Below image shows a monitoring device attached to a patient’s airway circuit displaying waveform and numerical values of exhaled gases. What is the primary use of this device?

1. A

   . To check peak inspiratory pressure

2. B

   To check expiratory pressure

3. C

   To check PCO₂ level in expired air

4. D

   . To check PO₂ in expired air

Appeared in: NORCET 10 Prelims-2026

Explanation

• The device shown is a capnography sensor (Capnostat 5), which is specifically designed to measure carbon dioxide.
• Capnography measures the concentration or partial pressure of carbon dioxide (PCO₂) in respiratory gases.
• The primary use is to monitor end-tidal CO₂ (EtCO₂), which provides a non-invasive approximation of arterial CO₂ (PaCO₂) levels.
• This monitoring is crucial for assessing ventilation, confirming endotracheal tube placement, and monitoring cardiopulmonary resuscitation (CPR) effectiveness.

Why Other Options Were Wrong

• Option A: Peak inspiratory pressure (PIP) is a measure of pressure, not gas concentration. It is measured using a manometer or the ventilator's built-in pressure sensors.
• Option B: Expiratory pressure, such as Positive End-Expiratory Pressure (PEEP), is also a pressure measurement, not a gas concentration measurement. It is monitored via the ventilator's pressure sensors.
• Option D: This device measures carbon dioxide (CO₂), not oxygen (O₂). Oxygen levels are measured by different devices.

Related Visual

• Visual 1: Infographic: A diagram showing the placement of a mainstream capnography sensor on an endotracheal tube within the ventilator circuit. The caption should explain how exhaled gas passes through the sensor.
• Visual 2: Chart: A typical capnogram waveform, labeling the different phases (inspiratory baseline, expiratory upstroke, alveolar plateau, inspiratory downstroke) and the location of the EtCO₂ reading. The caption should explain what each phase represents in the respiratory cycle.

Clinical Relevance

• Nursing practice connection: Prioritize focused assessment, early escalation, and real-time monitoring when managing Capnography and End-Tidal CO₂ Monitoring in acute care settings.
• Capnography is the gold standard for confirming correct placement of an endotracheal tube (ETT). A persistent EtCO₂ waveform confirms the tube is in the trachea, not the esophagus.
• During CPR, EtCO₂ monitoring provides real-time feedback on the quality of chest compressions and can indicate the return of spontaneous circulation (ROSC) with a sudden increase in the value.
• What if? If a patient being monitored with capnography suddenly shows a flatline (EtCO₂ drops to zero), the nurse's first action should be to assess the patient for respiratory and cardiac arrest, and then immediately check for equipment disconnection or malfunction (e.g., ETT dislodgement).

How to Approach the Question

• First, carefully examine the image. Identify the device if possible. The label 'CAPNOSTAT 5' is a strong clue.
• Recall or deduce the function of the device. 'Capno-' is a prefix related to carbon dioxide, and 'stat' implies measurement. This points towards CO₂ monitoring.
• Read the question, which asks for the 'primary use' of a device monitoring 'exhaled gases'.
• Evaluate the options based on your identification. Option A and B relate to pressure, which is incorrect. Option D relates to oxygen, which is incorrect.
• Option C, 'To check PCO₂ level in expired air,' directly matches the function of a capnograph. Select this as the correct answer.

Concept Tested & Keywords

• Concept Tested: Capnography and End-Tidal CO₂ Monitoring
• Stem keywords: monitoring device, airway circuit, exhaled gases, waveform
• Lead-in keywords: primary use
• Clinical cues: The image shows a device labeled 'CAPNOSTAT 5', which is a brand name for a capnography sensor.

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QvaJPjMi6AYZBxGZMFvvhm

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