Recognizing Transfusion Reactions: Transfusion Associated Circulatory Overload (TACO)

July 8, 2024

By Dominique Coco, M.D.

Medical Director, South Puget Sound Clinical Laboratories

As we continue to strive for excellence in patient care, I want to take a moment to highlight the critical importance of recognizing and promptly responding to transfusion reactions. These reactions, though relatively rare, can have serious and sometimes life-threatening consequences for our patients.

Transfusion reactions can range from mild allergic reactions to severe and life-threatening complications such as acute hemolytic reactions, anaphylaxis, and transfusion-related acute lung injury (TRALI), and transfusion associated circulatory overload (TACO).   The safety features of our modern transfusion practice are specifically designed to prevent the most serious of these reactions, acute hemolytic transfusion reactions.  Accordingly, these types of reactions are exceedingly rare.   However, other types of transfusion reactions are more difficult to prevent at a system level and require more direct clinical judgement to both recognize and treat.   At our ministry we have seen a rise in the number of patients impacted by transfusion associated circulatory overload (TACO).  This relatively newly recognized type of transfusion reaction was initially believed to primarily impact patients who received a large volume of transfused products over a short period of time, but we now understand that patients with certain underlying conditions can develop TACO with low volume infusions.  Early identification and intervention are crucial in minimizing harm and improving patient outcomes.  

Key Points to Remember:

1.        Recognizing patients at risk

a.        Age: patients who are 85 years old or older are at risk for developing TACO.

b.       Pre-existing disease: patients who have heart failure, renal disease, or chronic pulmonary disease are at risk for developing TACO.

2.        Vigilance is Key:

a.        Always monitor patients closely during and after a transfusion.

                                                                              i.        Vital signs should be checked at regular intervals.

                                                                            ii.        Pulse oximetry is recommended during the transfusion to assess for respiratory compromise:  Clinical symptoms of respiratory distress can be difficult to recognize in patients with pre-existing cardiovascular or pulmonary disease.

b.       Be aware of subtle changes in patient condition that may indicate a reaction.

3.        Order blood products conservatively: Consider ordering only one unit at a time and re-evaluate before transfusing more.

4.        Slow the transfusion rate:  Consider transfusing at a rate of 100 mL/hr or less for patients who are at risk. 

5.        Recognize the symptoms:

a.        Shortness of breath or wheezing

b.       Hypertension (and less commonly hypotension)

c.        Tachycardia

6.        Immediate Actions:

a.        Stop the transfusion immediately if a reaction is suspected.

b.       Maintain intravenous access with normal saline.

c.        Provide supportive care as needed (e.g., oxygen, diuretics).

d.       Notify the blood bank immediately.

e.        Order imaging to assess for pulmonary edema. 

o   Order brain natriuretic protein (BNP) or N-terminal pro-hormone BNP (NT-pro BNP).

7.        Differential diagnosis

a.        Transfusion associated acute lung injury (TRALI) - usually associated with hypotension and fever, normal BNP, doesn't respond to diuretics.

b.       Other causes of pulmonary hypertension - myocardial infarction, pulmonary embolism - imaging and serologic markers will likely be helpful.


The transfusion service is here to support you in your daily practice and to help ensure that our patients receive the safest and highest quality of care.  If you have any questions about transfusion reactions or any transfusion related questions, please reach out to the blood bank our team of caregivers and pathologists.    

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