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  • Earlobe Capillary Blood Gas Sampling in Adults Clinical Guideline V1.0

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    Capillary Blood Gas Sampling in Adults

    Clinical Guideline


    June 2018

  • Earlobe Capillary Blood Gas Sampling in Adults Clinical Guideline V1.0

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    1. Aim/Purpose of this Guideline

    Arterialised capillary blood samples obtained from the earlobe of stable adult patients may be used to measure a number of variables that are required to safely monitor patients undergoing treatment with Non-Invasive Ventilation (NIV). In the assessment of blood gas tensions, capillary blood specimens have been shown in the literature to be comparable to arterial blood specimens with the added benefits of improved patient satisfaction and decreased risk of complications.

    1.1. This guidance applies to all healthcare professionals performing this procedure. Those undertaking the procedure should ensure that it is appropriate for each patient and that they have achieved an adequate level of competency. It is the responsibility of the person performing the procedure to document the results in the medical notes and refer to medical staff if required.

    1.2. Competency in this procedure is assessed through the ‘Earlobe Capillary Blood Gas Sampling - Supervised Practice Workbook’. Completion of the associated eLearning package and ten supervised procedures are required prior to final competency sign off.

    2. The Guideline

    2.1. Arterial Blood Gas (ABG) sampling provides essential information for the management of patients with a wide range of conditions. In particular, those patients requiring NIV require serial monitoring with several samples over days1,2. This is known to cause discomfort to patients3 and carries a small risk of complications such as haematoma formation or vessel injury.

    2.1.1. Capillary Blood Gas (CBG) samples taken from an earlobe that has been ‘arterialised’ by use of a rubefacient cream represent a significantly less painful experience for patients and provide comparable results to ABGs in stable patients4.

    2.1.2. Variations in technique can introduce significant differences in results thereby making a standardised procedure essential for all staff5.

    2.2. Indications:

    There are a number of indications for CBG sampling in in-patients. These include:

    Monitoring of patients receiving NIV2 in line with trust policy: ‘The Use of Non-Invasive Ventilation in Patients with Acute Type 2 Respiratory failure; V1.0; May 2014.’

    In the assessment of respiratory function in haemodynamically stable patients4.

    Assessment of supplementary oxygen requirements7.

    2.3. Contraindications:

  • Earlobe Capillary Blood Gas Sampling in Adults Clinical Guideline V1.0

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    Haemodynamically unstable/shocked patients.

    Abnormal puncture site – e.g. inflamed, localised infection or oedematous earlobe.

    Previous reaction to Transvasin cream or chlorhexidine swabs.

    Arterial access available (e.g. radial arterial line)

    2.4. Equipment:

    Clean tray with sharps box

    Clean gloves and other Personal Protective Equipment (PPE)

    Transvasin cream

    2% chlorhexidine swab

    Size 11 retractable scalpel

    Heparinised capillary tube with mixing wire and end caps

    Sterile gauze

    Appropriate dressing (e.g. plaster)

    2.5. Procedure:

    Identify the patient in accordance with the ‘Positive Patient Identification Policy’. Explain the procedure to the patient and obtain informed verbal consent in accordance with the ‘Consent Policy’.

    Wash hands and don appropriate PPE. Minimum requirements are clean gloves and apron.

    Apply ‘Transvasin’ cream to the earlobe. Leave for a few minutes whilst preparing other equipment – the earlobe should become warm and erythematous.

    Insert the mixing wire into the capillary tube and attach an end cap to one end

    Remove the cream and disinfect the earlobe using a chlorhexidine swab. Allow to dry.

    Use a size 11 scalpel blade to make an incision to a depth of 3mm, parallel to and in the middle of the edge of the earlobe.

    Wipe away the first droplet of blood to ensure sample accuracy.

    Allow a second, large droplet of blood to form.

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    Place the end of the capillary tube into the droplet of blood and allow to fill, avoiding introducing air bubbles into the sample. Do not squeeze the earlobe.

    Once full, apply the end cap to the capillary tube.

    Apply firm pressure to the wound until bleeding has stopped, apply dressing.

    Run the magnet the length of the capillary tube 10 times to ensure thorough mixing.

