Transcript Evaluating patients with suspected hypoxic respiratory

Key messages from the
British Thoracic Society
Emergency Oxygen Guideline
This presentation was last updated on 19-07-2010
Oxygen - there is a problem
Published 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
Oxygen - there was a disagreement
• Chest Physicians
• Intensivists / Anaesthetists
• Emergency Medicine / A&E clinicians
• Ambulance teams
Time to do something!
• The British Thoracic Society, together with 21 other
Societies and Colleges has produced a multidiscipline Guideline for emergency oxygen use.
• This Guideline covers most aspects of emergency
oxygen use in pre-hospital care and in emergency
hospital care for adults (excludes NIV and IPPV)
British Thoracic Society
Guideline for emergency oxygen use in adult patients
Endorsed by:
Association of Respiratory Nurse Specialists
Association for Respiratory Technology and Physiology
British Association for Emergency Medicine
British Cardiovascular Society
British Geriatric Society
British Paramedic Association
Chartered Society of Physiotherapy
General Practice Airways Group (GPIAG)
Intensive Care Society
Joint Royal Colleges Ambulance Liaison Committee
Resuscitation Council (UK)
Royal College of Anaesthetists
Royal College of General Practitioners
Royal College of Midwives
Royal College of Nursing
Royal College of Obstetricians and Gynaecologists (approved)
Royal College of Physicians (London, Glasgow, Edinburgh)
Royal Pharmaceutical Society of Great Britain
Society for Acute Medicine
O’Driscoll BR. Howard LS, Davison AG. Thorax 2008; 63 Suppl VI
Basis of the BTS guideline
Prescribing by target oxygen saturation
Keep it normal/near-normal for all patients
except pre-defined groups who are at risk
from hypercapnic respiratory failure
What is normal and
what is dangerous?
Normal Range for Oxygen saturation
Normal range for healthy young adults is
approximately 96-98%
(Crapo AJRCCM, 1999;160:1525)
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
O’Driscoll R et al Thorax 2008; 63(suppl Vii): A126
Effects of sudden hypoxia
(e.g Removal of oxygen mask at altitude or in a pressure chamber)
• Impaired mental function; Mean onset at SaO2 64% No
evidence of impairment above 84% saturation
• Loss of consciousness at mean saturation of 56%
• Test Pilots in decompression chambers do not experience
breathlessness when the oxygen tension is lowered
Akero A et al Eur Respir J. 2005 ;25:725-30
Cottrell JJ et al Aviat Space Environ Med. 1995 ;66:126-30
Hoffman C, et al. Am J Physiol 1946, 145, 685-692
What happens at 9,000 metres
(approximately 29,000 feet) – it depends
Atmospheric pO2 5.7 kPa at 9,000m (Sea level pO2 is 20 kPa)
PaO2 ~3.3 kPa and arterial oxygen saturation ~54%
SaO2 34-70% at 8400m (Mean 54%, n=4) Grocott M et al NEJM 2009: 360:140-149
SUDDEN
Passengers unconscious in <60
seconds if depressurised
ACCLIMATISATION
Everest has been climbed without
oxygen
Why is oxygen
used?
Aims of emergency
oxygen therapy
• To correct or prevent potentially harmful hypoxaemia
• To alleviate breathlessness (only if hypoxaemic)
Oxygen has no effect on breathlessness if the oxygen saturation is normal
Fallacies regarding Oxygen Therapy
“Routine administration of supplemental oxygen is
useful, harmless and clinically indicated”
•
Little increase in oxygen-carrying capacity
•
Renders pulse oximetry worthless as a measure of ventilation
•
May prevent early diagnosis & specific treatment of hypoventilation
This guideline only recommends supplemental oxygen
when SpO2 is below the target range
or in critical illness or CO Poisoning
John B Downs MD Respiratory care 2003;48:611-20
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 (FIO2)
• Establish the reason for Hypoxia and
treat the underlying cause (e.g Bronchospasm, LVF etc)
• Patient may need, CPAP or NIV or Invasive ventilation
Defining safe lower
and upper limits of
oxygen saturation
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
Exposure to high concentrations of
oxygen may be harmful
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Absorption Atelectasis even at FIO2 30-50%
Intrapulmonary shunting
Post-operative hypoxaemia (on return to room air)
Risk to COPD patients
Coronary vasoconstriction
Increased Systemic Vascular Resistance
Reduced Cardiac Index
Possible reperfusion injury post MI
Hyperoxaemia was associated with INCREASED mortality in survivors of cardiac arrest
Oxygen therapy INCREASED mortality in non-hypoxic patients with mild-moderate stroke
This guideline recommends an upper
limit of 98% for most patients.
