Oxygen Medical Use Guideline BTS

British Thoracic Society

1. British Thoracic Society Guideline
for oxygen use in healthcare and
emergency settings
Key messages for doctors

2. BTS guideline for oxygen use in adults in
healthcare and emergency settings: Overview
•Why have a guideline?
•Oximetry as the basis of the guideline
•Normal range of oximetry
•Effects of hypoxaemia –sudden onset and gradual onset
•Aims of oxygen treatment and its place in resuscitation
•Recommended target saturations –with rationale
•Oxygen Alert cards
•Prescribing oxygen
•Devices
•What device and flow to use
•Monitoring

3. Oxygen -there is a problem
Published audits have shown that…
•Doctors and nurses have a poor understanding of how
oxygen should be used
•Oxygen is often given without a prescription
(In the 2015 BTS audit, 42% of hospital patients using oxygen had no prescription)
•If there is a prescription, patients do not always receive
what is specified on the prescription
•Where there is a prescription with target range, almost
one third of patients are outside the range
(9.5% of SpO
2results below target range and 21.5% above target range in 2015 BTS audit)

4. What is normal and what is
dangerous?

5. Normal Range for Oxygen saturation
Normal range for healthy young adults is
approximately 96-98% (Crapo AJRCCM, 1999;160:1525)
There is a slight fall with advancing age
A study of 871 subjects showed that age > 60 was associated with
minor SpO2 reduction of 0.4%(Witting MD et al Am J Emerg Med 2008: 26: 131-136)
An audit in Salford and Southend showed mean SpO2 of 96.7%
with SD 1.9 in 320 stable hospital patients aged >70 without lung
disease or heart failure (2 SD range 92.9 to 100%)
(O’Driscoll R et al Thorax 2008; 63(suppl Vii): A126)

6. What is a “normal”
nocturnal oxygen saturation?
Healthy subjects in all age groups routinely
desaturate to an average nadir of 90.4%
during the night (SD 3.1%)
GriesRE et al Chest 1996; 110: 1489-92
*Therefore, be cautious in interpreting a single oximetry measurement
from a sleeping patient. Watch the oximeter for a few minutes if in any
doubt (if the patient is otherwise stable) because normal overnight
dips are of short duration.

7. Effects of sudden hypoxaemia
(e.g Removal of oxygen mask at altitude or in a pressure chamber)
•Impaired mental function; Mean onset at SaO
264%
No evidence of mental impairment above SaO
2 84%
•Loss of consciousness at mean saturation of 56%
•Test Pilots in decompression chambers do not
experience breathlessness when the oxygen tension
is lowered, they make mistakes and then pass out
AkeroA et al EurRespirJ. 2005 ;25:725-30
Cottrell JJ et alAviatSpace Environ Med. 1995 ;66:126-30
Hoffman C, et al. Am J Physiol 1946, 145, 685-692

8. Clinical features of hypoxaemia
The effects are often non-specific
Depends if onset is chronic or acute
•Altered mental state
•Dyspnoea, cyanosis, Tachypnoea, arrhythmias, coma
•Hyperventilation when PaO
2<40mmHg (saturation <72%)
•Loss of consciousness ~ 32mmHg (saturation ~56%)
•Death approximately 20mmHg

9. Assessment/Measurement of hypoxaemia
CYANOSIS -Often not recognised,
-Absent with anaemia
BLOOD GASES -PaO
2 and SaO
2
PaO
2= Arterial oxygen partial pressure in blood gas specimen
SaO
2=Arterial oxygen saturation measured in blood gases
OXYGEN SATURATION -Easily measured by pulse oximetry
SpO
2 is widely available
SpO
2= Oxygen saturation measured by pulse oximeter

10. What happens at 9,000 metres
(approximately 29,000 feet) –it depends
Atmospheric pO2 5.7 kPa (< 1/3 sea level atmospheric oxygen tension)
PaO2 ~3.3 kPa Arterial Oxygen Saturation ~54%
Passengers unconscious in
<60 seconds if depressurised
Everest has been climbed without oxygen
SUDDEN
ACCLIMATISATION

