Overview of Blood Transfusion
The history and development of blood transfusion is quite fascinating. For thousands of years, medicine was based on the theory of the “four humors” where bloodletting was a common treatment. However, major progress was made in the 1600s when William Harvey explained how the circulatory system works. Shortly afterwards, scientists started experimenting with blood transfusions, initially from animals to humans. The very first human blood transfusion was conducted by a doctor named Philip Syng Physick in 1795, and by 1818, James Blundell in England used a blood transfusion to treat severe bleeding.
Over the last century, big steps forward have been made in our understanding of blood types, how to separate the various parts of blood, and how to store blood. These advances have led to the field of transfusion medicine. This field is collaborative, involving doctors and laboratory workers from various branches of medicine including blood disease specialists (hematology), pathology, anesthesiology, and pediatrics.
One of the key contributors to the field was Charles R. Drew, an American surgeon who was one of the trailblazers in the development of blood banks during World War II. Today, blood transfusions are quite common. In fact, about 15 million units of blood are transfused each year in the United States, and about 85 million units are transfused globally.
Fresh whole blood was originally used for transfusions. But with medical advancements, we’ve learned to separate and use specific components of blood for different uses. These components can include packed red blood cells (which contain a large amount of red blood cells), fresh frozen plasma (which is the clear liquid part of blood), certain clotting factors, and other components. As a result, we don’t often use whole blood for transfusions anymore. An exception to this is the buddy transfusion system used by the U.S. military, and in some civilian emergency settings. The red blood cells in the blood product contain hemoglobin, which is the protein responsible for carrying oxygen around our body. A single unit of packed red blood cells, similar to the quantity you would give in one donation, contains roughly 350 ml of blood and about 250 mg of iron.
Why do People Need Blood Transfusion
The American Association of Blood Banks suggests that doctors should limit the amount of red blood cell transfusions for stable patients who aren’t actively bleeding but have anemia. Anemia is usually defined as having lower levels of hemoglobin (a type of protein in red blood cells that carries oxygen) than normal – less than 13 g/dL in men and less than 12 g/dL in women. In the past, doctors typically gave a transfusion if a patient’s hemoglobin level was less than 10 g/dL, but now, a more cautious approach is recommended.
Current guidelines suggest that in healthy patients without symptoms, a transfusion should only be considered if the hemoglobin level drops to 7 g/dL or lower. If a patient has heart disease or is having orthopedic surgery, the guideline is a hemoglobin level of 8 g/dL or lower. Different thresholds apply to critically ill patients, with the threshold being set at 7 g/dL.
A transfusion may also be needed in patients who are actively bleeding, or those with symptoms of anemia (like fast heart rate, weakness, or shortness of breath) and a hemoglobin level under 8 g/dL. Severe bleeding can lead to a lack of oxygen supply to the body’s cells, and replenishing red blood cells is one way to manage this condition, known as shock.
When a patient isn’t actively bleeding, the guideline is to give one unit of packed red cells at a time, which can increase the hemoglobin level by 1 g/dL. Doctors would check the patient’s hemoglobin level after the transfusion.
In contrast, the American Society of Anesthesiologists advises a transfusion if the hemoglobin level drops to 6 g/dL or less. Emerging data suggest lower death rates when preanesthetic hemoglobin is above 8 g/dL, especially in patients getting a kidney transplant.
The transfusion of fresh frozen plasma, which contains clotting factors, is sometimes used when a patient is bleeding due to certain causes such as intensive surgery, major transfusion, failing liver, and some other significant medical events. In the past, warfarin (a blood-thinning drug) overdose was treated with fresh frozen plasma and vitamin K, but now we have other treatments available.
However, if patients are deficient in platelets or their platelets don’t work properly, transfusion with platelets could be beneficial. Platelets are components of the blood which help in clotting. The decision to transfuse depends on the patient’s platelet count and whether they have any other risk factors for bleeding, are about to undergo an invasive procedure, or are actively bleeding.
There is another type of transfusion, called cryoprecipitate transfusion, which is used when patients have low levels of a specific type of protein, fibrinogen, that helps in clotting. It is usually used when patients are bleeding, waiting on an invasive procedure, or will be going through major medical events.
When a Person Should Avoid Blood Transfusion
There are no firm reasons why someone should not have a blood transfusion. However, some people, or their parents in the case of children, might choose not to because of their religious beliefs. It’s often not necessary to have a whole blood transfusion; instead, patients are given specific parts of the blood to treat specific problems. For example, red blood cells can be given to a person who is anemic (a condition leading to tiredness due to lack of red blood cells), or fresh frozen plasma might be used to treat a coagulation problem (a condition that makes blood unable to clot properly).
