UHP is used as an oxidizer and disinfectant in the cosmetic and pharmaceutical industry, and, along with percarbonate, often appears in teeth whitening formulations. The hydrogen peroxide is then available to decompose to oxygen and water, and its rate of decomposition can be accelerated by various catalysts.
UHP is also moderately hygroscopic and must be stored in air-tight containers. The oxygen yield from UHP is substantial, with an oxygen delivery equivalence of 0. That is, UHP delivers The stinging is caused by the release and absorption of peroxide into the skin and subcutaneous reaction with catalase.
One utilizes sodium percarbonate and one utilizes UHP. In general, both offer similar advantages and disadvantages over the other chemistries described. The amount and rate of oxygen produced are generally determined by the amount of the peroxide species used.
If reacted freely, both reactions are also exothermic to a degree that could be hazardous. Mitigation of the heat produced is possible either through insulation, the use of additional water, or the use of additional chemistries, which absorb some of the heat produced.
Thus, if not carefully designed either from a mechanical housing or chemical engineering aspect, the above peroxide reactions could run unchecked, producing dangerous levels of heat and even poisoning the catalyst, causing the reaction to stop.
Unfortunately, the engineering factors required to safely control the reaction and produce sufficient oxygen flows come with a weight and size cost that are above those of the candle and KOH technologies.
We have taken a novel approach of pressing 23 mm diameter tablets made from these peroxide species. These large tablets dissolve slowly in a catalyst-containing aqueous reaction mixture, similar to the dissolution of a throat lozenge in the mouth, and present a reasonably constant surface area during the reaction.
The slowdown in rate that would otherwise accompany the eventual loss of surface is offset by controllably ramping the temperature, which increases the rate. This strategy allows for a high level of precision in the release and reaction of the H 2 O 2 to the point that near zero order release of oxygen is possible for the duration of the device's use. Because the solubility of urea increases linearly with temperature, the amount of cooling from urea dissolution increases as the device temperature rises.
Likewise, the rate of heat transfer to the surroundings increases as the internal temperature rises and the thermal gradient to the outside increases. Figure 1 illustrates the approach and kinetics of the chemical engineering behind the design. We measure the release of oxygen gravimetrically and numerically differentiate the data to determine a volumetric flow rate. Again, various formulations can be produced, which create almost any desired flow rate.
Lozenge type tablet creation of urea-hydrogen peroxide, allowing for slow dissolution and production of oxygen. The solid line in the upper graph represents perfect zero order production of oxygen.
The dotted line in the upper graph demonstrates real-time production of oxygen close to zero order kinetics. Such systems could even be envisioned to be used to supply supplemental oxygen to patients undergoing mechanical ventilation. The need to consider these types of approaches may be necessary in the event of pandemics such as avian flu, where use of mechanical ventilation without supplemental oxygen may have limited utility, and when ventilator use of such magnitude may overwhelm a hospital's usual ability to supply oxygen.
The typical large H cylinder contains approximately 7, L of oxygen. As indicated earlier, attempts to provide systemic oxygenation with H 2 O 2 have been tested by infusing H 2 O 2 into the intestines, including the large bowel. While it may be impractical to provide substantial systemic oxygenation via intraluminal bowel oxygenation, the use of intraluminal bowel oxygenation may have other important benefits.
The splanchnic bed liver and intestines accounts for over one third of the body's oxygen utilization. This vascular architecture makes the villi especially prone to ischemia, resulting in translocation of intestinal mediators into the systemic circulation.
The intraluminal microvascular surface area is immense and matched only by that of the lung. By providing an intraluminal source of oxygen to the villi and its vasculature, it should be possible to spare the intestines and even the liver which receives half of its blood supply by the portal vein emptying the intestines from severe tissue hypoxia.
Intraluminal oxygenation has been shown to significantly decrease intestinal permeability and necrosis from ischemia. Instillation of simple gaseous oxygen would seem to be an easy solution, but presents delivery challenges in terms of developing an apparatus for precise delivery and ensuring delivery through all parts of the intestines.
