Scientists have been able to keep rabbits alive for up to 15 minutes after their windpipes had been blocked by injecting microparticles (yellow in the image below) containing oxygen into their bloodstream. These microparticles are able to deliver the life-saving oxygen directly to red blood cells allowing the animals to survive with normal blood pressure and heart rates in the absence of the ability to inhale. Moreover, there was no evidence of heart, lung or liver damage from oxygen deprivation.
The problem with injecting oxygen bubbles has been coalescence of the smaller bubbles into larger ones blocking blood flow. Liquid oxygen is also a problem because it needs to be injected at low temperatures. The microparticles developed by Dr. John Kheir (Department of Cardiology, Children's Hospital Boston, Harvard Medical School) and his colleagues are comprised of a lipid "shell" surrounding a bubble of oxygen gas. This structure helps to prevent the formation of larger oxygen bubbles. Moreover, the microparticles are able to transfer the oxygen to red blood cells within seconds. As the oxygen diffuses out of the microparticle, the lipid shell breaks down so the body can absorb the lipid waste.
This technology has the potential to save the lives of many people suffering from acute obstructed breathing. It would not be useful for people with chronic obstructions since the microparticles break down in the blood. But it would be useful in an emergency situation until help arrived. Another bonus: According to Dr. Kheir, the microparticles are easy and cheap to produce. Although I wonder if people are now going to need phlebotomy training in their CPR courses to be able to inject these microparticles. I also wonder how long they would stay intact if left in a syringe in an emergency kit.
Considering the animals were also unable to exhale due to the obstruction, the real limitation of this new treatment may be the build up of carbon dioxide in the body creating an acidic environment. Maybe researchers now need to focus their attention on how to mop up carbon dioxide in the absence of breathing. The hypothetical ability to combine the two may just prolong life even longer in an emergency situation.
What are your thoughts?
Sources:
Science Translational Medicine
Image from: D. Kunkel/Dennis Kunkel Microscopy, Inc.; D. Bell/Harvard University; J. Kheir/Children’s Hospital Boston; C. Porter/Chris Porter Illustration
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I'm very grateful to you for posting this info. Years ago I worked in the donor center at Naval Hospital San Diego. I very much enjoyed the work and my training gave me a large appreciation for the complexity and intricacies of the circulatory system and erythropoesis. Unfortunately, I was unable to continue my formal training. But, solutions such as this and the development of synthetic RBC's has been something on my mind for a couple of decades. At the time of my training and work experience, HIV although not new greatly effected our ability to simply take in new donors. Of course HPV, HepC as well as HIV continue to effect our ability to harvest greater supplies of usable blood products. Synthetic responses would not only eliminate disease, but other transfusion incompatibilities as well. This solution, although not a volume replacement or even an RBC replacement would allow for more time in emergency situations for crossmatches to be performed and increases the chance of patient survival.
This could be a big leap forward for trauma care, so I am excited, but cautious. As you mentioned, CO2 accumulation is indeed a problem which the rapid O2 uptake, but if utilized in humans the article mentions the extra volume added by the lipid layer would circulate through the blood but would not immediately be broken down. If these microparticles need to be administered over a longer period of time not only does the CO2 but also this lipid layer needs to be managed. As to how long it could last in a syringe, it currently begins degrading within 2 weeks at their sub-body heat temperature, but they believe this can be fixed. Looking forward to seeing this develop.
The most immediate application I can think of for this would be severe asthma attacks. Something like this could make the difference between life and death for a young person in the midst of an uncontrollable attack, until the attack wears off.