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Nursing Guideline for the use of Pulse Oximetry in clinical practice

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									          THE ROYAL FREE HAMPSTEAD
                 NHS TRUST

Pulse oximetry in clinical practice nursing guideline

                  November 2008
Validation Grid

Policy title         Pulse oximetry in clinical practice nursing guideline
                     Tareq Ayoob (CNS Asthma/ COPD)
                     Fiona Fitzgerald-Khan (COPD Research Nurse)
                     This policy is relevant for all staff caring for adult patients in
Target audience
                     clinical areas of the Royal Free Hampstead NHS trust
                     Clinical Practice Committee
Stake holders        Clinical Practice Committee
consulted            Medical electronics
                     Clinical directorates:
                     Surgery, anesthetics and critical care
                     Clinical haematology, oncology and private practice
                     Hepatology, nephrology and transplantation
                     Women’s and children’s
                     RNTNE, ENT, audiology and ophthalmology
Linked policies      Guidelines for the administration of oxygen for self ventilating
                     Respiratory Assessment
                     Nursing Guidelines for the administration of Nebulisers
                     Care of patients receiving continuous positive airway
                     pressure (CPAP)
                     Guidelines for Non Invasive Ventilation (NIV)
                     Guideline on chest drains
                     Guideline for tracheal suction
                     Guideline for the care of a patient with a tracheostomy
                     Yes Pulse oximetry in clinical practice 2004
Date of submission   May 2008

Review date          May 2010

Key words            Pulse oximeter; Oxygen saturation; oximetry; O2 Sats;
Pulse oximeters are increasingly used to monitor patients in
various clinical areas. There is no specific training in the operation
of these machines for nursing staff. Although pulse oximetry is a
simple non-invasive method of monitoring, there are limitations to
use and misinterpretation of readings can be a problem. This
guideline is to provide information to the practitioner so that
monitoring of the patient is carried out safely, taking into account
all factors, which may make interpretation of the recordings
difficult. More recently, pulse oximetry offers a relatively
inexpensive, simple and reliable means to monitor respiratory
function in a wide variety of clinical areas, in hospitals and the

Pulse Oximetry in Clinical Practice Nursing Guideline
To provide a tool to enable clinical staff to monitor patients at risk
of ventilatory or pulmonary failure.

Staff Who May Undertake This Procedure
Within this Trust use of the Pulse Oximeter is regarded as a clinical
practice. A clinical practice may be defined as an aspect of care,
which may be undertaken by registered nurses, and midwives who
accept accountability for their actions and feel competent to
undertake the procedure. There is no formal assessment for these
practices but they may be aspects of care, which require a period
of supervised, guided practice. These should form part of
preceptorship or mentorship programmes.

Student nurses and midwives may undertake this practice under
the supervision of a registered nurse or midwife who feels
competent in this aspect of care and in the supervisory role.

In line with guidelines laid down by the NMC for records and record
keeping, there must be a current and appropriate plan of care for
patients. The plan must incorporate on-going evaluation and
reassessment of care and evidence that relevant interventions and
observations have been communicated to appropriate members of
the multidisciplinary team.
The N-560 uses pulse oximetry to measure functional oxygen
saturation in the blood. Pulse oximetry works by applying a sensor
to a pulsating arteriolar vascular bed, such as a finger or toe. The
sensor contains a dual light source and a photo detector. Bone,
tissue, pigmentation, and venous vessels normally absorb a
constant amount of light over time. The arteriolar bed normally
pulsates and absorbs variable amounts of light during the
pulsations. The ratio of light absorbed is translated into a
measurement of functional oxygen saturation (SpO2). Because a
measurement of SpO2 is dependent upon light from the sensor,
excessive ambient light can interfere with this measurement.
Specific information about ambient conditions, sensor application,
and patient conditions is contained throughout this manual. Pulse
oximetry is based on two principles: that oxyhaemoglobin and
deoxyhaemoglobin differ in their absorption of red and infrared light
(spectrophotometry), and that the volume of arterial blood in tissue
(and hence, light absorption by that blood) changes during the
pulse (plethysmography). A pulse oximeter determines SpO2 by
passing red and infrared light into an arteriolar bed and measuring
changes in light absorption during the pulsatile cycle. Red and
infrared low-voltage light-emitting diodes (LED) in the oximetry
sensor serve as light sources; a photo diode serves as the photo
detector. Because oxyhaemoglobin and deoxyhaemoglobin differ
in light absorption, the amount of red and infrared light absorbed
by blood is related to haemoglobin oxygen saturation. To identify
the oxygen saturation of arterial haemoglobin, the N-560 uses the
pulsatile nature of arterial flow. During systole, a new pulse of
arterial blood enters the vascular bed, and blood volume and light
absorption increase. During diastole, blood volume and light
absorption reach their lowest point. The N-560 bases its SpO2
measurements on the difference between maximum and minimum
absorption (measurements at systole and diastole). By doing so, it
focuses on light absorption by pulsatile arterial blood, eliminating
the effects of nonpulsatile absorbers such as tissue, bone, and
venous blood. There are various matrixes within the OXIMAX
algorithm. Some are used to assess the severity of conditions
presented to the N-560 in measuring SpO2 and pulse rate. These
individual matrixes or combinations of these matrixes are used to
drive the LED indicators on the N-560 front panel. During
challenging measurement conditions, which could be caused by
low perfusion, interference, external interference, like ambient light,
or a combination of these, the OXIMAX algorithm automatically
extends the amount of data required for measuring SpO2 and
pulse rate, depending on the measurement conditions. During
normal measurement conditions in the normal response mode, the
averaging time is 6 to 7 seconds. If the resulting dynamic
averaging time exceeds 20 seconds, the Pulse Search indicator is
continuously illuminated and SpO2 and pulse rate is updated every
second. As measurement conditions become even more
challenging, the amount of data required continues to extend. If the
dynamic averaging time reaches 40 seconds, the Pulse Search
indicator begins flashing and the SpO2 and pulse rate display
flashes zeros indicating a loss-of-pulse condition.

