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Feb.25.2021

Pulse Oximetry (Pediatric) - CE

ALERT

A pediatric patient with profound anemia may have a normal oxygen saturation level and still be hypoxemic.

OVERVIEW

Pulse oximetry provides a noninvasive, reasonably accurate estimate of arterial oxygen saturation. Hemoglobin (Hgb) saturated with oxygen absorbs light differently than unsaturated Hgb, and the pulse oximeter measures the amount of absorption and uses it in the calculation of the ratio of saturated Hgb to total Hgb (Figure 1)Figure 1. The pulse oximeter monitor displays the ratio as a percentage.

The patient's oxygenation status depends on the amount of Hgb and on how well it moves throughout the body and how easily oxygen leaves the Hgb and enters the cells. Normal pulse oximetry values vary by age and condition. The generally accepted range is more than 94% unless the patient has anemia.undefined#ref3">3 Probes come in infant, pediatric, and adult sizes. Clip-on probes are primarily used for spot checks, and circumferential tape probes are primarily used for continuous monitoring (Figure 2)Figure 2.

Inaccurate readings can occur in these patients:1

  • Pediatric patients with decreased Hgb concentrations (from anemia or hemorrhage) can have a normal oxygen saturation and still be hypoxemic. Even though the Hgb may be fully saturated, the patient does not have sufficient Hgb to carry enough oxygen to meet the body’s needs.
  • Pediatric patients with decreased perfusion (from shock, bradycardia, or cardiovascular disease) may start with a normal oxygen saturation, but because of decreased blood flow, the Hgb is in prolonged contact with the cells. The cells’ oxygen demands are increased, and the Hgb is stripped of oxygen, taking longer to return to the lungs for reoxygenation.

The dynamics of the oxyhemoglobin dissociation curve (ODC) include (Figure 3)Figure 3:

  • A shift to the right in the ODC means the Hgb's affinity for oxygen has decreased at the alveolar level. The Hgb readily releases oxygen at the cellular level.
  • A shift to the left in the ODC means the Hgb's affinity for oxygen has increased at the alveolar level. Oxygen binds more tightly to the Hgb and is released less readily at the cellular level.

Pulse oximetry readings are altered by:1

  • Incorrect placement of the sensor
  • Movement, causing artifact
  • Intravascular dyes
  • Low perfusion states
  • Dark skin pigmentation
  • Vinyl or gel nail polish and artificial nails
  • Severe anemia
  • Smoke inhalation or carbon monoxide poisoning
  • Sickle cell anemia vasoocclusive crises
  • Methemoglobinemia
  • Sulfhemoglobinemia
  • Severe hyperbilirubinemia
  • Hypothermia

EDUCATION

  • Provide developmentally and culturally appropriate education based on the desire for knowledge, readiness to learn, and overall neurologic and psychosocial state.
  • Explain the patient’s underlying condition, the reasons for pulse oximetry monitoring, and the meaning of the oxygen saturation reading.
  • Review the pulse oximeter alarm and explain the causes of false alarms, such as movement.
  • Encourage questions and answer them as they arise.

ASSESSMENT AND PREPARATION

Assessment

  1. Perform hand hygiene before patient contact.
  2. Introduce yourself to the patient and family.
  3. Verify the correct patient using two identifiers.
  4. Assess the patient’s developmental level and ability to interact.
  5. Assess the pertinent medical history and current condition predisposing the patient to alterations in oxygenation, ventilation, and acid-base balance.
  6. Assess the patient’s respiratory status, including respiratory rate, work of breathing, and breath sounds.
  7. Assess the patient for signs and symptoms of inadequate oxygenation and ventilation.
  8. Note the patient’s serum Hgb level.
  9. Assess the patient for conditions that prevent accurate monitoring of oxygen saturation with a pulse oximeter, such as carbon monoxide poisoning and nitric oxide administration.
  10. Assess the intended probe placement site for adequate perfusion, skin integrity, and nail polish.
  11. Assess the patient’s and family’s understanding of the reasons for and the risks and benefits of the procedure.

