Thoracic / Respiratory / Psych (September 2017)
Review: Oxygen-induced hypercapnia in COPD myths and facts
Research: YEARS study Dx of PE
AIR: Psychobehavioral
For a Review Article
- How has reading the article changed your practice?
- What information had you believed in previously that were debunked by reading this article?
- What new information did you learn from reading this article?
- What are current areas of uncertainty on this topic that can be potential areas for research?
For an Original Research Article
- What are some strengths of the study?
- What are the limitations?
- What are the main outcomes of the study?
- Does reading this article change your practice? If so, how?
5 comments
Review article: O2-induced hypercapnia in COPD
– no sig change in practice. have errored in giving too much oxygen to COPD exacerbation in past but did not understand mechanism (i.e. significance of haldane effect vs hypoxic drive)
– debunked thought of hypoxic drive as main mechanism of O2-induced hypercapnia. however, in studies quoted, oxygen/CO concentration measured over minutes and would like to know data an hour or two out in pt’s course
– (re-)learned about haldane effect
– see above re: measurement of serum oxygen/CO levels after hours of liberal supplemental oxygen therapy.
Original research: YEARS study
– strength: large, prospective, pt-centered outcomes, ED population with broad inclusion criteria and good/usable protocol
– weakness: scandanavian population, in deaths – unable to know if PE was cause in most cases.
– main outcome: YEARS v Wells reduced unnecessary CTPAs by 14% with acceptable rates of adverse events.
– kind of; it’s kind of a short-cut of the two step wells, then PERC and d-dimer if not low risk process. I like how simple it is, it’s likely what I’ll teach to new learners.
Same boat as Joe.
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I’ve always been judicious in giving too much O2 to COPDer’s. But now I have a much better understanding of why. And it’s nice to debunk some of the traditional myths, despite how much theoretical sense it might make.
YEARS study.
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I’m hoping this is going to be a game changer, at least for younger patients.
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Also, I”m glad age-adjusted d-dimer practice is now validated and gaining more traction overall.
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Jordan found these articles. Great reads!
I believed that the data supporting the hypoxic drive were of low quality and used to teach this when in BEMS. I also think that the evidence included in this review as supporting the potential harms with high flow 0xygen are also questionable.
See “Austin MA, Wills KE, Blizzard L, Walters EH, Wood-Baker R: Eff ect of high fl ow
oxygen on mortality in chronic obstructive pulmonary disease patients in
prehospital setting: randomised controlled trial. BMJ 2010, 341:c5462.”
– cluster by ambulance not patient
-suspected COPD prehospital
-not adjusted outcome (for example severity)
– major flaws
” Of the 214 patients with confirmed chronic obstructive pulmonary disease, ambulance records showed that 37% received treatment that did not comply with the study protocol (56% in the titrated oxygen arm and 21% in the high flow oxygen arm).
-“A second limitation of this study was the low rate of arterial blood gas sampling for study patients. Although we informed staff in the emergency department staff of the importance of arterial samples for this trial, compliance was low and only 11% of arterial samples were drawn within 30 minutes of arrival. ”
– use of NIV?
I still believe that a patient with severe COPD and marked hypoxemia (sat < 80%) needs oxygen and respiratory support, not titrated Venturi masks to try to get to sat 90%
Other cited study observational prehospital…
How has reading the article changed your practice?
-re-emphasized the concept of maintaining lower O2 sat 88-92% in COPDers, probably the most relevant in the severe COPD
-thank you Dr. Feldman for the comment above re: poor data for HFNC in COPD
What information had you believed in previously that were debunked by reading this article?
-understanding the mechanism behind oxygen-induced hypercapnea including Haldane effect and reducing hypoxic pulm vasoconstriction leading to increased V/Q mismatch
YEARS
-large prospective, few lost to followup, real world cohort including those w/ prior PE, cancer
-not randomized control
-primary outcome: #VTE at 3m after PE ruled out using YEARS algorithm—>0.61%
-secondary outcome: #CTPA reduced by applying YEARS vs Wells/Dimer–>14%
-I don’t think I would change my/my attending’s practice quite yet, although the incidence of missed PE was similar to Wells, can’t imagine ignoring a D dimer 999, not ready for prime time but definitely reminds us we are overutilizing CTPA