A new study published in Anesthesiology has found that exposing red blood cells to the gas nitric oxide may reduce pulmonary hypertension associated with transfusion of red blood cells. 

Transfusions are common procedures used to replace blood cells or blood products that are lost as a result of severe bleeding following an accident, trauma, or surgery. Red blood cells are the most common transfusion as most are not whole blood transfusions. Due to the limited supply of freshly stored red blood cells, the Food and Drug Administration (FDA) allows transfusion of human red blood cells that have been stored for up to 42 days. 

Recent studies, however, have suggested that transfusion of red blood cells stored for >30 days may result in pulmonary hypertension and decreased survival of transfused red blood cells, which can result in the body’s cells not receiving sufficient oxygen. 

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For the study, red blood cells taken from lambs were stored for 40 days then treated with nitric oxide. Nitric oxide is a gas typically administered to treat term infants with pulmonary hypertension. One group of lambs received the treated red blood cells through transfusion and another group received the stored red blood cells with no nitric oxide exposure.

The data showed transfusing red blood cells without nitric oxide pre-treatment almost doubled blood vessel constriction in the lungs vs. red blood cells pre-treated with nitric oxide. The study authors concluded that pre-treatment of the stored red blood cells with nitric oxide decreases the risk of pulmonary hypertension. Treatment with nitric oxide also increased the survival of the stored red blood cells post-transfusion. Most (87%) of the cells pre-treated cells remained in circulation after 1 hr vs. the 75% of non-treated cells. After 24 hours, 78% of pre-treated cells remained in circulation vs. 73% of non-treated cells. 

More studies with transfused human-stored red blood cells are needed to confirm the beneficial effects of nitric oxide exposure, the study authors noted.

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