NORCET 9 Mains - 2025: A nurse caring for an adult on high-flow nasal cannula (HFNC) should understand which statement is correct?&…

NORCET 9 Mains - 2025

Medical & Surgical Nursing

Medium

Appeared in: NORCET 9 Mains - 2025

Explanation

The prongs of a high-flow nasal cannula should occupy no more than 50% of the cross-sectional area of the nostrils.
This sizing is critical to create an intentional leak, which allows for the washout of carbon dioxide from the upper airway during exhalation.
Proper sizing prevents the dangerous buildup of unintended positive pressure (barotrauma) and ensures the therapy's primary mechanism of action is effective.
This principle defines HFNC as an 'open system' in contrast to 'closed systems' like CPAP masks which require a tight seal.

Option A: This is incorrect and dangerous. HFNC therapy relies on a leak around the prongs to flush out exhaled CO2. Choosing the largest size to create a seal would trap CO2 and could cause pressure-related injury (barotrauma).
Option B: This is factually incorrect. HFNC systems are equipped with an oxygen blender that allows for precise titration of the fraction of inspired oxygen (FiO2) from 21% (room air) all the way up to 100%.
Option D: This is incorrect. A core feature and major advantage of HFNC is the continuous delivery of heated and humidified gas. This improves patient comfort, prevents airway drying, and aids mucociliary clearance.

Clinical Relevance

Nursing practice connection: Knowing Principles of High-Flow Nasal Cannula (HFNC) Therapy helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Proper cannula sizing is a critical nursing assessment to ensure patient safety and the therapeutic effectiveness of HFNC, preventing complications like barotrauma and nasal pressure injuries.
Nurses must regularly assess the patient's nares for any signs of skin breakdown, which can occur if the cannula is too large or not secured properly.
What if? If a patient on HFNC develops a nosebleed (epistaxis), the nurse should pause the therapy, apply pressure, and notify the provider. The cause could be irritation from dry air (if humidification fails) or pressure from the prongs, necessitating a re-evaluation of the setup.

How to Approach the Question

First, identify the core topic of the question, which is High-Flow Nasal Cannula (HFNC) therapy.
The question asks for a 'correct' statement, meaning you must evaluate the truthfulness of each option based on the principles of HFNC.
Recall the key features of HFNC: 1) high flow rates, 2) continuous heated humidification, 3) variable FiO2 up to 100%, and 4) the need for a leak around the prongs for CO2 washout.
Evaluate Option A: 'Choose the largest cannula size to minimize leak.' This contradicts the principle of needing a leak. Eliminate it.
Evaluate Option B: 'HFNC provides an oxygen fraction below 50% only.' This is a factual error; HFNC can deliver up to 100% FiO2. Eliminate it.
Evaluate Option D: 'HFNC provides humidification intermittently.' This contradicts the principle of continuous humidification. Eliminate it.

Concept Tested & Keywords

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E6 Nelson Textbook of Pediatrics(2024) — Volume 1 pp. 663-665, 664-666

E6 Nursing Fundamentals Potter Perry 12e Part 5 p. 7-9