Place appropriate probe over finger or toe (earlobe and bridge of
the nose tend to be used in ITU and neonatal areas). When using
a finger probe utilize the arm not in use for blood pressure
monitoring. The sensor should be placed flush with the skin without
compromising the circulation in the finger. Allow a few seconds
before reading the output. Monitor the amplitude to ensure good
contact throughout procedure. Record both the measurement and
amount of inspired oxygen patient is receiving at that time. The
normal value for adults with no lung disease is 95% on room air.

Pulse oximetry can be used wherever a patient requires monitoring
with regard to respiratory illness, especially those receiving oxygen
therapy, those on sedatives and for postoperative recovery from
surgery. It can also help evaluate the effectiveness of
physiotherapy, as a screening tool for Obstructive Sleep Apnoea
and may be used to ensure adequate oxygenation during
bronchoscopy, intubation and airway suctioning. It also enables the
assessment of oxygen requirements during sleep and exercise.
Although 100% saturation is not normal when breathing air, it can
be achieved when supplementary oxygen is given. Oxygen, like
any drug, can have toxic effects. So if oximetry consistently shows
100% saturation, patients may be receiving unnecessarily high
levels of oxygen. However, 100% saturation may compensate for
other problems of oxygen carriage, for example anaemia, and
nurses should consult medical staff to establish whether any
change in oxygen therapy is appropriate.
As a rule of thumb, respiratory failure usually occurs when
saturation (SpO2) falls to 90%, although some patients with chronic
respiratory disease may tolerate lower saturations. Nurses should
consider the patient’s normal respiratory function and clarify the
point at which medical staff needs to be informed of any changes.
Alarm limits should be set at a level that identifies any significant
change in saturation. Setting lower alarm limits of 90% may be
appropriate when saturation is 95%, but inappropriate if saturation
is fluctuating at 90-91%. If setting alarm limits below 90%, nurses
should be cautious about the very narrow margin remaining before
respiratory failure. Setting a lower alarm limit of 85% or less should
always be avoided! Oxygen delivery to tissues, including vital
organs, is likely to be inadequate at this level, and such low
saturations usually require urgent medical intervention (intubation
and artificial ventilation).

The pulse oximeter may be used in a variety of situations that
require monitoring of oxygen status and may be used continuously
or intermittently. It is not a substitute for Arterial Blood Gases
(Abg’s), but could indicate decreasing arterial oxyhaemoglobin
saturation prior to the patient exhibiting clinical signs of hypoxia.

   Oximetry is an aid to observation of the patient and not a
     substitute. Any single measurement means little in isolation
     and should be placed in context of the whole person.
   Pulse oximeters do not offer information about haemoglobin
     concentration, efficiency of oxygen delivery to the tissues,
     the consumption or sufficiency of oxygenation, cardiac output
     or adequacy of ventilation.

