Acute and transient decrease in neutrophil count in transfusion-related acute lung injury: cases at one hospital

Red Blood Cell Transfusion

Blood is classified as a drug and transfusion is one of the most commonly performed procedures in the USA. General knowledge of blood manufacturing, shelf life and storage media, common component modifications, blood types, and product compatibility allows the clinician to better communicate their needs and to understand what options may be available when ordering blood products. All transfusions offer benefits, and the clinician must comprehend the possible adverse events, especially those related to TRALI, which continues to be the most common cause of transfusion-related death reported to FDA, with TACO as the second most-commonly reported event. Transfusing in the setting of hemorrhagic blood loss adds additional challenges regarding volume overload, coagulopathy, and optimum transfusion ratios of red cells, plasma, platelets, and cryoprecipitate. The information imparted in this chapter will help equip the clinician with the knowledge needed to make the best decisions for patients requiring blood products, especially injured patients.

Transfusion-related alloimmune neutropenia with no pulmonary complications: one donor-five cases

BACKGROUND

Neutrophil alloantibodies are well-known triggers of transfusion-related acute lung injury (TRALI) and also cause immune neutropenia. Alloimmune neutropenia due to transfusion is an isolated phenomenon that is only rarely identified. Its incidence is specified in the literature as being less than one in 10,000 transfused plasma-containing units. We expect that this phenomenon is underreported.

STUDY DESIGN AND METHODS

We observed five cases of alloimmune neutropenia with no respiratory complications with only one case initially reported as a suspected transfusion reaction. The other four cases were detected in the course of the subsequent lookback investigation.

RESULTS

The first case was reported as a potential transfusion reaction when a female patient showed a decrease in the white blood cell count after a platelet (PLT) transfusion. Examinations of the donor blood revealed an antibody against the human neutrophil antigen HNA-1b; the recipient was typed HNA-1b positive and HNA-1a negative. After examining the blood counts of other patients who previously received PLT concentrates from the same donor, we identified four other patients with an unreported decrease in the leukocyte and/or granulocyte count of more than approximately 50% after transfusion.

CONCLUSION

HNA antibodies are generally regarded as potential triggers of TRALI. Here we describe an HNA antibody that reproducibly caused transfusion-related neutropenia only without pulmonary complications. Factors predisposing patients to TRALI development are widely discussed. Our case suggests that antibody characteristics are also relevant in the development of TRALI. Current measures to prevent TRALI should also prevent transfusion-related alloimmune neutropenia.

Prospective study on the clinical course and outcomes in transfusion-related acute lung injury*

OBJECTIVE

Transfusion-related acute lung injury is the leading cause of transfusion-related mortality. A prospective study using electronic surveillance was conducted at two academic medical centers in the United States with the objective to define the clinical course and outcomes in transfusion-related acute lung injury cases.

DESIGN

Prospective case study with controls.

SETTING

University of California, San Francisco and Mayo Clinic, Rochester.

PATIENTS

We prospectively enrolled 89 patients with transfusion-related acute lung injury, 164 transfused controls, and 145 patients with possible transfusion-related acute lung injury.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients with transfusion-related acute lung injury had fever, tachycardia, tachypnea, hypotension, and prolonged hypoxemia compared with controls. Of the patients with transfusion-related acute lung injury, 29 of 37 patients (78%) required initiation of mechanical ventilation and 13 of 53 (25%) required initiation of vasopressors. Patients with transfusion-related acute lung injury and possible transfusion-related acute lung injury had an increased duration of mechanical ventilation and increased days in the ICU and hospital compared with controls. There were 15 of 89 patients with transfusion-related acute lung injury (17%) who died, whereas 61 of 145 patients with possible transfusion-related acute lung injury (42%) died and 7 of 164 of controls (4%) died. Patients with transfusion-related acute lung injury had evidence of more systemic inflammation with increases in circulating neutrophils and a decrease in platelets compared with controls. Patients with transfusion-related acute lung injury and possible transfusion-related acute lung injury also had a statistically significant increase in plasma interleukin-8, interleukin-10, and interleukin-1 receptor antagonist posttransfusion compared with controls.

CONCLUSIONS

In conclusion, transfusion-related acute lung injury produced a condition resembling the systemic inflammatory response syndrome and was associated with substantial in-hospital morbidity and mortality in patients with transfusion-related acute lung injury compared with transfused controls. Patients with possible transfusion-related acute lung injury had even higher in-hospital morbidity and mortality, suggesting that clinical outcomes in this group are mainly influenced by the underlying acute lung injury risk factor(s).

A prophylactic fresh frozen plasma transfusion leads to a possible case of transfusion-related acute lung injury

A 39-year-old man with cholangiocarcinoma presented with fever and abdominal pain. He was hypotensive, jaundiced and had right upper quadrant tenderness. Laboratory testing showed a leucocytosis, elevated liver function tests, total bilirubin and International Normalised Ratio (INR). Given the concern for cholangitis, the patient was given antibiotics and three units of fresh frozen plasma (FFP) before biliary drain placement. After drain placement, and within 3 h of receiving blood products, the patient became tachypnoeic and hypoxic with a chest X-ray revealing new bilateral airspace disease. The rapid development of respiratory distress was determined to most likely be transfusion-related acute lung injury (TRALI). He rapidly progressed to intubation and required 100% FiO2, high positive-end expiratory pressure (PEEP) and intermittent-prone ventilation for 48 h but eventually recovered and was extubated. TRALI is an under-recognised aetiology for respiratory distress in the critically ill. Adopting a conservative transfusion strategy may prevent TRALI.