Simply dripping H 2 O 2 into the intestines, which also would appear to be easy, will likely produce too much O 2 in the proximal portions or large bowel if delivered rectally. A potentially better strategy may be to develop an H 2 O 2 delivery system that will allow for a controlled release of O 2 as the H 2 O 2 traverses the length of the intestines Fig.
Representation of sustained release strategy of intestinal H 2 O 2 delivery and oxygen production vehicle. We have produced several early prototype methods to control for the release of H 2 O 2. One such system utilizes mesoporous silica particles, which exhibit low densities and high surface areas, as a result of the network of well defined nano-channels that emanate from the core to the outer surface of the particles.
In recent years, extensive efforts have been dedicated to incorporating drugs in mesoporous silica to achieve controlled delivery rates. Some of the drugs successfully loaded into silica particles include ibuprofen and others.
To mitigate the release rate of H 2 O 2 , palmitic acid is tethered to the surface of the free flowing silica particles and then suspended in olive oil with SPAN 80 to create a stable emulsion. In both cases the polar H 2 O 2 -rich particles are surrounded by non-polar alkyl tails and non-polar oil that acts as a barrier for the release of H 2 O 2 , since the solubility of H 2 O 2 in a non-polar phase is very low Fig. Scanning electron micrographs of H 2 O 2 loaded mesoporous silica particles tethered with palmitic acid.
Figure 4 shows the temporal evolution of O 2 from the H 2 O 2 that has diffused from loaded silica particles. The general idea is to provide a slow release of H 2 O 2 and thus continuous oxygen as the mixture makes its way through the gastrointestinal tract. We have tested this approach in animals swine made systemically hypoxemic by reducing the F IO 2 from 0.
Figure 5 demonstrates the intestinal wall P O 2 levels, systemic P O 2 , and mixed venous oxygen saturation in animals at baseline, during hypoxemia, and during hypoxemia after receiving a single intestinal mL bolus of the H 2 O 2 silica particle emulsion.
Measurements of the serosal intestinal wall P O 2 levels over the length of the small and large bowel showed return of P O 2 levels above critical ischemic levels.
The intraluminal P O 2 levels should be substantially higher. While not shown, liver P O 2 levels were also elevated above ischemic levels, indicating oxygen uptake from the portal vein.
While mixed venous oxygen saturations and P aO 2 levels were not elevated, it may be possible to do this with higher concentrations of loaded particles. The results, at the very least, indicate the strategy may be one that benefits operative and postoperative patients, and may reduce splanchnic ischemia leading to multi-organ failure.
No evidence of systemic toxicity was evident, and the intestinal pressures did not exceed 10 cm H 2 O. Release profile of H 2 O 2 loaded mesoporous silica particles tethered with palmitic acid and emulsified in olive oil, demonstrating delayed and prolonged release in a water solution saturated with catalase.
Use of such strategies overcomes the inherent limitations of blood flow cardiac output or regional flow as a part of the DO 2 equation above.
By supporting an organ system, such as the splanchnic bed in this case, it may be possible to enhance systemic recovery while avoiding additional organ failure. If provided with enough oxygen, it may be possible to create oxygen reserves as there would be less systemic oxygen utilization by the splanchnic bed , which may become even more valuable in the setting where substantial lung injury concomitantly exists.
Similar strategies using the topical application of oxygen to wounds and burns when edema and damaged vasculature impede traditional oxygen delivery to the tissues may be of value. As discussed earlier, intravenous and intra-arterial H 2 O 2 have been given to humans with some measure of success. However, the lack of its widespread reported use over the last 40 years, indicates that safety is a major factor.
Again, major challenges facing the use of intravascular H 2 O 2 include the rate at which oxygen is produced in relation to how quickly it can be kept in solution in plasma. Rates of reaction are thus key. Its use as an adjunct in the treatment of stroke and myocardial infarction could even be entertained. We have proposed and are working toward solutions to the challenges preventing safe usage of intravascular H 2 O 2.
