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Aug.26.2021

Pulse Oximetry (Home Health Care) - CE

ALERT

Consult the manufacturer’s instructions for the designated site placement of the sensor.

Do not attach the sensor to a finger, earlobe, or the bridge of the nose if the area is edematous or if skin integrity is compromised. Do not attach the sensor to fingers that are hypothermic.

Conditions that decrease arterial blood flow, such as peripheral vascular disease, hypothermia, hypotension, and peripheral edema, affect the accuracy of oxygen saturation readings. Pharmacologic vasoconstrictors also decrease arterial blood flow.

Pulse oximeters overestimate oxygen saturation in patients with acute respiratory failure, chronic bronchitis, and emphysema; however, monitoring trends is helpful. If a pulse oximeter reading is questionable, obtain arterial blood gas (ABG) values to determine oxygen saturation.undefined#ref1">1

OVERVIEW

Pulse oximetry is the noninvasive measurement of peripheral oxygen saturation (SpO2), which is expressed as the percentage of hemoglobin that is filled with oxygen. A pulse oximeter has a sensor with a light-emitting diode (LED) connected by a cable to an oximeter or contained in a one-piece portable battery-operated device. The LED emits light wavelengths that are absorbed differently by oxygenated and deoxygenated hemoglobin molecules. The more hemoglobin that is bound to oxygen, the higher the oxygen saturation.4 In general, the normal range for SpO2 is 95% to 99%.2 A consistent SpO2 of less than 95% should be investigated, and an SpO2 of 90% signifies developing hypoxemia.2 Pulse oximetry devices have a margin of error of 3% to 4%, especially in critically ill patients and newborns.3

Pulse oximetry is indicated for patients who are hypoxemic or who are at risk for impaired gas exchange. The measurement of SpO2 is simple and painless and has few of the risks associated with more invasive measurements of oxygen saturation (e.g., arterial blood gas sampling). Taking measurements with a digit or earlobe sensor requires a vascular, pulsatile area to detect the change in the sensor’s transmitted light. Conditions that decrease arterial blood flow (e.g., peripheral vascular disease, hypothermia, peripheral edema) affect accurate determination of oxygen saturation in these areas. For patients with decreased peripheral perfusion, a forehead reflectance sensor should be applied.

Factors that affect light transmission (e.g., outside light sources, patient motion) also affect the measurement of SpO2. Direct sunlight or fluorescent lighting should be avoided when using an oximeter, or the sensor should be protected with an opaque covering or towel. The sensors in most devices used in the home are contained in a light-blocking cover. Carbon monoxide in the blood, jaundice, and intravascular dyes can influence the light reflected from hemoglobin molecules. Levels of SpO2 measured in these conditions may be inaccurate. If factors affect light transmission, oxygenation levels should be obtained through arterial blood gas sampling instead.4

In adults, reusable and disposable oximeter sensors, if available, can be applied to the earlobe, finger, toe, bridge of the nose, or forehead. Each sensor is designated for a different part of the body. The sensors are not interchangeable, so a sensor for the finger (Figure 1)Figure 1 or toe should not be used on the ear or nose.

EDUCATION

  • Provide developmentally and culturally appropriate education based on the desire for knowledge, readiness to learn, and overall neurologic and psychosocial state.
  • Provide the patient, family, and caregivers with an explanation of the equipment and the procedure.
  • Teach the patient, family, and caregivers the signs and symptoms of hypoxemia, which include restlessness, confusion, dusky color, shortness of breath, and dyspnea.
  • Teach the patient, family, and caregivers about the effects of high-risk behaviors (e.g., cigarette smoking, vaping) while on oxygen saturation.
  • Explain to the patient, family, and caregivers that the procedure does not cause any pain or discomfort.
  • Encourage questions and answer them as they arise.

