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Emergency Oxygen Use

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					                                  Emergency Oxygen Use
           British Thoracic Society Guideline for Emergency Oxygen use in Adult Patients
                                – Thorax 2008, 63: suppl VI, Vi1-Vi73
Background

   In October 2008 new guidelines for the emergency use of oxygen in adult
    patients was prepared by the British Thoracic Society with the endorsement of a
    large number of other specialist societies.


Indications

   Oxygen is the treatment for hypoxaemia not the treatment for breathlessness
    (oxygen has not been shown to improve breathlessness in non-hypoxaemic
    patients).
   The essence of the guideline is the requirement for oxygen to be prescribed
    against a target saturation range with an indication of which delivery mechanism
    to use and the need for those who administer oxygen therapy to monitor the
    patient against the target saturation range.
   It is suggested that normal or near normal oxygen saturation is aimed for in all
    acutely ill patients except for those at risk of hypercapnoeic respiratory failure or
    those with terminal palliative care.
   Oxygen saturation (the fifth vital sign) should be checked by pulse oximetry in all
    breathless and acutely ill patients. Breathlessness does not always come from a
    low oxygen level and blood gases can sometimes be necessary to identify
    acidosis without the presence of hypoxia which can be driving breathlessness.
   All critically ill patients should be assessed and monitored using a physiological
    track and trigger system.


Oxygen Prescription

   Oxygen should be prescribed against a target saturation of 94-98% for most
    acutely ill patients or target saturation range of 88-92% for those at risk of
    hypercapnoeic respiratory failure (e.g. COPD, chronic neuromuscular disease,
    chest wall disorder and morbid obesity). The oxygen should be recorded on a
    drug chart.


Oxygen Administration

   An appropriate device and flow rate should be used to achieve the prescribed
    oxygen saturations.
   Typical appropriate devices include Venturi masks for those patients at risk of
    type II respiratory failure. Venturi masks include 24, 28, 35, 40 and 60% masks.
    Other appropriate devices include nasal cannulae which is typically prescribed
    between 1-4 l/min or simple face mask (5-6 l/min of oxygen) or reservoir mask
    (10-15 l/min of oxygen)




Emergency Oxygen Use                       Dr D N Leitch                              November 2008
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Oxygen Monitoring

   Those patients on oxygen should be regularly assessed and the delivery system
    recorded together with the pulse oximetry result and how this compares with the
    oxygen prescription saturation range.
   At the time of subsequent monitoring if the oxygen saturation falls outside the
    prescribed oxygen saturation range then the delivery system should be changed
    in accordance with the saturation.
   On each drug round patients on oxygen should have their saturation compared
    against a target saturation range.


Weaning and Discontinuation of Oxygen

   Oxygen should be reduced in stable patients with satisfactory oxygen saturation
    and removed from the drug chart once oxygen is discontinued.


Summary of Key Recommendations for Emergency Oxygen Use

   Recommended target saturation range for most acutely ill patients is 94-98%
    (recognising that some patients over 70 years of age may have target saturation
    range 92-94%).
   Most non-hypoxaemic breathless patients do not require oxygen however a
    sudden drop in saturation of 3% or more, even within the normal saturation
    range, should prompt fuller assessment.
   Most patients with COPD and risk factors for hypercapnoeic respiratory failure
    e.g morbid obesity, chest wall deformity or neuromuscular disease, should have a
    saturation range of 88-92% depending on the availability of blood gas results
    there after or previous available blood gas results which indicate vulnerability to
    hypercapnoeic respiratory failure. Any patients with previous hyper-apnoeic
    respiratory failure it is recommended have a target saturation of 88-92%.
   For most patients at risk of hypercapnoeic respiratory failure it is recommended
    that oxygen delivery is commenced with a 24 or 28% Venturi mask pending
    urgent blood gas results.
   For patients not at risk of hypercapnoeic respiratory failure with a target
    saturation of 94 to 98%. Initial oxygen delivery can either be with nasal cannulae
    3-4 l/min, simple face mask 5-10 l/min or reservoir mask as necessary assuming
    oxygen saturation is within the desired range.
   It should be noted that all patients requiring oxygen require arterial blood gases.
   Oxygen saturation generally falls in the supine position.