Acute lung injury after platelet transfusion in a patient with dengue fever

Transfusion-related acute lung injury (TRALI) is a serious clinical syndrome associated with the transfusion of plasmacontaining blood components. Recently, TRALI has come to be recognized as the leading cause of transfusion-related mortality. This complication typically presents as shortness of breath, hypoxemia, hypotension, fever, and non cardiogenic pulmonary edema, occurring within 6 h after transfusion. Although the mechanism of TRALI has not been exactly known, it has been associated with human leukocyte antigen antibodies and with biologically active mediators in stored cellular blood components. We, hereby, present a case of a patient with dengue fever who developed acute lung injury (ALI), presumably TRALI, after transfusion of platelet concentrates. He was treated with supportive measures and mechanical ventilation. Greater knowledge and increased awareness especially amongst the clinicians regarding TRALI is needed for prevention and treatment of this potentially severe complication of blood/component transfusion.

[Transfusion-related acute lung injury]

Transfusion-related acute lung injury (TRALI) developed into the leading cause of transfusion-related morbidity and mortality after the first description by Popovsky et al. approximately three decades ago. It was the most frequent reason for transfusion-related fatalities worldwide before implementation of risk minimization strategies by donor selection. Plasma-rich blood products, such as fresh frozen plasma and apheresis platelets seem to be the leading triggers of TRALI. Hypoxemia and development of pulmonary edema within 6 h of transfusion are the diagnostic criteria for TRALI. The differentiation between cardiac failure and other transfusion-related lung injuries, such astransfusion-associated circulatory overload ( TACO) is difficult and causal treatment is not available. Therapy is based on supportive measures, such as oxygen insufflationor mechanical ventilation. The exactly pathogenesis is still unknown but the most propagated hypothesis is the two-event-model. Neutrophils are primed by the underlying condition, e.g. sepsis or trauma during the first event and these primed neutrophils are activated by transfused leukoagglutinating antibodies (immunogen) or bioreactive mediators (non-immunogen) during the second-event. Transfusion of leukoagglutinating antibodies from female donors with one or more previous pregnancies is the most frequent reason. No more TRALI fatalities were reported after implementation of the donor selection in Germany in 2009.

Neutrophils contain cholesterol crystals in transfusion-related acute lung injury (TRALI)

OBJECTIVES

Intracellular components of transfusion-related acute lung injury (TRALI) were investigated by transmission electron microscopy.

METHODS

The lungs from 2 fatal TRALI cases and 2 controls, previously studied by scanning electron microscopy, were studied by transmission electron microscopy. Morphologic data by light and phase microscopy, along with scanning and transmission electron microscopic observations, were collated.

RESULTS

The 2 fatal TRALI cases exhibited dense laminated material within capillaries and postcapillary venules, similar to material identified within their neutrophils when viewed by transmission electron microscopy. This material polarized light and is presumed to be cholesterol crystals.

CONCLUSIONS

The damage to the pulmonary vascular endothelium in TRALI is related to formation of cholesterol crystals originating within neutrophils.

Pulmonary complications of transfused blood components

Three transfusion complications are responsible for the majority of the morbidity and mortality in hospitalized patients. This article discusses the respiratory complications associated with these pathophysiologic processes, including definitions, diagnosis, mechanism, incidence, risk factors, clinical management, and strategies for prevention. It also explores how different patient populations and different blood components differentially affect the risk of these deadly transfusion complications. Lastly, the article discusses how health care providers can risk stratify individual patients or patient populations to determine whether a given transfusion is more likely to benefit or harm the patient based on the transfusion indication, risk, and expected result.

Two septic transfusion reactions presenting as transfusion-related acute lung injury from a split plateletpheresis unit

OBJECTIVES

We report two simultaneous cases of Staphylococcus aureus sepsis initially consistent with and diagnosed as transfusion-related acute lung injury. The sepsis in both cases resulted from transfusion of two split products from a single contaminated plateletpheresis unit. In each case, the platelets were given along with numerous other blood products during posterior spine surgery. The discussion includes presentation, clinical course, diagnosis, and similarities between sepsis and transfusion-related acute lung injury. The cases and discussion highlight the importance of considering sepsis as part of the differential for any patient believed to have transfusion-related acute lung injury with clinical features of sepsis.

DATA SOURCES

Data were collected from the patients' electronic medical records and the hospital laboratory medicine database.

