4.1 Red Blood Cells, Whole Blood, Washed, Frozen, and Rejuvenated

4.1 Red Blood Cells, Whole Blood, Washed, Frozen, and Rejuvenated

Quick Answer: Whole blood stores at 1–6 °C and outdates at 21 days in CPD/CP2D or 35 days in CPDA-1. Additive-solution red cells are the usual issued unit: about 300–350 mL, hematocrit typically 55–65%, 42-day dating, and one unit raises a stable adult’s hemoglobin about 1 g/dL (hematocrit about 3%). Washed red cells remove plasma proteins for severe allergic reactions or IgA deficiency and expire 24 hours after an open-system wash. High-glycerol (~40%) frozen red cells store at ≤ −65 °C for up to 10 years; deglycerolized units are a 24-hour product unless a closed-system licensed date applies. Rejuvenation restores 2,3-DPG and ATP, then the unit is washed or frozen.

This section is I.D. manufacturing: what the red-cell family is, how each modifier is made, and which storage clock applies. Transfusion thresholds, massive-transfusion ratios, and pediatric mL/kg dosing belong in Chapter 17. If a stem asks dating, temperature, hematocrit, glycerol concentration, or open- versus closed-system outdate, answer it here.

Whole blood — licensed starting material, uncommon issue product

Most U.S. collections still begin as whole blood. A licensed 450 mL ± 10% draw enters 63 mL of CPD or CPDA-1 (or 500 mL into 70 mL). The bag then contains red cells, plasma, leukocytes, and platelets plus anticoagulant. Storage is 1–6 °C. At refrigerator temperature, platelet membranes are injured and platelet function is lost within hours, so whole blood is not a platelet dose. Dating follows the primary anticoagulant only: CPD or CP2D, 21 days; CPDA-1, 35 days. Additive solution is not run into an intact whole-blood unit, so there is no routine 42-day whole-blood product.

Civilian hospitals rarely issue whole blood as first-line inventory. The collected bag is centrifuged and separated into red cells, plasma, and a platelet or cryoprecipitate pathway. Whole blood still appears on BB(ASCP) because it remains a licensed 21 CFR 640.1–640.5 product, because some trauma and military programs issue low-titer group O whole blood, and because an autologous unit may be stored as whole blood. Do not call it obsolete. Call it uncommon as a routine issued civilian component and still the usual starting material for component production.

Total volume is about 500–570 mL including anticoagulant. Hematocrit is the donor’s hematocrit diluted by anticoagulant — roughly the mid-30s to low-40s — not the 55–65% of an additive-solution red-cell unit. That extra plasma is why whole blood is a volume-plus-oxygen product and a poor choice when the patient needs red-cell mass without more plasma. Cold-stored whole-blood platelets do not replace a 20–24 °C platelet dose.

Red Blood Cells — the default oxygen-carrying unit

After a hard spin, most plasma is expressed into a satellite bag. If the remaining packed cells stay in residual CPDA-1 plasma, the labeled product is Red Blood Cells with 35-day dating and a high hematocrit (AABB expects ≤ 80% so enough plasma remains for preservation). If an additive solution (AS-1, AS-3, AS-5, or AS-7, about 100–110 mL) is added in a closed system, dating becomes 42 days and hematocrit falls into the typical 55–65% range. That AS unit is what most adult issue refrigerators hold.

Typical AS-RBC volume is about 300–350 mL. Teach the adult increment as a property of the unit, not as a therapy lecture: one unit raises hemoglobin about 1 g/dL and hematocrit about 3% in a stable ~70 kg adult who is not bleeding or hemolyzing. Children are dosed in mL/kg; do not apply the 1 g/dL rule to a toddler. Most U.S. red-cell inventories are prestorage leukoreduced. Leukoreduction, irradiation, washing, and freezing are modifiers of this same red-cell class. They do not create a different oxygen-carrying cell.

The storage lesion is why the modified products exist. Extracellular potassium rises, 2,3-DPG falls (oxygen delivery curve shifts left), ATP and pH fall, and hemolysis slowly increases. Frozen storage stops that clock. Rejuvenation tries to wind the metabolite clock backward. Washing removes the supernatant potassium and plasma proteins but starts a 24-hour open-system clock.

Washed red cells — plasma proteins out

Washing suspends red cells in isotonic saline or a licensed wash solution and removes supernatant through a cell processor. The manufacturing goal is plasma-protein reduction: IgA, other allergens, residual donor isoagglutinins, most additive solution, and much of the extracellular potassium leave with the waste. The component-level reasons to manufacture a washed unit are recurrent severe allergic or anaphylactic reactions and IgA deficiency with anti-IgA. Washing is not leukoreduction, not irradiation, and not a substitute for an antigen-negative or hemoglobin S-negative unit.

If the bag is entered or the device is an open system, the unit expires 24 hours from the wash and must remain at 1–6 °C. Closed-system processors follow their FDA-cleared instructions; do not invent a 42-day washed date. Some red cells are lost in the bowl or kit, so a washed unit is a slightly smaller red-cell dose. After wash there is almost no residual plasma, so the product will not correct coagulation and will not deliver a meaningful antibody load in the supernatant.

Worked scenario. An IgA-deficient adult needs one red-cell unit. The blood bank washes an AS-1 unit at 14:00 in an open-system processor. The new expiration is 14:00 the next calendar day at 1–6 °C — not the original 42-day date and not a 28-day irradiation date.

Frozen and deglycerolized red cells

Glycerol is the licensed cryoprotectant. The dominant U.S. method is high-glycerol, about 40% weight/volume. After glycerolization the unit is frozen and stored at ≤ −65 °C. 21 CFR 610.53 dates Frozen Red Blood Cells at 10 years under that condition. This is how rare phenotypes, selected autologous units, and some military inventories are held. A historical low-glycerol (~20%) method stored in liquid-nitrogen vapor near ≤ −120 °C is not the default U.S. civilian method.

Glycerolized cells cannot be transfused. Deglycerolization is a controlled, stepwise wash that removes glycerol so the cells will not hemolyze in the recipient’s isotonic plasma. Open-system deglycerolization creates a 24-hour, 1–6 °C product. A closed-system device that adds additive solution after deglycerolization is federally dated 14 days (21 CFR 610.53) when used exactly as licensed. If the stem does not specify a closed licensed system, the safe exam answer is 24 hours after deglycerolization. Frozen inventory is chosen for rarity or long-term hold, not because frozen cells are better oxygen carriers on day 0. After thaw and deglycerolization they behave like a washed, plasma-poor red-cell unit with a short outdate.

Rejuvenated red cells

During 1–6 °C storage, 2,3-DPG and ATP decline. A licensed rejuvenation solution (classically pyruvate, inosine, phosphate, and adenine) is incubated with the red cells, usually about 60 minutes at 37 °C, to restore those metabolites. The solution itself is not for transfusion. After incubation the unit must be washed (open-system 24-hour dating) or glycerolized and frozen. Rejuvenation is a salvage and rare-unit tool: restore function in a near-outdated or previously stored unit, then wash for soon use or freeze into the rare inventory. It is not a routine additive-solution substitute and it does not reset a 42-day clock unless a specific licensed process says so.

Exam traps. Whole blood is 21 or 35 days, not 42. AS-RBC hematocrit is 55–65%, not the CPDA-1 80% ceiling. Washing and open deglycerolization are 24-hour clocks. High-glycerol frozen cells live at ≤ −65 °C for up to 10 years, not in the FFP freezer at −18 °C. Rejuvenation restores 2,3-DPG/ATP and then requires wash or freeze.