Clinical and Laboratory Assessment

   All patients should be assessed as clinically appropriate including pulse, blood
    pressure, respiratory rate with assistance as necessary.
   It is recommended that physiological track and trigger systems and early warning
    scores are used with subsequently assessment as necessary.
   The presence of a near normal or normal oxygen saturation does not always
    indicate the need for arterial blood gas measurement as abnormal pH or carbon
    dioxide can still be associated with breathlessness despite normal saturation.
    Similarly full blood count assessment is necessary.


Emergency Oxygen Use                  Dr D N Leitch                        November 2008
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Arterial Blood Gases

   It is recommended that local anaesthesia is used for checking arterial blood
    gases where possible.
   Arterial blood gases should be checked in the following circumstances:
    - All critically ill patients
    - Unexpected or inappropriate hypoxia <94%
    - Deteriorating oxygen saturation range, need for increased fraction of
         inspiratory oxygen to maintain oxygen saturation range.
    - Any patient at risk of hypercapnoeic respiratory failure who develops a
         deterioration, increased drowsiness or fall in oxygen saturation.
    - Patients thought to be at risk of diabetic ketoacidosis or renal failure.
    - Acutely breathless patients with poor circulation in whom reliable oximetry
         cannot be obtained.
    - Any other clinical circumstance where felt necessary such as a change in
         patient’s medical condition or unexpected fall in oxygen saturation >3%.


Oxygen Therapy in Pregnancy

   The use of oxygen during labour is not currently recommended except in
    circumstances where the mother is hypoxaemic except as part of a controlled
    trial. Where women who are pregnant have major trauma, sepsis, acute illness
    or suffer complications of pregnancy saturation target range should be 94-98%.
   Women with evidence of hypoxaemia who are more than 20 weeks pregnant
    should be managed with the left lateral tilt to improve cardiac output.


Emergency Use of Oxygen in Hospital Care

   Wherever oxygen is prescribed it should be clearly recorded what the specified
    dose of supplemental oxygen is.
   In most emergency situations oxygen is given without a formal prescription and
    the lack of a prescription should never preclude oxygen being given in an
    emergency situation however a subsequent record should be made as would be
    the case for all other emergency treatment including drugs.
   Patients at risk of type II respiratory failure such as COPD and as previously
    specified should be issued with an oxygen alert card and a 24-28% Venturi mask.
    Such information should be communicated to the primary care team, the
    ambulance service and out-of-hours services.
   Where an oxygen driven nebuliser is used for patients with COPD its use should
    be limited to six minutes which would reduce the risk of hypercapnoeic
    respiratory failure.
   Flow rates of <5 l/min for simple face masks can cause carbon dioxide re-
    breathing and increased resistance to inspiration and so a flow rate of 5-10 l/min
    should be used for simple face masks.
   Patients with COPD and a respiratory rate >30 breaths per minute should have
    the flow rate increased by 50% above the minimum flow rate specified for the
    Venturi masks. E.g. a 28% Venturi mask at 4 l/min with a high respiratory rate
    should be prescribed at 6 l/min using the same 28% Venturi mask.
   Humidification is not required for the delivery of low flow oxygen or the short term
    use of high flow oxygen but it is reasonable to use for those on high flow oxygen
    for more than 24 hours to improve comfort and reduce dryness.


Emergency Oxygen Use                   Dr D N Leitch                       November 2008
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   In emergency situations humidified oxygen should be confined to patients with
    tracheostomy or artificial airway.
   Humidification may help patients with viscus secretions difficult expectoration
    which can often be improved also with nebulised normal saline.

Oxygen Therapy During Nebulised Treatments

   For patients with asthma nebulisers should be driven by oxygen with a high flow
    >6 l/min. Where this is not possible and air driven nebuliser should be used with
    supplemental oxygen given by nasal cannulae to maintain appropriate oxygen
    saturations.
   When nebulised bronchodilators are given to patients with hypercapnoeic
    respiratory failure compressed air should be given and if necessary
    supplementary oxygen given by nasal cannula at 2-4 l/min to maintain oxygen
    saturations 88-92 but once the treatment is finished the patient should be
    returned to controlled oxygen therapy using a Venturi mask.