11. Why is oxygen used?

12. Aims of emergency oxygen therapy
•To correct potentially harmful hypoxaemia
•To alleviate breathlessness (only if hypoxaemic)
Oxygen has not been proven to have any consistent effect on
the sensation of breathlessness in non-hypoxaemicpatients

13. Fallacies regarding oxygen therapy
John B Downs MD Respiratory care 2003;48:611-20
THE FALLACY: “Routine administration of
supplemental oxygen is useful, harmless and
clinically indicated.”
THE FACTS
•Little increase in oxygen-carrying capacity if SpO
2
is normal
•Renders pulse oximetry worthless as a measure of
ventilation
•May prevent early diagnosis & specific treatment of
hypoventilation
The guideline only recommends supplemental oxygen
when SpO
2is below the target range.

14. Oxygen therapy is only one element of
resuscitation of a critically ill patient
The oxygen carrying power of blood may be increased by
•Safeguarding the airway
•Enhancing circulating volume
•Correcting severe anaemia
•Enhancing cardiac output
•Avoiding/Reversing Respiratory Depressants
•Increasing Fraction of Inspired Oxygen (FIO
2)
•Establish the reason for Hypoxia and
Treat the underlying cause(e.g. Bronchospasm, LVF etc)
•Patient may need,CPAPor NIVor Invasive ventilation

15. Defining safe lower and upper
limits of oxygen saturation

16. What is the minimum arterial oxygen
level recommended in acute illness?
Target oxygen Saturation
Critical care consensus guidelines Minimum 90%
Surviving sepsis campaign Aim at 88-95%
But these patients have intensive levels of nursing & monitoring
This guideline recommends a minimum of
94% for most patients –combines what is
near normal and what is safe

17. Exposure to high concentrations of
oxygen may be harmful
•Absorption Atelectasis even at FIO
230-50%
•Intrapulmonary shunting
•Post-operative hypoxaemia
•Risk to COPD patients
•Coronary vasoconstriction
•Increased Systemic Vascular Resistance
•Reduced Cardiac Index
•Possible reperfusion injury post MI
•Increased CK level in STEMI and increased infarct size on MR scan at 3 months
•Worsens systolic myocardial performance
•Association of hyperoxaemiawith increased mortality in several ITU studies
•This guideline recommends an upper limit of 98% for most patients
•Combination of what is normal and safe

18. Some patients are at risk of CO2 retention
and acidosis if given high dose oxygen*
•Chronic Hypoxic Lung Disease
•COPD
•Severe Chronic Asthma
•Bronchiectasis / CF
•Chest wall disease
•Kyphoscoliosis
•Thoracoplasty
•Neuromuscular disease
•Morbid obesity and OHVS (Obesity Hypoventilation Syndrome)
*Blood gases should be checked for all such patients if they need oxygen
*Target saturation range is 88-92% if CO
2level is elevated (or if it was high in the past)

19. What is a safe lower Oxygen level in acute COPD?
In acute COPD
pO
2above 50 mm Hg
will prevent death
(SpO
2above about 85%) SaO
2
mmHg
PaO
2
OxyHaemoglobin Dissociation Curve
This guideline recommends a minimum saturation
of 88% for most COPD patients

20. What is a safe upper limit of oxygen target range in
acute COPD patients who need oxygen therapy?
RECOMMENDED UPPER LIMITS
Keep PaO
2below 10 kPaand keep SpO
2≤ 92%
in acute COPD pending blood gas results
(Maintain target range 88-92% if hypercapnic)

21. High concentration oxygen may double the risk of
death in acute exacerbations of COPD (AECOPD)
•Less acidosis and less hypercapnia on controlled oxygen therapy
Austin M et al BMJ 2010; 341: c5642

22. Danger of Rebound Hypoxaemia
•If you find a patient who is severely hypercapnic due to
excessive oxygen therapy……
•Do NOT stop oxygen therapy abruptly
•The PaCO
2is very high which will cause low PAO
2 as soon as
oxygen is removed as demonstrated by the Alveolar Gas
Equation (PAO
2 ≈ PIO
2–PaCO
2/RER )
It is safest to step down to 35% oxygen if the patient
is fully alert or call your Critical Care team to provide
mechanical ventilation if the patient is drowsy

