Chapter 191. Autotransfusion

Trauma is the leading cause of death in children and adults under 44 years of age.1 Exsanguination plays a significant role in as many as half of these deaths, most commonly after the patient reaches the hospital and within the first 24 hours after injury.2 Hemorrhagic shock is a primary indication for the transfusion of homologous blood products. Transfusions with homologous blood products carry the possibility of associated complications including transfusion reactions, transmission of infectious diseases, and sensitization to antigens.3 Massive transfusions are associated with the additional complications of acidosis, dilutional coagulopathy, and hypothermia. Transfusion of homologous blood products in the trauma patient has been independently associated with an increase in both morbidity and mortality, particularly when transfusing older, stored blood products.4–6 Blood centers have more than doubled the prices of blood products in recent years due to a decline in blood donors, higher skilled labor costs, and increases in the cost of testing and processing blood.7

Alternative transfusion strategies have been developed for elective surgeries. These include autologous (acute) normovolemic hemodilution, autologous preoperative donation, and intraoperative cell salvage with autotransfusion. The first two are not possible in the acute Emergency Department setting. Cell salvage with autotransfusion represents a viable alternative to autologous transfusion in the Emergency Department, but has received limited attention in the trauma patient.

In the trauma setting, an autotransfusion was first performed by Elmendorf during the First World War on a soldier with a traumatic hemothorax.8 It was subsequently used sporadically as a life-saving procedure.9 A modified autotransfusion for a traumatic hemothorax was described in 1978.10 This technique was simple, safe, and easy to practice. It was used in approximately 400 patients with a traumatic hemothorax without any noticeable complications. This technique is still applicable to current practice.

Many of the patients with a life-threatening hemothorax either die before reaching the Emergency Department or experience severe hemodilution that accounts for some deaths in the Emergency Department and the Operating Room. Since hypovolemic shock secondary to trauma is the most frequent indication for a massive blood transfusion in the Emergency Department, it is therefore an indication for an autotransfusion. Much of the controversy surrounding practice paradigms centers on the disagreement as to what constitutes the proverbial perfect procedure.

An autotransfusion may occur in the Emergency Department, Operating Room, and Surgical ICU with increasing frequency. In this procedure, the shed blood is collected, mixed with an anticoagulant, concentrated, washed or filtered, and then returned through an intravenous (IV) line to the patient. Harmful contaminants such as potassium, fat, and free hemoglobin are removed from the salvaged blood. This blood is returned through a 40 micron blood filter to collect particulate matter and microthrombi. An autotransfusion in the Emergency Department is generally limited to an acute traumatic hemothorax associated with clinically significant hypovolemia.

An autotransfusion should be considered with the anticipated loss of at least 20% of the patient's estimated total body blood volume. It should also be considered if the Emergency Department cannot obtain or provide cross-matched compatible blood. It can be used for the patient unwilling to accept homologous blood, but willing to accept salvaged blood. The average amount of blood to be autotransfused should be expected to be greater than 1 unit to make this procedure cost effective.11–13

There are numerous advantages to an autotransfusion. It is convenient and immediately available as a blood product replacement. The blood is already warmed and at, or just below, body temperature. It addresses any special needs of the patient such as when they have religious preferences or a rare blood type. There is no chance of allergic reactions, alloimmunization, disease transmission, febrile reactions, and transfusion reactions. An autotransfusion requires no work on the part of the blood bank, has no compatibility issues, and ensures that the patient receives compatible blood. It conserves homologous blood products for other patients. An autotransfusion results in the blood having a normal pH, viable platelets, and viable clotting factors when compared to homologous blood supplies. Higher levels of 2,3-DPG in autologous blood results in the easier release of oxygen from hemoglobin in the tissues. Finally, there is the positive psychological benefit to the patient when they are informed that they received their own blood.

