Free ABFM® and ABIM® Sample Questions

Explanation:

This patient’s presentation is consistent with transfusion-related acute lung injury (TRALI).  Plasma is most frequently responsible for TRALI, but packed red blood cells, platelets, and other blood derivatives have also been implicated.  Transfusion-related acute lung injury is likely due to anti-leukocyte antibodies from the donor's plasma reacting with antigens on the recipient's leukocytes to initiate an inflammatory response within the pulmonary microvasculature.

Patients with TRALI usually present with sudden onset dyspnea, hypoxemia, and pulmonary infiltrates during or within 6 hours of any blood product transfusion (in the absence of circulatory overload).  Chest x-ray shows bilateral patchy alveolar infiltrates consistent with ARDS.  Importantly, TRALI diagnosis requires that patients not have preexisting ALI or other established ALI risk factors (e.g., septic shock, pneumonia, inhalation injury, etc.).

Management of TRALI involves immediately stopping the transfusion, providing respiratory support (sometimes intubation), and vasopressors for hypotension.  Clinical improvement occurs rapidly, even with severe hypoxemia, and most patients are extubated within 2 days.  Patients with TRALI should receive no further plasma-containing blood products from the implicated donor.  In addition, the blood bank should be notified and the donor investigated to prevent future incidents to other transfusion recipients from the donor.  Patients recovering from TRALI are not at a significantly increased risk for recurrent episodes following transfusions from other donors.

(Choice A)  Anaphylactic transfusion reaction (more common in patients with IgA deficiency) presents with a rapid onset of dyspnea, stridor, wheezing, respiratory distress, and hypotension.  However, anaphylactic transfusion reaction is not usually associated with abnormal chest x-ray findings, as seen in this patient.

(Choice B)  Aspiration pneumonia usually presents with cough, fever, purulent sputum, and dyspnea.  However, symptoms usually evolve over a period of time.  Aspiration pneumonitis (acid chemical pneumonitis) can cause acute distress and infiltrates but is rarely severe enough to cause florid ARDS.  Infiltrates are typically localized to one or both lower lobes.

(Choice C)  The probability of fat embolism syndrome (FES) with a single long bone fracture is 1-3%; this increases to 33% with bilateral femur fractures.  Fat embolism syndrome usually presents with the clinical triad of acute-onset neurologic abnormalities (e.g., confusion), hypoxemia, and petechial rash.  FES typically manifests 24-72 hours after the initial insult and usually with a normal chest x-ray in the majority of patients.

(Choice E)  Transfusion-associated circulatory overload (TACO) usually presents with physical findings suggesting volume overload (e.g., elevated JVD, presence of an S3).  Measurement of serum brain natriuretic peptide (BNP) or NT-Pro-BNP can also help in distinguishing TRALI from TACO.  This patient received approximately 2.5 liters of fluid and has had 1.1 liters of blood loss, making volume overload unlikely.

Educational objective:
Transfusion-related acute lung injury (TRALI) should be considered in patients with acute onset dyspnea, hypoxemia, and pulmonary infiltrates that occur during or within 6 hours after transfusion of any plasma containing blood product.  Treatment involves mainly supportive care, stopping the transfusion, and vasopressor support for hypotension.  The blood bank should be notified and the blood donor investigated to prevent future incidents in other recipients.