The saturation level of oxygen in the blood can be assessed by using

KGMU 2024

Medical Surgical Nursing

Easy

Appeared in: KGMU 2024

Explanation

Pulse oximetry is a non-invasive technique that measures the arterial oxyhemoglobin saturation (SpO₂) of the blood.
It works by using a probe with a light-emitting diode (LED) that passes light through a pulsating capillary bed (like a fingertip) to a photodetector.
The device calculates the percentage of hemoglobin saturated with oxygen based on the differential absorption of red and infrared light by oxygenated and deoxygenated blood.
A normal SpO₂ reading is typically between 95% and 100%. A reading below 90% is considered a clinical emergency.

Option A: A spirometer measures lung function, specifically the volume and flow of air a person can inhale and exhale. It does not measure the oxygen content in the blood.
Option C: A tonometer is a specialized instrument used to measure intraocular pressure (the pressure inside the eye). It has no function related to respiratory or circulatory assessment.
Option D: A cardiac monitor's primary function is to display the heart's electrical activity (ECG), heart rate, and rhythm. While many modern monitors have an integrated pulse oximetry module, the cardiac monitor itself does not measure oxygen saturation.

Visual 1: Diagram - An illustration showing a pulse oximeter probe attached to a patient's finger, detailing the light emitter and photodetector components. This helps visualize how the non-invasive measurement is taken.
Visual 2: Chart - A chart displaying SpO₂ levels and their clinical interpretations (Normal, Mild Hypoxemia, Severe Hypoxemia). This provides a quick reference for understanding the readings.

Clinical Relevance

Nursing practice connection: Knowing Assessment of Blood Oxygen Saturation helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Pulse oximetry is often considered the 'fifth vital sign' in clinical practice, allowing for rapid and continuous assessment of a patient's respiratory status.
Nurses must be aware of factors that can cause inaccurate SpO₂ readings, such as poor peripheral circulation, dark nail polish, patient movement, hypothermia, or incorrect probe placement.
A key limitation is that pulse oximetry cannot differentiate between hemoglobin saturated with oxygen and hemoglobin saturated with carbon monoxide (carboxyhemoglobin). Therefore, in cases of suspected smoke inhalation or carbon monoxide poisoning, an arterial blood gas (ABG) test is necessary for an accurate assessment.

How to Approach the Question

First, analyze the question to identify the key concept being tested, which is the measurement of 'oxygen saturation in the blood'.
Next, evaluate each option based on its primary medical function.
Eliminate 'Spirometer' as it relates to lung volume (breathing mechanics), not blood oxygen.
Eliminate 'Tonometer' as it is an ophthalmology tool for eye pressure.
Differentiate between 'Pulse oximetry' and 'Cardiac monitor'. A cardiac monitor tracks heart electricity (ECG). The term 'oximetry' itself points directly to the measurement of oxygen.
Conclude that pulse oximetry is the specific tool designed for measuring blood oxygen saturation.

Concept Tested & Keywords

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