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Wednesday, July 25, 2012

COPD: Is EMS Killing Patients with Oxygen? (2)

The Tasmanian Study
Disclosure - the lead author used to be my partner. We were both medics at the same two agencies (volunteer and hospital) in New Hampshire. He never seemed to run out of energy, and it doesn't seem like that's changing!

And since we're talking about Tasmania, we might as well get this out of the way...

Dr. Austin at work.
Effect of high flow oxygen on mortality in chronic obstructive pulmonary disease patients in prehospital setting: randomised controlled trial was well done, especially for EMS research. It's unfortunate that the bar is so low in our corner of health care research, but Austin et al. are working to change that.

The study utilized an EMS service that covered both rural and urban settings, but transported to only one hospital. Paramedics were supposed to identify patients with "breathlessness and a history or risk of COPD," and enroll those patients that they suspected of having an acute exacerbation of COPD.

Most of the treatment was the usual stuff - salbutamol (aka albuterol), ipratropium, dexamethasone, etc. CPAP was not available. The only difference had to do with how oxygen got delivered.

Prior to treatment, patients were randomized to receive either titrated oxygen, delivered by nasal cannula to maintain a sat around 90%, or high-flow oxygen, administered by NRB mask.  Transports lasted an average of 45 minutes, and then the folks in the ED treated as they saw fit.

Before we look at the results, you have to understand two huge issues:
  • Only about half of the patients had pre-existing COPD, as judged by a pulmonologist. There's no description of what the rest had. Perhaps many of them had a new diagnosis of COPD, while others where actually pneumonia or CHF with wheezing.
  • There were a lot of protocol violations: 56% of the titrated-oxygen group got high-flow oxygen, while 21% of the high-flow group didn't get high-flow.

With those facts in mind, they found:



Note how the results are broken down by all patients versus only those patients with previously confirmed COPD. The most important result is that there's a 5% difference in mortality for all of the patients.

So, what's the problem? It seems to be pretty clear evidence that paramedics should be withholding oxygen in suspected COPD exacerbations, but there are a few reasons why we should be cautious in using these results on the streets tomorrow.

1. The results seem almost too remarkable to be true.
They show 5% increase in mortality between the high-flow and the titrated oxygen groups.  That's a "number needed to harm," or NNH, of 20. In other words, for every 20 patients you give a NRB to, 1 will die.

That's a really high number! Usually you have to do a lot of work in medicine to show that kind of effect. For example, you have to treat 20 STEMI patients with aspirin and streptokinase (versus placebos) to save one life.

And you know all that fuss about rushing the STEMI patient into the cath lab? We have to treat 50 STEMI patients with angioplasty (versus thrombolysis), to save 1 life.

Given this context, the result almost seems "too good to be true." Given that there is little randomized controlled data out there with similar results, and given the good-quality data that conflicts with it (as with the ICU studies described in the prior post), it is reasonable to be skeptical about the conclusions, and await validating data.

2. The oxygen therapy was brief.
The intervention only lasted during transport, on average about 45 minutes. Compare that with the Gomersall study in my last post, where patients in the ICU received higher levels of oxygen for 2 days. While certain brief EMS interventions can have important long-term consequences (defibrillation anyone?), the onus is on the authors to make the case that it was solely the EMS intervention that differed between the two treatment groups. They concede that it was difficult to isolate the effect of the EMS intervention, and state that:
"Unfortunately, collection of data on in-hospital management was beyond the scope of the study, so we cannot dissect the effect of prehospital and in-hospital oxygen administration."

3. Paramedics don't treat "confirmed" COPD
Although withholding oxygen in the cases of "confirmed" COPD looked very effective, the unfortunate truth is that paramedics apparently misidentified half of the patients as COPD.

Now, this may not be entirely true. Some of the "non-confirmed" cases may have been a first-time COPD attack, and the medics were spot on. Or, perhaps some of the cases were actually, say, CHF, or pulmonary emboli. We aren't given any data on what this sizeable subgroup was ultimately diagnosed with.

Remember, though, that most other causes of hypoxia are treated with oxygen. With that in mind, we are left to consider the effect on mortality for the patients who did not have COPD. It does not seem likely that their treatment was improved by leaving them hypoxic.