There are various factors, which can influence the measurements
and output of the pulse oximeter:
   Peripheral vasoconstriction: As the probe relies on
     detecting a pulsatile volume of blood, weak peripheral pulses
     will be difficult to read and may give false low
   Low blood pressure: When the patient’s blood pressure is
     low, the oximeter has difficulty differentiating the light
     wavelengths of arterial blood. It should not be used in low
     flow states, such as blood pressure below 60 systolic
    Dysrhythmias: Dysrhythmias such as atrial fibrillation may
     cause inadequate and irregular perfusion and unreliably low
     saturation measurements.
    Shivering: Shivering, or any movement, may cause
     problems with detecting saturation and falsely high pulse
    Strong external lighting: Lighting, particularly florescent
     lighting, and bright overhead lighting can cause over
    Intravenous dyes: Intravenous dyes can reduce readings by
     absorbing light.
    Smoke inhalation, heavy smokers and carbon monoxide
     poisoning:      The    pulse    oximeter     may     interpret
     dyshaemoglobins       such    as     methaemoglobin       and
     carboxyhaemoglobin as oxyhaemoglobin and, therefore,
     show an erroneously high value.
    Further consideration should be given in patients with
     anaemia (low Hb), jaundice and deeply pigmented skin.
    Nail polish: The darker the polish, the more likely that the
     SpO2 reading will be inaccurate. Blue, black, and green
     polishes cause the most problems. If unable to remove
     polish, place the probe on an ear lobe, a toe, or position the
     probe sideways on the finger, rather than across the nail bed
     (you may need to tape the sensor in place).

Infection control:
If the device probe is intended for multiple patients use, the probe
should be cleaned between patient applications according to
manufacturer recommendations. The external part of the monitor
should be cleaned according to manufacturer’s recommendations
whenever the device remains in a patient’s room for prolonged
periods, when soiled, or when it has come in contact with
potentially transmissible organisms.

Pulse oximetry has provided many clinical areas with a simple,
reliable and relatively inexpensive means to monitor the respiratory
functions of patients, detecting problems long before cyanosis
becomes visible. However monitoring equipment can lull staff, and
patients, into a false security. Oximeters are sometimes introduced
into clinical areas without staff being given sufficient information to
understand fully how to interpret the information they provide.
Nurses using oximetry should be aware of their limitations, so that
individual measurements can be placed in a more meaningful
context of the whole patient.

Compliance with the guideline should be monitored. This can be
achieved with regular checks by the Thoracic team members,
Respiratory physiotherapists and senior nurses. An official audit
should be performed on an annual basis, led by the CNS for
Asthma and COPD.

  1. AARC Clinical Practice Guideline, Pulse Oximetry. 1991.
     Respiratory Care. 36:1406-1409.
  2. Casey G. 2001. Oxygen transport and the use of pulse
     oximetry. Nursing Standard. Vol. 15 (47), Aug; 46-55.
  3. Clarke A. 2002. Legal lessons: ‘But his o2 sat was normal!’
     Clinical Nurse Specialist. Vol. 16 (3). May. 162-163.
  4. Coull A. 1992. Making sense of pulse oximetry. Nursing
     Times. Vol. 88, Aug, No. 32, 42-43.
  5. Howell M. 2002. Pulse oximetry: an audit of nursing and
     medical staff understanding. British Journal of Nursing. Vol.
     11, No. 3, 191-197.
  6. NMC (2008) Standard for medicines management.
  7. Netzer N, Eliasson A, Netzer C, Kristo D. 2001. Overnight
     Pulse Oximetry for Sleep-Disordered Breathing in Adults: A
     Review. Chest. Vol. 120 (2), Aug, 625-633.
                                                        Full Equality Impact Assessment Matrix

Name of policy/service                                                          Pulse Oximetry in clinical practice nursing guideline
Name of Manager responsible for completing impact assessment                    Tareq Ayoob and Fiona Fitzgerald-Khan
Is this a new policy/service or a review of an existing policy/service?         Review/update of existing policy
What is the purpose of the policy/service?                                      To provide guidance for staff on the safe, effective and appropriate
                                                                                use of pulse oximetry in the clinical setting
Who is intended to benefit from the policy and in what way?                     Staff and students, to ensure safe best practice in relation to
                                                                                monitoring & interpretation of oxygen saturation.
Date commenced                          Aug 2008                                Date completed                         Nov 2008
Policy/service review date              Nov 2010

