A large study published some time ago in the New England Journal of Medicine suggested that cardiac surgery patients who received older blood during surgery were almost twice as likely to die than those who received younger blood. Although studies like this are always multifactorial, considering what you pay for these surgeries you may be within your rights to inquire about the shelf life of the blood you may be receiving during your next procedure. A new study under the lead of anesthesiologist Steven Frank from the Johns Hopkins School of Medicine has just provided the means and the mechanism to back your concerns.
Using the same definition for old as the NEJM study, namely three weeks, Frank showed that red blood cells (RBCs) become significantly less flexible than in younger blood. He used a technique called ektacytometry, a mouthful of a name for a method that determines the ability of the cell to elongate when exposed to shear stress. It is not a huge leap to imagine that if cells lose the ability to deform or elongate, they may not only have trouble traversing small capillary beds — they may block them altogether. Other imaging studies have revealed just how tight these passages are. In fact the close fit may be critical to the efficiency of the oxygen release process in the first place.
Blood banks have traditionally maintained that the blood on their shelves is good for six weeks. Yet, according to Frank, it is no industry secret that the freshest blood is often highly sought after for pediatric surgeries. Those with rare blood types in particular have always shouldered slightly greater uncertainties whenever they are wheeled into the OR.
Frozen plasma or other enriched stocks do not come cheap, and refreezing is probably best avoided. The result is the inevitable time delay between the moment you need the blood, and the time by which it might be suitably warmed. Perhaps the latest findings will motivate improvements in the system to offer the freshest blood possible to all patients.
Study abstract in Anesthesia and Analgesia: Decreased Erythrocyte Deformability After Transfusion and the Effects of Erythrocyte Storage Duration
Press release: ‘SHELF LIFE’ OF BLOOD? SHORTER THAN WE THINK
Image credit: makelessnoise
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