A client is receiving oxygen at 2 L/min via a nasal cannula. What oxygen concentration is the client receiving?

Choice A rationale
While it’s true that a nasal cannula allows the patient to remove it for a while when it gets uncomfortable, this is not the primary reason for using a nasal cannula. The main purpose of a nasal cannula is to deliver oxygen.
Choice B rationale
A nasal cannula delivers the low concentration of oxygen that the patient needs. It is designed to provide a specific amount of oxygen, and the flow rate can be adjusted as needed.

Choice C rationale
While a nasal cannula does deliver a specific concentration of oxygen, it does not do so constantly. The amount of oxygen delivered can vary depending on the patient’s breathing rate and depth.
Choice D rationale
A nasal cannula does not deliver the highest concentration of oxygen possible. Other devices, such as non-rebreather masks, can deliver higher concentrations of oxygen.

Choice A rationale

Full-thickness tissue loss extending to underlying support structures such as muscle, tendon, or bone is characteristic of a stage 4 pressure ulcer, not a stage 312.
Choice B rationale
A stage 3 pressure ulcer involves full-thickness skin loss and may appear as a deep crater. There may be damage to or necrosis of subcutaneous tissue that may extend down to, but not through, underlying fascia. This description matches the statement in Choice B, making it the correct answer.
Choice C rationale
A shallow, ruptured or intact skin blister without slough is more indicative of a stage 2 pressure ulcer. In a stage 2 pressure ulcer, there is partial-thickness loss of dermis presenting as a shallow open ulcer with a red-pink wound bed.
Choice D rationale
Unbroken skin with un-blancheable erythema is characteristic of a stage 1 pressure ulcer, not a stage 3. In a stage 1 pressure ulcer, the skin is not broken, but it has redness that does not lighten (or blanch) when you press on it.