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; 42% of patients in the 2015 BTS audit had no accompanying prescription When it is prescribed this doesn't always correlate with delivery 1/3 of patients were outside of target SpO2 range (10% below & 22% above) 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? Normal Oxygen saturations for healthy young adults is approximately 96-98%, there is minor decrease with increasing age. Healthy subjects desaturate to 90% SpO2 during night time; be cautious interpreting a single oximetry reading from a sleeping patient, short duration overnight dips are normal   Will mental status give me an early indication of hypoxaemia? No, impaired mental function at a mean value of SaO2 64%, no evidence above SaO2 84% Loss of consciousness at a mean SaO2 56%   Aims of oxygen therapy Correct potentially harmful hypoxia Alleviate breathlessness only in those hypoxic   Why the fuss about hyperoxia? Hyperoxia has been shown to be associated with Risk to COPD patients and those at risk of type II respiratory failure Increased CK level in STEMI and increased infarct size on MR scan at 3 months Association of hyperoxaemia with increased mortality in several ITU studies Worsens systolic myocardial performance Absorption Atelectasis even at FIO2 30-50% Intrapulmonary shunting Post-operative hypoxaemia Coronary vasoconstriction Increased Systemic Vascular Resistance Reduced Cardiac Index Possible reperfusion injury post MI 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? Chronic hypoxic lung disease COPD/CF/Bronchiectasis Chest wall disease Kyphoscoliosis Thoracoplasty Neuromuscular disease Morbid obesity with hypo ventilatory syndrome   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.   Delivery Devices Reservior masks can deliver O2 concentrations between 60-80% Nasal cannualae at 1-6L/min can deliver 24-50% Venturi masks allow accurate delivery of O2 If tachypnoeic over 30 breaths per minute an increase over the marked flow rate should be delivered, note this won't increase the FiO2! 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 respirat