High-flow oxygen may be on its way out...

[spenac]

Dr Bledsoe posted the following on another site.

Resuscitation technique after brain injury may do more harm than good

Published: Tuesday, July 1, 2008 - 09:22 in Health & Medicine

UT Southwestern Medical Center

The current standard practice of giving infants and children 100 percent

oxygen to prevent brain damage caused by oxygen deprivation may actually

inflict additional harm, researchers at UT Southwestern Medical Center have

found. Brain damage caused by oxygen deprivation, known as hypoxic-ischemic

brain injury, is one of the most common causes of death and long-term

neurological damage among infants and children. This can happen during birth

trauma, near drowning and other crises.

The UT Southwestern researchers found that mice treated with less than a

minute of 100 percent oxygen after a hypoxic-ischemic brain injury suffered

far greater rates of brain-cell death and coordination problems similar to

cerebral palsy than those allowed to recover with room air.

"This study suggests 100 percent oxygen resuscitation may further damage an

already compromised brain," said Dr. Steven Kernie, associate professor of

pediatrics and developmental biology and senior author of the study, which

appears in the July issue of the Journal of Cerebral Blood Flow &

Metabolism.

Most of the damage involved cells that create myelin, a fatty substance that

insulates nerve cells and allows them to transmit electrical signals quickly

and efficiently. Infants have much less myelin than adults; as myelin

develops in children they become more coordinated. Areas of the brain with

dense areas of myelin appear white, hence the term "white matter."

"Patients with white-matter injuries develop defects that often result in

cerebral palsy and motor deficits," Dr. Kernie said.

Myelin comes from cells called glial cells, or glia, which reach out and

wrap part of their fatty membranes around the extensions of nerve cells that

pass electrical signals. The brain creates and renews its population of

glial cells from a pool of immature cells that can develop into mature glia.

In their study, the researchers briefly deprived mice of oxygen, then gave

them either 100 percent oxygen or room air, which contains about 21 percent

oxygen, 78 percent nitrogen and 1 percent other gases.

After 72 hours, mice given 100 percent oxygen fared worse than those given

room air. For example, they experienced a more disrupted pattern of

myelination and developed a motor deficit that mimicked cerebral palsy.

The population of immature glial cells also diminished, suggesting that the

animals would have trouble replacing the myelin in the long term.

"We wanted to determine whether recovery in 100 percent oxygen after this

sort of brain injury would exacerbate neuronal injury and impair functional

recovery, and in these animals, it did impair recovery," Dr. Kernie said.

"Our research shows even brief exposure to 100 percent oxygen during

resuscitation actually worsens white-matter injuries."

Dr. Kernie said adding pure oxygen to the damaged brain increases a process

called oxidative stress, caused by the formation of highly reactive

molecules. The researchers found, however, that administering an

antioxidant, which halts the harmful oxidation process, reversed the damage

in the mice given 100 percent oxygen.

"Further research is needed to determine the best possible concentration of

oxygen to use for optimal recovery and to limit secondary brain injury," Dr.

Kernie said. "Research is now being done to determine the best way to

monitor this sort of brain damage in humans so we can understand how it

correlates to the mouse models. There are many emerging noninvasive

technologies that can monitor the brain."

[rock_shoes]

Very interesting article. The research that will be required to properly investigate findings like this will be long and arduous but I suspect very worthwhile. I always had my trepidations about just throwing people on high-flow without thinking about it. I guess I was right to have some concern.

[mshow00]

On a side note to the argument made by the article, my medical control doctor has received a grant to explore the little researched affects of high-flow to ICP. Some possible changes in the years to come.

[reaper]

In a system I used to work for, the MD had protocols for strokes or head injury. The pt was placed on 4 lpm via NC, unless in resp distress.

He stated that he did not like brain injury Pt's to be flooded with O2, due to the further injury it could cause.

[VentMedic]

TBIs and ICP have and are continuously being studied by many hospitals across the country. We do have protocols for specific O2 titration in these patients in the hospital but we also have the advantage of SjvO2 monitoring. Not every patient will behave the same and may require different pharmacological and/or ventilatory/oxygenation intervention.

