3-15. INTRODUCTION

Transfusions of blood or blood products are normally initiated at the direction of the physician during surgery. These transfusions differ from the infusion of other fluids in many ways. The products used are generally prepared in a laboratory. Many products need to be matched to the patient by using laboratory analysis. The rate of transfusion is often slower, and a greater variety of complications is possible. The venipuncture site may be different. Even the equipment differs from other administration sets. Most blood products have special refrigeration requirements to prevent spoilage.

The most common reasons for transfusions are replacement of red blood cells for oxygen-carrying capacity or restoration of blood volume. Transfusion should not be initiated too hastily. Most patients in good general health can sustain a loss of about 1,000 milliliters and need replacement by colloid or crystalloid solutions infusion alone. Transfusion should be used as a last resort. It may lower the production of erythrocytes by the patient’s own body. The normal red cell has a life span of about 80 to 120 days. Each unit of blood contains red blood cells of all ages between 1 and 120 days. As a unit of blood is stored, the red blood cells continue to age. A unit of blood is stored for no more than 35 days. These aged blood cells are removed from the patient’s circulation by his own body within 24 hours after transfusion of the unit of blood. About 70 to 79 percent of the red blood cells survive 24 hours after transfusion and begin to age normally. Many surgeons believe that surgical blood loss can usually be replaced with packed red blood cells and saline.

3-16. PRODUCTS FOR TRANSFUSION

Sodium chloride solution (normal saline) is the only solution suitable for use in the transfusion of blood products containing red blood cells, platelets, or leukocytes. Any other solution causes adverse effects on the body and/or blood product. There are three general categories of products used for transfusion-products containing red blood cells, plasma products, and plasma expanders.

a. Red Blood Cell Products. Red blood cell products generally require type and cross-match laboratory procedures. Examples of these are:

(1) Whole blood (human). Whole blood is anticoagulated blood from which none of the components have been removed. Acute significant hemorrhage is the only indication for whole blood in medical patients. Traditionally, whole blood has been used to replace blood loss at surgery. This use is gradually changing to the use of packed red blood cells and a balanced saline solution.

(2) Packed red blood cells. Packed red blood cells have 75 percent of the plasma removed in the laboratory. This preparation is frequently used where the patient needs the oxygen-carrying capacity of the erythrocytes, but would not benefit from the extra fluid or the small amount of protein in the plasma. In many chronic diseases, a further expansion of the plasma volume can cause heart failure. The packed red blood cells also tend to cause less plasma transfusion reactions from donor antibodies. It is safer to use type O Negative packed red blood cells than whole blood when there is no time for cross-match.

b. Plasma. Plasma (or other blood fraction) products are made either from whole blood or from some other process that leaves part of the blood behind. Some examples of these are:

(1) Whole plasma. Whole plasma may be a by-product from the preparation of packed red blood cells, made from blood a few days before the expiration date on the blood unit or drawn by plasmapheresis. Plasma is used as fluid replacement caused by hemorrhage, burns, or in other situations where blood volume must be increased without replacement of blood proteins.

(2) Cryoprecipitate. To make cryoprecipitate, fresh frozen plasma (FFP) is first thawed at 4ºC until all ice is melted. Then the cold insoluble fraction of plasma protein is recovered by centrifugation. The product is used for patients with hemophilia. Cryoprecipitate can be stored for two years at -20º C (20 degrees below 0 Celsius).

(3) Platelet rich plasma. Platelet rich plasma is used in the treatment of some forms of malignancy. This product may be effective in controlling serious active bleeding, especially in surgery. Because of the short survival rate of platelets, the product has limited use. A-B-O group type match is required. No cross-match of other factors is required prior to platelet transfusion unless the platelet product contains many red blood cells. This does not apply to the platelet rich plasma since the plasma itself may carry antibodies.

c. Plasma Expanders. Plasma expanders are used to treat or prevent acute and severe fluid loss due to trauma or surgery. These products are usually used instead of whole blood in emergency-situations in which whole blood is not available. Below are examples of plasma expanders.