CONCLUSIONS

Our cases highlight the importance of vigilant investigation in patients suspected of transfusion-related acute lung injury, as septic transfusions are easily missed and may mimic or coexist with transfusion-related acute lung injury. Sepsis should be strongly considered whenever clinical features such as hypotension, leucopenia, and fever are noted in patients with suspected transfusion-related acute lung injury. In comparison to patients receiving red blood cells or plasma, platelet transfusion recipients are at a greater risk for sepsis from a contaminated unit. Patients developing sepsis from a contaminated blood product may meet the clinical definition of transfusion-related acute lung injury. In such cases, if the clinical syndrome is attributed solely to transfusion-related acute lung injury and bacterial sepsis is not suspected, the correct diagnosis may be missed or delayed. Consequently, appropriate treatment for sepsis would also be delayed or not provided and likely result in increased morbidity and mortality.

Pathology consultation on transfusion-related acute lung injury (TRALI)

Transfusion-related acute lung injury (TRALI) is a serious condition characterized by respiratory distress, hypoxia, and bilateral pulmonary infiltrates, which occur within 6 hours of transfusion. Several theories have been proposed to explain the underlying pathologic mechanisms of TRALI. Immune-mediated TRALI accounts for over 80% of reported cases and is mediated by donor antibodies to HLAs and/or human neutrophil antigens (HNA). Immune-mediated TRALI is most commonly associated with donor plasma transfusion or other blood products from multiparous women, which has led many countries to reduce or exclude women from donating high-volume plasma products. This policy change has resulted in a decrease in the incidence of TRALI and highlighted the importance of nonimmune-mediated TRALI, which is thought to be caused by bioreactive lipids and other biologic response modifiers that accumulate during storage of blood products. When TRALI is suspected, clinical consultation with a transfusion medicine specialist helps differentiate it from other transfusion reactions with similar characteristics.

The paradox of the neutrophil's role in tissue injury

The neutrophil is an essential component of the innate immune system, and its function is vital to human life. Its production increases in response to virtually all forms of inflammation, and subsequently, it can accumulate in blood and tissue to varying degrees. Although its participation in the inflammatory response is often salutary by nature of its normal interaction with vascular endothelium and its capability to enter tissues and respond to chemotactic gradients and to phagocytize and kill microrganisms, it can contribute to processes that impair vascular integrity and blood flow. The mechanisms that the neutrophil uses to kill microorganisms also have the potential to injure normal tissue under special circumstances. Its paradoxical role in the pathophysiology of disease is particularly, but not exclusively, notable in seven circumstances: 1) diabetic retinopathy, 2) sickle cell disease, 3) TRALI, 4) ARDS, 5) renal microvasculopathy, 6) stroke, and 7) acute coronary artery syndrome. The activated neutrophil's capability to become adhesive to endothelium, to generate highly ROS, and to secrete proteases gives it the potential to induce local vascular and tissue injury. In this review, we summarize the evidence for its role as a mediator of tissue injury in these seven conditions, making it or its products potential therapeutic targets.

Transfusion-related acute lung injury

Transfusion-related acute lung injury is a clinical syndrome that occurs within 6 hours of transfusion. It is the leading cause of transfusion-related mortality. It presents with shortness of breath, acute pulmonary edema, fever, hypotension, or hypertension followed by hypotension. Treatment consists of respiratory support and fluid administration to support blood pressure. A majority of cases are associated with antibodies to white blood cells in the blood donor. Blood centers in the United States are currently taking measures to reduce the risk of transfusion-related acute lung injury from blood components.

Platelet depletion and aspirin treatment protect mice in a two-event model of transfusion-related acute lung injury

Transfusion-related acute lung injury (TRALI) is the leading cause of transfusion-associated mortality in the US. Previously, we established an immune-mediated TRALI mouse model, wherein mice with cognate antigen were challenged with MHC class I mAb. In this study, when mice housed in a rodent, specific pathogen-free barrier room were challenged with MHC I mAb, there was significant protection from TRALI compared with nonbarrier mice. Priming mice with LPS restored lung injury with mAb challenge. Using TLR4-deficient bone marrow chimeras, the priming phenotype was restricted to animals with WT hematopoietic cells, and depletion of either neutrophils or platelets was protective. Both neutrophils and platelets were sequestered in the lungs of mice with TRALI, and retention of platelets was neutrophil dependent. Interestingly, treatment with aspirin prevented lung injury and mortality, but blocking the P selectin or CD11b/CD18 pathways did not. These data suggest a 2-step mechanism of TRALI: priming of hematopoietic cells, followed by vascular deposition of activated neutrophils and platelets that then mediate the severe lung injury. Furthermore, our data offer an explanation for the increased incidence of TRALI in patients with immune priming conditions, and we suggest what we believe to be a novel therapeutic approach.

TRALI is due to pulmonary venule damage from leucocytes with cholesterol crystal formation

BACKGROUND

There are two presumed mechanisms for the pulmonary oedema in transfusion-related acute lung injury (TRALI). One is antibodies to leucocytes while the other is biologically active lipids. We evaluated the vascular injury due to the former.

METHODS

The pulmonary vasculature was studied by light microscopy (LM) and scanning electron microscopy (SEM) in three fatal cases of TRALI and compared with that of two autopsied control patients. Lung tissue from two of the TRALI cases and both controls was studied by gas chromatography-mass spectroscopy (GC-MS) to identify crystals present in the former.