Of course, it is well known for the effects of high FiO2 and the infant with cyanotic heart disease.

Nitrogen washout and absorption atelectasis on an FiO2 of 1.0 over extended periods of time is also well documented. Thus, some doctors want the ventilators on 95% when running a sepsis protocol instead of 100%.

Occassionally you will hear of someone speak of the oxygen clock in the ICU.

Other areas that have also be studied is O2 resuscitation of the neonate.

http://www.fsrc.org/NRPUpdate1-16-07.pdf

2. Use of supplementary oxygen use during delivery room resuscitation

The NRP recommendation that 100% oxygen be used when positive-pressure ventilation is required or in the

presence of central cyanosis was not changed. Because the evidence suggests that 21% may be as effective

as 100% oxygen, however, the 2005 guidelines also state that individual providers may take the option of

starting with less than 100% oxygen. No evidence is available to support a recommendation for using a

specific oxygen concentration between 21% and 100% at present. If an oxygen concentration <100% is used

to initiate resuscitation, crossover to 100% oxygen is recommended if there is no improvement in 90 seconds.

Saugstad OD, Rootwelt T, Aalen O. Resuscitation of asphyxiated newborn infants with room air or oxygen:

an international controlled trial: The Resair 2 study. Pediatrics 1998; 102:1-7.

Vento M, Asensi M, Sastre J, et al. Resuscitation with room air instead of 100% oxygen prevents oxidative

stress in moderately asphyxiated term neonates. Pediatrics 2001; 107: 642-7.

However, it gets complicated when some patients have mixed problems that have conflicting protocols for oxygen. ARDS protocols have the goal of sparing the lungs from volutrauma and getting the patient off the oxygen clock quickly. If that is also a sepsis protocol, it recommends that the patient be kept on 100% or 95% until the lactate level starts declining and/or 4 mmol/L or lower.

For the Stroke patient that has not presented with any other issues, we use a very minimal amount of O2 or none after any other problems that may require oxygen, such as pulmonary problems from aspiration, have been ruled out or do not give an indication of compromise.

[Novisen]

Our new guidelines says FI02 40% when resuscitation children with neonatal asphyxia.

[VentMedic]

Our new guidelines says FI02 40% when resuscitation children with neonatal asphyxia.

That's a good number since you don't actually need a blender to obtain an FiO2 near to that.

[Lone Star]

One consideration that we have to factor in, especially out in the field is this:

Are we actually using 100% oxygen in our portables, or are we actually delivering nothing more than compressed atmosphere?

In Michigan, the color coding for the receptacles for 'pure oxygen' is yellow, and the receptacles for 'compressed atmosphere' is green.

Since our portable tanks are color coded in green, wouldn't the same color coding apply as well?

I know that the service I worked for in Detroit would fill their own portable tanks from a 'cascade system' (which we also used for the fire department), and the 'supply tanks' were refilled from a local welding supply.....

I know that in MI, to give 'pure oxygen' (which I'm presuming is what they're referring to when they reference 100% oxygen), required a doctor's order, but the green tanks (which as I've stated before contained nothing more than 21% compressed atmosphere), we could administer PRN.

[reaper]

Any where in the country that I have been, Green is the marking for medical grade pure O2.

You have a Dr's orders to administer "pure O2", It is considered Standing orders!

[akroeze]

One consideration that we have to factor in, especially out in the field is this:

Are we actually using 100% oxygen in our portables, or are we actually delivering nothing more than compressed atmosphere?

In Michigan, the color coding for the receptacles for 'pure oxygen' is yellow, and the receptacles for 'compressed atmosphere' is green.

Since our portable tanks are color coded in green, wouldn't the same color coding apply as well?

I know that the service I worked for in Detroit would fill their own portable tanks from a 'cascade system' (which we also used for the fire department), and the 'supply tanks' were refilled from a local welding supply.....

I know that in MI, to give 'pure oxygen' (which I'm presuming is what they're referring to when they reference 100% oxygen), required a doctor's order, but the green tanks (which as I've stated before contained nothing more than 21% compressed atmosphere), we could administer PRN.

Think that through logically.... if it is nothing but compressed atmosphere, what benefit is there in applying it?