(1) Normal human serum albumin. Normal serum albumin is a part of whole blood. It is clear, moderately viscous, brownish fluid contains 25 grams of serum albumin in 100 milliliters of product. Because each gram of albumin holds approximately 18 milliliters of water, it is used as a blood volume expander in the treatment of hemorrhage or shock. In this use, the albumin draws fluid into the circulatory system from the surrounding tissues. This product has also been used as a protein replacement in cases where the level of protein in the serum is very low (for example, in nephrosis). Normal human serum albumin should not be given to dehydrated patients since it draws fluid from the body tissues. If nine-tenths percent, the product may be administered to dehydrated patients if it is necessary. Sodium chloride solution or five percent dextrose solution is administered at the same time. Fortunately, this product is very stable. Therefore, it is not necessary to keep it refrigerated in its liquid state.

(2) Plasma protein fraction (plasmanate). Plasma protein fraction is a sterile solution of stabilized human plasma proteins in nine tenths. Sodium chloride solution. Each 100 milliliters of this product contains approximately five grams of protein. This product is nearly colorless (slightly brown). Plasma protein fraction is used in the treatment of nonhemorrhagic shock (that is, shock not associated with loss of whole blood). Side effects associated with this product are uncommon, but they include increased salivation, nausea, and vomiting.

(3) Hetastarch. Balanced electrolyte solution that resembles the composition of the principal ionic constituents of normal plasma. Total dosage and rate of infusion depend on the amount of blood or plasma lost and the resultant hemoconcentration as well as age, weight, and clinical condition of the patient. Generally no more than 1L of Hextend (hetastarch in lactated Ringer’s solution) should be given. Side effects include systemic overload, and it can inhibit the clotting processes.

3-17. SITE FOR VENIPUNCTURE WHEN A BLOOD PRODUCT IS USED

Blood products should be administered intravenously although other routes (intraperitoneal, intra-arterial, intraosteous are possible. A vein should be selected which will be large enough to accommodate the infusion needle but is comfortable for the patient. Veins in the antecubital fossa are probably more accessible and most widely used; however, infusion in these veins limits the patient’s ability to flex the elbow during transfusion. Veins in the forearm and hand are equally suitable for infusion, although venipuncture in these areas is often more painful to the patient.

3-18. RATE OF TRANSFUSION

a. The rate of transfusion of blood products depends upon the clinical condition of the patient and the product being transfused. In most administration sets, 15 drops equal one milliliter.

b. Most patients who are not in congestive heart failure or in danger of fluid overload tolerate the transfusion of one unit of red blood cells in a 1 1/2 to 2 hour period. One unit of whole blood equals about 500 milliliters (about 450 milliliters of blood plus 60 milliliters of anticoagulant). The transfusion should be completed in less than four hours because of the dangers of bacterial growth and red blood cell hemolysis at room temperature. During the first 15 minutes, the rate of transfusion of red blood cells should be very slow, about 100 milliliters per hour. This will keep the volume of red blood cells low in case the patient has an immediate adverse reaction. Watch the patient attentively during the first five minutes and then check after fifteen minutes. At that point, the rate may be increased if the physician orders. After the transfusion, record any adverse reaction and discontinue the intravenous infusion.

3-19. ADVERSE BLOOD PRODUCT REACTIONS

Most adverse transfusion reactions are caused by leukocytes, platelets, and plasma proteins (since red blood cell antibodies have already been checked). All the care in cross-matching blood in the laboratory can be negated by administering the blood to the wrong patient. Always double-check.

a. Immediate Effects. An adverse effect can be either immediate or delayed. If the effect is immediate and the transfusion reaction involves more than just a reddening of the skin, the transfusion should be stopped immediately, but the intravenous line should be kept open.

(1) Congestive heart failure. Congestive heart failure that is caused by circulatory overload shows up as coughing, cyanosis, and difficulty in breathing. This is probably the most preventable adverse reaction to transfusion. If a patient is susceptible to circulatory overload, concentrated red blood cells should be transfused at no faster than one milliliter per kilogram of body weight per hour.

(2) Febrile reactions. Febrile reactions (fever), often preceded by chills, are the most common adverse transfusion reactions. These reactions are usually mild and result mainly in patient anxiety and discomfort. Rarely, there is some infiltration in the lungs, reduction in the body’s white cells, shock, or death. There are variations in blood products or medications that may lessen febrile complications.

(3) Allergic reactions. Allergic reactions are usually relatively mild. Most are local skin redness, hives, and itching. These are treated with antihistamines. Flushing, nausea and vomiting, diarrhea, changes in blood pressure and anaphylaxis are severe reactions that sometimes require a specially prepared blood product. Some severe reactions can be treated by antihistamines. Others require epinephrine.

