Useful life. Whole blood is collected in a citrate anticoagulant-preservative solution. The original acid-citrate-dextrose (ACD) formulation was replaced by citrate-phosphate-dextrose (CPD), which has a storage limit of 21 days when refrigerated between 1°C and 6°C. Addition of adenine (CPDA-1) increased the shelf-life to 35 days. More recently, other nutrient-additive solutions (e.g., AS-1, Adsol) have extended storage capability to 42 days, at which time there is at least 70% red blood cell (RBC) viability 24 hours after transfusion. AS-1 is currently approved only for packed RBCs, not for whole blood. If preserved in CPDA-1, plasma potassium on day 1 is about 4.2 mEq/L (4.2 mmo1/L) and on day 35 is 27.3 mEq/L (27.3 mmol/L). Plasma hemoglobin (Hb) on day 1 averages about 82 mg/L and on day 35 averages about 461 mg/L. It takes about 24 hours for RBCs stored more than two thirds of maximum storage life to regain all of their normal hemoglobin function (this is also true for packed RBC units).

Platelets in whole blood. Platelets devitalize rapidly on storage in refrigerated whole blood (discussed in greater detail in Chapter 11). Platelets in fresh whole blood are about 60% effective at 24 hours and almost completely ineffective after 48 hours. Ordinary stored whole blood or packed RBCs, therefore, essentially have no functioning platelets even though the platelet count may be normal. This may produce difficulty in massive transfusions using stored whole blood or packed RBCs, although there is usually no problem when administration takes place over longer periods of time.

Transfusion indications. The traditional cutoff point for transfusion, especially when a patient is undergoing surgical procedures, is a Hb level of 10.0 gm/100 ml (100 g/L) or a hematocrit of 33%. Based in part on experience from open-heart surgery, use of this level has recently been challenged, and a Hb level of 9.0 gm/100 ml (or hematocrit of 25%-30%) is being advocated to replace the old standard. Even more recently, based in part on surgical experience with Jehovah’s Witnesses who refuse transfusion on religious grounds, it was found that transfusion could be avoided in most cases without undue risk with Hb as low as 7.0 gm/100 ml or even lower. This led to a 1988 National Institutes of Health (NIH) Consensus Conference endorsement of Hb 7.0 gm as a suggested cutoff point. This in turn led to a study commissioned and adapted into guidelines by the American Academy of Physicians in 1992 that recommended “avoid an empiric automatic transfusion threshold.” The most important trigger was to be symptoms related to the need for blood that could not be corrected by other means.

Whole blood is used for restoration of blood volume due to acute simultaneous loss of both plasma and RBCs. This is most frequently seen in acute hemorrhage, both external and internal. Stored blood is adequate for this purpose in most cases. Actually, packed RBCs are being used in many of these patients.

Transfusion speed. Under usual circumstances, the American Association of Blood Banks (AABB) recommends that one unit of whole blood or packed cells be administered in 1.5 hours. The infusion rate should be slower during the first 15 minutes (100 ml/hour), during which time the patient is observed for signs and symptoms of transfusion reaction. One unit of whole blood or packed cells raises the Hb level approximately 1 gm/100 ml and hematocrit approximately 3 percentage units. (Various factors can modify these average values.) RBCs will hemolyze when directly mixed with 5% dextrose in either water or 0.25% saline or with Ringer’s solution.

Fresh whole blood is used within 2 days and preferably 1 day after collection. Platelets are still viable, and the labile coagulation factor VIII (antihemophilic globulin) and factor V still retain nearly normal activity. Most other disadvantages of prolonged storage are obviated. Obviously, donor and administrative problems greatly limit use and availability of fresh blood. Also, there is usually not sufficient time to perform screening tests for hepatitis B and C or human immunodeficiency virus-I (HIV-I) and II. Current official policy of the AABB states that there are no valid indications for specifically ordering fresh whole blood. Specific blood components would be more effective. In a few circumstances when whole blood is useful but long-term storage is undesirable (e.g., infant exchange transfusion), blood less than 4-5 days old is acceptable.