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Acid Phosphatase
Cardiolipin Antibodies
Cold Agglutinins
Endoscopic Ultrasound
External Fetal Monitoring
Plasma Cortisol
Plasma Renin Activity
Prostate Specific Antigen
Pulse Oximetry
Rheumatoid Factor
Sweat Test
Technetium Pyrophosphate Scanning
Tensilon Test
Thallium Imaging

Pulse Oximetry

Pulse oximetry is a continuous noninvasive study of arterial blood oxygen saturation (Sao2) using a clip or probe attached to a sensor site (usually earlobe or fingertip). The percentage expressed is the ratio of oxygen to hemoglobin.


  • To monitor oxygenation of the tissues and organs peri operatively and during an acute illness
  • To monitor oxygenation in patients with higher oxygen needs (such those on a ventilator or those receiving a high percentage of oxygen) or when weaning from an oxygen source.
  • To monitor oxygen saturation during activities to determine patient tolerance.
  • To determine effectiveness of bronchodilators
  • To monitor oxygenation during testing for sleep apnea

Patient preparation

  • Explain to the patient that this test assesses oxygen content in the hemoglobin. Describe the procedure and answer all questions.
  • Explain who will perform the test and where and its duration.
  • Make sure that the patient has no false fingernails or nail polish.
  • Explain to the patient that the area where the clip or probe is attached must be massaged to increase blood flow.

Procedure and posttest care

  • Place the probe or clip over the finger or other intended sensor site so that the light beams and sensors are opposite each other.
  • Turn on the monitor and ensure that it accurately detects the patient's pulse and reads the percentage of oxygen.
  • If the monitor is to remain on continuously, ensure that the skin remains intact under the probe or clip and that the circulation is adequate. Select alternate sensor sites if the skin doesn't remain intact.
  • After the test is performed, remove the probe and clean it with alcohol.

Closely observe the monitor and report decreasing or abnormal Sao2 levels.

Normal findings

Sao2 levels are normally greater than 95%.

Abnormal findings

Hypoxemia with levels less than 95% indicate impaired cardiopulmonary function or abnormal gas exchange.

Interfering factors
  • Movement of the finger, ear, or alternate sensor site
  • Improper placement of the probe or clip
  • Anemic conditions, vasoconstriction, certain medications (such as vasopressors), hypotension, vessel obstruction, nail polish or false fingernails, administrations of lipid emulsions

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