Performing a whole blood transfusion can sometimes cause complications, like volume overload, where there is too much blood in the body. This can lead to other health problems. Because of this, the use of specific blood components is generally preferred whenever it’s possible.
Equipment used for Blood Transfusion
Blood products are given to patients through an IV tube that includes filters. These filters, which have small holes ranging from 170 to 260 microns in size, are there to stop any particles or debris from going into the patient’s body. But these trapped particles can lead to bacterial growth, so the American Association of Blood Banks (AABB) suggests not using a filter for more than four hours. Before giving the blood products, the IV tubing is prepped with a solution that doesn’t have any calcium and can mix with blood, such as normal saline. This is done because the red blood cells in the blood product are preserved with a substance called citrate. If there is too much calcium, clots might form in the IV line.
The equipment needed for a blood transfusion can include:
- The blood product or whole blood can be given through a central venous access device (connections to the large veins in your body) or through a small tube in the vein of the arm (peripheral intravenous catheters). The suitable sizes include:
- 20 to 22 gauge (a measurement of the tube’s thickness) for adults in routine cases
- 16 to 18 gauge for adults if the blood needs to be given quickly
- 22 to 25 gauge for children
- The requirements for administration sets (the equipment used to transfer the blood) might differ
- Blood filters are needed
- Certain supplies are required to provide platelet-poor plasmas, these vary depending on the product or brand
- Devices like infusion pumps, blood warmers, rapid infusers, and pressure devices can be used to give the blood products to the patient
- A device that gives high pressure may be needed if the blood products need to be given rapidly
A blood warmer device may be needed in situations where blood components are administered quickly, like in trauma situations or surgeries. This is to stop the patient’s body temperature from dropping due to the cold blood components.
Who is needed to perform Blood Transfusion?
Before a blood transfusion is given, it’s important that two medical professionals double-check the blood being used. This ensures the safety of the patient. It is also necessary for the patient to be watched carefully during the transfusion by someone qualified. This is to monitor and react quickly if any unexpected issues arise.
A variety of medical staff, including registered nurses, skilled vocational nurses, or licensed practical nurses, can perform a blood transfusion. However, they typically perform this task only under the recommendation of a doctor. These professionals are well educated in doing this procedure because they have been taught in their medical and educational training programs how to conduct blood transfusions safely and efficiently.
Preparing for Blood Transfusion
Before you receive a blood transfusion, some tests and preparations are done to ensure it is safe. Medical professionals will take a sample of your blood to do what’s called a ‘type and screen’ test. This test checks your blood type and sees if you have any unusual antibodies in your blood that might react to the blood you’ll be receiving. If this test is clear, it’s unlikely there will be any issues with the transfusion. If not, further steps will be taken to make sure you get blood that is safe for you.
Here is a list of key steps taken before starting a blood transfusion:
1. A blood sample is taken and sent to a special lab known as the blood bank. This sample must be correctly labeled with the date and time. Then the blood bank prepares the blood units that you will receive.
2. Medical professionals will discuss the procedure with you, talk about your medical history, and make sure you don’t have any allergies that might interfere with the transfusion process. You’ll be asked to give informed consent, which means you understand the procedure and agree to it.
3. A larger-than-normal intravenous, or IV, access point must be put into your vein. This is because the blood must be delivered relatively quickly, usually within 2-4 hours. Another IV access point should be readied in case you need other medications during the transfusion.
4. All the necessary supplies will be gathered for the transfusion.
5. Your baseline vital signs – things like your heart rate, body temperature, blood pressure, oxygen levels, and your breathing rate – will be measured to make sure it’s safe to start the transfusion. Doctors will also listen to your breathing sounds and document your urine output.
6. When the blood units are ready at the blood bank, they will be brought to you. You can only receive one unit of blood at a time. From the moment the blood reaches you, the transfusion needs to start in about 20-30 minutes and finish before 4 hours have passed.
How is Blood Transfusion performed
Here are some simple steps that doctors and nurses follow when giving a blood transfusion:
* They first check the blood product to confirm it’s correct.
* They explain to the patient what could happen if the body reacts negatively to the new blood. It’s important that the patient tells the medical staff if they feel any of these symptoms during the transfusion.
* They check the patient’s general health condition – things like heart rate, breathing, color of the skin, and how much the patient is urinating.