In regards to rate control, we are working toward various methods of H 2 O 2 encapsulation that would provide for controlled release of H 2 O 2 over time, so as not to overwhelm the ability of catalase to convert H 2 O 2 to oxygen and water, as well as to keep oxygen levels from exceeding plasma solubility.
This strategy requires high-level knowledge of water transport across biomaterials, which must be coupled with knowledge of blood flow and tissue oxygen consumption.
Figure 6 demonstrates one such strategy. This approach attempts to microencapsulate the solid urea-H 2 O 2 adduct in a biocompatible and water permeable coating of poly lactic-co-glycolic acid PLGA. While the urea-H 2 O 2 is split by water, this would be impeded by loading the capsule with a hydrophobic material such as a perfluorocarbon.
The advantage of microencapsulation and controlled release is that H 2 O 2 would be released and converted to oxygen throughout the circulation. This is opposed to direct delivery of H 2 O 2 intravenously or intra-arterially, which basically would immediately react within seconds. Current working strategy of producing intravenous H 2 O 2 delivery platform for intravenous oxygen production.
Urea-hydrogen peroxide UHP and a hydrophobic carrier such as perfluorodecalin are encapsulated in a water permeable biocompatible coating such as poly lactic-co-glycolic acid PLGA. The combination controls water entry into the microcapsule, allowing spitting of the urea-hydrogen peroxide UHP adduct into urea and H 2 O 2 , where H 2 O 2 then leaves the capsule, making contact with catalase, where it is broken down into water and oxygen. In regard to further optimizing H 2 O 2 produced oxygen dissolution into plasma, concomitant use of compounds such as intravenous perfluorocarbons should enhance the solubility of oxygen in plasma, given their ability to carry nonpolar gases in substantially greater concentrations over 5 volume percentage of oxygen than plasma.
The combination of these techniques, while complex, shows some promise in closed circuit experimental chambers. Since encapsulation coating thicknesses as well as the UHP loading of the microcapsules can be varied, different delivery profiles are theoretically possible that may allow for a single bolus of H 2 O 2 to provide for prolonged oxygen production capable of matching some portion of oxygen consumption Fig.
This controlled delivery and release of H 2 O 2 with such a vehicle could theoretically create oxygen at a rate commensurate with consumption. Its creation throughout the vasculature would ensure that hemoglobin is continually saturated, with excess oxygen being dissolved in a circulating perfluorocarbon.
It is particularly exciting to consider its production at the microcirculatory level, including capillaries and venules, which would help ensure that tissues are oxygenated despite areas that may be experiencing critical reductions in microvascular flow.
Substantial additional engineering and biomaterials work is required before this strategy can be tested. Concerns, of course, will exist regarding the downstream potential free radical effects and tissue injury with such a strategy. The choice to use an oxygenation rescue that incorporates H 2 O 2 , may depend on the urgency of the clinical situation. Changing the loading of urea-hydrogen peroxide particles, size of microsphere, and thickness of capsule coating in Figure 6 will result in various release profiles of H 2 O 2 from the microcapsule and thus oxygen production profiles.
On-site chemically produced oxygen for human utilization is not new and has been experimented with for close to a century. However, its safe and ubiquitous use in healthcare is not yet realized. We have reviewed its use for breathable oxygen as well as its delivery as an intravascular and gastrointestinal agent to treat systemic and regional hypoxemia. A unique knowledge of chemistry, engineering, and physiology will be required to consider, optimize, and deal with the various challenges that could make chemically produced oxygen a valuable asset in emergency care.
Now, how long you could make it run, I'm not sure, but peroxides have been looked at to use in membrane oxygenation when there's not gas around to do bypass. I'd love to see that happen. John Heffner's historical report noted that the early pioneers in oxygen manufactured O 2 by electrolysis. Not until there's a huge leap in cathode technology.
The thing is the fouling of the anode and cathode, and that's something the electrochemists have not been able to solve. The system has to be so pure. However, the amount of O 2 that can be released with the catalysis of water is huge.
