2017/02/16 - Medical Tidbits: too much oxygen … the good and bad
… too much oxygen … the good and bad ..
For years we have been taught that people with shortness of breath, chest pain, stroke symptoms to put oxygen on them. The question is how much oxygen should we put … or really should we be putting oxygen on them at all???
Over the past several years there has been a strong look at how much oxygen we are giving in the hospital setting … this of course started with the neonatal patients, moved to the pediatric patients and then into the chest pain / stroke and trauma patients. Since that time we have also started looking at how much oxygen we should give in the prehospital setting.
Stub et al put together the AVOID study … A randomized controlled trial of oxygen therapy in acute myocardial infarction Air Verses Oxygen In myocarDial infarction study (AVOID Study) [https://doi.org/10.1161/CIRCULATIONAHA.114.014494, Circulation. 2015; CIRCULATION AHA.114.014494 Originally published May 22, 2015 ] where they looked at patients having chest pain and randomized to receive oxygen or not receive oxygen. Those in the oxygen group received 8 L / min and those in the non-oxygen group received no oxygen unless their oxygen saturation fell below 94% and then were given either 4 L / min via nasal cannula or 8 L / min via face mask. End result ..... those receiving oxygen did worse. These individuals had an increase rate of recurrent myocardial infarction, had an elevation in their serum creatinine kinase (component of the heart) and at 6 months has an overall increase in the infarction size of the myocardium. If you want more information on the AVOID trial [http://www.hamalrad.com/wp-content/uploads/2015/04/AVOID.pdf]
Cochrane review from 2010 - Our systematic review and metanalysis of three randomised controlled trials suggested that oxygen might even be associated with worse patient outcome, with a three-fold increase in relative risk of mortality compared to the use of air alone, raising further concerns about patient safety .. but the 2016 Cochrane review indicated that more data is needed.
End conclusion … patients with an oxygen saturation > 94% does not need large amounts of oxygen. We do not know if small amounts 2 (L / min) is harmful or helpful … but again … over 94% … avoid the non-rebreather and high flow oxygen.
Keep up the good work … and remember that sometimes … doing “NOTHING” is actually doing “SOMETHING” …