Whats New in the Patient Safety World
October 2017
End of the Oxygen in MI and Stroke Debate?
In the past we often
routinely provided supplemental oxygen to patients who had suffered stroke or
MI. But evidence began to appear that using oxygen in patients lacking evidence
of hypoxemia might be of no benefit. Indeed, some evidence that hyperoxia might even be harmful began to appear (see our
numerous columns on the potential dangers of oxygen listed at the end of
todays column). The debate about use of oxygen in stroke and MI continued in
the absence of randomized controlled trials.
Now, hopefully, the
debate should end with the recent publication of results of randomized trials
of oxygen in these two conditions.
First, the DETO2X-AMI trial was a registry-based randomized
clinical trial using nationwide Swedish registries for patient enrollment and
data collection (Hoffmann
2017). Patients with suspected myocardial infarction and an oxygen
saturation of 90% or higher were randomly assigned to receive either
supplemental oxygen (6 liters per minute for 6 to 12 hours, delivered through
an open face mask) or ambient air. The study was open-label (that is, it was
not double-blinded). Though hypoxemia developed more frequently in the ambient
air group than the oxygen group (7.7% vs. 1.9%) there was no difference in the
primary outcome of death from any cause within 1 year (5.0% and 5.1% in the
oxygen and ambient air groups, respectively). Though more patients in the
oxygen group were rehospitalized with MI within one
year, this difference did not reach statistical significance. Results were
consistent across all predefined subgroups. The authors conclude that routine
use of supplemental oxygen in patients with suspected myocardial infarction who
did not have hypoxemia was not found to reduce 1-year all-cause mortality.
Regarding stroke,
the Stroke Oxygen Study (Roffe
2017) was a single-blind randomized clinical trial in the United
Kingdom. Patients were enrolled within 24 hours of hospital admission if they
had no clear indications for or contraindications to oxygen treatment. Participants
were randomized 1:1:1 to continuous oxygen for 72 hours, nocturnal oxygen
(21:00 to 07:00 hours) for 3 nights, or control (oxygen only if clinically
indicated). Oxygen was given via nasal tubes at 3 L/min if baseline oxygen
saturation was 93% or less and at 2 L/min if oxygen saturation was greater than
93%. The primary outcome was reported using the modified Rankin Scale score assessed
at 90 days by postal questionnaire. The unadjusted odds ratio for a better
outcome was 0.97 for oxygen vs control, and the odds ratio was 1.03 for
continuous vs nocturnal oxygen (neither statistically significant). No subgroup
could be identified that benefited from oxygen. The authors concluded that among
nonhypoxic patients with acute stroke, the
prophylactic use of low-dose oxygen supplementation did not reduce death or
disability at 3 months. These findings do not support low-dose oxygen in this
setting.
So we now have evidence from randomized trials that fail to
show any benefit from routine use of oxygen in patients with MI or stroke who
are not hypoxemic. Hopefully, the debate is now over.
Also timely is the
recent publication of the updated British Thoracic Society Guideline for
Oxygen Use in Adults in Healthcare and Emergency Settings (O'Driscoll 2017).
We discussed the BTS guideline in our January 27, 2009 Patient Safety Tip of
the Week Oxygen
Therapy: Everything You Wanted to Know and More!.
Many of the recommendations in the 2008 BTS guideline are unchanged but the
scope of the guideline has been expanded to cover several new categories. The guideline continues to make the
distinction in target oxygen saturation goals for most (9498%) and those at
risk for hypercapnic respiratory failure (8892%).
Some of our prior
columns on potential harmful effects of oxygen:
April 8, 2008 Oxygen
as a Medication
January 27, 2009 Oxygen
Therapy: Everything You Wanted to Know and More!
April 2009 Nursing
Companion to the BTS Oxygen Therapy Guidelines
October 6, 2009 Oxygen
Safety: More Lessons from the UK
July 2010 Cochrane
Review: Oxygen in MI
December 6, 2011 Why
You Need to Beware of Oxygen Therapy
February 2012 More
Evidence of Harm from Oxygen
March 2014 Another
Strike Against Hyperoxia
June 17, 2014 SO2S
Confirms Routine O2 of No Benefit in Stroke
December 2014 Oxygen
Should Be AVOIDed
August 11, 2015 New
Oxygen Guidelines: Thoracic Society of Australia and NZ
November 2016 Oxygen
Tank Monitoring
November 2016 More
on Safer Use of Oxygen
References:
Hofmann R, James SK, Jernberg T,
et al. Oxygen Therapy in Suspected Acute Myocardial Infarction. NEJM 2017;
published online first August 28, 2017
http://www.nejm.org/doi/full/10.1056/NEJMoa1706222?query=featured_home
Roffe C, Nevatte
T, Sim J, et al for the Stroke Oxygen Study Investigators and the Stroke Oxygen
Study Collaborative Group. Effect of Routine Low-Dose Oxygen Supplementation on
Death and Disability in Adults With Acute Stroke. The
Stroke Oxygen Study Randomized Clinical Trial. JAMA 2017; 318(12): 1125-1135, September 26,
2017
O'Driscoll BR, Howard LS, Earis J,
Mak V. British Thoracic Society Guideline for Oxygen
Use in Adults in Healthcare and Emergency Settings. BMJ Open Respir Res 2017; 4(1)
http://bmjopenrespres.bmj.com/content/4/1/e000170
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