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June 29, 2008 Close to fifty years is a long time for drive to breathe 'myth' to be perpetuated

Posted Jun 29 2008 4:05pm

Picture: 10,600 ft in Loveland Ski basin parking lot...

Close to fifty years is a long time for drive to breathe 'myth' to be perpetuated

Mark Mangus replies:

question as to why the general medical pulmonologists seem to feel

that there could be a problem with too much oxygen and are hesitant to

approve a higher flow.

"You ask a very good question. I can't deny that there are a LARGE

number of physicians AND other health care professionals who still

to the 'myth' that "too much oxygen can cause those who

retain CO2 to stop breathing or to at least decrease their ventilation

enough to put them at risk for 'acute respiratory failure'".
That is a

premise that was birthed out of our misunderstanding of how human beings

breathe going back to the late 1950's - early 1960's; hence why I call

it a 'myth'
. It was based on what we NOW know to be fallacious

understanding of respiratory physiology and the mechanisms - - -

chemical and neurological - - - that drive breathing.
In the 1990's

and on into this century, a mounting number of studies (some impressive

and audacious, done by the Japanese!) have attempted to invoke the

phenomenon - - - 'apnea' - cessation of breathing - - - in CO2-retaining

COPD'ers, several studies using subjects that were in full blown 'acute

respiratory failure' with extremely high CO2's, by having them breathe

80 % oxygen and higher. In not one instance have they been able to

stop one's breathing. In several studies, breathing

fact of the matter is that
we have only empiric, reproducible evidence

to show that the myth is NOT true
while we have not a single shred of

reproducible or empiric evidence to support the 'myth'

Close to fifty years is a long time for a 'myth' to be perpetuated. It

literally pervades ALL levels of health care training. You know the

old adage: "Tell a lie long enough and it becomes the reality, but not

necessarily the 'truth'." That sums up the gist of the debate.

Today, in most respiratory care training materials, it is taught as a

"historical misunderstanding" in contrast with the correct - - - and

scientifically verifiable - - - explanation.As evidenced by revisions

of recent textbooks by our nation's prominent pulmonologists (Barry

Make, Brian Tiep, Thomas Petty, to name a few)
to include partial

revisions of the old 'myth' to work towards denying that it exists at

all. They are tiptoeing toward the truth while trying not to totally

upset the thinking ship of the greater medical community! While they

have not flatly said it's bogus
, they are saying that even if it does

affect a rare individual , to practice using the 'just enough oxygen'

therapy approach - - - where they allow one's oxygen to be raised only

to above 88 %, but not above, say, 92 %,notonly robs those with

hypoxia and CO2-retention of a decent level of comfort
,but it drives

them to right heart failure and an earlier death while robbing them of

considerable function and livelihood in the meantime.

The concern is mounting to such a degree that our NIH/
NHLBI recently

initiated a long term study to evaluate (1) earlier intervention with

oxygen therapy when hypoxia below 92 % is FIRST detected, so as to

assess survival statistics and (2) to assess the affect on physical

function, right heart function and length survival by attempting to

correct hypoxia to a more "normal" level of >/= 94 % saturation.

Another fallacy that is being studied is the notion that detrimental

effects on function and the right heart are directly influenced by

"paO2" and NOT by "saturation". Yet, with more study of 'dynamic

hyperinflation' and the discovery that desaturation resulting from this

factor does NOT lower paO2 as much as it causes 'respiratory acidosis'

(increased CO2 with decreased pH) suggests that it is indeed saturation

and acidosis that is responsible for secondary pulmonary hypertension

and quicker onset right heart failure, while paO2 can be "adequate"

according to clinical evidence
.When you see me responding to folks

who talk about their CO2 being elevated, or being CO2-retainers and they

are concerned about oxygen use, you will always see me asking about

their pH on their blood gas
That is because the pH is the ALL

PORTANT factor in whether or not we need to worry about what the CO2

is. A CO2 that is elevated in the presence of a pH that is equally

decreased spells trouble, regardless of what the oxygen is

saturation will ALWAYS be decreased with that combination. On the

other hand, a CO2 that is increased in the presence of a normal pH is

NOT a problem and saturation remains high/normal
. Further, 99 % of

those who retain CO2 have a NORMAL pH, which is WHY there is NO fear

that they will breathe any different, much less worse, if given enough

oxygen to run their saturation up to 96 % and higher

The bottom line is that those clinicians who are still adamant about

restricting oxygen use by CO2-retainersare, (1) not informed/up to date

or (2) simply are not convinced of the evidence, so far
. I am

confident that with the work going on and the voices in the wilderness,

like me, that we will come to a point when folks will slap their

foreheads and figure it out. Until then, you must do what your

conscience and your doctor agree is best for you. We know that the

likelihood of avoidable mishap exists as long as they withhold adequate

oxygen. But, it is the accepted standard by a large segment of the

medical community and we haven't convinced enough of the medical

community to act accordingly."

Mark W. Mangus, Sr. BSRC, RPFT, RRT

Pulmonary Rehabilitation

Christus Santa Rosa Health Care

San Antonio, TX


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