There are numerous contraindications to the use of an autotransfusion. The presence of a coagulopathy regardless of its etiology or when it occurs (i.e., in the Emergency Department, preoperative, intraoperative, or postoperative) or evidence of disseminated intravascular coagulopathy (DIC) may be more optimally managed with the administration of specific blood component therapy. Evidence or suspicion of serious infectious processes (e.g., mediastinal, pericardial, respiratory, or systemic) precludes the use of an autotransfusion. Do not autotransfuse blood if there is the presence of a malignant neoplasm at collection site (i.e., abdominal or chest cavity) that can lead to possible contamination of the blood with malignant cells. Do not autotransfuse blood which is collected from a potentially contaminated abdominal or thoracic cavity (e.g., esophageal tear). Do not autotransfuse from a cavity that was irrigated with a solution that can cause lysis of red blood cells prior to blood collection and potentially precipitate end-organ damage if the salvaged product is administered. This includes sterile water, hydrogen peroxide, alcohol, hypotonic irrigation solutions, or povidone-iodine antiseptic gels or solutions. Blood collected from body cavities that have had the administration of topical thrombin or microfibrillar hemostatic agents should not be autotransfused. Patients with renal or hepatic failure may not tolerate the increased levels of plasma-free hemoglobin or potassium that occurs with an autotransfusion. Relative contraindications include cesarean delivery and sickle cell disease.

• Sterile gloves and gown
• Face mask with a face shield or goggles
• Cap
• Povidone iodine or chlorhexidine solution
• Chest tube drainage apparatus with either a water seal or a dry one-way valve
• In-line autotransfusion system blood collection bag
• Whole blood in-line microaggregate filter for reinfusion (usually 40 microns, but can vary between 20–170 microns)14
• Nonvented blood compatible IV administration set
• 250 mL bag of sterile normal saline for priming of IV tubing and microaggregate filter prior to blood infusion
• Pressure bag for rapid blood infusion
• Blood warming system if it is anticipated that multiple units of blood will need to be infused to help prevent hypothermia15–17
• Citrate anticoagulants
• Tube thoracostomy supplies (Chapter 39)

Anticoagulation for an autotransfusion in the ED setting is generally recommended to help prevent the formation of clots in the autotransfusion system. While the administration of anticoagulants can be beneficial, it is not without risk and its use and dosage are at the discretion of the treating Physician. Heparin anticoagulation is one option. However, the local administration of heparin can lead to the formation of platelet microaggregates and potentially lead to systematic heparinization which can result in further hemorrhage in a patient who is already bleeding.18 Citrate anticoagulants, which are considered local anticoagulants, are thus preferred over heparin. Citrate works by binding with calcium ions to inhibit the conversion of fibrinogen into the insoluble protein fibrin, preventing the blood from clotting. Since citrate only binds with calcium, it only anticoagulates the blood it is collected with. The liver rapidly metabolizes the citrate once the anticoagulated blood is reinfused.16

Citrate phosphate dextrose (CPD) is a commonly used anticoagulant. It is recommended to use 1 mL of CPD for every 7 mL of blood. Because it is difficult to estimate the amount of blood in a patient's chest cavity, one approach is to instill 60 mL of CPD into the autotransfusion bag, enough to anticoagulate one unit of blood. When 1 unit of blood has been collected (about 500 mL total volume of blood plus CPD), it may be reinfused or additional CPD may be added to continue the collection. If bloody drainage is ongoing, prepare a new collection bag and inject anticoagulant before disconnecting the filled collection bag for reinfusion. The CPD injection may be facilitated by the use of a volume-control IV chamber. Run the desired amount of CPD into the chamber and then infuse it via the IV tubing to the injection port.

Citrate phosphate dextrose adenine (CPDA) may also be used as an anticoagulant at a ratio of 1 mL per 7 mL of blood. Some consider CPDA the anticoagulant of choice for an autotransfusion of a traumatic hemothorax. It provides a reduced pH mixture that is advantageous to the platelets. The CPDA solution maintains the viability of the platelets. It also reduces clot formation in autotransfusion equipment, plugging of the blood filter with microemboli, and clotting of the IV lines.

Assess the patient for the signs and symptoms of hypovolemia, hypoperfusion, and/or a hemothorax. Describe the procedure, its risks, and benefits to the patient and/or their representative. Obtain written or oral consent, if possible. This procedure requires strict aseptic technique. Clean any dirt and debris from the patient's chest wall. The Emergency Physician should don full sterile and personal protective equipment at this point. This should include sterile gloves, a sterile gown, a face mask with an eye shield or goggles, and a cap. Apply povidone iodine or chlorhexidine solution to the skin over the chest wall and allow it to dry. Apply sterile drapes to delineate a sterile field.

