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

NORCET 9 Mains - 2025

Medical Surgical Nursing

Hard

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 nares.
This sizing ensures there is an intentional leak around the prongs, which is essential for the therapy to work correctly.
The leak allows for the washout of carbon dioxide (CO₂) from the pharyngeal anatomic dead space during exhalation.
Proper sizing prevents the dangerous buildup of unintended positive airway pressure (barotrauma) and ensures patient comfort.

Option A: This is incorrect and potentially dangerous. A key principle of HFNC is to have a leak around the cannula to allow for CO₂ washout. Sealing the nares can cause barotrauma.
Option B: This is false. HFNC systems are equipped with an air-oxygen blender that allows for precise titration of the fraction of inspired oxygen (FiO₂) from 21% (room air) up to 100%.
Option D: This is false. A core feature and major advantage of HFNC is the continuous delivery of heated and humidified gas. This improves patient comfort and mucociliary function.

Visual 1: Diagram - A side-by-side comparison showing correct vs. incorrect HFNC prong sizing in the nares. The correct side shows the prong occupying less than 50% of the nostril diameter, with arrows indicating gas leakage. The incorrect side shows a large prong occluding the nostril.

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 patient safety measure to prevent barotrauma and ensure effective ventilation by allowing CO₂ washout.
Nurses must regularly assess the patient's nares for skin breakdown, a common complication if the cannula is too tight or improperly secured.
What if? If a patient on HFNC develops a headache, nasal pressure, or becomes agitated, the nurse should immediately assess the cannula fit. An oversized cannula could be trapping CO₂ or causing excessive pressure, leading to these symptoms.

How to Approach the Question

First, identify the core subject of the question: High-Flow Nasal Cannula (HFNC) therapy.
Recall the key principles of HFNC: high flow, heated humidification, FiO₂ blending, and the mechanism of CO₂ washout.
Evaluate each option against these principles.
Option A suggests minimizing leaks, which contradicts the CO₂ washout mechanism. Eliminate it.
Option B limits FiO₂, which contradicts the capability of HFNC blenders. Eliminate it.
Option D suggests intermittent humidification, which contradicts a core feature of HFNC. Eliminate it.

Concept Tested & Keywords

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