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# 6066
In October of 2010 I wrote a blog called BMJ: Oxygen Delivery and COPD that looked at a fascinating, but controversial study out of Australia that looked at high flow oxygen treatment compared with titrated oxygen treatment in the pre-hospital (ambulance/paramedic) setting.
Although long ago, in a galaxy far, far away . . . (when I was a paramedic) . . . it was standard operating procedure to limit oxygen to 2 liters for COPD patients, in recent decades the trend has been to go with high flow (6 - 10 liters/min) supplemental oxygen.
In the (BMJ 2010; 341:c5462) study referenced last year, researchers followed the pre-hospital or in-hospital mortality rates of 405 patients with presumed COPD (chronic obstructive pulmonary disease) who received either high flow oxygen or titrated oxygen (2 l/m) in the ambulance or emergency department.
What they found was (from the abstract):
Titrated oxygen treatment reduced mortality compared with high flow oxygen by 58% for all patients (relative risk 0.42, 95% confidence interval 0.20 to 0.89; P=0.02) and by 78% for the patients with confirmed chronic obstructive pulmonary disease (0.22, 0.05 to 0.91; P=0.04).
Patients with chronic obstructive pulmonary disease who received titrated oxygen according to the protocol were significantly less likely to have respiratory acidosis (mean difference in pH 0.12 (SE 0.05); P=0.01; n=28) or hypercapnia (mean difference in arterial carbon dioxide pressure −33.6 (16.3) mm Hg; P=0.02; n=29) than were patients who received high flow oxygen.
While this issue is far from settled, we’ve a new retrospective study that appears in the Archives of Internal Medicine that lends weight to the argument that when it comes to oxygen for emergency patients, less may be more.
Supplemental Oxygen Therapy in Medical Emergencies: More Harm Than Benefit?
Alexander D. Cornet, MD; Albertus J. Kooter, MD; Mike J. L. Peters, MD, PhD; Yvo M. Smulders, MD, PhD
Arch Intern Med. Published online January 9, 2012. doi:10.1001/archinternmed.2011.624
This study is, sadly, behind a pay wall. So those of us without a subscription must rely on other summaries.
Luckily, Frederik Joelving of Reuters gives us the highlights, in his report titled:
Extra oxygen may harm emergency patients: report
By Frederik Joelving
NEW YORK | Wed Jan 11, 2012 4:34pm EST
(Reuters Health) - That oxygen mask they strap on patients rushed to the ER after a heart attack or a stroke? It could be doing more harm than good in many cases, Dutch researchers say in a new report.
<SNIP>
"There is not a single study that points to beneficial effects," said Dr. Yvo Smulders, a professor at VU University Medical Center in Amsterdam. "All of the evidence that we found points to detrimental effects."
Smulders' team reviewed 18 previously conducted studies that looked at patient outcomes following oxygen treatment for common medical emergencies that included heart attacks, strokes, cardiac arrest, and COPD.
What they claim to have found is little or no evidence that high-dose oxygen improves survival, and weak evidence that it may even be detrimental.
And not just for COPD patients.
The authors suggest that hyperoxia (excessive oxygen levels in the lungs, blood, or tissues) may cause hemodynamic changes that may actually increase myocardial ischemia (depriving heart muscle of oxygen) during a heart attack.
They also propose that a relationship exists between hyperoxia and greater mortality and complications in non-cardiac emergencies as well.
You’ll find another (brief) summary of this paper on the NHS National Electronic Library for Medicines (NeLM) website.
Supplemental high-dose oxygen therapy linked to more harm than benefit in medical emergencies?
Reference: Archives of Internal Medicine, published early online on 9 January 2012
Source: Archives of Internal Medicine
Date published: 10/01/2012 16:56
Since it is counter-intuitive to reduce the amount of oxygen we give to those already suffering respiratory difficulties, I suspect it will take a lot more evidence before these findings are widely accepted.
Still, it is absolutely fascinating that a debate that raged among EMS providers nearly 40 years ago - when I was a fledgling EMT-II - still continues unresolved.
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