By the way, this is the same reason you don't treat "hyperventilation" with a paper bag. Seriously, you aren't doing that, are you?

"Med control, we have a problem."

4. There was no difference in rates of mechanical ventilation.
In general, it's hard to show a difference in mortality for any given therapy, because deaths are far less frequent than other bad events. For instance, you need to treat 13 patients in CHF with non-invasive positive pressure ventilation (NIPPV) to prevent 1 death, but you only have to treat 8 patients to prevent an intubation (figures from The NNT).

In fact, we also know that NIPPV cuts the rate of mortality of COPD exacerbations by about 42%, but drops the intubation rate more, by 52%.

So it's kind of odd to see this profound difference in mortality, but no difference in the rates of mechanical ventilation. Similarly, there's no difference in the average length of hospital stay here, another sensitive measure of the effectiveness of a therapy.

5. Oxygen is not the issue.
Ultimately, the study is not asking a relevant question. We know that COPD is primarily an issue of impaired ventilation, and that NIPPV is the treatment of choice for severe exacerbations, along with steroids, bronchodilators, and antibiotics.

In a way, designing a study that only looks at levels of oxygen delivery in COPD exacerbation is sort of like designing a CHF study that only focused on fluid restriction, but didn't use nitroglycerin or NIPPV.

Yes, it would probably show a benefit of fluid restriction, but that's not the problem!

The Bottom line
  1. Suppressing the "hypoxic drive" is a rare entity, and concern for it should not drive management.
  2. Withholding oxygen could be very dangerous if you are wrong about the diagnosis.
  3. Treat bad COPD with bronchodilators, steroids, antibiotics, NIPPV, and, if hypoxic below their baseline, oxygen. Intubate PRN.
  4. We're looking forward to more high-quality studies from Tasmania!

11 comments:

  1. I think it's an area that needs serious study. As does the question of whether we should used compressed air (21% O2) or compressed O2 to drive the nebulizer.

    The question I would ask is, which of those treatments is better? Or is there no difference at all?

    I'd also like to know if the patient's O2 sat and ETCO2 were monitored during the study. O2 sat by itself is not particularly informative, but with ETCO2 I at least have found it much easier (although not perfect) to differentiate CHF vs. COPD or Asthma.

    Does Oxygen help COPD patients? In and of itself it might, especially if they are hypoxie (duh), but the question to me at least is if Oxygen itself is a good treatment.

    I'm not sure the Tasmanian study looked at that, but someone should.

    ReplyDelete
    Replies
    1. Healing from COPD, i never taught DR AYes who could ever get my COPD cured with his healing herbs, i have tried almost everything but i couldn't find any solution on my disease, despite all these happening to me, i always spend a lot to buy a COPD drugs from hospital and taking some several medications but no relieve, until one day i was just browsing on the internet when i come across a great post of ! Williams Fran-ca who truly said that she was been diagnose with COPD and was healed that very week through the help of these great powerful healing doctor, sometime i really wonder why people called him Baba Ayes i never knew it was all because of the great and perfect work that he has been doing that is causing all this. so i quickly contacted him, and he ask me some few questions and he said a thing i will never forget that anyone who contacted him, is always getting his or her healing after take the herbs cure in a week so i was amazed all the time i heard that from him, so i did all things only to see that at the very day which he said i will be healed, all the strength that has left me before rush back and i became very strong and healthy, this disease almost kills my life all because of me, so i rush to hospital for the final test. So the disease and the doctor said i am COPD negative, i am very amazed and happy about the healing DR.Ayes gave to me from the ancient part of Africa, you can email him now for your own healing too at Dr's email is: unstopableshrine@gmail.com and unstopableshrine@outlook.com
      website: http://unstopableshrine.webs.com
      Good Luck