Using the matrix below, review the policy/service under consideration, in relation to the six equality strands, for differential impact
upon service users or trust staff and identify what these might be:
Group (highlight          Age            Race/ethnicity         Gender             Disability        Religion/belief          Sexual
relevant groups)                                                                                                            orientation
1.                       Appropriate          A patient               No evidence seen    Appropriate          No evidence seen      No evidence seen
Is there any             communication        information leaflet                         communication
evidence that            should be employed   has been prepared                           should be employed
groups have              to ensure consent    Appropriate                                 to ensure consent
different needs,         and understanding    communication                               and understanding
experiences or           is gained.           should be employed                          is gained.
priorities in relation   Language and         to ensure consent                           Language and
to this policy and if    communication        and understanding                           communication
so, what?                requirements are     is gained. The trust                        requirements are
                         routinely recorded   has a robust                                routinely recorded
                         in the nursing       interpreting service,                       in the nursing
                         documentation        enabling patients to                        documentation
                                              access information
                                              in different
                                              Language and
                                               requirements are
                                               routinely recorded
                                               in the nursing
2.                     The policy promotes     The policy promotes     The policy promotes   The policy promotes     The policy promotes   The policy promotes
Is the any evidence/   principles of good      principles of good      principles of good    principles of good      principles of good    principles of good
concern that this      care and safety for     care and safety for     care and safety for   care and safety for     care and safety for   care and safety for
proposal could         all groups              all groups              all groups            all groups              all groups            all groups
result in a
qualitative or
differences in
impact on any
group and if so
3.                     A patient               A patient               The policy promotes   A patient               The policy promotes   The policy promotes
Does the proposal      information leaflet     information leaflet     principles of good    information leaflet     principles of good    principles of good
promote equality of    has been prepared       has been prepared       care and safety for   has been prepared       care and safety for   care and safety for
opportunity/           Appropriate             Appropriate             all groups            Appropriate             all groups            all groups
access/good            communication           communication                                 communication
relations within the   should be employed      should be employed                            should be employed
organisation and       to ensure consent       to ensure consent                             to ensure consent
the wider              and understanding       and understanding                             and understanding
community and how      is gained. The trust    is gained. The trust                          is gained. The trust
is this evidenced?     has a robust            has a robust                                  has a robust
                       interpreting service,   interpreting service,                         interpreting service,
                       enabling patients to    enabling patients to                          enabling patients to
                       access information      access information                            access information
                       in different            in different                                  in different
                       languages.              languages.                                    languages.
                       Language and            Language and                                  Language and
                       communication           communication                                 communication
                       requirements are        requirements are                              requirements are
                       routinely recorded      routinely recorded                            routinely recorded
                      in the nursing           in the nursing                                    in the nursing
                      documentation            documentation                                     documentation
4.                    Clinical practice        Clinical practice        Clinical practice        Clinical practice        Clinical practice        Clinical practice
Who are the key       group, TNMC,             group, TNMC,             group, TNMC,             group, TNMC,             group, TNMC,             group, TNMC,
stakeholders in       clinical risk            clinical risk            clinical risk            clinical risk            clinical risk            clinical risk
relation to this      committee, risk and      committee, risk and      committee, risk and      committee, risk and      committee, risk and      committee, risk and
policy and how are    safety department        safety department        safety department        safety department        safety department        safety department
they being            and the equipment        and the equipment        and the equipment        and the equipment        and the equipment        and the equipment
consulted?            library, clinical        library, clinical        library, clinical        library, clinical        library, clinical        library, clinical
                      directorates.The         directorates.The         directorates.The         directorates.The         directorates.The         directorates.
                      guideline was            guideline was            guideline was            guideline was            guideline was            The guideline was
                      widely consulted on      widely consulted on      widely consulted on      widely consulted on      widely consulted on      widely consulted on
5.                    No evidence of           No evidence of           No evidence of           No evidence of           No evidence of           No evidence of
Are there any         potential differential   potential differential   potential differential   potential differential   potential differential   potential differential
concerns that the     impact.                  impact.                  impact.                  impact.                  impact.                  impact.
development could
have a differential
impact on any
group(s) and how
might this be
6.                    No evidence of           No evidence of           No evidence of           No evidence of           No evidence of           No evidence of
Do you anticipate     inconsistencies          inconsistencies          inconsistencies          inconsistencies          inconsistencies          potential differential
any areas where       found                    found                    found                    found                    found                    impact.
there may be
inconsistencies in
application and are
there alternative
arrangements that
Using the information from the matrix complete the following action plan:
     Area of concern              Groups likely to          Action planned to                Monitoring                    Review date
                              experience differential             minimise                  arrangements
                                                            equality of access
1. Provision of accessible New staff not orientated to Staff to receive induction     Ward managers to ensure         November 2010
information for staff and  equipment use               on equipment use in the        staff competence in
patients                                               clinical setting prior to      equipment use.
                           Patients and staff for      being assessed competent       Yearly Pulse oximetry
                           whom English is not the     to use it.                     audit to include monitoring
                           first language              Staff to explain the           adverse incidents
                                                       guidance to colleagues as      Matrons documentation
                           Patients with a disability  required                       audits
                           impacting on vision,        Interpreting service to be     Audit of referrals to PALS
                           hearing or comprehension accessed through the              Audit of referrals to nursing
                                                       PALS team as required          disability link nurse
                                                       Guidance to be sought
                                                       from the learning
                                                       disabilities link nurse with
                                                       regard to provision of easy
                                                       read and pictorial guides
                                                       For children the Fraser
                                                       competence should be
                                                       applied and recorded in
                                                       the child’s nursing notes

Name/signature of manager completing assessment                       Tareq Ayoob and Fiona Fitzgerald-Khan
Date assessment sent to Equality and Diversity Manager                07.11.2008
Name/signature of Equality and Diversity Manager                      Jennifer Kenward
Date of publication of Impact assessment                              December 2008

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