23. Use of target ranges

24. Target Saturation Scheme
•Target oxygen saturation
prescription integrated into
patient drug chart and
monitoring

25. Recommended target saturations
The target ranges are a consensus agreement by the
guidelines group and the endorsing colleges and societies
Rationale for the target saturations is combination of what is
normalor near-normal and what is safe
Most patients 94 -98%
Risk of hypercapnic respiratory failure 88 –92%*
*Or patient specific saturation on Alert Card

26. Safeguarding patients at risk of
type 2 respiratory failure
•Lower target saturation range for these patients (88-92%)
•Education of patients and health care workers
•Use of controlled oxygen via Venturi masks or low flow nasal O
2
•Use of oxygen alert cards
•Issue of personal Venturi masks to high-risk patients

27. OXYGEN ALERT CARD
Name: __________________________________________________
I have a chronic respiratory condition and I am at risk of having a raised carbon
dioxide level in my blood during flare-ups of my condition (exacerbations)
Please use my ______% Venturi mask to achieve an oxygen saturation of
_____ % to _____ % during exacerbations of my condition
Use compressed air to drive nebulisers (with nasal oxygen a 2 l/min)
If compressed air is not available, limit oxygen-driven nebulisers to 6 minutes
12/05/2017

28. Oxygen Alert Cards and 24% masks can
avoid hypercapnic respiratory failure
associated with high flow oxygen masks
•Oxygen alert card (and a 24% Venturi mask) given to
patients admitted with hypercapnic acidosis with a
PO
2> 10kPa
•Patients instructed to show these to ambulance and
A&E staff

29. Prescribing Oxygen

30. DRUG OXYGEN
(Refer To Trust Oxygen Policy)
Circle target oxygen saturation
88-92% 94-98% Other___
STOP DATE
Starting device/flow rate________
PHARM
(Saturation is indicated in almost all cases except for
palliative terminal care)
SIGNATURE / PRINT NAME DATE
ddmmyy
Tick if saturation not indicated
Oxygen prescription on paper chart
Model for oxygen section in hospital prescription charts

31. Example of electronic prescription
*Electronic prescribing
can be linked to electronic
bedside observations to
calculate EWS/NEWS
automatically according
to oxygen target range.
Hypoxaemia

32. Oxygen use in palliative care
•Most breathlessness in cancer patients is caused by
specific issues such as airflow obstruction, infections or
pleural effusions and the main issue is to treat the cause
•Oxygen has been shown to relieve dyspnoea in
hypoxaemic cancer patients but not if PaO2 is >7.3 kPa
(saturation above about 90%)
•Morphine and Midazolam also relieve
breathlessness and are probably more effective

33. Devices

34. •Non re-breathing Reservoir Mask
•Critical illness / Trauma patients
•Post-cardiac or respiratory arrest
•Delivers O
2concentrations
between 60 & 80% or above
•Effective for short term treatment
High Concentration Reservoir Mask (RM)

35. Nasal Cannulae (N)
•Recommended in the Guideline as
suitable for most patients with both
Type I and II respiratory failure.
•1-6L/min gives approx 24-50% FIO
2
•FIO
2depends on oxygen flow rate
and patient’s minute volume and
inspiratory flow and pattern of
breathing.
•Comfortable and easily tolerated
•No re-breathing
•Low cost product
•Preferred by patients (vs simple mask)

36. Venturi or Fixed Performance Masks (V)
•Aim to deliver constant oxygen
concentration within and between breaths.
•24-40% VenturiMasks operate accurately
A 60% Venturimask gives ~50% FIO
2
•With TACHYPNOEA (RR >30/min) the
oxygen flow rate should be increased by
above the minimum flow rate shown on the
packaging -see next slide
•Increasing flow does not increase oxygen
concentration because it is a fixed dose
device

37. 24% Venturi -2 L/min -Use 3 l/min if RR >30
28% Venturi -4 L/min -Use 6 l/min if RR >30
35% Venturi -8 L/min -Use 12 l/min if RR >30
40% Venturi -10 L/min -Use 15 l/min if RR >30
60% Venturi -15 L/min -Change to RM if 60%
Venturi is not sufficient