PROCEDURE

  1. Perform hand hygiene. Don appropriate personal protective equipment (PPE) based on the patient’s need for isolation precautions or risk of exposure to bodily fluids.
  2. Introduce yourself to the patient, family, and caregivers.
  3. Verify the correct patient using two identifiers.
  4. Explain the procedure to the patient, family, and caregivers and ensure that the patient agrees to treatment.
  5. Verify the practitioner’s order and assess the patient for pain.
  6. Prepare an area in a clean, convenient location and assemble the necessary supplies.
  7. Assess the patient for risk factors for decreased oxygen saturation.
    1. Acute or chronic respiratory dysfunction
    2. Opioid medications
    3. Injury to the chest wall
    4. Ventilator dependence
    5. Sleep apnea
  8. Assess the patient for signs and symptoms of alterations in oxygen saturation.
    1. Altered respiratory rate, depth, or rhythm
    2. Adventitious breath sounds
    3. Cyanotic appearance of nail beds, lips, mucous membranes, and skin
    4. Restlessness, irritability, confusion, or bizarre behavior
    5. Decreased level of consciousness
    6. Labored breathing or difficulty breathing
  9. Assess the patient for factors that influence the measurement of SpO2.
    1. Oxygen therapy
    2. Chest physiotherapy (e.g., postural drainage, percussion)
    3. Hemoglobin level
    4. Medications (e.g., bronchodilators)
  10. Obtain the previous baseline SpO2 (if available) from the patient’s record.
  11. Determine the most appropriate site (i.e., finger or toe [digit], earlobe, bridge of nose, or forehead) for sensor placement.
    Do not place a reusable clip-on finger sensor on the thumb; it is not designed for the thumb.
    1. Assess the temperature of the site. If the site is cold to the touch, select an alternative site.
      Rationale: Peripheral vasoconstriction alters Sp O 2.
      Do not attach the sensor to fingers or toes that are hypothermic.
    2. Assess the skin integrity of the site. If the site is edematous or skin integrity is compromised, select an alternative site.
      Rationale: The site must have adequate local circulation and be free of moisture.
    3. If the patient has tremors or is likely to move, use an earlobe or forehead sensor.
    4. If the patient is obese, use a wrap sensor (Figure 1)Figure 1.
      Rationale: If the patient is obese, a clip-on sensor may not fit properly.
  12. Select the appropriate sensor for the site and prepare the site as appropriate.
    1. Consult the manufacturer’s instructions for the designated site placement of the sensor.
      Place the sensor on its designated site only; otherwise, an erroneous reading may be obtained.
      Do not use a clip-on digit sensor on the patient’s thumb.
    2. If using the patient’s finger, first remove nail polish with acetone or polish remover, if the patient agrees.
      Rationale: Opaque coatings decrease light transmission; nail polish containing blue pigment absorbs light emissions and alters the Sp O 2 measurement.
  13. Position the patient comfortably. If using a finger as the monitoring site, position the hand so the finger is clear of obstructions.
    Rationale: Correct hand positioning ensures sensor position and decreases motion artifact that interferes with Sp O 2 determination.
  14. Instruct the patient to breathe normally.
    Rationale: Normal breathing prevents large fluctuations in minute ventilation and possible changes in Sp O 2.
  15. If using a clip-on finger sensor (Figure 2A)Figure 2A, inform the patient that the sensor will feel like a clothespin on the finger but does not hurt.
  16. Attach the sensor to the selected monitoring site (Figure 2B)Figure 2B. Make sure that the light source and the photodetector inside the sensor are aligned directly opposite each other.
  17. When the sensor is in place, turn on the oximeter.
  18. Observe the pulse waveform or intensity display and listen for the audible beep, if available (Figure 3)Figure 3.
    Rationale: The pulse waveform display and audible beep are proportional to the pulse and Sp O 2 value. Manually obtaining the pulse rate confirms oximeter accuracy.
  19. Correlate the oximeter pulse rate with the patient’s radial pulse.
  20. Leave the sensor in place until the oximeter readout reaches a constant value and the pulse display reaches full strength during each cardiac cycle.
    1. Read the SpO2 on the digital display.
    2. Remove the sensor from the patient’s finger and turn off the device.
  21. If assessing the patient’s SpO2 for the first time, establish it as baseline if it is within an acceptable range.
  22. Compare the current SpO2 with the patient’s previous baseline and acceptable SpO2. Notify the practitioner of abnormal findings.
  23. Discard or store supplies, remove PPE, and perform hand hygiene.
  24. Document the procedure in the patient’s record.