Combination of what is normal and safe
Downs JB. Respiratory Care 2003; 48: 611-20
Kaneda T et al. Jpn Circ J 2001; 213-8
Haque WA et al. J Am Coll Cardiol 1996; 2: 353-7
Ronning OM et al. Stroke 1999; 30 : 2033-37
Harten JM et al J Cardiothoracic Vasc Anaesth 2005; 19: 173-5
Frobert O et al. Cardiovasc Ultrasound 2004; 2: 22
Thomaon aj ET AL. BMJ 2002; 1406-7
Kilgannon JH et al. JAMA 2010; 302: 2165-71
Exposure to high concentrations of
oxygen may be harmful
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Absorption Atelectasis even at FIO2 30-50%1
Intrapulmonary shunting1
Post-operative hypoxaemia (on return to room air)1
Risk to COPD patients2
Coronary vasoconstriction3
Increased Systemic Vascular Resistance3
Reduced Cardiac Index after coronary bypass surgery4
Possible reperfusion injury post Myocardial Infarction5
Oxygen therapy increased mortality in non-hypoxic patients with mild-moderate stroke6
Hyperoxaemia was associated with increased mortality in survivors of cardiac arrest7
This guideline recommends an upper limit of 98% for
most patients. Combination of what is normal and safe
1. Downs JB. Respiratory Care 2003; 48: 611-20
5. Kaneda T et al. Jpn Circ J 2001; 213-8
2. Thomson AJ et al. BMJ 2002; 1406-7
6. Ronning OM et al. Stroke 1999; 30 : 2033-37
3. Farquhar H et al. Am Heart J. 2009;158:371-7
7. Kilgannon JH et al. JAMA 2010; 302: 2165-71
4. Harten JM et al J Cardiothoracic Vasc Anaesth 2005; 19: 173-5
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
• Obesity hypoventilation
What is a safe lower Oxygen
level in acute COPD?
In acute COPD
pO2 above 6.7 kPa
or 50 mm Hg
will prevent death
SaO2 above about 85%
SaO2
OxyHaemoglobin Dissociation Curve
(Keep SpO2 ≥88% to allow for oximeter
error and ensure PaO2 >85% )
mmHg
PaO2
Murphy R, Driscoll P, O’Driscoll R Emerg Med J 2001; 18:333-9
This guideline recommends a minimum
Sp02 of 88% for most COPD patients
What is a safe upper limit of oxygen
target range in acute COPD ?
• 47% of 982 patients with exacerbation of COPD were hypercapnic on
arrival in hospital
• 20% had Respiratory Acidosis (pH < 7.35)
• 5% had pH < 7.25 (and were likely to need ICU care)
• Most hypercapnic patients with pO2 > 10 kPa were acidotic
(equivalent to oxygen saturation of above ~ 92%)
Plant et al Thorax 2000; 55:550
i.e. They had been given too much oxygen
RECOMMENDED UPPER LIMITS
Keep PaO2 below 10 kPa and
keep SpO2 ≤ 92% in acute COPD
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 normal and what is safe
Most patients
94 - 98%
Risk of hypercapnic respiratory failure
88 – 92%*
*Or patient specific saturation on Alert Card
Using Target Saturation Scheme
• O2 prescribed by target saturation
(like an Insulin “BM sliding-scale chart”)
• Oxygen delivery device and flow
administered and changed if necessary
to keep the SpO2 in the target range
• Target oxygen saturation prescription
integrated into patient drug chart and
monitoring
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
• Use of oxygen alert cards
• Issue of personal Venturi masks to high-risk patients
OXYGEN ALERT CARD
Name:
______________________________
I am at risk of type II respiratory failure with a raised CO2 level.
Please use my
% Venturi mask to achieve an
oxygen saturation of _____ % to _____ % during exacerbations
Use compressed air to drive nebulisers (with nasal oxygen a 2 l/min).
