Venturi mask provides 40-50 percentage of oxygen at a rate of ______ litre/minute to a patient experiencing breathing difficulty?

Appeared in: RUHS, Jaipur, M.Sc Nursing Entrance Exam-2021

Explanation

A Venturi mask is a high-flow device that uses the Venturi effect to entrain a fixed proportion of room air to deliver a precise fraction of inspired oxygen (FiO2).
Different color-coded adapters are used to set the specific FiO2.
To achieve an FiO2 of 40%, the red adapter is used, which requires an oxygen flow rate of 10 L/min.
To achieve an FiO2 of 50%, the pink adapter is used, which requires a flow rate of 12 L/min.
Therefore, the flow rate range of 10-15 L/min correctly covers the oxygen concentration of 40-50%.

Option A: A flow rate of 1-5 L/min is too low to achieve a 40-50% oxygen concentration with a Venturi mask.
Option C: A flow rate of 16-20 L/min is higher than the standard recommendations for any of the common Venturi mask adapters.
Option D: This range represents oxygen concentration percentages (FiO2), not the oxygen flow rate, which is measured in litres per minute (L/min).

Clinical Relevance

Nursing practice connection: Prioritize focused assessment, early escalation, and real-time monitoring when managing Venturi mask flow rates and corresponding oxygen concentration (FiO2) in acute care settings.
The Venturi mask is the preferred oxygen delivery device for patients with Chronic Obstructive Pulmonary Disease (COPD) because it delivers a precise, fixed FiO2, which prevents CO2 retention.
In COPD patients, the respiratory drive is often dependent on mild hypoxemia (hypoxic drive). Administering too much oxygen can suppress this drive, leading to hypoventilation and hypercapnia (high CO2 levels).
What if? If a COPD patient requires a precise but lower FiO2 of 28% to maintain adequate oxygen saturation without suppressing their respiratory drive, the nurse would select the white adapter and set the flowmeter to exactly 4 L/min.

How to Approach the Question

First, identify the key terms in the question: 'Venturi mask', '40-50 percentage of oxygen', and 'flow rate in litre/minute'.
This is a factual recall question. You need to access your knowledge about oxygen delivery devices.
Recall the principle of the Venturi mask: it uses color-coded adapters to deliver a precise FiO2, and each adapter has a specific required flow rate.
Mentally (or by writing down) list the common Venturi adapters and their corresponding FiO2 and flow rates.
Find the adapters that deliver 40% and 50% oxygen. The red adapter delivers 40% at 10 L/min, and the pink/green adapters deliver 50-60% at 12-15 L/min.
Based on this, determine the correct flow rate range that encompasses these values, which is 10-15 L/min.

Concept Tested & Keywords

Concept Tested: Venturi mask flow rates and corresponding oxygen concentration (FiO2).
Stem keywords: Venturi mask, 40-50 percentage of oxygen, flow rate, litre/minute
Lead-in keywords: BEST, MOST RELEVANT CLUE
Clinical cues: patient experiencing breathing difficulty
Negative lead-in flag: false

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E6 Nursing Fundamentals Taylor p. 731-733

E6 Nelson Textbook of Pediatrics(2024) — Volume 1 p. 663-665

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