The Use of Oxygen in Specific Circumstances

Critical Illness Requiring High Levels of Supplemental Oxygen
 Initial oxygen therapy is a reservoir mask of 15 l/min. Once stable reduce oxygen
    aiming for target saturation range of 94-98%. Patients with COPD and other risk
    factors for hypercapnoea with critical illness should still have a target saturation
    range of 94-98% pending the results of arterial blood gas measurement after
    which the oxygen saturation range can be reduced depending on the need for
    supported ventilation and the presence or absence of respiratory failure.
 Examples of critical illness include cardiac arrest or resuscitation, shock, sepsis,
    major trauma, near drowning, anaphylaxis, major pulmonary haemorrhage, major
    head injury, carbon monoxide poisoning.
 With carbon monoxide poisoning it is important to check the carboxyhaemoglobin
    levels. A normal or high pulse oximetry reading should be disregarded as the
    oxygen saturation monitor cannot differentiate between carboxyhaemoglobin and
    oxyhaemoglobin. Blood gas pAO 2 will also be normal despite the presence of
    tissue hypoxia.

Serious Illness Requiring Moderate Levels of Supplemental Oxygen if the Patient is
Hypoxic
 Initial oxygen therapy should be commenced with nasal cannulae 2-6 l/min
   (preferable) or simple face mask at 5-10 l/min unless stated otherwise.
 For patients not at risk of hypercapnoeic respiratory failure with saturation <85%
   treatment should be commenced with a reservoir mask 10-15 l/min.
 Recommended saturation range 94-98% unless at risk of hypercapnoeic
   respiratory failure.
 Arterial blood gases should be checked in all patients requiring supplemental
   oxygen.
 If at risk of hyercapnoeic respiratory failure aim for saturation 88-92% pending
   blood gas results but if pACO 2 is normal adjust saturations to 94-98% (unless
   previous hypercapneoic respiratory failure or NIV). A repeat set of arterial blood
   gases are required at 30-60 minutes.
 Examples of serious illness requiring supplemental oxygen include acute
   hypoxaemia – cause not yet diagnosed, acute asthma, pneumonia, lung cancer,
   post-operative breathlessness, acute heart failure, pulmonary embolism, pleural
   effusion, possible pneumothorax.

Emergency Oxygen Use                  Dr D N Leitch                        November 2008
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COPD and Other Conditions Requiring Controlled or Low Dose Oxygen Therapy
 Prior to the results of blood gas use 24 or 28% Venturi mask aiming for oxygen
  saturation 88-92%.
 Adjust to 94-98% target saturation range if pACO 2 is normal and recheck blood
  gases after 30-60 minutes (unless previous episode of type II respiratory failure,
  or NIV).
 In patients with significant likelihood of severe COPD that might cause
  hypercapnoeic respiratory failure should be triaged as very urgent and blood
  gases measured on arrival at hospital.
 If CO2 is raised but pH is > 7.3 maintain target saturation of 88-92% and recheck
  gases after 30-60 minutes. If the patient has high CO2 and is acidotic, pH <7.35
  the patient may require non-invasive ventilation especially if the abnormal blood
  gas persists after appropriate medical therapy for 30-60 minutes.


In addition to the above please see the enclosed Oxygen Prescription Flow Chart as
Taken from the British Thoracic Society Guidelines and also the Oxygen Prescription
Administration flow chart as taken from the guidelines.


In summary the guidelines strongly recommended the following:

For The Doctor
 Identify if the patient is likely to be at risk of type II respiratory failure.
 Identify an appropriate target oxygen saturation range (94-98% most patients, 88-
    92% patients at risk of type II respiratory failure).
 Identify the most appropriate equipment through which to deliver the oxygen:
    – reservoir mask 15 l/min
    – nasal cannula 2-6 l/min
    – face mask 5-10 l/min
    – venture mask 24, 28%
  To review oxygen prescription and saturation range daily.


For The Nurse
 Regularly check oxygen saturation range comparing this to the target saturation
    range.
 Record on each drug round how the range compares, the oxygen saturation
    result, the mode of delivery and any action taken to correct any deficiency.
 Change the oxygen delivery mechanism to achieve the desired target saturation
    range and inform the doctor as required for any changes.
 Reduce oxygen in stable patients according to appropriate flow chart.




Emergency Oxygen Use                 Dr D N Leitch                      November 2008
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