pulse oximetry: purpose, uses and reading

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Pulse oximetry, a painless and non-invasive procedure, gauges your blood’s oxygen levels and distribution to extremities like the arms and legs. This assessment employs a pulse oximeter device, which, despite its current prominence due to the pandemic, has been in use for over five decades.

Traditionally, pulse oximeters have served as indispensable tools for monitoring and evaluating blood oxygenation in individuals with chronic heart and lung conditions, typically within medical settings, under the purview of healthcare professionals.

However, the COVID-19 pandemic has prompted a surge in the use of pulse oximeters, making them a standard household device. During the pandemic, these instruments played a transformative role by enabling accurate and continuous monitoring of patients’ oxygen levels, significantly saving lives.

A pulse oximeter is a compact handheld device that attaches to your fingertip, estimating oxygen saturation in arterial blood. Comprising a monitor with a display screen, a probe equipped with light-emitting diodes (LEDs), a photodetector, and batteries, it operates on the principle of light absorption by oxygenated haemoglobin (O2Hb). Oxygenated haemoglobin absorbs more infrared light, allowing more red light to pass through. The pulse oximeter calculates the ratio between red and infrared light measurements, converting it into SpO2, then displayed on the screen.

what is the purpose of pulse oximetry?

Pulse oximetry has become an integral part of medical practice, often hailed as the fifth vital sign alongside pulse rate, body temperature, respiration rate, and blood pressure.

Unlike a direct blood sample measurement, an oximeter’s primary goal is indirectly assessing blood oxygen saturation.

Several conditions affect lung function and blood oxygen levels. A pulse oximeter is used primarily in situations such as:

  • Pneumonia
  • Lung cancer
  • Asthma
  • Chronic Obstructive Pulmonary Disease
  • Anaemia
  • Congenital heart disease
  • COVID 19

In these scenarios, an oximeter reading assumes crucial significance:

  • Treatment Response Assessment: To gauge your response to medical interventions.
  • Ventilator Effectiveness Evaluation: For determining the ventilator’s efficacy in aiding respiration.
  • Indication for Respiratory Assistance: To ascertain the necessity for respiratory support or supplemental oxygen therapy.
  • Monitoring Oxygen Therapy: To assess the effectiveness of ongoing supplemental oxygen therapy and make adjustments if necessary.
  • Post-Sedation Surgical Monitoring: After surgeries involving sedation, continuously monitor and assess oxygen levels.

what are pulse oximetry reading ranges?

Understanding accurate measurement methods is essential before delving into pulse oximeter reading ranges. Whether in a hospital setting or using a fingertip pulse oximeter at home, adhering to critical guidelines is crucial. Here’s your guide on how to effectively use a pulse oximeter:

  • Invest in Quality: Opt for a reliable device like the Scure, Contec pulse oximeter, known for its user-friendliness and consistent, dependable readings.
  • Prepare Properly: Sit upright and unwind for a minimum of 5 minutes, refraining from talking, moving, or walking.
  • Optimal Positioning: Place your hand on your chest, aligning it with your heart’s level.
  • Device Setup: Activate the oximeter and affix it to your index finger securely.
  • Wait for Steady Readings: Allow time for the reading to stabilize. Keep the device on if fluctuations persist.
  • Pulse Monitoring: Many oximeters also display pulse rates. Familiarize yourself with how to interpret this information.
  • Recording Readings: Note the highest reading once stability is achieved for at least 5 seconds.

Following these steps ensures accurate and dependable readings for effective monitoring.

It is essential to note that certain things affect fingertip pulse oximeter readings. These include:

  • Dark nail paint
  • Measuring your blood saturation in cold surroundings
  • If you have a deformity in your finger
  • Skin pigmentation and thickness
  • Tobacco use immediately before or during your blood saturation measurement

This is how oximeter readings are organised:

Oxygen saturation (SpO2) %Observation
95 or moreNormal
92 or lessAbnormal

what do pulse oximetry readings tell us?

Learning how to interpret your oximeter data is crucial to grasp the significance of your readings. Here’s a breakdown of how to decipher the lessons from your fingertip pulse oximeter:

  • Healthy Range: A pulse rate within 97-100% indicates good health. Note that older adults often have lower saturation levels than younger individuals. A saturation level of 95% is acceptable in the absence of lung impairments.
  • Normal Oxygen Levels: A blood oxygen level of 95% is typical for healthy individuals and doesn’t raise concerns.
  • Low Oxygen Warning: Saturation below 92% suggests low oxygen and potential hypoxemia.
  • Critical Level: Consistent levels below 88% demand immediate medical attention; consult a doctor promptly.

Remember, these readings are influenced by your health status and situations, such as:

  • Health Conditions: Obesity, lung diseases, heart issues, sleep apnea, asthma, etc., may yield lower saturation levels.
  • Medical Treatments: Those undergoing cancer chemotherapy might exhibit reduced saturation.
  • Habits and Environment: Smoking, movement or talking during readings, extreme cold, and related hypothermia or reduced peripheral perfusion can impact tasks.

Understanding these factors enhances your comprehension of oximeter data.


At Portea, we prioritize your well-being. While pulse oximeters are safe for monitoring blood saturation levels, their usage should be prudent. If you encounter any of the mentioned health concerns while using our healthcare services, like home nursing, doctor consultations, or physiotherapy, promptly share your oximeter readings with our professionals. This proactive step ensures you receive timely and suitable medical attention, aligning with our commitment to your health and care. Your well-being is our utmost concern.

Also Know About:


1. Which is the best finger for an oximeter? 

The middle finger of your right hand is ideal for a pulse oximeter. Research indicates it yields the most accurate results. Ensure the finger is free from nail polish and not cold, as this may affect the accuracy of readings.

2. What is the full form SpO2 ? 

SpO2 stands for Saturation of Peripheral Oxygen. This abbreviation can be broken down into its components: “S” for saturation, “P” for pulse (or serum pressure), and “O2” for oxygen. SpO2 is synonymous with oxygen saturation, reflecting the amount of oxygen bound to haemoglobin in your blood’s peripheral areas. It’s a critical metric to assess respiratory health and overall oxygen levels.

3. Are SpO2 and BP the same?

SpO2 and blood pressure are separate medical metrics employed to assess an individual’s health status. Though closely tied to the heart, pivotal for overall well-being, they represent distinct aspects of physiological evaluation.

4. Which sensor is used in the oximeter?

Pulse oximetry employs red and infrared LEDs in its sensors to gauge oxygenated and deoxygenated haemoglobin levels. However, LED contamination can impact the oximeter’s calibration, leading to erroneous SpO2 readings, particularly below 80%.

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