EXPECTED OUTCOMES

  • Patient’s SpO2 is greater than 92%2 or it represents a satisfactory level for the patient’s condition.
  • Patient’s oxygenation therapies are adjusted without requiring invasive assessment measures.
  • Patient’s skin is free from signs of injury from spring tension of the oximetry sensor.

UNEXPECTED OUTCOMES

  • SpO2 is less than 92%2 or it is below the patient’s baseline.
  • Pulse waveform or intensity display is dampened or irregular.
  • Pulse rate on oximeter is less than the radial or apical pulse rate.
  • Skin shows signs of injury from spring tension of the oximetry sensor.

DOCUMENTATION

  • SpO2
  • Type and amount of oxygen therapy (if applicable)
  • Signs and symptoms of oxygen desaturation
  • Education
  • Patient’s progress toward goals
  • Unexpected outcomes and related interventions
  • Assessment of pain, treatment if necessary, and reassessment

OLDER ADULT CONSIDERATIONS

  • Identifying an acceptable pulse oximeter sensor site is difficult in older adults because of the likelihood of peripheral vascular disease, cold-induced vasoconstriction, and anemia.
  • Older adults require more frequent assessment of the skin under the sensor because of tissue fragility and decreased elasticity.
  • Consider using a sensor designed for the forehead or earlobe. Peripheral circulation may be compromised in the older adult, resulting in inaccurate pulse oximetry values.

REFERENCES

  1. Amalakanti, S., Pentakota, M.R. (2016). Pulse oximetry overestimates oxygen saturation in COPD. Respiratory Care, 61(4), 423-427. doi:10.4187/respcare.04435 (Level IV)
  2. Jubran, A. (2015). Pulse oximetry. Critical Care, 19(1), 272. doi:10.1186/s13054-015-0984-8 (classic reference)*
  3. Nitzan, M., Romem, A., Koppel, R. (2014). Pulse oximetry: Fundamentals and technology update. Medical Devices (Auckl), 7, 231-239. doi:10.2147/MDER.S47319 (classic reference)*
  4. Pretto, J.J. and others. (2014). Clinical use of pulse oximetry: Official guidelines from the Thoracic Society of Australia and New Zealand. Respirology, 19(1), 38-46. doi:10.1111/resp.12204 (classic reference)* (Level VII)

ADDITIONAL READINGS

National Health Service (NHS). (2020). Guidelines on oxygen and oximetry. Retrieved July 15, 2021, from

Siegel, B., Heuer, A., Kallet, R. (2021). Chapter 19: Analysis and monitoring of gas exchange. In R. Kacmarek, J. Stoller, A. Heuer (Eds.), Egan’s fundamentals of respiratory care (12th ed., 368-394). St. Louis, MO: Elsevier.

*In these skills, a “classic” reference is a widely cited, standard work of established excellence that significantly affects current practice and may also represent the foundational research for practice.

Elsevier Skills Levels of Evidence

  • Level I - Systematic review of all relevant randomized controlled trials
  • Level II - At least one well-designed randomized controlled trial
  • Level III - Well-designed controlled trials without randomization
  • Level IV - Well-designed case-controlled or cohort studies
  • Level V - Descriptive or qualitative studies
  • Level VI - Single descriptive or qualitative study
  • Level VII - Authority opinion or expert committee reports

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