Much preparation is required before starting an autotransfusion. The autotransfusion system requires prior assembly. Therefore, consider setting up the autotransfusion components for patients who are at high risk for a hemothorax before inserting the chest tube. Otherwise, blood that drains immediately upon chest tube insertion is lost to recovery. Refer to all manufacturers' directions for use, warnings, and cautions regarding anticoagulant medications, microemboli filters, and IV blood administration sets prior to their use. Prophylactic broad-spectrum antibiotics may be administered immediately before the chest incision is made for the tube thoracostomy or just prior to the reinfusion. Follow all hospital protocols for blood handling, waste disposal handling, and infection control. Insert a large-bore chest tube. Refer to Chapter 39 for the complete details regarding the tube thoracostomy.

There are several manufacturers of chest drainage and autotransfusion systems. The Pleur-Evac System (Teleflex Medical, Research Triangle Park, NC) is one of the commonly used systems in many Emergency Departments.30 The Atrium Chest Drain Autotransfusion System (Atrium Medical Corp., Hudson, NH) is the second of the two more commonly used systems (Figure 191-1).31

Three different techniques for blood collection are in-line, self-filling, and continuous. The in-line autotransfusion blood bag is a standard bag that attaches to the chest drain (Figure 191-2). The self-filling autotransfusion bag incorporates a low vacuum that is activated to improve the flow of fluid from the chest drain into the bag (Figure 191-3). The final option is the continuous autotransfusion. It is used to directly reinfuse shed autologous blood via a blood compatible infusion pump, a microemboli blood filter, and a nonvented blood compatible IV administration set. This is a true closed system and reduces the potential for contamination. It does not require the clamping and unclamping of tubes, exchanging autotransfusion bags, and the interruption of chest drainage to change autotransfusion bags. It results in less exposure to the patient's blood with a closed system. It saves time and money by not changing autotransfusion bags, filters, and IV tubing. Unfortunately, this closed system is rarely available in the Emergency Department and requires additional training for its use.

The technique chosen depends upon the chest tube drainage system used in your institution. Some chest tube drainage systems allow for more than one technique to collect blood for an autotransfusion. The specific port locations and connections will vary slightly among the different manufacturers, but the general concepts are relatively universal. The general technique will be described below. The specific steps depend upon the actual equipment available.

Attach the autotransfusion bag to the chest drain. Inject anticoagulant into the collection unit as soon as possible during or before the blood collection if this is required. Collect the blood. When one unit of blood has been collected (about 500 mL of blood plus the volume of anticoagulant), it may be reinfused. Remove the filled autotransfusion bag and replace it with a new one containing anticoagulant. Discontinue blood collection when it is determined that an autotransfusion is no longer required or there is no further bloody drainage from the chest tube.

Reinfuse the blood. Prime the IV blood administration and microemboli blood filter with sterile saline. Invert the autotransfusion bag so that the spike port points upward. Remove the protective cap covering the spike. Insert blood tubing into the spike port by using a constant twisting motion. Attach a microfilter onto the blood tubing. Remove the air from the autotransfusion bag. Keep the unit inverted and squeeze all the air from the bag carefully through the filter and the drip-chamber assembly to prevent an air embolus. Close the infusion set clamp. Invert the autotransfusion bag and suspend it from an IV pole with the plastic strap. Open the infusion set and flush the administration line to remove all of the air. Attach the distal end of the infusion set to the IV line. Infuse the blood using gravity or pressure.

Keep in mind some general principles when performing an autotransfusion. Do not hang or hand carry the autotransfusion bag by its tubing. Use the hanger provided. Replace the spike port cap immediately following removal of the blood filters and IV tubing to prevent air entering the system. The air vent must remain closed at all times when not in use. A new microemboli blood filter and IV blood tubing must be used for each autotransfusion bag. When using vacuum suction with the collection apparatus, it is important to use the lowest level possible to reduce the risk of red blood cell hemolysis during collection.32 The recommended starting vacuum pressure is 20 mmHg.15,33

Assess the patient's cardiopulmonary status and vital signs frequently during the autotransfusion and at least until 1 hour after the autotransfusion is complete. Periodically monitor laboratory data to include hematocrit, prothrombin time, partial thromboplastin time, platelet count, serum lactate, and arterial blood gas values. Monitor and mark amount and type of drainage from the collection system hourly for the first 8 hours, then every 2 hours as volume loss can cause hypovolemic shock. Evaluate and maintain drainage tube patency every 2 to 4 hours. Mark the drainage level on the outside of the drainage-collection chamber in hourly or shift increments. Document the assessments and laboratory values in the medical record.

