Oxygen is probably the drug that we give the most but possibly has the least governance over. More has got to be good except in those at high risk of type II respiratory failure right?? Well as we know the evidence base has swung to challenge that idea in recent years and the new BTS guidelines for Oxygen use in Healthcare and Emergency Settings has just been published with a few things that are worth reviewing since the original publication in 2008. No apologies that this may be predominantly old ground here, this is an area we're all involved with day in and day out that is simple to correct and affects mortality
Historically oxygen has been given without prescription;
If nothing else is taken from this document then reinforcement of the fact that we need to keep oxygen saturations normal/near normal for all patients, except groups at risk of type II respiratory failure
Prescribe and delivery oxygen by target oxygen saturations
What is normal?
Will mental status give me an early indication of hypoxaemia?
Aims of oxygen therapy
Why the fuss about hyperoxia?
Hyperoxia has been shown to be associated with
In patients with COPD studies have showed most hypercapnia patients arriving at hospital with the equivalent of SpO2 > 92% were acidotic, high concentration O2has been associated with more than double the mortality rate in those with acute exacerbations of COPD. Titrate O2 delivery down smoothly
Which patients are at risk of CO2 retention and acidosis if given high dose oxygen?
What is the oxygen target?
Oxygen titrated to an SpO2 of 94-98%
Except in those at risk of hypercapnia respiratory failure, then 88-92%(or specific SpO2 on patient's alert card)
What about in Palliative Care?
Most breathlessness in cancer patients is caused by airflow obstruction, infections or pleural effusions and in these cases the issues need to be addressed. Oxygen does relieve breathlessness in hyperaemic cancer patients but not if SpO2 >90%. Midazolam and morphine also relieve breathlessness and are more likely to be effective.
Equivalent doses of O2
24% venturi = 1L O2
28 % venturi = 2L O2
35% venturi = 4L O2
40% venturi = nasal/facemask 5-6LO2
60% venturi = 7-10L simple face mask
Approach to oxygen delivery
Firstly determine if at risk of type II respiratory failure
If at risk of type II respiratory failure
Points specific to prehospital oxygen use
So the bottom line? Well just like Goldielock's porridge, with oxygen we don't want too little, we don't want too much but we want just the right amount!
There is no doubt that hypoxia kills but beware that too much of anything is bad for you and in the same way we need to be vigilant to targeting oxygen delivery to our patients target SpO2
BTS Guideline for oxygen use in healthcare and emergency settings
How many patients are admitted from your ED with suspected cardiac chest pain? What strategy of testing do you employ to rule out acute myocardial infarction? When and why do you send troponins in this process?
In this podcast Ed Carlton, Emergency Medicine Consultant at North Bristol Hospital and Troponin Researcher, talks to us about troponin rule out strategies, recent publications on the topics, where the future of troponin research is heading and most importantly what this all means for our practice.
Our previous podcast on troponins acts as a good introduction to this episode. Have a listen to both and we'd love to hear your comments at the bottom of the page and we hope you found this as useful as we did!
Rapid Rule-out of Acute Myocardial Infarction With a Single High-Sensitivity Cardiac Troponin TMeasurement Below the Limit of Detection: A Collaborative Meta-analysis. Pickering JW. Ann Intern Med. 2017
Effect of Using the HEART Score in Patients With Chest Pain in the Emergency Department: A Stepped-Wedge, Cluster Randomized Trial. Poldervaart JM. Ann Intern Med. 2017
This month we've got a good variety of topics.
We look at an recent systematic review and meta analysis on the prognostic value of echo in life support, an update from Blyth's paper in 2012. We review a paper looking at testing gin patients presenting to the emergency department in SVT. Finally we cover a paper looking at different methods employed when running an Emergency Department.
As always make sure you go and have a read of the papers yourselves and come up with your own conclusions, we'd love to hear your feedback.
References & Further Reading
Accuracy of point-of-care focused echocardiography in predicting outcome of resuscitation in cardiac arrest patients: A systematic review and meta-analysis. Tsou PY. Resuscitation. 2017
Usefulness of laboratory and radiological investigations in the management of supraventricular tachycardia. Ashok A. Emerg Med Australas.2017
What do emergency physicians in charge do? A qualitative observational study. Hosking I. Emerg Med J. 2017