(4) Hemolytic reactions. These are often difficult to detect. Initial hemolytic reactions can be flushing, a feeling of apprehension, chest or back pain, chills, fever and nausea, or vomiting. During anesthesia, diffuse bleeding may be the only evidence. Severe reactions include excessive hemoglobin in the blood plasma, hemoglobin in the urine, abnormally low blood pressure, coagulation in the blood vessels, renal failure, and death.

(5) Bacterial contamination. This rarely occurs. When it does occur, a life-threatening reaction is likely. Signs and symptoms of bacterial contamination include the rapid onset of chills, high fever, vomiting, diarrhea, very low blood pressure, and acute renal tubular necrosis.

(6) Hypothermia. If blood is not warmed before a massive transfusion, hypothermia can cause ventricular arrhythmia and cardiac arrest.

(7) Hyperkalemia. Certain patients can react to the potassium that slowly leaks into the blood plasma during storage. The patient may exhibit neuromuscular problems such as muscular weakness and paralysis. Heartbeat may be irregular (usually slowed), and death could result from cardiac arrest.

(8) Microemboli. Transfusion of large volumes of banked blood may require filtering to remove debris accumulated from the breakdown of platelets, fibrin, and leukocytes during storage. This can lead to impaired oxygen transport ability in some patients who are administered large amounts of banked blood. The patient will exhibit breathing difficulties and pain in the extremities.

b. Delayed Effects. Adverse reactions can sometimes take weeks to show up. These are generally beyond the capability of the medical NCO to correct.

(1) Hemolytic. Delayed hemolytic reactions occur and usually result in extravascular removal of transfused cells from the circulation. This effect may take days or even weeks after the transfusion.

(2) Viral Hepatitis. The occasional occurrence of post-transfusion hepatitis remains a serious consequence of blood transfusion. Albumin, plasma protein fraction, and immunoglobulin preparations are regarded as safe derivatives since hepatitis virus is usually inactivated or removed during preparation.

(3) Others. Diseases such as malaria, acquired immune-deficiency syndrome (AIDS), hepatitis, and syphilis can be transmitted. Adequate donor screening is the only effective protection against these diseases presently.

3-20. GENERAL PRINCIPLES OF TRANSFUSION

Most of the rules for infusions also apply to transfusions. The rules below also apply to transfusions.

a. The venipuncture should be started before or at the same time the blood component is being obtained. This will allow the transfusion to begin immediately after the blood component has arrived and minimize the risk of improper storage.

b. The administration set should be cleared of air before venipuncture. Venipuncture can be performed with a needle attached to a syringe or attached directly to the blood administration set.

c. Red blood cells or whole blood should be administered using a needle of 18 gauge or larger. Other blood products such as platelets, cryoprecipitate, fresh frozen plasma, and albumin can be administered through smaller needles.

d. Warming of blood may be necessary if large amounts of blood are being transfused at a rapid rate.

e. Identification of the blood product at time of transfusion requires:

(1) Check the ABO group and the Rh type on the label of the blood container to be certain it agrees with the compatibility record (that portion of the patient’s hospital record that shows his blood type and other pertinent information).

(2) Check the number on the label of the blood container to be certain it agrees with the compatibility record.

(3) Check the blood compatibility record for the patient’s name and hospital number.

(4) Check the name and hospital number on the patient’s wrist identification band against the information on the compatibility record.

(5) When possible, ask the patient to identify himself by stating his name.

NOTE: Never ask, “Are you Mr. ________?”

(6) The person who identifies that the correct blood product is being administered to the patient should then sign the compatibility record, and that record should be placed in the patient’s chart at the completion of the transfusion. Do not begin the transfusion until any discrepancies in the above information are resolved.

3-21. BLOOD TESTS

The results of blood examinations are required to definitely rule out practically every disease. A physician would hesitate to declare a patient free from a disease until certain blood tests have been performed and the results of these tests can be included with the patient’s health examination by other means. Even if the specific suspected disease is not expected to produce changes in the patient’s hematologic (or blood picture) profile, this fact is required to support diagnosis.

