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

[Guest guest]

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. 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. "

[Guest guest]

We judge our vent setting based on ETCO2 and FIO2 trying to maintain a good

balance. ETCO2 around 35 and FIO2 in the 90's. What is your take?? 

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

To: texasems-l , Paramedicine

Date: Wednesday, July 23, 2008, 9:42 PM

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. 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. "