That would be the ultimate answer for storing O 2. But the electrochemistry challenges for that are extraordinary. Kevin, because the dry chemistry basically lasts forever, have you looked at larger systems that you could drive in after a disaster and set up and start creating oxygen?
We would love to see that happen, but you'll never reach the efficiency of the concentrator if you have electricity or liquid O 2 systems if there is no supply problem. There's always some price to pay for the dry chemistry. To make the dry chemistry safe you'd have to probably use the percarbonates. Candle chemistry is not the answer. The candle chemistry is attractive because it's the most efficient solid, in terms of making the most O 2 per weight. The problem is how it's made with that temperature.
If you had a big block the size of this room, you could make a heck of a lot of O 2. The issue would be insulating it and making sure you don't melt down to the middle of the earth. Its attractive that the stuff doesn't break down and you can keep it for a really long time, but controlling the rate of reaction, coupled with the fact that you can't turn it on and off, is problematic.
Once you start these solid peroxides into action, that's a problem. That's why I like the idea of converting usable solids into a liquid that then can be metered into a system as needed.
We've tested some of these things for the military special ops community. Sometimes they take them not to deliver O 2 but just to warm up their hands. One of them was advertised to help mitigate heat loss during shock. And storage is an issue. This would be especially true for any military application. I think it's important that, for some reason, the O 2 in airplanes is considered emergency O 2 and is not governed by the FDA. And some people have made these devices thinking they aren't governed by the FDA either, and I think those people have made the wrong assumption.
In a disaster scenario, particularly in a cold weather situation where you don't have electricity, could the heat have a useful purpose outside of O 2 delivery? There's a whole science of heat transfer. You could use the heat to boil water to make steam and run something. The issue would be getting the investment for somebody to create that sort of infrastructure to make it happen. The cost and lead times may be a bit perilous.
Certainly, if you're going to create a system like that to use, you'd want to leverage every bit of the chemistry you can for the common good. The authors have disclosed relationships with Virginia Commonwealth University and GetO 2 , which have patents on products discussed herein. NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail.
We do not capture any email address. Skip to main content. Research Article Conference Proceedings. Kevin R Ward. Huvard Research and Consulting, Chesterfield, Virginia. GetO Inc, Sanford, Connecticut. Abstract While pressurized oxygen in tank form, as well as oxygen concentrators, are ubiquitous in civilian healthcare in developed countries for medical use, there are a number of settings where use of these oxygen delivery platforms is problematic.
Introduction Oxygen is essential for life, having its main role at the cellular level, where it is used by the mitochondria during oxidative phosphorylation to produce adenosine triphosphate, which is essential for the myriad of metabolic processes that keep us alive. These include: Use of oxygen in emergencies in austere environments.
Chemically Produced Oxygen Chemical oxygen production and delivery, in several forms, has been experimented with since the early s. Current Examples of Chemical Oxygen Generation A little appreciated but ubiquitous application of chemical oxygen generation exists in the airline industry. Newer Evolution to Older Approaches Chemical Oxygen Generators While the mainstay of chemical oxygen generation for individual use has resided in the airline and mining industries, as outlined above, there has been a desire to revise or re-engineer various facets of stored oxygen chemistry and hardware design to produce small, portable, lightweight, and safe chemical oxygen generators COGs.
Three main options exist for creation of COGs. These include: Adaption of candle technology, as described earlier. Alternative Chemical Delivery Methods Splanchnic Oxygenation As indicated earlier, attempts to provide systemic oxygenation with H 2 O 2 have been tested by infusing H 2 O 2 into the intestines, including the large bowel.
Intravenous Chemical Oxygenation Revisited As discussed earlier, intravenous and intra-arterial H 2 O 2 have been given to humans with some measure of success. Summary On-site chemically produced oxygen for human utilization is not new and has been experimented with for close to a century. Kevin Ward: Yes. Jeff Ward: John Heffner's historical report noted that the early pioneers in oxygen manufactured O 2 by electrolysis.