    Attach a patient identification label to the tube at the patient’s bedside and note the inspired oxygen concentration (FiO2).

    Immediately analyse the sample, in accordance with Point of Care Testing Policy.

    Document result and FiO2 in medical notes. Refer results to medical team immediately.

    2.6. Interpreting Results:

    When using a standardised technique, arterialised CBG results closely correlate to ABG results and have similar normal ranges. An exception is for values for paO2 greater than 20kPa where significant variation is encountered

    4. For these patients the FiO2 should be reduced and the test repeated. The adjusted reference ranges4 are shown in Table 1.

    Table 1. Current Trust ABG ranges with adjusted CBG ranges. Calculated using method described by Richter et al4.

    Value ABG range Adjusted CBG Range

    pH 7.350-7.450 7.342-7.442

    paO2 (kPa)

    for values

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    2.7. Audit Tool

    To be undertaken annually, with results reported at Respiratory Weekly Meeting.

    Criteria Expected Compliance

    Staff undertaking procedure to have completed competency sign off or be directly supervised


    Result documented in medical notes 100%

    FiO2 documented 100%

    Documentation that result has been referred immediately to medical team


    3. Monitoring compliance and effectiveness

    Element to be monitored

    Adherence to full guideline

    Lead Ward Managers/Lead Consultant

    Tool Adult Tool in Section 2.7.

    Frequency Annual

    Reporting arrangements

    Respiratory weekly meeting

    Acting on recommendations and Lead(s)

    Where changes required, a lead person will be identified, reporting to the respiratory meeting

    Change in practice and lessons to be shared

    Required changes to practice will be identified and actioned within 3 months. A lead member of the team will be identified to take each change forward. These will be presented at the weekly respiratory meeting where required.

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    4. Equality and Diversity

    4.1. This document complies with the Royal Cornwall Hospitals NHS Trust service Equality and Diversity statement which can be found in the 'Equality, Diversity & Human Rights Policy' or the Equality and Diversity website.

    4.2. Equality Impact Assessment

    The Initial Equality Impact Assessment Screening Form is at Appendix 2.


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    Appendix 1. Governance Information

    Document Title Earlobe Capillary Blood Gas Sampling in Adults Clinical Guideline V1.0

    Date Issued/Approved: 1 June 2018

    Date Valid From: 1 June 2018

    Date Valid To: 1 June 2021

    Directorate / Department responsible (author/owner):

    Respiratory Directorate Dr Alexander Lomas Dr James Pickering

    Contact details: [email protected]

    [email protected]

    Brief summary of contents Procedural guidance on sampling and processing of earlobe capillary blood specimens in adult patients

    Suggested Keywords: Capillary blood gas, non-invasive ventilation, CBG, NIV

    Target Audience


    Executive Director responsible for Policy:

    Medical Director

    Date revised: New document

    This document replaces (exact title of previous version):

    New document

    Approval route (names of committees)/consultation:

    Respiratory Governance Meeting,

    Cardio-respiratory Directorate,

    Divisional Business and Governance

    Divisional Manager confirming approval processes

    Divisional Manager, Medicine/ED

    Name and Post Title of additional signatories

    Not Required

    Name and Signature of {Original Copy Signed}

    mailto:[email protected]

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    Divisional/Directorate Governance Lead confirming approval by specialty and divisional management meetings


    Signature of Executive Director giving approval

    {Original Copy Signed}

    Publication Location (refer to Policy on Policies – Approvals and Ratification):

    Internet & Intranet Intranet Only

    Document Library Folder/Sub Folder Clinical / Respiratory

    Links to key external standards



    Related Documents:

    1. Guideline for emergency oxygen use in adult patients. British Thoracic Society. Emergency Oxygen Guideline Group. Thorax 2008; 63 (Suppl VI):vi1–vi68. doi:10.1136/thx.2008.102947

    2. BTS/ICS Guidelines for the Ventilatory Management of Acute Hypercapnic Respiratory Failure in Adults. British Thoracic Society/Intensive Care Society Acute Hypercapnic Respiratory Failure Guideline Development Group. Davidson AC, et al. Thorax 2016; 71:ii1–ii35. doi:10.1136/thoraxjnl-2015-208209

    3. An audit of the patient's experience of arterial blood gas testing. Crawford A. Br J Nurs. 2004 May 13-26; 13 (9):529-32.