RESULTS

All three TRALI cases exhibited massive pulmonary oedema by weight and light microscopy and extensive defects by SEM in the endothelium of venules of the lungs. Such endothelial defects were absent in controls. Thrombi, composed of crystals, were present in venules and small veins diffusely throughout the lungs in Case 1. Similar crystals were identified in Case 2. The crystals in the lung vessels were identified morphologically as cholesterol and were proximate to the cytoplasmic defects of the endothelial surfaces. By GC-MS, there were markedly elevated levels of cholesterol and fatty acids in the two TRALI lungs tested compared with the lungs of the two controls.

CONCLUSIONS

Pulmonary damage in TRALI is related to formation of cholesterol crystals that appear to pierce endothelial membranes of venules. The endothelial defects lead to plasma extravasation into the alveoli causing TRALI.

Transfusion-related acute lung injury (TRALI): a clinical review with emphasis on the critically ill

Transfusion-related acute lung injury (TRALI) is the leading cause of transfusion-related morbidity and mortality world-wide. Although first described in 1983, it took two decades to develop consensus definitions, which remain controversial. The pathogenesis of TRALI is related to the infusion of donor antibodies that recognize leucocyte antigens in the transfused host or the infusion of lipids and other biological response modifiers that accumulate during the storage or processing of blood components. TRALI appears to be the result of at least two sequential events and treatment is supportive. This review demonstrates that critically ill patients are more susceptible to TRALI and require special attention by critical care specialists, haematologists and transfusion medicine experts. Further research is required into TRALI and its pathogenesis so that transfusions are safer and administered appropriately. Avoidance including male-only transfusion practises, the use of leucoreduced components, fresher blood/blood components and solvent detergent plasma are also discussed.

Transfusion-related acute lung injury: current concepts for the clinician

The leading cause of transfusion-related morbidity and mortality in the United States is transfusion-related acute lung injury (TRALI). Diagnostic criteria for TRALI have recently been developed and primarily consist of hypoxia and bilateral pulmonary edema occurring during or within 6 h of a transfusion in the absence of cardiac failure or intravascular volume overload. The primary differential diagnosis is transfusion-associated circulatory overload and differentiation can be difficult. Treatment is supportive with oxygen and mechanical ventilation. Diuresis is not indicated and the role of steroids is unproven. Patients typically recover within a few days. All types of blood products have been associated with TRALI, however, the plasma-rich components, such as fresh frozen plasma and apheresis platelets, have been most frequently implicated. The pathogenesis of TRALI is not completely understood. Leukocyte antibodies in donor plasma have been implicated in most cases with antibodies directed at human leukocyte antigen (HLA) class I, HLA class II or neutrophil-specific antigens, particularly HNA-3a. Activation of pulmonary endothelium is important in the development of TRALI and may account for most cases being observed in surgical or intensive care unit patients. Transfused leukoagglutinating antibodies bind to recipients' neutrophils localized to pulmonary endothelium resulting in activation and release of oxidases and other damaging biologic response modifiers that cause capillary leak. In a minority of TRALI cases, no antibodies are identified and it is postulated that neutrophil priming factors in the transfused component can mediate TRALI in a patient with pulmonary endothelial activation, the so called "two hit" mechanism. Recognition of the role of anti-leukocyte antibodies has led to new strategies to reduce the risk of TRALI. Female blood donors with a previous pregnancy frequently have HLA antibodies with an overall prevalence of 24% and increasing prevalence related to the number of previous pregnancies. Since HLA antibodies have been implicated in TRALI, blood centers have adopted policies to produce plasma components primarily from male donors. Strategies to reduce the risk from apheresis platelets are problematic and are likely to involve testing female apheresis platelet donors for HLA antibodies. Much more research is needed to understand the blood component and patient risk factors for TRALI so that novel strategies for treatment and additional measures to reduce the risk of TRALI can be developed.

Transfusion-related acute lung injury: a rare and life-threatening complication of a common procedure

Transfusion-related acute lung injury (TRALI) has emerged as one of the leading causes of transfusion-related morbidity and mortality and is undoubtedly under diagnosed. It is a serious pulmonary syndrome that can lead to death if not recognised and treated promptly. The diagnosis of TRALI is based primarily upon clinical signs and symptoms and is, in part, a diagnosis of exclusion.

Transfusion-related acute lung injury following intravenous anti-D administration in an adolescent

Transfusion-related acute lung injury (TRALI) is associated with administration of all plasma containing blood products. We present a 14-year-old adolescent diagnosed with idiopathic thrombocytopenic purpura who developed acute respiratory insufficiency compatible with TRALI within 5 hr following intravenous anti-D. Full blown noncardiogenic pulmonary edema was noted after 9 hr. Mechanical ventilation was not required and the patient made a full recovery after 36 hr. Analysis of the anti-D preparation revealed reactivity against the neutrophil FcgammaRIIIb. A postinfusion serum sample contained antibodies against class I human HLA-A11 antigen. Clinicians should consider TRALI in patients developing unexplained dyspnea after receiving intravenous anti-D.

