Uses and Limitations of Pulse Oximetry

Overnight pulse oximetry testing helps doctors with various kinds of diagnosis. It also saves the patient all the unnecessary needles and probing for tests that could otherwise be determined with a device like an oximeter.
In recent years, pulse oximetry has shown great assistance in clinical settings and helped greatly in making treatments better. However the human body is a complex mechanism and the ever changing conditions have shown the devices have some limitations.

Uses of Pulse Oximeter:
A pulse oximeter is a non-invasive device used for evaluating the oxygen status in a patient’s blood. The frequent use and constant advancements in the device have made it one of the most widely used medical equipment in clinical settings. It’s major uses span around monitoring the condition of patients and diagnosing various medical conditions.

Let’s have a look at all the ways overnight pulse oximetry testing can be utilized

  • The device is used in intensive care units to closely monitor the steadiness of oxygen in a patient’s tissues.
  • A pulse oximeter is very effective during transport from one medical facility to another. It is also used abundantly in ambulances.
  • Pulse Oximetry is used for diagnostic purposes. Overnight pulse oximetery testing can help diagnose various respiratory conditions, sleep conditions and exercise testing.

Like most things a pulse oximeter has its limitations. However knowing these limitations can help the medical practitioners and nurses take better care of their patients. Let’s learn about these limitations:


  • Pulse oximeter readings will only be accurate when the blood flow in the body is accurate and steady. If, for any reason the blood flow is slow, there’s a high chance that the readings will not be accurate.
  • While pulse oximeter is very feasible with determining the oxygen level in the blood, it cannot determine the level of carbon dioxide. In situations where a patient is suffering with conditions such as asthma or COPD, the pulse oximeter will still show the oxygen level completely normal.
  • In case of slow perfusion and small pulse amplitude, the pulse oximeter testing will be inaccurate.
  • Cold extremities will result in unsatisfactory signals. For instance patients suffering from hypothermia and hypotension will result in inaccurate readings.
  • When a patient is going into cardiac arrest the peripheral pulse goes completely weak, so much so that the device fails to even detect them. Not being able to detect pulse can be a sign of danger and swift measures should be taken immediately.
  • Unexpected movement and motion can also disrupt the readings of the pulse oximeter. Tremors or shivering due to any physical condition can result in inaccurate readings.
  • The presence of methemoglobin, carbon monoxide poisoning or abnormal levels of haemoglobin in blood can result in erratic readings. 

It’s very important that clinicians conducting the oximetry testing must be aware of these limitations.