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SAN FRANCISCO -- Critically ill patients receiving blood transfusions of 10 or more units had substantially better survival when it brought hemoglobin levels close to normal, according to a single-center study reported here.

In a retrospective analysis of 476 massively transfused patients treated over a 5-year period, each 1-g/dL increase in hemoglobin level was associated with a 22% reduction in odds of in-hospital mortality (OR 0.78, 95% CI 0.63-0.96), reported Janet Adegboye, MD, of Johns Hopkins University in Baltimore.

Half of patients whose last hemoglobin reading was less than 6 g/dL died in the hospital, she told attendees at the American Society of Anesthesiologists annual meeting.

Currently, clinicians must rely on their own judgment in determining how many units to transfuse in patients with massive blood loss, Adegboye noted -- "there are no specific guidelines for when to stop a massive transfusion protocol," she said.

Overtransfusion is a genuine risk, she added, as excessive blood input can harm patients as well as increase costs and deplete what is a chronically scarce resource.

As a starting point for developing a guideline, Adegboye and colleagues looked at patients' records at Johns Hopkins from 2018 to 2022, identifying patients who had received at least 10 units of red blood cells within a 24-hour period. Data were adjusted to account for potential confounders including patient age, sex, race/ethnicity, transfusion indication, and number of blood units transfused.

Overall in this cohort, 17% died prior to discharge, and about half experienced complications. The latter ranged from cardiovascular events and renal impairment to adverse effects from the transfusions.

Mortality varied according to the reason for massive transfusions. More than half of all patients with gastrointestinal hemorrhages died, with high hemoglobin levels offering only minor protection. Adegboye pointed out, however, that only 13 patients in the cohort had such bleeds and the high death rate was likely the product of chance.

Trauma patients and those having cardiac surgery appeared to get the most benefit from increased hemoglobin; these patients, accounting for about one-quarter of the cohort, had mortality rates in the 50% range with very low hemoglobin, but the death rate was halved when levels reached 10 g/dL or more.

General surgery patients, who were 41% of the cohort, had mortality of about 25% with hemoglobin below 6 g/dL, but it was less than 10% with levels of 10 g/dL or more. Mortality among transplant patients (one-third of the cohort) was near zero irrespective of hemoglobin level.

Adegboye said benefits seemed to diminish beyond the 10-g/dL level, but otherwise she did not suggest a specific hemoglobin target. But it was plain that levels substantially below 10 g/dL were associated with poorer survival, so transfusing enough to maintain hemoglobin close to that mark, while not exceeding it, would appear prudent.

Limitations to the study included its reliance on administrative records and its single-center design.

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