Nurse giving oxygen therapy should know that it has to be humidified because

Appeared in: JIPMER Nursing Officer-2017

Explanation

Medical oxygen supplied from cylinders or wall outlets is completely dry.
Inhaling dry gas removes moisture from the respiratory mucous membranes, causing them to become dehydrated.
Dehydration of the mucosa leads to the thickening of respiratory secretions (mucus).
Thickened mucus is difficult to clear, impairs the function of the mucociliary escalator, and can lead to airway obstruction (mucus plugging) and an increased risk of infection.

Option A: Oxygen is not a hot gas. As a compressed gas expands, it cools due to the Joule-Thomson effect. It does not pose a thermal risk to the trachea.
Option C: Humidification does not clean or sterilize oxygen. Conversely, the water reservoir in a humidifier can become a source of bacterial contamination if not properly maintained with sterile water and changed regularly.
Option D: This statement is chemically inaccurate. Humidification adds water vapor (H₂O), not free hydrogen ions (H⁺). The process does not alter the partial pressure of oxygen or its diffusion across the alveolar-capillary membrane.

Clinical Relevance

Nursing practice connection: Knowing Principles of Oxygen Therapy helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Humidification is a key nursing intervention to prevent complications of oxygen therapy, especially for high-flow rates (greater than 4 L/min) or long-term use.
Failure to humidify oxygen when indicated can lead to patient discomfort, thickened secretions, and potentially atelectasis or pneumonia due to retained secretions.
Nurses are responsible for ensuring the humidifier is filled with sterile water (not saline or tap water) to the correct level and that the equipment is changed per facility protocol to prevent infection.

How to Approach the Question

First, identify the core concept of the question: the reason for humidifying therapeutic oxygen.
Analyze the stem: The question asks for the 'why' behind a common nursing practice.
Evaluate each option based on physiological and physical principles.
Option A: Recall the properties of compressed gases. They cool on expansion, they are not hot.
Option B: Consider the effect of a constant flow of dry gas on a moist surface like the respiratory tract. It will have a drying effect, which would logically make mucus thicker.
Option C: Think about the function of a simple bubble humidifier. It holds water for the gas to pass through; it doesn't have a filtration mechanism. It can be a source of infection if not clean.

Concept Tested & Keywords

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E6 Nursing Fundamentals Taylor pp. 729-731, 724-726, 730-732

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