Oxygen and COPD – A New Study

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A study published in the British Medical Journal on line first edition dated October 18, 2010 shows the results of a study done in Australia involving the Tasmanian Ambulance Service (Hobart) and Royal Hobart Hospital. The study was conducted by the Menzies Research Institute of the University of Tasmania, Hobart.

Effect of high flow oxygen on mortality in chronic obstructive pulmonary disease patients in prehospital setting: randomised controlled trial

The entire study is available on line for free at the link posted above.

The results are interesting and once again stand conventional EMS wisdom on it’s head. In the randomized study paramedics were instructed to give either Oxygen by nasal cannula titrated to achieve O2 saturations of 88-92% and nebulized bronchodilators by air compressor or Oxygen by non rebreather mask at 8-10 lpm and nebulized medications.

The results were quite interesting. From the Conclusions and Policy Implications of the study,

Conclusions and policy implications

This randomised controlled trial found that titrated oxygen treatment in the prehospital setting resulted in a 78% reduction in the risk of in-hospital respiratory failure and subsequent mortality, compared with high flow oxygen treatment, and a decreased risk of hypercapnia and respiratory acidosis for patients with an acute exacerbation of chronic obstructive pulmonary disease. Our findings provide the first high quality evidence from a randomised controlled trial for the development of universal guidelines and support the British Thoracic Society’s recent guidelines on acute oxygen treatment, which recommend that oxygen should be administered only at concentrations sufficient to maintain adequate oxygen saturations. Although our findings may need to be confirmed in larger studies across other health systems, implementation of the new guidelines will now be easier. However, resources for an aggressive campaign of education will still be needed to change the “more is better” oxygen culture that may ignore the potential dangers of hyperoxia.

The British Thoracic Society’s recommendations referenced here were that patients with Oxygen saturations above 92% did not benefit from supplementary oxygen. The guidelines are actually more complex than that and not entirely applicable to prehospital care. You can read the Executive Summary at this link. The BTS supports universal use of Pulse Oximetry as a continuous monitoring tool instead of the snap shot tool that most EMS personnel seem to use it for. The BTS does not mention capnography, but I expect that in the future that will also become a standard for all levels of care.

I would expect that with this study and the AHA guidelines both questioning high flow Oxygen for a wide variety of respiratory and cardiac patient conditions that EMS systems will soon start to change their protocols. This won’t be without it’s own problems because as I mentioned yesterday EMTs and paramedics learn almost from day one that Oxygen is a benign drug and can’t hurt patients.

In fact, the Australian study refers to this,

One limitation of our trial was the lower than expected rate of adherence to study protocols, in both prehospital oxygen treatment and the measurement of arterial blood gases on arrival at hospital, showing the difficulties associated with modifying practice. 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). In the titrated oxygen arm, all protocol violations involved administration of high flow oxygen at some point during prehospital treatment. We expect that this would have minimised any treatment effect in the intention to treat analysis, but we still found a significant reduction in mortality for titrated oxygen treatment. The frequent lack of compliance in the titrated oxygen arm is probably a result of the entrenched culture and training in emergency medicine, which emphasises that high flow oxygen will save lives in acute respiratory emergencies by preventing severe hypoxaemia. From reviews of charts and interviews with paramedics, we found no evidence that the breaches of protocol were a result of malfunction of monitoring of saturation (oximeter), patients requesting more oxygen, or lack of understanding of the protocol. However, feedback indicated that some paramedics were concerned about insufficient delivery of oxygen in distressed patients, which suggests that they believed the entrenched cultural training that “more is better.” This culture, combined with the absence of high quality evidence on the potential dangers of oxygen, may have been responsible for the ongoing practice of routine delivery of high flow oxygen.

That reminds me of the quote that I had at the old blog site,
The difficulty lies, not in the new ideas, but in escaping from the old ones.
John Maynard Keynes (1883-1946)

I should probably find a way to put that on this site too.

I’m sure that at least Rogue Medic, if not other bloggers will have some more commentary on the difficulty in unteaching old knowledge and trying to teach new ways of doing things. Sometimes, well many times, we are our own worst enemies in this business.

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