(P-TS-71) Intraoperative Hypotensive Transfusion Reaction and the Administration of Methylene Blue: A Case Report

Background/Case Studies: Acute hypotensive transfusion reactions (AHTR) are rare transfusion reactions. There is a known association of hypotensive transfusion reactions occurring in patients who regularly take Angiotensin Converting Enzyme (ACE) inhibitors. This association is thought to be due to the increase in bradykinin and therefore the downstream activation of nitric oxide, resulting in vasodilation and decreased blood pressure. Typically, hypotensive transfusion reactions are non-severe and do not require specific treatment or prevention. In more severe cases, transfusion cessation and supportive care are recommended. According to previous case reports, the use of Methylene Blue for treating severe hypotension has been administered to patients experiencing vasoplegia and hypotensive shock, unrelated to transfusions. The mechanism of action is thought to be due to its inhibition of guanylate cyclase and prevention of accumulation of cyclic guanosinemonophosphate(cGMP), which are vasodilatory enzymes that are activated by nitric oxide.

Study

Design/Methods: The patient in this case is a 74-year-old female, on long term lisinopril for hypertension, who was undergoing a L5-S1 laminectomy with arthrodesis for spinal stenosis and radiculopathy. Approximately 4 hours into surgery, after the patient’s hemoglobin had dropped to 6.6 due to blood loss, a transfusion of one unit of packed red blood cells was then started and the patient’s blood pressure dropped from 130/80 to 50/30 within minutes. The transfusion was stopped and multiple vasopressors and IV fluids were required to stabilize the patient. After multiple failed attempts at transfusion which resulted in hypotension, the patient’s hemoglobin became undetectable.

Results/Findings: Due to the urgent need for a blood transfusion, 15mg of methylene blue was administered concurrently with a unit of red cells, followed by two additional doses prior to post-op. The patient’s blood pressure was stabilized, the transfusion was successful, the vasopressors were decreased, and the surgery was able to be completed.

Conclusions: After performing a literature search, the use of Methylene Blue as an emergent treatment of outpatient and intraoperative hypotension has been described in previous case reports, however, this case is the first to document the use of Methylene Blue in relation to hypotensive transfusion reactions. This is a novel use of Methylene Blue as a potentially effective therapy in treating a patient with life-threatening hypotension due to a blood transfusion, where a blood transfusion cannot be postponed.