How long can blood stored with CPD – A ?
**Core Concept**
The question tests the knowledge of blood storage and the role of **CPD-A (Citrate-Phosphate-Dextrose-Adenine)** in extending the shelf life of whole blood and red blood cells. CPD-A is a solution used for preserving blood by preventing clotting and providing nutrients to maintain cellular function.
**Why the Correct Answer is Right**
CPD-A allows blood to be stored for up to 35 days due to the adenine, which helps in maintaining the level of **ATP (Adenosine Triphosphate)** in red blood cells, thereby preserving their viability. The citrate acts as an anticoagulant by chelating calcium, phosphate helps in maintaining the osmotic balance, and dextrose serves as a nutrient for the cells.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it underestimates the storage duration achievable with CPD-A.
**Option B:** This option might seem plausible but does not accurately represent the maximum storage time with CPD-A.
**Option D:** This option overestimates the storage capability of CPD-A.
**Clinical Pearl / High-Yield Fact**
Remember, the key to extended blood storage is maintaining the viability of red blood cells, and **CPD-A** significantly contributes to this by supporting the metabolic needs of the cells.
**Correct Answer:** C. 35 days