PROCEDURE

  1. Perform hand hygiene.
  2. Verify the correct patient using two identifiers.
  3. Explain the procedure to the patient and family and ensure that they agree to treatment.
  4. Select an appropriate oximeter probe site (Figure 2)Figure 2. Preferred sites for a neonate include the foot, hand, and forehead; for an infant, the great toe, ball of the foot, palm of the hand, earlobe, and wrist; and for an older pediatric patient, the index finger or another digit.
    Rationale: Site selection can affect the accuracy of pulse oximeter readings. For instance, in pediatric patients with cyanotic heart disease, a preductal saturation can be obtained in the right arm, and a postductal saturation may be obtained in the left arm or in either foot.
    Avoid sites distal to arterial lines and noninvasive blood pressure cuffs and sites on the same side as a Blalock-Taussig shunt.
  5. Apply the probe to the patient, ensuring that the light source is directly opposite the photodetector and the probe fits snugly without any gaps between it and the skin.
    Rationale: For accurate saturation measurement, the light source and the photodetector must be directly opposite each other.
    Do not apply the probe so tightly that it interrupts blood flow to or from the site. Tissue perfusion can be impaired by circumferential restriction of arterial flow. Venous return and venous congestion may lead to venous pulsations and false readings.
  6. Plug the oximeter into a grounded outlet, plug the cable into the oximeter or oximetry box, and plug the probe into the cable.
    Plug portable pulse oximeters into an electrical outlet to keep the battery charged.
  7. Turn the oximeter on and allow an initializing period for detection and averaging of pulse rate and saturations.
    For spot checking saturations, allow the oximeter several minutes to average and obtain a reliable saturation reading.
  8. Set the appropriate alarm parameters according to the patient’s age, underlying health problem, and medical history per the practitioner’s order or the organization’s practice. Make sure that alarms are turned on, functioning properly, and audible to health care team members.2
    Rationale: Setting the appropriate alarm parameters decreases the number of false alarms.
  9. Verify the accuracy of the pulse oximeter reading by correlating it with the patient’s heart rate. Analyze the size and shape of the waveform and the height and fluctuation of the graphic display bar.
    Rationale: Correlating the reading with the patient’s heart rate ensures the accuracy of the pulse oximeter value. The patient’s measured electrocardiogram or palpated heart rate should match the heart rate displayed by the pulse oximeter.
    If the oximeter displays the pulse wave graphically, the pulse waveform should resemble an arterial waveform without a dicrotic notch. If the pulsatile flow past the probe is sluggish, the waveform may be dampened, and the reading may be incorrect.
  10. Perform hand hygiene.
  11. Document the procedure in the patient's record.

MONITORING AND CARE

  1. Assess the patient's physiologic stability, including vital signs, respiratory status, and clinical appearance.
    Rationale: Pulse oximetry provides only one piece of information. The patient's physiologic status must be considered to gain a complete understanding of the patient's condition.
    Reportable conditions: Hypoxia, including decreased level of consciousness; tachypnea and tachycardia; increased work of breathing; cyanosis; decreased oxygen saturation level
  2. Assess the probe site for breakdown and rotate the site daily or per the organization’s practice. This is especially important when using circumferential probes for continuous monitoring.
    Rationale: Skin probes can cause skin injury. Certain conditions, such as low perfusion states, norepinephrine and other vasoconstrictive infusions, hypoxia, hypotension, prolonged probe contact, and hypothermia, can increase the likelihood of injury.
    Reportable conditions: Skin discoloration, decreased capillary refill time, skin breakdown at or distal to the probe site
  3. Assess, treat, and reassess pain.

EXPECTED OUTCOMES

  • Oxyhemoglobin saturation levels are continuously monitored.
  • All periods of desaturation are identified, and appropriate action is taken.
  • Number of false alarms is reduced.
  • Skin integrity is maintained.

UNEXPECTED OUTCOMES

  • Pulse oximetry saturation readings do not correlate with measured saturation from arterial blood gas analysis.
  • Equipment fails.
  • Patient decompensates without identification of changes in pulse oximetry.
  • Excessive motion or decreased tissue perfusion interferes with proper functioning of the pulse oximeter.
  • Pulse oximeter probe causes breakdown in skin integrity.

DOCUMENTATION

  • Pulse oximetry readings
  • Amount and delivery method of supplemental oxygen (if used)
  • Patient's physical assessment findings
  • Patient's response to interventions
  • Condition of probe site
  • Episodes of desaturation
  • Unexpected outcomes and related interventions
  • Education

REFERENCES

  1. Fetzer, S.J. (2018). Chapter 5: Vital signs. In A.G. Perry, P.A. Potter, W.R. Ostendorf (Eds.), Clinical nursing skills and techniques (9th ed., pp. 66-104). St. Louis: Elsevier.
  2. Joint Commission, The. (2021). National patient safety goals for the hospital program. Retrieved February 1, 2021, from https://www.jointcommission.org/-/media/tjc/documents/standards/national-patient-safety-goals/2021/hap_npsg_jan2021.pdf (Level D)
  3. Topjian, A.A. and others. (2020). Part 4: Pediatric basic and advanced life support: 2020 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation, 142(16 Suppl. 2), S469-S523. doi:10.1161/CIR.0000000000000901 Retrieved February 1, 2021, from https://www.ahajournals.org/doi/10.1161/CIR.0000000000000901 (Level D)

ADDITIONAL READINGS

Deacon, A.J., Pratt, O.W. (2017). Measurement of pulse oximetry, capnography and pH. Anaesthesia & Intensive Care Medicine, 18(12), 639-643, doi:10.1016/j.mpaic.2017.09.004.

AACN Levels of Evidence

  • Level A - Meta-analysis of quantitative studies or metasynthesis of qualitative studies with results that consistently support a specific action, intervention, or treatment
  • Level B - Well-designed, controlled studies, with results that consistently support a specific action, intervention, or treatment
  • Level C - Qualitative studies, descriptive or correlational studies, integrative reviews, systematic reviews, or randomized controlled trials with inconsistent results
  • Level D - Peer-reviewed professional organizational standards with clinical studies to support recommendations
  • Level E - Multiple case reports, theory-based evidence from expert opinions, or peer-reviewed professional organizational standards without clinical studies to support recommendations
  • Level M - Manufacturer's recommendations only
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