Patient-specific transfusion-related acute lung injury

Transfusion-related acute lung injury (TRALI) is one of the leading causes of transfusion-associated mortality. The inadvertent transfusion of neutrophil antibodies can cause pulmonary transfusion reactions and TRALI. However, not all patients transfused with neutrophil antibodies experience transfusion reactions. A 22-year-old man with severe aplastic anaemia (SAA) experienced TRALI after a platelet transfusion. The donor was found to be alloimmunized to human neutrophil antigen (HNA)-3a, an antigen expressed by neutrophils from approximately 90% of Caucasians. Eleven other platelet components from this donor were transfused prior to this event and two caused reactions: one chills and one TRALI. Both episodes of TRALI occurred in the same male patient with SAA. The fact that one patient experienced TRALI following both exposures to anti-HNA-3a from the same donor whereas nine other recipients did not adds evidence to the observation that patient factors make a significant contribution to neutrophil antibody-mediated transfusion reactions.

Transfusion-related acute lung injury: a clinical challenge

Transfusion-related acute lung injury is a life-threatening clinical syndrome. In the last 3 years, it has become the leading cause of reported transfusion-related deaths in the United States. This syndrome is characterized by acute hypoxemia and noncardiogenic pulmonary edema directly linked in time to a blood transfusion. All types of blood products have been implicated in transfusion-related acute lung injury, but transfusion of plasma-containing products from multiparous women seems to carry the highest risk. The purpose of this article is to raise awareness of this syndrome for the critical care nurse. This article discusses the widely accepted clinical features of transfusion-related acute lung injury, its pathogenesis, differential diagnosis, and treatment.

Transfusion-Related Acute Lung Injury

Transfusion-related acute lung injury (TRALI) refers to a clinical syndrome of acute lung injury that occurs in a temporal relationship with the transfusion of blood products. Because of the difficulty in making its diagnosis, TRALI is often underreported. Three not necessarily mutually exclusive hypotheses have been described to explain its etiogenesis: antibody mediated, non-antibody mediated, and two hit mechanisms. Treatment is primarily supportive and includes supplemental oxygen. Diuretics are generally not indicated, as hypovolemia should be avoided. Compared with many other forms of acute lung injury, including the acute respiratory distress syndrome, TRALI is generally transient, reverses spontaneously, and carries a better prognosis. A variety of prevention strategies have been proposed, ranging from restrictive transfusion strategies to using plasma derived only from males.

TRALI--definition, mechanisms, incidence and clinical relevance

Transfusion-related acute lung injury (TRALI) is defined as new acute lung injury (ALI) that occurs during or within six hours of transfusion, not explained by another ALl risk factor. Transfusion of part of one unit of any blood product can cause TRALI. The mechanism may include factors in unit(s) of blood, such as antibody and biologic response modifiers. In addition, yet to be described factors in a patient's illness may predispose to the condition. The current incidence is estimated to be 1 in 5000 units. Patients present with acute dyspnea, or froth in the endotracheal tube in intubated patients. Hypertension, hypotension, acute leukopenia have been described. Management is similar to that for ALI and is predominantly supportive. When TRALI is suspected, Blood banks should be notified to quarantine other components from the same donation. No special blood product is required for subsequent transfusion of a patient who has developed TRALI.

The transfusion of neutrophil-specific antibodies causes leukopenia and a broad spectrum of pulmonary reactions

BACKGROUND

Antibodies to neutrophil-specific antigens are the best characterized cause of transfusion-related acute lung injury (TRALI).

CASE REPORT

A double-apheresis platelet (PLT) component was divided and transfused into two patients. One experienced chills, rigors, and dyspnea and the other experienced chills and headache. Transient leukopenia developed in both patients.

RESULTS

Evaluation of donor plasma revealed an anti-HNA-2a and no HLA Class I antibodies. The donor had donated 26 previous apheresis PLT components. The 27 donations resulted in 39 separate transfusions and 12 transfusion reactions in 9 patients. Five reactions occurred immediately after the transfusion, 10 within 1 hour, and all within 2.5 hours. Nine of the reactions involved symptoms or signs of pulmonary dysfunction. The symptoms were mild to moderate in nature. None of the inpatients required intensive care transfer nor did any outpatients require hospital admission. Recipient white blood cell (WBC) counts were measured within 8 hours after 38 of 39 transfusions. Leukopenia occurred in 9 of 12 (75%) transfusions with reactions and in 9 of 26 (35%) transfusions without. The reactions did not correlate with pretransfusion WBC count.

CONCLUSIONS

Neutrophil antibodies cause a wide variety of transfusion reactions that do not necessarily meet the definition of TRALI. Donors of blood products causing even mild pulmonary reactions or leukopenia should be tested for neutrophil-specific antibodies.

[Transfusion-related acute lung injury]

OBJECTIVES

The transfusion-related acute lung injury frequency was for a long time underestimated since it lacked both a widely accepted clinical definition and a comprehensive etiologic description. Recent clinical and biological data have underlined its frequency and have allowed a better understanding of its mechanisms.