If compressed air not available, limit oxygen-driven nebulisers to 6 minutes.
Oxygen Alert Cards and Venturi masks can avoid
hypercapnic respiratory failure associated with
high flow oxygen masks
• Oxygen alert card (and a Venturi mask) given to patients admitted
with hypercapnic acidosis with a PO2 > 10kPa.
• Patients instructed to show these to ambulance and A&E staff.
After introduction of alert cards
• Use of Venturi mask: 63% in Ambulance
94% in A&E
Gooptu B, Ward L, Davison A et al. Oxygen alert cards and controlled oxygen masks:
Emerg Med J 2006; 23:636-8
Danger of Rebound Hypoxaemia
• If you find a patient who is severely hypercapnic due to
excessive oxygen therapy (e.g pH 7.23 Pa CO2 13 PaO2 35)
• Do NOT stop oxygen therapy abruptly.
• The PaCO2 is very high which causes low PAO2 due to
the Alveolar Gas Equation (PAO2 ≈ PIO2 –PACO2/RER )
If suddenly changed to air -- PAO2 = 20 – 16.2 = 4 kPa ( PaO2 will be even lower)
It is safest to step down to 35% oxygen if the patient is
fully alert or call your Critical Care team arrive to provide
mechanical ventilation if the patient is drowsy.
Prescribing Oxygen
Oxygen prescription
Model for oxygen section in hospital prescription charts
DRUG
OXYGEN
(Refer To Trust Oxygen Policy)
STOP DATE
Circle target oxygen saturation
88-92%
94-98%
Other___
Starting device/flow rate________
PRN / Continuous
Tick if saturation not indicated
PHARM
(Saturation is indicated in almost all cases except for
palliative terminal care)
SIGNATURE / PRINT NAME
DATE
ddmmyy
Oxygen prescription
and Administration
• Clinician (usually a doctor) prescribes oxygen by
circling the desired oxygen saturation target range
• Staff use appropriate device and flow rates in order
to maintain saturation within the target range
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
hypoxic cancer patients
• Morphine and Midazolam may also relieve
breathlessness
Devices
High Concentration Reservoir Mask
• Non re-breathing Reservoir Mask.
• Critical illness / Trauma patients.
• Post-cardiac or respiratory arrest.
• Delivers O2 concentrations
between 60 & 80% or above
• Effective for short term treatment.
Nasal Cannulae
• Recommended in the Guideline as
suitable for most patients with both type I
and II respiratory failure.
• 2-6L/min gives approx 24-50% FIO2
• FIO2 depends 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)
Simple face mask
(Medium concentration,
variable performance)
• Used for patients with type I respiratory
failure.
• Delivers variable O2 concentration
between 35% & 60%.
• Low cost product.
• Flow 5-10 L/min
Flow must be at least 5 L/min to avoid
CO2 build up and resistance to
breathing
(although packaging may say 2-10L)
Venturi or Fixed Performance Masks
Aim to deliver constant oxygen concentration
within and between breaths.
24-40% Venturi Masks operate accurately
A 60% Venturi mask gives ~50% FIO2
With TACHYPNOEA (RR >30/min) the oxygen
supply should be increased by 50%
Increasing flow does not increase oxygen
concentration
Operation of Venturi valve
Air
O2
O2
+
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)
Oxygen Flow Meter
The centre of the ball indicates the correct flow rate.
3
3
2
2
1
1
This diagram illustrates the correct
setting of the flow meter to deliver
a flow of 2 litres per minute
What device and
flow rate should you
use in each
situation?
Standard Oxygen Therapy 1960s-2008
Acute Patients
Stable Patients
Oxygen therapy 2008 onwards
Selected
COPD
patients
Critical
illness
Most patients
Many patients need high-dose oxygen to
normalize saturation
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Severe Pneumonia
Severe LVF
Major Trauma
Sepsis and Shock
Major atelectasis
Pulmonary Embolism
Lung Fibrosis
Etc etc etc
BTS Recommendations
Serious Illness Requiring Moderate Levels of
Oxygen if the Patient is Hypoxaemic
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
Prescribe to target
Critical Illness Requiring High Levels
of Oxygen Supplementation
Prior to Blood Gas Analysis
Is the patient
critically ill*?
