whole blood |

WHOLE BLOOD

Shaurya Sisodia

Post graduate resident, department of medicine, LHMC

INTODUCTION

Blood transfusion is a fairly common and important lifesaving procedure in modern medicine. However, things were not like this before.

In the 1600s, William Harvey demonstrated how the circulatory system functioned. Shortly after that, scientists became interested in transfusion, initially transfusing animal blood into humans. Dr. Philip Syng Physick carried out the first human blood transfusion in 1795, and the first transfusion of human blood for treating haemorrhage happened in England in 1818 by Dr. James Blundell.

Blood is typically stored in components. Medical advancement has allowed the efficient use of the different components, such as packed red blood cells (PRBCs), individual factor concentrates, fresh frozen plasma (FFP), platelet concentrates, and cryoprecipitate. Consequently, current indications for whole blood transfusion are generally very few.

CONTENTS OF WHOLE BLOOD

450 mL donor blood
63 mL anticoagulant preservative solution.
Hemoglobin ~ 12 g/mL
Hematocrit 35% – 45%
No functional platlets
No labile coagulation factor ( V and VIII )

INDICATION

Acute hypovolemic coagulopathy
Massive blood transfusion
Exchange transfusion in neonates

STORAGE AND ADMINISTRATION

Storage – between 2-6 °C
Dosage – As per clinical status
Administration :
- Donor – recipient compatibility : ABO and RhD compatible / group O with low anti-A/B antibody
- Transfusion should be started within 30 min of removal from refrigerator.
- Transfusion should be completed within 4 hours of initiation.

FRESH WHOLE BLOOD (FWB)

FWB refers to whole blood (WB) collected on an emergency basis from a “walking blood bank” (WBB).
FWB can either be stored at room temperature and used within 24 hours of collection (current practice is to destroy it if not used, though available data suggest that it could be used for up to 72 hours following collection and storage at room temperature) or it can be refrigerated within 8 hours of collection, after which point it becomes stored whole blood (SWB).
FWB is considered to have full hemostatic function.
FWB is collected from pre-screened donors when possible, but does not undergo complete TTD testing prior to transfusion; this fact makes it not approvable by the FDA in the civilian setting. Because FWB presents a higher risk of disease transmission, it is reserved for situations in which tested blood products are unavailable and the need for transfusion is urgent.

ADVANTAGES

SWB and FWB provide FFP:RBC:PLTs in a nearly physiologic ratio and return to the bleeding patient what has been lost.
It should be noted that the 1:1:1 ratio of blood components (PLTs:plasma:RBC) recommended for damage control resuscitation does not faithfully reconstitute WB. The 1:1:1 ratio yields a dilute blood mixture with a hematocrit of 29%, a platelet count of approximately 90,000/μL, and coagulation factors diluted to approximately 62% of WB concentrations due to the presence of anticoagulants and red cell additive solution.
WB delivers all needed elements of blood in only one product, which only requires refrigeration for storage (i.e. the same conditions that already exist for RBC storage and transport).

In contrast, component therapy requires multiple products and storage modalities (refrigeration, freezing for FFP and generally room temperature storage with agitation for PLTs – though PLTs can also be refrigerated), greatly increasing workload and complexity for clinical teams.

ALTERNATIVE

Component ratio (1:1:1) — For massive transfusion in most patient populations, a 1:1:1 ratio of plasma to platelets to pRBCs is generally used.

Plasma – 1 unit (as frozen plasma [FP], thawed plasma, or other plasma product) has a volume of 200 to 300 mL.
Platelets – 1 unit of apheresis platelets contains 300 billion platelets, one-fourth of what normally circulates and one-sixth of what is in the body (one-third of platelets are in the spleen), but only half of transfused platelets typically circulate.
pRBCs – 1 unit of pRBCs has a volume of approximately 325 mL and contains 160 to 220 mL of RBCs.

Correct ratio of all the three components has always been a point of discussion for which PROPPR [Pragmatic Randomized Optimal Platelet and Plasma Ratios] trial was conducted, which evaluated the outcomes of blood resuscitation protocols using a ratio of 1:1:1 (1 unit of RBCs for each unit of plasma and platelets) versus 1:1:2 (2 units of RBCs for each unit of plasma and platelets). The PROPPR trial found no statistically significant difference in 24-hour and 30-day mortality with the 1:1:1 versus the 1:1:2 component ratios

MASSIVE TRANSFUSION

Massive transfusion has been arbitrarily defined as the replacement by transfusion of ≥10 units of whole blood (WB) or red blood cells (RBCs) in 24 hours as an approximation of the replacement of at least one blood volume.
Ultra massive transfusion has been defined as using ≥20 units of RBCs in 24 or 48 hours.
CAT-1 (critical administration threshold for 1 hour) – It is an alternative functional definition for acute catastrophic bleeding, in which the administration of ≥3 units of RBCs over one hour identifies patients with substantial immediate blood use.
Commonly massive transfusion is used in obstetric , cardiac , liver disese and trauma patients,
Correction of a deficit in blood volume with crystalloid volume expanders works well for most mildly and moderately ill or injured patients. However, large volume resuscitation with crystalloid alone in severe trauma with massive blood loss can lead to dilutional coagulopathy as well as severe tissue swelling, with stiff lungs and abdominal compartment syndrome.
Replacement with plasma, platelets, and red blood cells (RBCs) or whole blood (WB) should be started early.