CURRENT KNOWLEDGE AND KEY POINTS

Trali is an interstitial lung injury occurring within 6 hours after the beginning of a blood transfusion. This time relationship between blood injection and the occurrence of lung edema is sufficient for a positive diagnosis, if any other cause of interstitial lung edema have been excluded. The clinical definition relies on a desaturation of arterial blood associated to a lack of any cardiac failure or circulation overload. The link between transfusion and lung edema is not univocal and several categories of mechanisms have been discussed. At least 2 of them are well identified; the first one is an immune conflict, and the second one is an activation of neutrophils by injection of biological modifiers such as lipids or CD40 soluble ligand. Evidences exist for the occurrence of Trali only in predisposing condition that mostly consists of a preceding leucostase in lung capillaries. Trali is treated like other lung interstitial edema by oxygen therapy and mechanical ventilation.

FUTURE PROJECTS

A better knowledge of Trali offers the opportunity of improving the understanding of the role of blood transfusion in lung edema occurring in complex situations and open the way for a better definition of at risk patient and at risk blood components.

Pulmonary transfusion reactions

Transfusion reactions remain a common complication of transfusion therapy; reactions affecting the lungs are some of the most serious. Several different mechanisms are responsible for pulmonary transfusion reactions, and most cause adverse effects in addition to lung injury. Fluid overload can lead to pulmonary edema, antibodies reacting with plasma proteins can cause bronchospasm and anaphylaxis, and particulate matter can produce microemboli. These reactions are well understood and usually can be prevented. Transfusions are also associated with acute lung injury and acute respiratory distress syndrome (ARDS), but their etiology is poorly understood and they remain clinically problematic. Neutrophil antibodies cause some of these serious as well as mild pulmonary reactions, but the exact role of leukocyte antibodies in pulmonary reactions remains unclear. Other blood donor, blood component, and transfusion recipient factors likely play a contributing or modulating role in pulmonary transfusion reactions, but prospective studies are needed to better understand their role.

Transfusion-related Acute Lung Injury

With the success of reducing the risk of transfusion-transmitted infectious diseases, noninfectious serious hazards of transfusion have come to the forefront with respect to transfusion safety. Transfusion-related acute lung injury has emerged as a dominant noninfectious serious hazard of transfusion. Improved understanding of its pathophysiology is needed to improve clinical strategies to deal with the risk. Such understanding, in turn, will depend on the continued progress in development of good model systems, in vitro and in vivo, for experimental studies. As the pathologic mechanisms are elucidated, a universal definition and strategies for the prevention and/or mitigation may become more tangible. This article reviews the clinical manifestations, evolving definition, incidence, pathophysiology, animal modeling, and donor screening and deferral algorithms as they relate to transfusion-related acute lung injury.

Newly recognized causes of acute lung injury: transfusion of blood products, severe acute respiratory syndrome, and avian influenza

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) is a clinical syndrome that has an ever-growing list of potential causes. The transfusion of blood products is often a life-saving therapy, but it can be associated with the development of ALI/ARDS. Transfusion-related ALI is now the leading cause of transfusion-associated fatalities in the United States. Two infectious causes of ALI/ARDS, severe acute respiratory syndrome and H5N1 influenza, have recently emerged and have the potential for pandemic spread. This article discusses the clinical importance, pathogenesis, diagnosis, management, and prevention of these newly recognized causes of respiratory failure.

Transfusion-related acute lung injury in the paediatric patient: Two case reports and a review of the literature

Transfusion-related acute lung injury (TRALI) is increasingly recognized as a major complication of transfusion therapy; it was the leading cause of transfusion-related fatalities in the United States in 2003. Most cases of TRALI that have been reported are in adult patients. We present two cases of TRALI that occurred in children and review the existing literature of paediatric TRALI. The paediatric TRALI case reports highlight two laboratory findings that can help in the diagnosis of TRALI: transient leucopenia and an elevated pulmonary oedema fluid/plasma protein ratio. These two simple diagnostic tests can help rule out other diagnoses and add confidence to the clinical diagnosis of TRALI. Finally, our first case also highlights the potential danger of directed maternal blood donations, which may increase the risk of paediatric TRALI.

Transfusion therapy in the intensive care unit

PURPOSE OF REVIEW

Transfusion therapy in the intensive care unit is an ever-growing field, with new understanding of potential complications, new drug therapies to reduce the need for transfusion, and new additions in component therapy. In addition to the risks of sepsis, ABO blood group mismatch, and other complications associated with transfusion, the intensivist needs to be familiar with alternative therapies to minimize transfusion.

RECENT FINDINGS

Transfusion-related acute lung injury and immunosuppression are two newly recognized complications in transfusion. Transfusion-related acute lung injury can lead to respiratory failure in an acute respiratory distress syndrome-like picture, often necessitating intubation and critical care services. Immunosuppression following transfusion has been linked to cytokine and complement activation. Recombinant erythropoietin (rHuEPO, Epogen, Procrit), by maximizing red cell counts, and aprotinin (Trasylol), by inhibiting fibrinolysis, are two old drugs being used with increasing frequency in a new setting: the intensive care unit. A new component therapy, recombinant factor VIIa (rFVIIa, NovoSeven), assists in turning on the extrinsic pathway of the coagulation cascade.