Blood tests are normally ordered by the physician and completed in a clinical hematology laboratory. The medical NCO should be aware of the commonly ordered tests and how some of the test results may indicate or point toward disease diagnosis. Most blood changes do point toward disease. The more common blood examinations are frequently all that are required for a patient. Their chief purpose is to indicate whether more detailed hematologic procedures are required. Listed below are some of the commonly performed tests you might expect to encounter in a clinical setting. The tests to be discussed here are the complete blood count (CBC), hematocrit, hemoglobin, sedimentation rate, partial thromboplastin time, and prothrombin time. There are many others. The selection of the test(s) will depend on the suspected disease, physician’s preference, and the laboratory facilities.

a. Complete Blood Count. The complete blood count (CBC) includes the red blood count and the white blood cell count. These may be done either by using manual or by using automated methods.

(1) The red blood cell count (RBC) results in million RBCs per cubic millimeter in the sample. The normal values are 4.2-5.4 million RBCs per cubic millimeter for adult males and 3.6-5.0 million RBCs per cubic millimeter for adult females. To perform the test, a sample of blood is diluted with a special isotonic solution. When the sample has been mixed enough, part of the sample is put into a ruled counting chamber. Five ruled sections are counted, and the RBC is calculated.

(2) When the total leukocytes (white blood cells) are counted, no distinction is made for the type of white cell (for example, lymphocyte, monocyte, and so forth). If distinction is required, further testing must be done. The normal range for adults is 4,500-11,500 per cubic millimeter. Leukocyte counting is usually done electronically, but can be performed manually. A blood sample is mixed with required solutions, and gentian violet is added for color. A measured sample is put into a ruled counting chamber. Four marked sections are counted, and the white blood cell count (WBC) is calculated.

b. Hematocrit (Packed Cell Volume). The hematocrit is the volume of erythrocytes expressed as a percentage of whole blood in a sample. An anticoagulant is added to a small blood sample, and the tube is tightly capped to avoid evaporation. The sample is placed on a centrifuge and turned for five to thirty minutes (depending on the method and equipment used). The red cell column is measured in height (millimeters) against the height (in millimeters) of the whole column. The normal hematocrit for males is between 40 and 54. For females, the normal range is between 38 and 47. A value below the patient’s normal or below the normal range may indicate anemia. A higher reading may indicate polycythemia.

c. Hemoglobin. The hemoglobin concentration in the blood bears a direct relationship to its oxygen carrying capacity. Because of the relationship, this test is performed on practically every patient, especially for suspected diseases associated with anemia. There are several ways to measure hemoglobin. The most widely used and recommended method uses cyanide compounds to convert the hemoglobin. This process will eventually result in a compound called “cyanmethemoglobin”. The hemoglobin content can then be determined. The use of cyanide compounds in this process increases the danger of accidental poisoning in the laboratory. Proper ventilation and protection for the technician must be available. The normal values are 14 to 17 grams hemoglobin (per deciliter) for adult males and 12 to 16 grams hemoglobin (per deciliter) for adult females.

d. Erythrocyte Sedimentation Rate. The erythrocyte sedimentation measures the rate at which the red blood cells settle out of the cellular-plasma suspension. The rate is usually increased in inflammatory infections, toxemia, cell or tissue destruction, severe anemia, active tuberculosis, syphilis, acute coronary thrombosis, rheumatoid arthritis, and malignant processes. The rate is generally decreased by sickle cell anemia, polycythemia, hypofibrinogenemia, and certain drugs. The procedure is to place a measured amount of anticoagulated blood in a tube and measure the distance the erythrocytes fall within a given time interval.

Normal values are 0 to 9 millimeters for adult males and 0 to 20 millimeters for adult females. This test is inconclusive. It indicates the need for further testing. In some cases, such as acute rheumatic fever or congestive heart failure, the sedimentation rate has remained within normal limits.

e. Partial Thromboplastin Time. The partial thromboplastin time is the most useful screening method for detecting blood coagulation disorders. This procedure tests all three stages of blood coagulation and can show abnormalities in almost all of the clotting factors. Freshly collected blood is combined with certain compounds and observed for clot formation. Using most commercially prepared and some laboratory prepared compound, the clot should form in less than 35 seconds to be considered normal.

f. Prothrombin Time. The prothrombin time procedure detects abnormalities in the clotting time in some stages of the clotting process. If certain amounts of thromboplastin, calcium, and citrated plasma are carefully mixed under controlled conditions, fibrin strands will normally form within seconds. The time between the addition of plasma and the formation of the fibrin web is read. Normal values are 12 to 15 seconds. The prothrombin activity of the patient’s plasma has important significance in diseases of the liver, in vitamin K deficiency, and in the use of dicumarol as an anticoagulant.