Which cannula number is used for BT (Blood Transfusion)?

Appeared in: NORCET 2 - 2021 (shift-1)

Explanation

An 18-gauge cannula is the standard and preferred size for routine blood transfusions in adults.
Its large internal diameter (bore) allows blood components, especially viscous packed red blood cells, to flow easily.
This size minimizes the mechanical shearing forces on red blood cells, reducing the risk of hemolysis (cell destruction).
It also permits a rapid rate of infusion, which is essential in cases of major hemorrhage or trauma.

Option B: A 21-gauge cannula is smaller than the recommended size for adult blood transfusions. While sometimes used, it slows the infusion rate and increases the risk of hemolysis.
Option C: A 22-gauge cannula has a smaller bore, which significantly slows the flow of blood and increases the risk of hemolysis. It is not recommended for routine adult transfusions.
Option D: A 24-gauge cannula is very small and poses a high risk of causing hemolysis. The flow rate is extremely slow, making it unsuitable for transfusing blood in adults.

Visual 1: Chart - An infographic showing different IV cannula sizes, their corresponding gauge numbers, color codes, and typical clinical applications, highlighting the 18G for blood transfusion.

Clinical Relevance

Nursing practice connection: Knowing IV Cannula Gauge for Blood Transfusion helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Selecting the correct cannula size is a critical nursing responsibility to ensure patient safety and the effectiveness of the blood transfusion.
Using a cannula that is too small can lead to hemolysis, rendering the transfusion ineffective and potentially causing complications like acute kidney injury from the release of free hemoglobin.
What if? If the patient is in hemorrhagic shock and requires massive transfusion, the nurse should attempt to place an even larger cannula, such as a 16-gauge or 14-gauge, to facilitate very rapid fluid and blood product administration.

How to Approach the Question

First, identify the core of the question: selecting the correct IV cannula size for a blood transfusion.
Recall the properties of blood: it is more viscous (thicker) than standard IV fluids.
Understand the principle of flow: a thicker fluid requires a wider tube (larger bore) to flow smoothly and quickly.
Relate cannula gauge to size: remember that a smaller gauge number corresponds to a larger cannula diameter.
Evaluate the options: 18G is the largest cannula among the choices, making it the most suitable for transfusing viscous blood products in an adult, minimizing cell damage (hemolysis) and allowing for rapid infusion if needed.

Concept Tested & Keywords

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Practise the full NORCET 2 - 2021 (shift-1)

Attempt every question from this paper in a timed mock, then review the full solution for each one.