      Delete
    2. I found more Courage, Happiness and Faith in me, when I contacted Dr Ayes over the issue I have on me on ground, But all thanks goes to God Almighty for using the great healer called Dr Ayes to heal me and it has been six months from now and I have been free from all diseases. My Names are Angelina Virgina, Living in the US now, I was diagnosed positive of COPD since Two Years Ago now, and I have tried all my possible best I can to get rid of it, but nothing is working out, I have spend hell, spend all my savings but nothing work out, and I even stop smoking and taking alcohol drinks, I have been directed and advise in different types/aspect of cures still yet no changes, One faithful morning, when I was listening to the news at the TV set, and Later on they switch to COPD discussion, and I was really interested in it, I focus my mind listening and a man came and started sharing a testimony about a particular doctor called Dr. Ayes, he said this man has helped thousands of people out there and people still do run to him for help and this has make him 30yrs of experienced in curing people from different diseases and God has been helping him, Mightily, they showed the contact of this great Dr and I quickly copied everything out and contact him immediately, I send all my information's to him and after three days, i received a parcel from him containing the medicine/cure and I was told to use it for Just a week, and I greatly use it and God be all the Glory, I am now negative and I have gone to the hospital many times without numbers, and the Doctor confirmed I am clean and OK, all thanks to Dr. Ayes for his miraculous Healing.
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      Thanks and Remain Bless


      Delete
    3. Healing from COPD, i never taught dr.abegbu who could ever get my COPD cured with his healing herbs, i have tried almost everything but i couldn't find any solution on my disease, despite all these happening to me, i always spend a lot to buy a COPD drugs from hospital and taking some several medications but no relieve, until one day i was just browsing on the internet when i come across a great post of ! Williams Fran-ca who truly said that she was been diagnose with COPD and was healed that very week through the help of these great powerful healing doctor, sometime i really wonder why people called him Baba ABEGBU i never knew it was all because of the great and perfect work that he has been doing that is causing all this. so i quickly contacted him, and he ask me some few questions and he said a thing i will never forget that anyone who contacted him, is always getting his or her healing after take the herbs cure in a week so i was amazed all the time i heard that from him, so i did all things only to see that at the very day which he said i will be healed, all the strength that has left me before rush back and i became very strong and healthy, this disease almost kills my life all because of me, so i rush to hospital for the final test. So the disease and the doctor said i am COPD negative, i am very amazed and happy about the healing DR.ABEGBU gave to me from the ancient part of Africa, you can email him now for your own healing too at DR.ABEGBUHEALER@GMAIL.COM

      Delete
    4. I am from USA, I was diagnosed of Emphysema (COPD) in 2015 and I have tried all possible means to get cured, i even visited pulmonologist but all to no avail, until i saw a post in a health forum about a herbal doctor from West Africa who prepare herbal medicine to cure all kind of diseases including Emphysema, at first i doubted if it was real but decided to give it a try, when i contact this herbal doctor via his email he sent me Emphysema herbal medicine through courier service, when i received this herbal medicine, he gave me step by instructions on how to apply it, when i applied it as instructed i was totally cured of this deadly disease within 12-14 days of usage, if you are suffering of this diseases you can as well Contact this great herbal doctor via his email dr.akpajaspelltemple@gmail.com

      Delete
    5. I was diagnosed of Emphysema (copd)9 months ago which affected my breathing badly, my doctor advice me for Lungs Volume reduction surgery (LVRS) because my both upper lobes of the lungs were involved, i was making preparation for this when a friend of mine told me about a herbal doctor from Africa, doctor Unuareghe who prepares herbal medicine to cure all kind of diseases including Emphysema, i contacted Dr Unuareghe via his email and he sent me Emphysema herbal medicine via courier service, when i received this herbal medicine i applied it as instructed and was totally cured of Emphysema within 10 days of usage, i never had to go for the surgery again as i was totally free from emphysema, all thanks to Dr Unuareghe, contact Dr Unuareghe via his email dr.unuareghecuringhome@gmail.com

