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Alternative transfusion policy feasible for unknown blood types in emergency setting
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Patients with an unknown blood type could receive O Rhesus D–positive blood cell concentrates in urgent red blood cell transfusions, according to a prospective, single-center, observational study.
This transfusion policy demonstrated a low risk for inducing anti-D alloimmunization, while saving 10% of total demand of O Rhesus D–negative red blood cell concentrates.
The blood group O Rhesus D–negative can universally donate to other blood groups; however, providing ABO–negative and Rhesus-specific red blood cell concentrates to patients in the ED with massive bleeding is not always feasible.
As a result, common practice for those who require emergency transfusion includes transfusion with four to six O Rhesus D–positive red blood cell concentrates until the blood group has been determined.
“Only 6% to 8% of the blood donor population have the blood group O Rhesus D–negative, whereas most (emergency) patients are Rhesus D–positive (roughly 85%),” Kathleen Selleng, MD, from the department of immunology and transfusion medicine at University Medicine Greifswald in Germany, and colleagues wrote. “The use of O Rhesus D–negative red blood cell concentrates as universal blood, therefore, leads to an over proportionately high consumption of O Rhesus D–negative red blood cell concentrates and, consequently, increases the risk for shortages.”
The researchers hypothesized an alternative transfusion policy — which included the use of O Rhesus D–positive red blood cell concentrates for emergency transfusion of patients with unknown blood type — could reduce possible shortages of O Rhesus D–negative red blood cell concentrates and the risk for anti-D alloimmunization in the overall Rhesus D–negative population.
Selleng and colleagues evaluated 437 consecutive emergency patients (median age, 68 years) with an unknown blood type who received 2,836 O Rhesus D–positive red blood cell concentrates due to shortage of Rhesus D–negative red blood cell concentrates over a 15-year period.
Development of anti-D antibodies at 2 months of follow-up or later served as the primary endpoint.
Researchers later identified 85 patients (20%) as Rhesus D–negative.
Seventeen patients (4%; 95% CI, 2.44–6.14) developed anti-D antibodies, assuming all patients lost to follow-up developed anti-D alloimmunization.
During the 15-year follow-up, 110 patients with known Rhesus D–negative blood type received 1,279 Rhesus D–positive red blood cell concentrates outside of the ED, usually during elective surgery in times of Rhesus D–negative red blood cell concentrate shortages. Twenty-nine of these patients developed anti-D alloimmunization, which represented a significantly greater rate than that observed among emergency patients with unknown blood type (26% vs. 4%; OR = 8.85; 95% CI, 4.45–17.72).
Selleng and colleagues noted this policy should be considered for transfusion guidelines.
“As such, the need to transfuse Rhesus D–positive red blood cell concentrates to patients with known Rhesus D–negative blood type, in whom the risk for inducing anti-D production is much higher (20%–30%) will be reduced,” they wrote. “In medical systems with shortages of Rhesus D–negative red blood cell concentrates, transfusing all patients with unknown blood type who require urgent red blood cell transfusions with O Rhesus D–positive red blood cell concentrates, therefore, reduces the overall risk to induce anti-D alloimmunization in the population.” – by Kristie L. Kahl
Disclosure: Selleng reports personal fees and nonfinancial support from CSL Behring; grants, personal fees and nonfinancial support from Janssen Cilag; and nonfinancial support from Novo Nordisk and Bayer Vital. Please see the full study for a list of all other researchers’ relevant financial disclosures.
Perspective
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Jed B. Gorlin
This study nicely documents the safety of using O Rhesus D–positive units during emergency transfusions for men or women beyond child-bearing age. It further quantifies the savings of O Rhesus D–negative units for patients who truly need them by limiting their use. Many institutions previously provided only group O-negative red blood cell concentrates in the event of emergency transfusion prior to availability of type-specific units, which require patient typing and transport from a centralized storage site, typically the hospital transfusion service.
Selleng and colleagues reviewed data from a 15-year span in their trauma center, evaluating all cases in which Rhesus D–positive units were sent to Rhesus D–negative recipients, and assessed for Rhesus D alloimmunization in their records. The analysis included 437 patients who received emergency transfusions. These patients — of whom 85 (20%) were Rhesus D–negative — received 2,836 Rhesus D–positive red blood cell concentrates. Up to 4% developed documented anti-D alloimmunization.
During this same period, 110 Rhesus D–negative patients received Rhesus D–positive units after a decision to switch was made due to low supplies of Rhesus D–negative concentrates. Of these, 29% developed anti-D alloimmunization. This policy increased supply of O-negative units by decreasing demand on O-neg supply by 10%, a significant change for their inventory.
Although documenting the lower-than-published rate of anti-D formation and confirming the relative safety of this policy for patients without child-bearing potential, this has long been common practice in many large trauma centers. Indeed, this practice was nicely summarized in a paper by Schmidt and colleagues published in 1988.
A similar review from Maryland Shock Trauma hospital transfusion service nicely documented these same findings in 2008. My own level one trauma center has been following this policy for years with the observation that a majority of massive transfusions — especially those related to trauma — occur in males. This has allowed us to stock two or three group O Rhesus D–negative units at each of 14 different air ambulance sites, a great benefit to the community.
In short, this paper confirms the practice that has largely been in place at many centers. Ironically, the switch to greater computerization has made this policy difficult to implement at many smaller centers. Laboratory information systems often do not allow dispensing of Rhesus D–positive units to patients who are Rhesus D–negative or whose type is unknown, and some sort of work around is required.
References:
Murthi SB, et al. Expert Rev Hematol. 2008;doi:10.1586/17474086.1.1.99.
Schmidt PJ, et al. Surg Gynecol Obstet. 1988;167:229-233.
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