100 percent O2 not best treatment anymore....

[akflightmedic]

Bare with me guys, I am still trying to locate the original article to give proper credit but for now.....enjoy.

UCLA imaging study reveals how pure oxygen harms the brain

by

It's a scenario straight out of Gray's Anatomy – a paramedic or doctor plops a mask over the face of a person struggling to breathe and begins dispensing pure oxygen.

Yet growing research suggests that inhaling straight oxygen can actually harm the brain. For the first time, a new UCLA brain-imaging study reveals why. Published in the May 22 edition of Public Library of Science (PLoS) Medicine, the findings fly in the face of national guidelines for medical practice and recommend a new approach adding carbon dioxide to the gas mix to preserve brain function in patients.

"For decades, the medical community has championed 100 percent oxygen as the gold standard for resuscitation. But no one has reported what happens inside our brains when we inhale pure oxygen," explained Ronald Harper, distinguished professor of neurobiology at the David Geffen School of Medicine at UCLA. "What we discovered adds to a compelling body of evidence for modifying a widely practiced standard of care in the United States."

Harper's team used functional magnetic resonance imaging (fMRI) to capture detailed pictures of what occurs inside the human brain during two different breathing scenarios. The technique detects subtle increases in blood flow triggered by the activation of different parts of the brain, causing these regions to glow or "light up" on the color scan.

The researchers scanned the brains of 14 healthy children, ages 8 – 15, as they inhaled 100 percent oxygen through a mouthpiece, and monitored their breathing and heart rates. After waiting eight minutes for the youngsters' breathing to return to normal, the team added 5 percent carbon dioxide to the gas mixture and repeated the scan.

A comparison of the two scans revealed dramatic differences.

"When the children inhaled pure oxygen, their breathing quickened, resulting in the rapid exhalation of carbon dioxide from their bodies," said coauthor Paul Macey, associate researcher in neurobiology. "The drop in carbon dioxide narrowed their blood vessels, preventing oxygen from reaching tissue in the brain and heart."

That's when something surprising happened on the MRI scan.

Three brain structures suddenly lit up: the hippocampus, which helps control blood pressure; the cingulate cortex, which regulates pain perception and blood pressure; and the insula, which monitors physical and emotional stress.

All this activity awakened the hypothalamus, which regulates heart rate and hormonal outflow. Activation of the hypothalamus triggered a cascade of harmful reactions and released chemicals that can injure the brain and heart.

"Several brain areas responded to 100 percent oxygen by kicking the hypothalamus into overdrive," explained Harper. "The hypothalamus overreacted by dumping a massive flood of hormones and neurotransmitters into the bloodstream. These chemicals interfere with the heart's ability to pump blood and deliver oxygen – the opposite effect you want when you're trying to resuscitate someone."

When the children inhaled the carbon dioxide-oxygen mix, the hypothalamus' hyperactivity vanished from the MRI scan.

"Adding carbon dioxide to the oxygen relaxed the blood vessels, allowed oxygen to reach the heart and brain, calmed the hypothalamus and slowed the release of dangerous chemicals," said Macey.

"Pure oxygen kindles the match that fuels a forest fire of harm to the body," said Harper. "But a little whiff of carbon dioxide makes it all go away."

Based on their findings, the researchers strongly encourage healthcare providers to add carbon dioxide to oxygen dispensation, especially when resuscitating infants or administering oxygen for more than a few minutes. The new direction could hold particular implications for patients of stroke, heart attack, carbon monoxide poisoning and any long-term oxygen therapy.

"When in doubt about a case, the current medical approach is to increase oxygen levels and wait to see if the patient improves," explained Harper. "But no one has ever scanned patients' brains to examine how they respond to oxygen therapy."

Earlier data on high oxygen's harmful effects have already resulted in policy changes overseas. Instead of using straight oxygen, many European hospitals now resuscitate patients with room air, which contains a mixture of nitrogen, oxygen and carbon dioxide; or with a blend of oxygen and carbon dioxide.