Yes – treat with
reservoir or bag-valve
mask
No
Is the patient at risk of
hypercapnic respiratory failure?
No – is SpO2
< 85%?
No – aim for SpO2
94-98%
Yes – aim for SpO2 88-92% or
level on alert card pending ABG
Start with 24 or 28%
Venturi mask
Start with
nasal cannulae (2-6 l/min)
or face mask (5-10 l/min)
*Critical illness is defined as cardiopulmonary arrest, shock, major trauma & head injury, near-drowning, anaphylaxis, major pulmonary haemorrhage
and carbon monoxide poisoning.
Yes – aim for SpO2 88-92% or
level on alert card pending ABG
Reduce FiO2 if SpO2 > 92%
Perform Arterial Blood Gases
pH < 7.35 and
PaCO2 > 6.0 kPa or
patient tiring
Consider NIV or IPPV
Yes – aim for SpO2 88-92% or
level on alert card pending ABG
Reduce FiO2 if SpO2 > 92%
Perform Arterial Blood Gases
pH < 7.35 and
PaCO2 > 6.0 kPa or
patient tiring
pH > 7.35 and PaCO2
> 6.0 kPa
Consider NIV or IPPV
Maintain SpO2 88-92%
with lowest FiO2
Repeat ABG in 30-60 mins
Yes – aim for SpO2 88-92% or
level on alert card pending ABG
Reduce FiO2 if SpO2 > 92%
Perform Arterial Blood Gases
pH < 7.35 and
PaCO2 > 6.0 kPa or
patient tiring
pH > 7.35 and PaCO2
> 6.0 kPa
PaCO2 < 6.0 kPa
Consider NIV or IPPV
Maintain SpO2 88-92%
with lowest FiO2
Maintain SpO2 94-98% with
lowest FiO2 unless previous
NIV or IPPV
Repeat ABG in 30-60 mins
Titrating Oxygen up and down
.
This table below shows APPROXIMATE conversion values.
Venturi 24% (blue) 2-4l/min
OR
Nasal specs 1L
Venturi 28% (white) 4-6 l/min
OR
Nasal specs 2L
Venturi 35% (yellow) 8-10l/min
OR
Nasal spec 4L
Venturi 40% (red)10-12l/min
OR
Simple face mask 5-6L/min
Venturi 60% (green) 15l/min
OR
Simple face mask 7-10L/min
Reservoir mask at 15L oxygen flow
seek medical advice
I f reservoir mask required
seek senior medical Input immediately
Monitoring patients
• Oxygen saturation and delivery system should
be recorded on the monitoring chart.
• Delivery devices and/or flow rates should be
adjusted to keep oxygen saturation in target
range.
Model for respiratory section of observation chart
Respiratory Rate, Oxygen saturation and oxygen therapy
Clinical review required if saturation is outside target range
Continuous Oxygen / PRN / Not on oxygen therapy
Target range:
88-92%
94-98%
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*
Codes for recording oxygen delivery on observation chart
A
Air. (Patient not requiring oxygen therapy)
AX Measurement on air for a patient who is on PRN Oxygen therapy
AW Measurement on air for a patient who is being weaned off oxygen but not yet discontinued on chart
N
Nasal Cannulae
SM Simple mask
V24 Venturi 24% V28 Venturi 28% V35 Venturi 35% V40 Venturi 40% V60 Venturi 60%
H28 Humidified oxygen at 28% (“Quatro” or similar device) (also H 35, H40, H60)
RM Reservoir Mask
TM Tracheostomy Mask
CP Patient on CPAP system
NIV Patient on NIV system
OTH Other device
*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 (unless the oxygen prescription is part of a timed protocol
From the BTS Emergency Oxygen
Guideline To the patient
• Guideline agreed by the whole UK medical, nursing and AHP community
(endorsed by 21 Colleges and Societies)
• Medical and Nurse/Physio Champions in every Hospital Trust
• New prescription charts and monitoring charts in every hospital
• Training packages on BTS website
• NPSA Rapid Response Report September 2009
• Audit tools on BTS website www.brit-thoracic.org.uk
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)
2.
Administer oxygen to achieve target saturation
3.
Monitor oxygen saturation and keep in target range
4.
Taper oxygen dose and stop when stable
5.
Audit your practice
6.
All information on www.brit-thoracic.org.uk