    4. Capillary blood gas as a substitute for arterial blood gas: a meta-analysis. Richter et al. British Journal of Hospital Medicine, March 2014, Vol 75, No 3.

    5. Vaquer et al.: Earlobe arterialized capillary blood gas analysis in the intensive care unit: a pilot study. Annals of Intensive Care 2014 4:11.

    6. Sampling Techniques – Collecting a capillary sample from an adult or a child three months of age or older. Radiometer 2012. Available at http://www.avoidpreanalyticalerrors.com/

  • Earlobe Capillary Blood Gas Sampling in Adults Clinical Guideline V1.0

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    child_3_months_older.pdf (accessed 03/02/2017)

    7. Capillary blood gas analysis for long term oxygen therapy assessment. Ridley et al. Clinical Medicine 2001. Vol 1 No 4:326.

    Training Need Identified? Yes

    Version Control Table

    Date Version No

    Summary of Changes Changes Made by

    (Name and Job Title)

    8 Nov 17 V1.0 Initial Issue Dr Alexander Lomas ACCS CT1

    All or part of this document can be released under the Freedom of Information Act 2000

    This document is to be retained for 10 years from the date of expiry.

    This document is only valid on the day of printing

    Controlled Document

    This document has been created following the Royal Cornwall Hospitals NHS Trust Policy on Document Production. It should not be altered in any way without the express

    permission of the author or their Line Manager.

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    Appendix 2. Initial Equality Impact Assessment Form

    Name of the strategy / policy /proposal / service function to be assessed:

    Earlobe Capillary Blood Gas Sampling in Adults Clinical Guideline V1.0.

    Directorate and service area: Respiratory Directorate/ Medicine Inpatient Wards

    Is this a new or existing Policy? New

    Name of individual completing assessment: Dr Alexander Lomas

    Telephone: 01872 252103

    1. Policy Aim* Who is the strategy / policy / proposal / service function aimed at?

    Guidance on the safe and accurate sampling of earlobe blood specimens for blood gas analysis in adult in-patients

    2. Policy Objectives* Standardised care, technique to ensure patient and staff safety

    3. Policy – intended Outcomes*

    Standardised care

    4. *How will you measure the outcome?


    5. Who is intended to benefit from the policy?

    Medical and nursing staff, patients

    6a Who did you consult with

    b). Please identify the groups who have been consulted about this procedure.

    Workforce Patients Local groups

    External organisations


    Please record specific names of groups

    What was the outcome of the consultation?

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    Are there concerns that the policy could have differential impact on:

    Equality Strands: Yes No Unsure Rationale for Assessment / Existing Evidence

    Age x

    Sex (male, female, trans-gender / gender reassignment)


    Race / Ethnic communities / groups


    Disability -Learning disability, physical impairment, sensory impairment, mental health conditions and some long term health conditions.


    Religion / other beliefs


    Marriage and Civil partnership


    Pregnancy and maternity


    Sexual Orientation, Bisexual, Gay, heterosexual, Lesbian


    You will need to continue to a f ull Equality Impact Assessment if the following have been highlighted:

    7. The Impact

    Please complete the following table. If you are unsure/don’t know if there is a negative impact you need to repeat the consultation step.

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    You have ticked “Yes” in any column above and

    No consultation or evidence of there being consultation- this excludes any policies

    which have been identified as not requiring consultation. or

    Major this relates to service redesign or development

    8. Please indicate if a full equality analysis is recommended. Yes No


    9. If you are not recommending a Full Impact assessment please explain why.

    Signature of policy developer / lead manager / director

    Date of completion and submission

    Names and signatures of members carrying out the Screening Assessment

    1. Dr Alexander Lomas

    2. Human Rights, Equality & Inclusion Lead

    Keep one copy and send a copy to the Human Rights, Equality and Inclusion Lead

    c/o Royal Cornwall Hospitals NHS Trust, Human Resources Department, Knowledge Spa, Truro, Cornwall, TR1 3HD

    Signed: Dr. Alexander Lomas

    Date: 13 February 2018

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