Pulse Oximetry (Home Health Care) - CE/NCPD

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., ABG 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 ABG 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) or toe should not be used on the ear or nose.

Some limitations may impact the accuracy of pulse oximeters, such as poor circulation; dark skin pigmentation; thick skin; current use of nicotine-containing products; cool skin; dark fingernail polish; and long, artificial nails. The pulse oximeter reading should not be used alone to determine the state of health.²

SUPPLIES

See Supplies tab at the top of the page.

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) 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

Perform hand hygiene. Don appropriate personal protective equipment (PPE) based on the patient’s need for isolation precautions or the risk of exposure to bodily fluids.
Introduce yourself to the patient, family, and caregivers.
Verify the correct patient using two identifiers.
Explain the procedure to the patient, family, and caregivers and ensure that the patient agrees to treatment.
Verify the practitioner’s order and assess the patient for pain.
Prepare an area in a clean, convenient location and assemble the necessary supplies.
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
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 unusual behavior
5. Decreased level of consciousness
6. Labored breathing or difficulty breathing
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)
Obtain the previous baseline SpO₂ (if available) from the patient’s record.
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 SpO₂.
  
  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 a forehead sensor.
4. If the patient has obesity, use a wrap sensor (Figure 1).
  Rationale: If the patient has obesity, a clip-on sensor may not fit properly.
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 SpO₂ measurement.
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 SpO₂ determination.
Instruct the patient to breathe normally.
Rationale: Normal breathing prevents large fluctuations in minute ventilation and possible changes in SpO₂.
If using a clip-on finger sensor (Figure 2A), inform the patient that the sensor will feel like a clothespin on the finger but will not hurt.
Attach the sensor to the selected monitoring site (Figure 2B). Make sure that the light source and the photodetector inside the sensor are aligned directly opposite each other.
When the sensor is in place, turn on the oximeter.
Observe the pulse waveform or intensity display and listen for the audible beep, if available (Figure 3).
Rationale: The pulse waveform display and audible beep are proportional to the pulse and SpO₂ value. Manually obtaining the pulse rate confirms oximeter accuracy.
Correlate the oximeter pulse rate with the patient’s radial pulse.
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.
If assessing the patient’s SpO₂ for the first time, establish it as baseline if it is within an acceptable range.
Compare the current SpO₂ with the patient’s previous baseline and acceptable SpO₂. Notify the practitioner of abnormal findings.
Discard or store supplies, remove PPE, and perform hand hygiene.
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.
Use of a sensor designed for the forehead or earlobe should be considered. Peripheral circulation may be compromised in older adult patients, resulting in inaccurate pulse oximetry values.

REFERENCES

American Lung Association. (2024). Pulse oximetry. Retrieved July 3, 2024, from https://www.lung.org/lung-health-diseases/lung-procedures-and-tests/pulse-oximetry
Jubran, A. (2015). Pulse oximetry. Critical Care, 19(1), 272. doi:10.1186/s13054-015-0984-8
Nitzan, M., Romem, A., Koppel, R. (2014). Pulse oximetry: Fundamentals and technology update. Medical Devices (Auckland), 7, 231-239. doi:10.2147/MDER.S47319
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

ADDITIONAL READINGS

National Health Service (NHS). (2022). Guidelines on oxygen and oximetry. Retrieved July 3, 2024, from https://handbook.ggcmedicines.org.uk/guidelines/respiratory-system/guidelines-on-oxygen-and-oximetry/

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

Clinical Review: Suzanne M. Casey, MSN-Ed, RN

Published: August 2024

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