Pulmonary transfusion reactions: Clinical sciences

A pulmonary transfusion reaction refers to an acute lung injury within 6 hours of a blood product transfusion that results in pulmonary edema and respiratory distress. Now, based on the underlying mechanism, there are two main types of pulmonary transfusion reactions! The first one is a nonimmunologic reaction called transfusion-associated circulatory overload, or TACO for short. TACO occurs due to volume overload and subsequent increase in hydrostatic pressure that eventually leads to cardiogenic pulmonary edema.

The second type refers to an immune-mediated reaction called transfusion-related acute lung injury, or TRALI for short. In TRALI, the donor’s blood products usually contain anti-leukocyte antibodies that bind the recipient leukocytes and cause an inflammatory reaction. This ultimately results in endothelial damage, capillary leakage, and eventually noncardiogenic pulmonary edema, often also associated with fever and hypotension.

Okay, if a patient presents with a chief concern suggesting a pulmonary transfusion reaction, first, you should perform an ABCDE assessment to determine if they are unstable or stable. If unstable, stabilize the airway, breathing, and circulation and stop transfusion! If your patient is hypotensive, start intravenous fluids for volume resuscitation and consider vasopressors. Next, provide supplemental oxygen to maintain oxygen saturation. In severe cases, you might need to intubate the patient and put them on mechanical ventilation. Finally, put your patient on continuous vital sign monitoring including blood pressure, heart rate, and pulse oximetry, as well as cardiac telemetry.

Here’s a clinical pearl to keep in mind! Unstable patients with rapidly progressive dyspnea and bilateral pulmonary edema have a wide differential diagnosis. While a recent blood product transfusion may point you in the direction of a pulmonary transfusion reaction, be sure to consider similar clinical presentations, such as acute respiratory distress syndrome, pneumonia, or cardiac conditions, like congestive heart failure.

Now, let’s return to the ABCDE assessment and take a look at stable patients. In this case, obtain a focused history and physical exam and check the patient’s saturation using pulse oximetry. Your patient will typically report shortness of breath within 6 hours of blood product transfusion. Additionally, the physical exam will reveal tachycardia and signs of respiratory distress, such as tachypnea, dyspnea, and respiratory rales, while the pulse oximetry will show a drop in oxygen saturation, usually below 90%!

Now, here’s a clinical pearl! If the patient is already on a mechanical ventilator, they may have difficulty communicating their shortness of breath. Instead, you might observe oxygen desaturation and frothy secretions collecting in the endotracheal tube.

With these findings, you should suspect a pulmonary transfusion reaction, so your next step is to order additional labs including CBC, and BNP. You should also order imaging studies, including chest x-ray and echocardiogram; and a 12-lead ECG.

Alright, let’s start with TACO! In this case, history will typically reveal risk factors associated with TACO, such as older age and chronic cardiovascular, renal, or pulmonary conditions. Next, the physical exam will reveal signs of fluid overload! These include hypertension, jugular venous distention, peripheral edema, as well as S3 gallop! Additionally, since there’s fluid overload, the patient’s body weight will increase!

Next, since TACO is a non-immune mediated reaction, CBC will show no signs of immunologic reaction, so, usually, there will be no leukopenia and thrombocytopenia. But, since there’s fluid overload and ventricles are getting overstretched, you will find elevated BNP levels!

Now, let’s take a look at imaging! The chest X-ray will reveal signs of fluid overload, such as enlarged cardiac silhouette, but also signs of cardiogenic pulmonary edema, including Kerley B lines, bilateral pulmonary infiltrates, and peribronchial cuffing. In some cases, you might even notice pleural fluid! Additionally, the echocardiogram will show signs of left ventricular dysfunction, while the ECG will reveal no signs of acute myocardial ischemia or infarction!