      Delete
  2. Healing from COPD, i never taught dr.abegbu who could ever get my COPD cured with his healing herbs, i have tried almost everything but i couldn't find any solution on my disease, despite all these happening to me, i always spend a lot to buy a COPD drugs from hospital and taking some several medications but no relieve, until one day i was just browsing on the internet when i come across a great post of ! Williams Fran-ca who truly said that she was been diagnose with COPD and was healed that very week through the help of these great powerful healing doctor, sometime i really wonder why people called him Baba ABEGBU i never knew it was all because of the great and perfect work that he has been doing that is causing all this. so i quickly contacted him, and he ask me some few questions and he said a thing i will never forget that anyone who contacted him, is always getting his or her healing after take the herbs cure in a week so i was amazed all the time i heard that from him, so i did all things only to see that at the very day which he said i will be healed, all the strength that has left me before rush back and i became very strong and healthy, this disease almost kills my life all because of me, so i rush to hospital for the final test. So the disease and the doctor said i am COPD negative, i am very amazed and happy about the healing DR.ABEGBU gave to me from the ancient part of Africa, you can email him now for your own healing too at DR.ABEGBUHEALER@GMAIL.COM

    ReplyDelete
  3. My name is SMITH SANDRA, I am here to give my testimony about a doctor who helped me in my life. I was infected with COPD VIRUS in 2006, i went to many hospitals for cure but there was no solution, so I was thinking how can I get a solution out so that my body can be okay. One day I was in the river side thinking where I can go to get solution. so a lady walked to me telling me why am I so sad and i open up all to her telling her my problem, she told me that she can help me out, she introduce me to a doctor who uses herbal medication to cure COPD VIRUS and gave me his email, so i email him. He told me all the things I need to do and also give me instructions to take, which I followed properly. Before I knew what is happening after four weeks the COPD VIRUS that was in my body got cured so if you are also heart broken and also need a help, you can also email him at dr.obhiotorherbalhome@gmail.com or call+2347064851317
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    ReplyDelete
  4. Healing from COPD, i never taught DR AYes who could ever get my COPD cured with his healing herbs, i have tried almost everything but i couldn't find any solution on my disease, despite all these happening to me, i always spend a lot to buy a COPD drugs from hospital and taking some several medications but no relieve, until one day i was just browsing on the internet when i come across a great post of ! Williams Fran-ca who truly said that she was been diagnose with COPD and was healed that very week through the help of these great powerful healing doctor, sometime i really wonder why people called him Baba Ayes i never knew it was all because of the great and perfect work that he has been doing that is causing all this. so i quickly contacted him, and he ask me some few questions and he said a thing i will never forget that anyone who contacted him, is always getting his or her healing after take the herbs cure in a week so i was amazed all the time i heard that from him, so i did all things only to see that at the very day which he said i will be healed, all the strength that has left me before rush back and i became very strong and healthy, this disease almost kills my life all because of me, so i rush to hospital for the final test. So the disease and the doctor said i am COPD negative, i am very amazed and happy about the healing DR.Ayes gave to me from the ancient part of Africa, you can email him now for your own healing too at Dr's email is: unstopableshrine@gmail.com and unstopableshrine@outlook.com
    website: http://unstopableshrine.webs.com
    Good Luck


    ReplyDelete
  5. This comment has been removed by a blog administrator.

    ReplyDelete
  6. I am from USA,i am giving thanks to a great doctor who help me out of my illness i was very sick,i thank god who use this man to help me, i was diagnosed of Emphysema (COPD) in 2013 and i have tried all possible means to get cured, i even visited pulmonologist but all to no avail, until i saw a post in a health forum about a herbal doctor from West Africa who prepare herbal medicine he is 100% sure he cure all kind of diseases like, HPV, STD, HERPES VIRUS, HIV AID VIRUS,ALS VIRUS, HEPATITIS B, including Emphysema, at first i doubted if it was real but decided to give it a try, when i contact this herbal doctor via his email he sent me Emphysema herbal medicine through courier service, when i received this herbal medicine, he gave me step by instructions on how to apply it, when i applied it as instructed i was totally cured of this deadly disease within 13 days of usage, if you are suffering of this diseases you can as well Contact this great herbal doctor via his email DRALUKOSPELLALTER@GMAILL.COM OR call and what-apps him via: +2349051292839, OR you can contact me on my mail for further assusatnt at winnifredcole000@gmail.com .thank you DR ALUKO i will never stop shearing your testimony.

    ReplyDelete