Kevin Ward: Not until there's a huge leap in cathode technology. Branson: Kevin, because the dry chemistry basically lasts forever, have you looked at larger systems that you could drive in after a disaster and set up and start creating oxygen? Kevin Ward: We would love to see that happen, but you'll never reach the efficiency of the concentrator if you have electricity or liquid O 2 systems if there is no supply problem.
Branson: We've tested some of these things for the military special ops community. Kevin Ward: One of them was advertised to help mitigate heat loss during shock. Branson: I think it's important that, for some reason, the O 2 in airplanes is considered emergency O 2 and is not governed by the FDA. Kallet: In a disaster scenario, particularly in a cold weather situation where you don't have electricity, could the heat have a useful purpose outside of O 2 delivery? Kevin Ward: Sure. References 1.
Monitoring of oxygen transport and oxygen consumption. In: Tobin MJ , editor. Principles and practice of intensive care. New York : McGraw-Hill ; : - Assessing shock resuscitation strategies by oxygen debt repayment.
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Gas embolism produced by hydrogen peroxide abscess irrigation in an infant. Anaesth Intensive Care ; 27 4 : - Cardiac arrest following the use of hydrogen peroxide during arthroplasty. J Arthroplasty ; 4 4 : - Hydrogen peroxide poisoning. Toxicol Rev ; 23 1 : 51 - Intraperitoneal oxygenation.
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One can collect this Oxygen gas produced over water through water-displacement and store it inside a bottle for later use. A far less sophisticated reaction vessel will still work if the above pieces of glassware are not available. In the above set up, the flow of Hydrogen Peroxide down from the addition funnel into the flat-bottom flask can be controlled via a stop-cock, so more H 2 O 2 may be added as needed and some degree of control over the reaction can be achieved. The gas flowing out of the reaction vessel through the attached rubber hose will be forced down beneath the water in the water-filled bowl.
When the gas reaches the end of the tubing it will bubble out and float upward. An inverted, water-filled, bottle is positioned above the end of the tube will collects the gas bubbles.
To aid in the collection of gas bubbles, one might consider using a small funnel placed in the mouth of the bottle. It is important to always keep the mouth of the inverted bottle below the water level in order to prevent the water from draining out and sucking air inside. As the gas bubbles accumulate at the top of the bottle they force the water out the bottom. If allowed to continue, the gas will eventually fill the entire bottle and all the water originally inside will be pushed out into the bowl.
When the Oxygen generating reaction is complete, while keeping the mouth of the bottle submerged, reach under the water and screw the lid on. As the Oxygen production reaction starts, the gas flowing out of the reaction vessel will be mostly air presuming the flask was initially filled with air.
The amount of water vapor contained in the collected gas depends on the temperature which, in turn, determines the vapor pressure of water. To minimize water vapor in the collected gas, one should use a cool collection bath. Additionally, one may pass the gas through a drying tube filled with a deliquescent material such as Calcium Chloride before use. This method of production is very similar in many respects to the first method. The difference between the two is the chemicals involved in the process.
The reaction may be performed in an identical apparatus to the first method and, again, the Oxygen gas produced may be collected over water for later use. The only other products of the reaction are "salt" Sodium Chloride and water.
The same set-up was used for the second method as was used for the first method of Oxygen production. For the second method, the addition funnel becomes much more important to dispense the liquids since the reaction proceeds very quickly once the H 2 O 2 and bleach are mixed. A magnetic stirrer and stir bar was added to help mix the two liquids inside the flask, but the process will still work very well without one.
In the first method, one did not necessarily have a maximum amount of Oxygen which could be generated; one could always add more Hydrogen Peroxide to the reaction vessel until the flask became full where the H 2 O 2 would be decomposed into water and Oxygen gas.
However, in the second method, the amount of Oxygen gas which may be produced is constrained by the limiting reagent which will be, in practice, the reactant initially placed in the flask.
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