A nurse caring for an adult on high-flow nasal cannula (HFNC) should understand which statement is correct?

NORCET 7 Prelims -2024

Medical & Surgical Nursing

Easy

Appeared in: NORCET 7 Prelims -2024

Explanation

The core principle of HFNC is to function as an 'open system,' which requires space around the nasal prongs.
Standard clinical guidelines recommend that the prongs should not occlude more than 50% of the nostril's diameter.
This intentional 'leak' is crucial for the washout of carbon dioxide from the nasopharyngeal dead space during exhalation.
Proper sizing prevents the buildup of unintended and potentially harmful positive airway pressure, ensuring patient safety and comfort.

Option A: HFNC delivers continuous, not intermittent, heated and humidified gas. The high flow rates would be intolerable and damaging to the nasal mucosa without constant humidification.
Option C: HFNC systems are capable of delivering a wide range of oxygen concentrations, from 21% (room air) up to 100%, via an integrated air-oxygen blender.
Option D: This is the opposite of the correct procedure. A deliberate leak is necessary for CO₂ washout. Attempting to seal the nares can cause barotrauma and prevent the device from working as intended.

Visual 1: Diagram - Correct vs. Incorrect HFNC prong sizing. One image shows prongs occupying less than 50% of the nostril with arrows indicating gas leakage. The other shows prongs occluding the entire nostril, marked as incorrect.
Visual 2: Infographic - The key mechanisms of HFNC, illustrating CO2 washout, PEEP effect, humidification, and meeting inspiratory flow demand.

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.
Nurses are responsible for selecting the correct cannula size, setting the prescribed flow rate and FiO₂, and monitoring the patient's respiratory status, comfort, and skin integrity (especially around the nares and ears).
Regularly assess for signs of respiratory distress (increased work of breathing, tachypnea, hypoxia) which may indicate the patient is failing HFNC and may need escalation of care.
What if? If the patient's oxygen saturation does not improve despite increasing the FiO₂ on HFNC, the nurse should assess for other issues. This could include an inadequate flow rate, poor prong positioning, or a worsening of the underlying respiratory condition requiring escalation to a physician, as the patient may need non-invasive or invasive mechanical ventilation.

How to Approach the Question

First, identify the core concept of the question, which is the correct application and principles of High-Flow Nasal Cannula (HFNC) therapy.
Evaluate each option as a true or false statement based on your knowledge of HFNC.
Option 1: Recall that high flows require continuous humidification to prevent mucosal damage. This statement is false.
Option 2: Remember that HFNC is an 'open' system that relies on a leak for CO2 washout. The 50% rule is a key guideline. This statement is likely true.
Option 3: Recall that HFNC is a high-level support that can deliver up to 100% FiO2. This statement is false.
Option 4: This contradicts the principle of an 'open' system. Minimizing leak is the goal of 'closed' systems like CPAP. This statement is false.

Concept Tested & Keywords

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