Once the infusion of the autologous blood has started, it is important to monitor the patient's clinical status in response to the infusion during the patient's stay in the Emergency Department. This will involve monitoring their vital signs and other hemodynamic parameters, including central venous pressure.12 Monitor laboratory data to assess the success and possible complications of the autotransfusion process. This generally includes electrolytes, renal function, hemoglobin and hematocrit, platelet count, coagulation profile, and DIC profile to assess for a consumptive coagulopathy.12

The Emergency Physician, in conjunction with the nursing staff, must also maintain the integrity of the autotransfusion system during the infusion of autologous blood. It is necessary to ensure the autotransfusion bag is replaced each time it is filled to capacity to prevent overflow of blood into the chest drainage apparatus. Ensure each collection bag has anticoagulant added to it prior to the collection of blood. A new microaggregate filter must be used for each collection bag prior to it being infused. Prior to infusing blood, inspect it through the collection bag for evidence of clotting. Discard the autotransfusion bag and do not reinfuse it if it contains clotted blood or particulate matter. Purge all the air from the collection bag, intravenous tubing, and microaggregate filter to prevent an air embolism. Observe the autotransfusion to ensure that the entire contents of the collection bag are not allowed to infuse through the microaggregate filter and intravenous tubing. The transfusion of shed blood collected under post-traumatic conditions should begin within 6 hours of initiating the collection at the longest so as to reduce the risk of bacterial overgrowth and minimize damage to the blood components during storage.19

In general, the complications from an autotransfusion are clinically insignificant if the proper technique is followed and if less than 3000 mL of blood is reinfused. Overall, the complications are categorized as hematologic and nonhematologic. Refer to Chapter 39 regarding the complications associated with a tube thoracostomy.

Hematologic

A coagulopathy may occur in trauma patients following an autotransfusion. However, the autotransfusion itself has not been overwhelmingly proven to be the etiology.3 These patients are more likely to have other independent risk factors for a coagulopathy such as hypothermia and acidosis.20 This makes it difficult to determine the contribution of the autotransfusion to the development of a coagulopathy.20 DIC is a rare complication but should be anticipated and treated accordingly. A dilutional coagulopathy may occur when greater than 3500 mL of autologous blood is transfused. Treatment includes administration of fresh frozen plasma and platelets to compensate for the proportional decrease in platelets and fibrinogen.21 Hemolysis of red blood cells secondary to mechanical factors during the collection process, the use of hypotonic irrigation fluids, excessive suction pressure, aspiration of clotted blood, or the use of hemolytic solutions (e.g., povidone iodine, hydrogen peroxide, or alcohol) to collect blood.22,23 Hemolysis can also occur secondary to the prolonged exposure of red blood cells to the serosal linings of traumatized body cavities.24 Thrombus formation may occur as a result of increased plasma-free hemoglobin that promotes a procoagulant effect and increases the risk of free hemoglobin precipitation in the renal tubules.25,26

Nonhematologic

Particulate embolism has been reported to occur during and after an autotransfusion. Most components of the equipment are designed for singe use. Resterilization or reuse may compromise the structural integrity and lead to device failure. An air embolism may result from inadequate use of the IV set or the microemboli blood filter. An air embolism has also been associated with the reinfusion of the entire autotransfusion blood bag contents that contain residual air and a pressurized infusion of the autotransfusion bag with the air vents open. Citrate toxicity and myocardial depression may occur after the rapid infusion of citrate-anticoagulated blood. The clinical manifestations of citrate toxicity include a perioral tingling sensation followed by abdominal cramping and cardiac dysrhythmias. Citrate toxicity can be prevented by ensuring that the ratio is not greater than 1:5 of the citrate anticoagulant to blood. Sepsis in patients with an isolated hemothorax is considered only a minimal risk. Sepsis has been associated with the difficulty that exists in maintaining a completely sterile environment in patients receiving an autotransfusion.27–29

An autotransfusion is a basic technique that is possible in the Emergency Department. It is not the standard of care under all settings. The procedure requires familiarity with the equipment, continuing education, and quality control. This may be the reason it is underutilized in many Emergency Departments. Anticipation of which patients would benefit from this technique might be problematic and time consuming, especially when assembling equipment that may not be used frequently. Proper use of the devices can be advantageous to avoid the multiple complications associated to hypovolemic shock in trauma patients. The low risk of complications related to this technique make an autotransfusion a viable option to a homologous transfusion.