38. Operation of Venturi valve
O
2
O
2
+
Air
Air
Air
For 24% Venturi mask, the typical oxygen flow of 2 l/min gives a total gas flow of 51 l/min
For 28% Venturi mask, 4 l/min oxygen flow, gives a total gas flow of 44 l/min(Table 10.2)

39. Simple face mask (SM)
(Medium concentration, variable performance)
•Used for patients with Type-I
respiratory failure.
•Delivers variable O
2concentration
between 35% & 60%.
•Low cost product.
•Flow 5-10 L/min
Flow must be at least 5 L/min to
avoid CO
2 build up and resistance to
breathing

40. Humidified Oxygen (H)
•Tracheostomy
•Bronchiectasis
•Cystic Fibrosis patients
•Physiotherapists may advise
humidification
•Patients on High flow whisper CPAP
•Humidification may be provided by
cold or warm humidifiers
•( H24, H28, H35etc )
The illustration shows a cold humidifier delivering 28% oxygen at 5 l/min flow
N.B. There is little evidence for humidification in routine oxygen therapy

41. Tracheostomy Mask (TM)
•“Neck breathing patients”
•Adjust oxygen flow to
maintain target saturation
•Prolonged oxygen use
requires humidification
•Patients may also need
suction to remove airway
mucus
12/05/2017

42. High flow humidified nasal oxygen (HFN)
•High flow nasal oxygen using
specialised equipment may be used
as an alternative to reservoir mask
treatment in patients with acute
respiratory failure without
hypercapnia
•It is mostly used in Intensive Care
Units, High Dependency Units and
other specialised areas
12/05/2017

43. Oxygen Flow Meter3
2
1
3
2
1
This diagram
illustrates the
correct setting of
the flow meter to
deliver a flow of 2
litres per minute
The centre of the ball indicates the correct flow rate.
12/05/2017

44. Beware of airoutlets
They may be mistaken for oxygen outlets
Use a cover for
air outlets or else
remove the flow
meter for air
when not in use
Oxygen outlet
(Usually white)
Air outlet
(usually black)
12/05/2017

45. What device and flow rate
should you use in each
situation?

46. Many patients need high-dose oxygen
to normalize saturation
•Severe Pneumonia
•Severe LVF
•Major Trauma
•Sepsis and Shock
•Major atelectasis
•Pulmonary Embolism
•Lung Fibrosis
•Etc etc etc
12/05/2017

47. Oxygen use in specific illnesses
4 Major groups of patients
See Tables 1-4 and Charts 1-2 in BTS Emergency Oxygen Guideline
•Critical illness requiring high levels of supplemental oxygen
•Serious illness requiring moderate levels of supplemental
oxygen if a patient is hypoxemic
•COPD and other conditions requiring controlled or low-dose
oxygen therapy
•Conditions for which patients should be monitored closely but
oxygen therapy is not required unless the patient is
hypoxaemic(This group includes most cases of chest pain, heart attacks, stroke
etc)
12/05/2017

48. Is this patient at risk of hypercapnic respiratory failure
(Type 2 Respiratory Failure)?
YES
Target saturation is 88-92% whilst
awaiting blood gas results
NO
Aim for SpO2 94-98%
Specific instructions are given for each category of patient depending on blood gas results etc
•Is the patient critically ill
(see Table 1 and section
8.10 in Guideline)
Commence treatment with
reservoir mask or bag-valve
mask and manage as advised in
Table 1
Yes
No
Chart 1
Oxygen prescription for acutely hypoxaemic patients in hospital

49. Yes
CHECK ABGs
Monitor SpO
2
Oxygen may not be
required
Prescribe target
range in case SpO
2
falls
No
SpO
2≤ 93%
PaCO
2<
45mmHg
(Normal or
low)
PaCO
2 >45mmHg
or patient tiring
Seek immediate
senior review
Consider invasive
ventilation
Treat
appropriately
aiming to keep
SpO
294-98%
and repeat
gases in 30-60
minutes
Seek immediate
senior review
Consider NIV or
invasive ventilation
Repeat ABG’s:
If Respiratory Acidosis
( pH <7.35 & PCO2>45)Seek
immediate senior review,
consider NIV/ICU.
Consider reducing FiO
2
if PO
2 > 60
Treat urgently. Aim for
SpO2 of 94-98%until
immediate senior
review.
Also consider COPD
needing SpO2 88-92%
Treat with low flow nasal
oxygen or lowest
strength Venturimask
that will keep SpO
2
between 88-92%
pH >7.35
and PaCO2 >45mmHg
(Hypercapnia)
Treat with lowestFiO
2via
Venturi mask or 1-2 l/
min nasal oxygen to keep
SpO
288-92%pending
senior medical advice or
NIV or ICU admission
pH <7.35
and PaCO
2 >45mmHg
(Respiratory Acidosis)
or patient tiring
Obtain ABGs
Treat
appropriately
aiming to keep
SpO
294-98%
YES
(Risk of CO
2Retention)
No known Risk
of CO
2Retention

