False low Pulse Oximetry Reading

Pulse oximetry generally provides an accurate noninvasive estimate of arterial hemoglobin saturation, but various confounders can lead to errors.

  • Factors that can produce falsely low estimates of pulse oximetry arterial hemoglobin saturation (SaO2) include
  • the presence of methemoglobin
  • anemia combined with hypotension
  • move your hands at the time of diagnosis
  • dark skin pigmentation
  • certain skin dyes
  • blue or green nail polish and
  • severe regurgitation

Therefore, caution should be exercised when using pulse oximetry to estimate arterial saturation in patients.

False low Pulse Oximetry Reading
False low Pulse Oximetry Reading

Causes of low pulse oximetry reading

One of the causes is hypoxemia, it occurs when oxygen levels in the blood are lower than normal. If the oxygen levels in your blood are too low, your body may not work properly.

Blood carries oxygen to cells throughout the body to keep them healthy. Hypoxemia can cause mild problems like headaches and shortness of breath. In severe cases, it can interfere with heart and brain function. Hypoxemia that causes low oxygen levels in your body’s tissues is called hypoxia. Sometimes people use the two terms interchangeably, but they are not the same.

What Causes Hypoxemia?

A variety of conditions and circumstances can interfere with the body’s ability to supply normal levels of oxygen to the blood. Some of the more common causes of hypoxemia include:

  • Heart conditions
  • Heart defects
  • Pulmonary conditions such as
    • asthma,
    • emphysema and
    • bronchitis
  • High altitude places
  • Strong painkillers
  • Sleep apnea
  • Inflammation or scarring of lung tissue

Pulse oximeter false low reading

How to interpret an oximeter reading

When taking measurements with the pulse oximeter, pay attention to whether the oxygen level is lower than previous measurements or is decreasing over time.

Changes or trends in measurements can be more significant than a single measurement.

  • The over-the-counter products that you can buy in the store or online are not intended for medical purposes.
  • Do not rely solely on a pulse oximeter to assess your health or oxygen level.
  • If you monitor oxygen levels at home, watch for other signs or symptoms of low oxygen levels, such as:
  • Bluish discoloration of the face, lips, or nails
  • Shortness of breath, trouble breathing, or a cough that gets worse
  • Restlessness and discomfort
  • Chest pain or tightness
  • Fast or racing pulse.

Be aware that some patients with low oxygen levels may show none or none of these symptoms. Only a healthcare provider can diagnose a medical condition such as hypoxia (low oxygen levels).

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