SUMMARY

Recognizing early signs of transfusion-related acute lung injury may aid in the treatment and reporting of this entity. Realizing the mechanism and severity of immunosuppression associated with transfusion may alter transfusion triggers in the intensive care unit. rHuEPO and aprotinin are now being used with increasing frequency to increase red cell counts and minimize the need for transfusion. Recombinant factor FVIIa targets coagulation cascade activation which helps to reduce the number of units of blood products transfused in the actively bleeding patient.

Transfusion-related acute lung injury: a literature review

Transfusion-related acute lung injury (TRALI) is a serious and potentially fatal complication of transfusion of blood and blood components. TRALI is under-diagnosed and under-reported because of a lack of awareness. A number of models have been proposed to explain the pathogenesis of TRALI: an antibody mediated model; a two-event biologically active mediator model; and a combined model. TRALI can occur with any type of blood product and can occur with as little as one unit. Its presentation is similar to other forms of acute lung injury and management is predominantly supportive. The main strategy in combating TRALI is prevention both through manipulation of the donor pool and through clinical strategies directed at reducing transfusion of blood products including, but not limited to, evidence-based lower transfusion thresholds. This article presents a review of TRALI and addresses the definition, pathology, pathogenesis, clinical manifestations, treatment and prevention of the syndrome.

Transfusion-Related Acute Lung Injury (TRALI): Current Clinical and Pathophysiologic Considerations

Transfusion-related acute lung injury (TRALI) is a rare transfusion reaction presenting as respiratory distress during or after transfusion of blood products. TRALI varies in severity, and mortality is not uncommon. TRALI reactions have equal gender distributions and can occur in all age groups. All blood products, except albumin, have been implicated in TRALI reactions. TRALI presents as acute respiratory compromise occurring in temporal proximity to a transfusion of a blood product. Other causes of acute lung injury should be excluded in order to definitively diagnose TRALI. Clinically and pathologically, TRALI mimics acute respiratory distress syndrome (ARDS), with neutrophil-derived inflammatory chemokines and cytokines believed to be involved in the pathogenesis of both entities. Anti-HLA and anti-neutrophil antibodies have been implicated in some cases of TRALI. Treatment for TRALI is supportive; prevention is important. It is suspected that TRALI is both underdiagnosed and underreported. One of the difficulties in the evaluation of potential TRALI reactions is, until recently, the lack of diagnostic criteria. A group of transfusion medicine experts, the American-European Consensus Conference (AECC), recently met and developed diagnostic criteria of TRALI, as well as recommendations for management of donors to prevent future TRALI reactions. In light of the AECC consensus recommendations, we report an incident of TRALI in an oncology patient as an example of the potential severity of the lung disease and the clinical and laboratory evaluation of the patient. We also review the literature on this important complication of blood transfusion that internists may encounter.

Commentary on TRALI in leukemia

The paper by Fung YL and Williams BA describes TRALI in leukemic children in order to raise awareness of the need to include this in the differential diagnosis of acute respiratory distress. Detection of TRALI in children with other co-morbidities is difficult. Well-documented cases of TRALI in children are few due to the lack of recognition and difficulty in identifying the antibodies since these may not be always present. Hematology/oncology patients who are chronically transfused and are allo-immunized are at greater risk than the general pediatric population. Thus an awareness of this reaction to blood transfusion helps facilitate prompt treatment and preventive measures.

Animal models of transfusion-related acute lung injury

OBJECTIVE

To examine the existing animal models of transfusion-related acute lung injury (TRALI) for insight into disease pathogenesis.

DATA SOURCE

The data were taken from published research and from our own experimental results.

RESULTS

Animal models have disproved the microaggregate theory of acute lung injury from blood transfusions. The two major hypotheses of TRALI, passively transfused neutrophil and human leukocyte antigen antibodies and biologically active lipids that accumulate in older, cellular blood products, have been replicated in animal models. The proposed two-hit model of TRALI is also supported by animal studies. A new in vivo mouse model of TRALI based on major histocompatibility complex (MHC) I antibodies has replicated several features of human TRALI, focusing prominently on the role of neutrophils.

CONCLUSIONS

Experimental animal models support both the antibody and lipid theories of TRALI. The essential role of neutrophils to producing lung injury is common to all existing models of TRALI. There is a lack of clinically relevant animal models that explain why transfusion of donor antibodies to cognate antigens in the recipient does not always lead to TRALI.

Transfusion-related acute lung injury (TRALI): clinical presentation, treatment, and prognosis

The term transfusion-related acute lung injury (TRALI) was coined in 1983 to describe a constellation of clinical and laboratory features seen within 6 hrs of the transfusion of plasma-containing blood products. These products contain antibodies directed to human leukocyte antigens (and subsequently described to nonhuman leukocyte antigens) found on white blood cells. In the intervening 2 decades, other cases not associated with antibodies have been reported as TRALI and an association with passive infusion of lipids accumulated in stored cellular blood products has been made in those cases. This has led to confusion as to what should be considered to constitute TRALI. Therefore, the true incidence of this pulmonary reaction to blood products is currently conjectural at best. Recent consensus development conferences have been held to develop and standardize definitions of TRALI so that epidemiologic and research aspects of this condition can be explored in a scientific manner. These conferences have set out criteria by which TRALI is distinguished from other causes of acute lung injury. This review outlines the widely accepted clinical (mainly pulmonary) features of TRALI, the treatment options, and the excellent long-term prognosis for patients who survive the initial pulmonary insult.