###

Mary Woo, professor at the UCLA School of Nursing, was a coauthor of the study, which was supported by the National Institute of Child Health and Development.

[JPINFV]

It doesn't look like it's really been published yet. The article cites the May edition of the Public Library of Science (PLoS) Medicine, but the website for the journal is still on the April edition. PubMed and Google Scholar searches are coming up empty.

[Dustdevil]

Bare with me guys...

Is that allowed here? :shock:

I love this article! It gives us an excuse to take one more drug away from EMT-Bs!

[JPINFV]

^

One more drug? O2 is just about the only thing Basics CAN give in my county.

[CBEMT]

Thankfully, one article does not a standard of care make.

[Dustdevil]

Despite the hyperbole in this article, this really isn't anything new or earthshaking. We were discussing this in RT school 25 years ago, and I worked with some physicians who were already mixing carbon dioxide.

The only thing really new here is that somebody finally got around to documenting the effects with an MRI. With that, I don't think the rest of the scientific and medical community will be too far behind in exploring this deeper and becoming more judicious in their use of oxygen.

And the protocol monkeys are going to be SOL when they can no longer just put 6 or 15 litres on everything without thinking about it.

[MedicNorth]

This is definitely interesting and may have some effects on what we do down the road.

I am curious as to why the subjects were all children <16. If they are making blanket statements such as those in the study, it would be better to include data with subjects in the young adult, middle aged, and geriatric categories as well. There may be no difference, but if they are touting this study as one that may change standards, a broader base should be involved.

[Just Plain Ruff]

correct me if I'm wrong but aren't kids more susceptible and more receptive to these types of changes? don't they show the results of this type of study more readily than older humans?

I think this is a great study, more will need to be done but it seems that some evidence has been shown here that will make progressive and forward thinking physicians, especially medical directors of EMS services, begin to question how their crews treat their patients?

If this reduces mortality and morbidity then the cost of retrofitting the many thousands of ambulances and emergency rooms in this country would be worth the effort.

I do agree that until this is studied in a more varied age group and the results are similar to the peds age group then the study will be just as limited as the protocols and treatment guidelines that will derive from it.

[VentMedic]

Right DustDevil, RT has been using CO2 for about 25 years for various applications. Rescusitation though we have just monitored our rate frequency to keep CO2 levels normal and not blow off CO2. We've also no longer doing the profound hyperventilation for head trauma. Of course in the hospital we have blood gases and if ETCO2 is used, we have correlated the ABGs to the monitors and noted any discreptencies. We also have the ability to monitor oximetry and BG values from the SjVO2 and A-lines to titrate O2 as needed to keep in a 80 - 110 mmHG PaO2 range. The pulse-ox will probably say 99 - 100% for any or all the values depending on Hb.

Medically mixed gases are expensive and not as easy to get as one might thing. The US medical system will have a problem with this unfortunately. Even Nitric Oxide is scrutinized under cost containment and Flolan is used instead in many hospitals. Pulmonary Labs have difficult times ordering their mixes and ensuring delivery of "certified" medical mix gases.

In neonates there are some new guidelines in the delivery room for 21% O2 rescusitation.

http://www.hopkinscme.org/ofp/eneonatalrev...tters/1206.html

This study was done on healthy children with no lung function impairment. If there is a disease process, chronic or acute as it may present in pre-hospital, to cause significant V/Q mismatching, the results probably would not be the same.

[JakeEMTP]

I was wondering the same thing as MedicNorth. :? Why was the test group all <16y/o?

A question for all providers using CPAP. We just recently started using it and have had the opportunity to use it twice. Is the sort of case stated in the article a good prerequisite for CPAP? I mean. instead of giving 6 lpm or 15 lpm, with CPAP as providers we can adjust the rate of O2 and the pressure of which it flows.. It also sounds like a Venturi mask may need to make a comeback.