intraperitoneal jet ventilation, a continuous low-pressure oxygen system (PEROX) and the use of phospholipid-coated oxygen microbubbles (OMBs) through peritoneal microbubble oxygenation (PMO). We conclude that peritoneal oxygenation is a promising technique that warrants further investigation and might be used in clinical settings in the future.

Systemic oxygen delivery by peritoneal perfusion of oxygen microbubbles

Severe hypoxemia refractory to pulmonary mechanical ventilation remains life-threatening in critically ill patients. Peritoneal ventilation has long been desired for extrapulmonary oxygenation owing to easy access of the peritoneal cavity for catheterization and the relative safety compared to an extracorporeal circuit. Unfortunately, prior attempts involving direct oxygen ventilation or aqueous perfusates of fluorocarbons or hemoglobin carriers have failed, leading many researchers to abandon the method. We attribute these prior failures to limited mass transfer of oxygen to the peritoneum and have designed an oxygen formulation that overcomes this limitation. Using phospholipid-coated oxygen microbubbles (OMBs), we demonstrate 100% survival for rats experiencing acute lung trauma to at least 2 h. In contrast, all untreated rats and rats treated with peritoneal oxygenated saline died within 30 min. For rats treated with OMBs, hemoglobin saturation and heart rate were at normal levels over the 2-h timeframe. Peritoneal oxygenation with OMBs was therefore shown to be safe and effective, and the method requires less equipment and technical expertise than initiating and maintaining an extracorporeal circuit. Further translation of peritoneal oxygenation with OMBs may provide therapy for acute respiratory distress syndrome arising from trauma, sepsis, pneumonia, aspiration, burns and other pulmonary diseases.

Effect of transpleural perfusion with oxygenated perfluorocarbon in a rat model of acute lung injury

BACKGROUND

Despite advances in critical care, more effective methods of systemic oxygenation in patients with acute lung injury or acute respiratory distress syndrome are needed. The goal of this study was to determine if it is possible to increase systemic oxygenation by transpleural perfusion with oxygenated perfluorocarbon in animals with induced acute lung injury.

METHODS

Eighteen Sprague-Dawley rats were intubated, and acute lung injury was induced by aspiration of 0.1N HCl (1 mL/kg) through the tracheal tube. Inflow and outflow tubes were placed in the thoracic cavity and connected to a perfusion circuit containing a roller pump, warmer, and oxygenator. Rats in group I were not treated after aspiration of HCl, those in group II were perfused with oxygenated saline, and those in group III were perfused with oxygenated perfluorocarbon. Arterial blood gases were collected every 30 minutes for 180 minutes. At the last step of the experiments, pathological examination of the lungs and parietal pleura was performed.

RESULTS

PaO(2) in group III was significantly higher than that in group I or II. PaCO(2) in group III was significantly lower than that in the other two groups. Histological examination showed relatively well-delineated zones of inflammation-free coagulative necrosis of lung parenchyma in all groups.

CONCLUSIONS

Transpleural perfusion with oxygenated perfluorocarbon in an animal model of induced acute lung injury resulted in a significant increase in systemic oxygenation and depletion of systemic carbon dioxide, and might be a useful method for improving systemic oxygenation in patients with acute lung injury.

Efficacy of peritoneal oxygenation using a novel artificial oxygen carrier (TRM-645) in a rat respiratory insufficiency model

PURPOSE

Supplemental oxygenation is essentially important in critically ill patients with potentially reversible pulmonary insufficiency. An extracorporeal membrane oxygenator and percutaneous cardiopulmonary support have been used for these patients. However, these techniques are associated with so many complications that an additional new therapeutic modality is required. The purpose is to investigate if the peritoneal cavity can be used as "extrapulmonary respiration" that is analogous to peritoneal dialysis and utilizes the efficacy of liposome-encapsulated hemoglobin (artificial oxygen carrier; TRM-645).

METHODS

Rats weighing an average of 300 g (n = 18) received an incision in the right chest to generate pneumothorax, which resulted in severe and lethal hypoxia. Oxygenated TRM-645 and human red blood cells (MAP group) were administered into the peritoneum in the experimental rats' pneumothorax model. No treatment except the right pneumothorax was administered to the sham group.

RESULTS

Survival times from the pneumothorax were significantly longer in the TRM-645 and MAP groups than in the sham group (32.0 +/- 6.9 and 22.0 +/- 4.9 min vs 9.2 +/- 1.9 min, P < 0.01). In addition, an arterial blood gas analysis showed that the oxygenation in levels significantly improved.

CONCLUSIONS

The abdomen (peritoneum) can potentially become an "artificial lung" that can be employed in critical care settings. TRM-645 provides an alternative to the use of washed human red blood cells.