Neutrophils and their Fc gamma receptors are essential in a mouse model of transfusion-related acute lung injury

Transfusion-related acute lung injury (TRALI) is the most common cause of transfusion-related mortality. To explore the pathogenesis of TRALI, we developed an in vivo mouse model based on the passive transfusion of an MHC class I (MHC I) mAb (H2Kd) to mice with the cognate antigen. Transfusion of the MHC I mAb to BALB/c mice produced acute lung injury with increased excess lung water, increased lung vascular and lung epithelial permeability to protein, and decreased alveolar fluid clearance. There was 50% mortality at a 2-hour time point after Ab administration. Pulmonary histology and immunohistochemistry revealed prominent neutrophil sequestration in the lung microvasculature that occurred concomitantly with acute peripheral blood neutropenia, all within 2 hours of administration of the mAb. Depletion of neutrophils by injection of anti-granulocyte mAb Gr-1 protected mice from lung injury following MHC I mAb challenge. FcRgamma-/- mice were resistant to MHC I mAb-induced lung injury, while adoptive transfer of wild-type neutrophils into the FcRgamma-/- animals restored lung injury following MHC I mAb challenge. In conclusion, in a clinically relevant in vivo mouse model of TRALI using an MHC I mAb, the mechanism of lung injury was dependent on neutrophils and their Fc gamma receptors.

Transfusion-related acute lung injury: an update

Transfusion-associated acute lung injury (TRALI) has emerged as a leading cause of transfusion-related morbidity and mortality. TRALI is characterized by acute non-cardiogenic pulmonary edema and respiratory compromise in the setting of transfusion. The study of TRALI has been hampered by inadequate case definitions and an incomplete understanding of the pathologic mechanisms. Recent consensus conferences took an important first step by providing a framework for case definition. Recent advances in the understanding of the pathogenesis of TRALI have also occurred. TRALI has been primarily attributed to donor leukocyte antibodies that are thought to interact with recipient neutrophils, resulting in activation and aggregation in pulmonary capillaries, release of local biologic response modifiers causing capillary leak, and lung injury. An alternate mechanism termed the "two hit" or "neutrophil priming" hypothesis postulates that a pathway to neutrophil activation and aggregation can occur without leukocyte antibodies. A first event such as sepsis or trauma can induce pulmonary endothelial activation, release of cytokines, and priming of neutrophils. A subsequent second event such as exposure to lipids, cytokines or antibodies in a blood component would then cause activation of adherent neutrophils and a release of bioreactive molecules leading to lung injury. There are limited clinical and animal studies to support the "two hit" model. These proposed mechanisms are not mutually exclusive in that donor leukocyte antibody can be pathogenic in both models and have implications for new strategies to prevent TRALI.

Transfusion-related acute lung injury

Transfusion-related acute lung injury (TRALI) is a life-threatening adverse event of transfusion, which has an increasing incidence in the United States and is the leading cause of transfusion-related death. TRALI and acute lung injury (ALI) share a common clinical definition except that TRALI is temporally- and mechanistically-related to transfusion of blood or blood components. A number of different models have been proposed to explain the pathogenesis. The first is an antibody-mediated event whereby transfusion of anti-HLA, class I or class II, or anti-granulocyte antibodies into patients whose leukocytes express the cognate antigens. The antibody:antigen interaction causes complement-mediated pulmonary sequestration and activation of neutrophils (PMNs) resulting in TRALI. The second is a two-event model: the first event is the clinical condition of the patient resulting in pulmonary endothelial activation and PMN sequestration, and the second event is the transfusion of a biologic response modifier (including anti-granulocyte antibodies, lipids, and CD40 ligand) that activates these adherent PMNs resulting in endothelial damage, capillary leak, and TRALI. These hypotheses are discussed with respect to animal models and human studies that provide the experimental and clinical relevance. The definition of TRALI, patient predisposition, treatment, prevention and reporting guidelines are also examined.

Transfusion-related acute lung injury

PURPOSE OF REVIEW

Transfusion-related acute lung injury is an uncommon complication of blood transfusion typically manifested by shortness of breath, fever, and hypotension. Transfusion-related acute lung injury is an important cause of transfusion-related morbidity and mortality.

RECENT FINDINGS

Much about the pathogenesis, treatment, and prevention of transfusion-related acute lung injury is poorly understood or is controversial. There is increasing recognition that transfusion-related acute lung injury is an important clinical syndrome, causing most transfusion-related deaths.

SUMMARY

In this report, what is known about transfusion-related acute lung injury is summarized with particular emphasis on recent studies. Some of the areas in which knowledge and/or consensus are currently lacking are identified.