1. Emergency Oxygen Therapy
Is there a problem?

2. Clinical Case No. 1 79-year-old female, diabetic, morbidly obese
Admitted with ‘LVF’
Overnight ‘Reduced GCS ?cause’
15L oxygen via non-rebreathe in situ
ABG showed pH 6.9, pCO2 15.9kPa normal range kPa
Woke up when oxygen removed!
Oxygen prescribed with target SpO %, documented in notes
Following morning on AMU GCS 3/15 and 15L NRB back in situ!
Not a candidate for NIV → RIP

3. Clinical Case No. 2
75-year-old male, cervical myelopathy (cord compression due to OA)
Admitted with reduced GCS (9/15)
pH 7.1, pCO2 9.6kPa (respiratory acidosis)
Improved with controlled O %
Treated for pneumonia
Became drowsy again with rising pCO2 and low RR
Miotic (small) pupils
Covered in fentanyl patches
Improved once patches removed and naloxone given!

4. Clinical Case No. 3 86-year-old female from RH, osteoporosis
Admitted with pneumonia
Asked to see on AMU because of ‘fitting’
Hypotensive, myoclonic jerks, bounding pulse
On 10L O2 via NRB since admission
ABG showed pH 7.23, pCO2 12.9kPa
Minimal improvement with reduced FiO2
Not a candidate for HDU or NIV on the respiratory ward → RIP

5. Oxygen —there is a problem!
Published national audits have shown;
Doctors and nurses have a poor understanding of how oxygen should be used
Oxygen is often given without any prescription
If there is a prescription, it is unusual for the patient to receive what is specified on the prescription
Monitoring of oxygen administration is often poor
→OXYGEN IS DANGEROUS NPSA alert 2009

6. Emergency Oxygen Use in Adult Patients
BTS Guideline 2009
Prescribing by target oxygen saturation
Keeping SpO2 within normal limits
Target SpO % for most patients 92-98% if >70
Target SpO % (pO kPa) for those with or at risk of hypercapnic (high CO2) respiratory failure

7. Aims of Emergency Oxygen Therapy
To correct or prevent potentially harmful hypoxaemia
To alleviate breathlessness only if hypoxaemic
Increasing FiO2 (inspired oxygen concentration) is only one way of increasing overall O2 carrying capacity of blood:
Protect airway
Enhance circulating volume and cardiac output
Correct severe anaemia
Avoid or reverse respiratory depressants e.g. morphine
Treat underlying cause e.g. LVF, asthma

8. Indications for Emergency Oxygen
SpO2 <94% <88% if risk of hypercapnia
Critical illness e.g. septic shock, major trauma, anaphylaxis, acute LVF during initial ABCDE
Carbon monoxide poisoning irrespective of SpO2

9. Too much O2 can be harmful…
Risk of hypercapnia (high CO2) in selected patients
some patients with chronic hypercapnia are dependent on hypoxaemia to maintain respiratory drive
Constriction of coronary arteries
high O2 levels INCREASED mortality in survivors of cardiac arrest
Constriction of cerebral arteries
high O2 levels INCREASED mortality in non-hypoxic patients with mild-moderate stroke

10. Patients at risk of hypercapnia?
COPD not all patients with COPD —elevated HCO3- on ABG is a useful clue to chronic CO2 retention
Morbid obesity OHS and OSA
Neuromuscular weakness MND, myasthenia, GBS
Chest wall deformity kyphoscoliosis
Reduced conscious level
Morphine and other respiratory sedatives

11. How should oxygen be delivered to…
Critically unwell / severely hypoxaemic patients?
high-concentration reservoir / non- rebreathe mask
delivers 60-80% O2 at 10-15L/min
SHORT-TERM use only
ensure bag is filled with oxygen before attaching to patient
DO NOT turn down oxygen flow below 10L/min

12. How should oxygen be delivered to…
Most other patients?
nasal cannulae / specs
comfortable, well-tolerated, low- cost and no risk of re-breathing
2-6L/min gives ~24-50% oxygen
concentration actually delivered also depends on patient’s:
tidal volume
respiratory rate
patients with COPD tend to breath disproportionately more oxygen than air with every breath → risk of hypercapnia

13. How should oxygen be delivered to…
Patients at risk of hypercapnic respiratory failure?
Venturi / fixed performance masks
increasing oxygen flow does NOT increase FiO2
accurate between 24-40%
60% venturi delivers ~50% oxygen
less affected by tidal volume and respiratory rate (useful in COPD)

14. Monitoring and Titration of O2
ALWAYS
question whether oxygen is actually required and if so, what is the target saturation range
monitor oxygen saturations frequently / continuously
titrate flow rate and / or device up or down until target saturations achieved
use minimum flow rate required
seek to wean off oxygen as soon as possible
NEVER
leave patients on high- concentration O2 without repeating ABGs
use non-rebreathe masks with flow rates <10L/min
adjust the flow rate through a Venturi device without changing the mask
suddenly stop high-concentration oxygen in a hypercapnic patient without titrating down first (35%)

15. BTS National Oxygen Audits
Audit Year
2008
2009
2010
2011
2012
2013
2015
Oxygen prescribed with a target range?
10%
40%
41%
43%
46%
51%
53%
Percent of drug rounds on which oxygen was signed for on the drug chart? 5%
27 %
16 %
20%
21%
28%
Percentage of patients within target range where this was prescribed 69%
9% of patents at risk of iatrogenic hypercapnia due to being >2% above their target range (despite recognised hypercapnic risk)

16. How can we improve?
Nurse-led and delivered process —ask yourself these key questions:
Does this patient actually need oxygen?
check saturations on air oxygen won’t help unless hypoxaemic
only give oxygen if patient is outside of their target range
if in doubt, ask somebody!
Is oxygen prescribed on the drug chart?
immediately ask a clinician to prescribe if not
Which device is best for my patient
nasal cannulae for majority, Venturi mask if risk of hypercapnia
What is the target saturation range and is this being achieved?
titrate oxygen up or down until target SpO2 is achieved

17. Key Learning Points
Oxygen is a drug —if it’s not prescribed, DON’T GIVE IT except in an emergency —like most drugs, oxygen has the potential to kill
Consider risk of CO2 retention not just COPD patients
Select best device for delivery nasal cannulae > Venturi > non-rebreathe
Frequent monitoring of SpO2 is required in all patients on oxygen
Titrate O2 up or down to achieve target SpO % 88-92% if high risk
Avoid hyperoxaemia risk of hypercapnia and adverse cerebral / coronary effects
Wean down oxygen at the earliest opportunity once stable
NEVER leave patients on high-concentration O2 for prolonged periods