* They prepare special tubing (called Y-tubing) with a salt solution, and have the blood bag close-by in a machine that helps to pump the blood.
* They start the transfusion slowly for the first fifteen minutes, around 2 milliliters per minute or 120 milliliters per hour.
* Medical staff keep a very close eye on the patient during the first fifteen minutes because this is when a reaction to the blood transfusion is most likely.
* If the patient is doing well, the rate of the transfusion can be increased after this period.
* They will continue to check the patient’s vital signs after fifteen minutes, then every hour, and again at the end of the transfusion.
If the patient shows any signs of a bad reaction during the blood transfusion, doctors and nurses stop the transfusion right away. They automatically disconnect the blood tube from the patient and inform the doctor in charge. They keep a close watch on the patient and document everything. After the transfusion, they clean up the tubing using a normal saline solution and throw the used tube in a special bin for biohazard waste. They then recheck the patient’s vital signs. Some patients may feel a little soreness at the injection site, but this should go away soon.
Possible Complications of Blood Transfusion
There can be several medical issues that follow after someone receives a blood transfusion. These can include infections, reactions due to the body breaking down blood cells too quickly (hemolytic reactions), allergic reactions, a lung injury related to transfusion (TRALI), an overload in your blood’s circulation as a result of the transfusion, and changes in the balance of your body’s salts (electrolytes).
The American Association of Blood Banks (AABB) reports that a reaction with fever is the most common issue after a blood transfusion. This can be followed by issues due to an overload of blood circulation, allergic reactions, TRALI, hepatitis C and B infections, HIV infection, and fatal hemolysis, a severe instance where your body breaks down blood cells too rapidly. The latter is very rare, with only one in two million cases of blood transfusion experiencing this.
Here’s a breakdown of the risks per unit of blood transfused: Fever reaction: 1 in 60. Overload of blood circulation: 1 in 100. Allergic reaction: 1 in 250. TRALI: 1 in 12,000. Hepatitis C infection: 1 in 1,149,000. HIV infection: 1 in 1,467,000. Fatal hemolysis: 1 in 1,972,000.
The chance of a fever reaction can be reduced if the blood used for transfusion has a reduced number of white cells (leukocyte-reduced blood products), which is mostly what is used in the United States. If this fever reaction occurs, the transfusion should be stopped immediately and the patient checked as it can be initially similar to a hemolytic reaction which is more serious.
Overload of blood circulation is characterized by breathing trouble due to fluid build-up in the lungs. This is more likely to occur in patients who already have similar problems, such as congestive heart failure or kidney failure. Diagnosis includes symptom onset within 6 to 12 hours post-transfusion and a response to diuretics, which help get rid of unneeded water and salt from the body through urine.
The allergic reaction emerges as a rash and itching, happening usually less than 1% of transfusions. Severe symptoms such as difficulty in breathing and a drastic and sudden allergic reaction, are rare.
TRALI is also rare, occurring around 1 in 12,000 transfusions. Symptoms usually develop within 2 to 4 hours post-transfusion, often looking similar to a condition called ARDS which is a type of respiratory failure. About 10% of such cases can be fatal, but the rest typically resolve within 96 hours with supportive care only.
Infections such as hepatitis C, HIV, and bacterial infections are potential complications of a blood transfusion. However, due to thorough screening of potential donors, the risk of such infections is significantly decreased.
Fatal hemolysis, a condition wherein the body destroys its own blood cells, is extremely rare, occurring less than 1 in a million transfusions. If it does occur, treatment methods involve stopping the transfusion immediately, maintaining urine output, preventing shock, and a thorough examination of blood.
Alteration in the levels of the body’s salts or electrolytes can also happen, although these are rare and usually associated with a large blood transfusion.
What Else Should I Know About Blood Transfusion?
The field of transfusion medicine, which involves the transfer of blood (including red blood cells) to another person, has undergone a lot of changes over the past hundred years. This has brought together professionals from various medical fields to advance the care and safety of patients. The ability to transfuse, or transfer, red cells from one person to another, particularly quickly and safely, has been transformative for the treatment of patients experiencing trauma, undergoing surgery, or having problems like gastrointestinal bleeding.
Transfusion medicine is still evolving. Scientists continue to find ways to enhance this process. For example, they are trying to find alternative ways to carry oxygen to our body cells. This could potentially decrease the chance of negative reactions and infections during transfusion. It could also simplify the storage of blood. This is important because blood has a limited shelf life and needs specific storage conditions.