50. Titrating Oxygen up and down
Venturi 24% (blue) 2-3 l/min ORNasal cannulae1L
Venturi 28% (white) 4-6 l/min ORNasal cannulae2L
Venturi 35% (yellow) 8-12 l/min ORNasal cannulae4L
Venturi 40% (red) 10-15 l/min ORNasal cannulaeor Simple face mask 5-6L/min
Venturi 60% (green) 15 l/minORSimple face mask 7-10L/min
Reservoir mask at 15L oxygen flow
Seek medical advice
If reservoir mask required
seek senior medical input immediately
This table below shows APPROXIMATE conversion values.

51. FLOW CHART FOR OXYGEN ADMINISTRATION ON GENERAL WARDS IN HOSPITALS
See target saturation in the patient’s drug chart. Choose the most suitable delivery system and flow rate
Titrate oxygen upor down
to maintain the target
oxygen saturation
The table below shows available
options for stepping dosage up
or down.
The chart does NOT imply any
equivalence of dose between
Venturi masks and nasal
cannulae.
Allow at least 5 minutes at each
dose before adjusting further
upwards or downwards
(except with major and sudden
fall in saturation –falls ≥3% also
require clinical review)
Once your patient has
adequate and stable saturation
on minimal oxygen dose,
consider discontinuation of
oxygen therapy.
Patients in a peri-arrest situation and critically ill patients should be given oxygen therapy at 15 l/min via reservoir mask or bag-valve mask whilst immediate medical help is arriving.
(Except for patients with COPD with known oxygen sensitivity recorded in patient’s case notes and drug chart or in the Electronic Patient Record (EPR): keep saturation at 88-92% for
this sub-group of patients)

52. Monitoring patients
•Oxygen saturation and delivery system should be
recorded on the bedside monitoring chart or EPR
•Delivery devices and/or flow rates should be
adjusted to keep oxygen saturation in target range

53. Respiratory Rate, Oxygen saturation and oxygen therapy
Clinical review required if saturation is outside target range
Target range: 94-98% 88-92% Other________
Respiratory
Rate
Respiratory
Rate
Oxygen
Saturation %
Oxygen
Saturation %
Oxygen
Device or Air
Oxygen
Device or Air
Oxygen flow
rate L/min
Oxygen flow
rate L/min
Your
Initials*
Your
Initials*
Key elements of an oxygen observation chart
*It is recommended that the 2017 NEWS chart should be used*
*All changes to oxygen delivery systems must be initialled by a registered
nurse or equivalent
If the patient is medically stable and in the target range on two consecutive
rounds, report to a registered nurse to consider weaning off oxygen

54. Standard abbreviations for oxygen delivery devices
A Air
NNasal Cannulae HFNHighFlow Humidified Nasal Cannulae
V24VenturiMask 24% V28VenturiMask 28% V35VenturiMask 35%
V40VenturiMask 40% V60VenturiMask 60%
H28Humidified O
228% H40Humidified O
240% H60Humidified O
260%
RMReservoir Mask SMSimple Face Mask TMTracheostomyMask
CPAPContinuous Positive
AirwayPressure
NIVNon-Invasive
Ventilation

55. Summary
1.Prescribe oxygen to a target saturation for each group of
patients
•94 -98% for most adult patients
•88 -92% if risk of hypercapnia
(or patient-specific target on alert card)
1.Administer oxygen to achieve target saturation
2.Monitor oxygen saturation and keep in target range
3.Taper oxygen dose and stop when stable
4.Audit your practice