Acquired cytomegalovirus infection and blood transfusion in preterm infants

Assessment of synthetic red cell therapy for extremely preterm ovine fetuses maintained on an artificial placenta life-support platform

BACKGROUND

Artificial placenta therapy (APT) is an experimental care strategy for extremely preterm infants born at 21-24 weeks' gestation. In our previous studies, blood taken from the maternal ewe was used as the basis of priming solutions for the artificial placenta circuit. However, the use of maternal blood as a priming solution is accompanied by several challenges. We explored the use of synthetic red cells (hemoglobin vesicles; HbV) as the basis of a priming solution for APT used to manage extremely early preterm ovine fetuses.

METHODS

Six ewes with singleton pregnancies at 95 d gestation (term = 150 d) were adapted to APT and maintained with constant monitoring of key vital parameters. The target maintenance period was 72 h in duration. A synthetic red cell solution consisting of HbV, sheep albumin and electrolytes was used as priming solutions for the APT circuit. Fetuses were evaluated on gross appearance, physiological parameters and bleeding after euthanasia.

RESULTS

Two out of six APT fetuses were successfully maintained for the targeted 72 h experimental period with controllable anemia (>10 g/dl) and methemoglobinemia (<10%) using an infusion of blood transfusion and nitroglycerin delivered >1 h after APT commencement, a sufficient period of time to cross-match blood products and screen for viral agents of concern.

CONCLUSIONS

Extremely preterm sheep fetuses were maintained for a period of up to 72 h using APT in combination with circuit priming using a synthetic red cell (HbV) preparation. Although significant further refinements are required, these findings demonstrated the potential clinical utility of synthetic blood products in the eventual clinical translation of artificial placenta technology to support extremely preterm infants.

Transfusion-transmitted CMV infection - current knowledge and future perspectives

Transmission of human cytomegalovirus (CMV) via transfusion (TT-CMV) may still occur and remains a challenge in the treatment of immunocompromised CMV-seronegative patients, e.g. after stem cell transplantation, and for low birthweight infants. Measures to reduce the risk of TT-CMV have been evaluated in clinical studies, including leucocyte depletion of cellular blood products and/or the selection of CMV-IgG-negative donations. Studies in large blood donor cohorts indicate that donations from newly CMV-IgG-positive donors should bear the highest risk for transmitting CMV infections because they contain the highest levels of CMV-DNA, and early CMV antibodies cannot neutralise CMV. Based on this knowledge, rational strategies to reduce the residual risk of TT-CMV using leucoreduced blood products could be designed. However, there is a lack of evidence that CMV is still transmitted by transfusion of leucoreduced units. In low birthweight infants, most (if not all) CMV infections are caused by breast milk feeding or congenital transmission rather than by transfusion of leucoreduced blood products. For other patients at risk, no definitive data exist about the relative importance of alternative transmission routes of CMV compared to blood transfusion. As a result, only the conduction of well-designed studies addressing strategies to prevent TT-CMV and the thorough examination of presumed cases of TT-CMV will achieve guidance for the best transfusion regimen in patients at risk.

Cytomegalovirus infection in neonates following exchange transfusion

OBJECTIVES

This study was undertaken to ascertain the acquisition of cytomegalovirus infection following exchange transfusion and factors affecting such transmission in newborn infants at a tertiary care hospital in India.

METHODS

Neonates undergoing double volume exchange transfusion (for any indication) with whole blood in the Neonatal Intensive Care Unit were enrolled over a 8 month period. Serum samples from the infant were collected for CMV serology before exchange transfusion, and at 6 and 12 weeks following the exchange. CMV serology was also conducted on samples obtained from the respective maternal and donor blood.

RESULTS

Of 47 neonates who received exchange transfusion during the study period; only 26 (55.3%) neonates were finally followed up till 12 weeks of age. Only 3 (11.5%) children demonstrated CMV seroconversion during follow-up; all were low birth weight and small for gestational age. None of them demonstrated any clinical, hematological, biochemical, or radiological signs suggestive of perinatal CMV infection either at birth or during the course of follow-up.

CONCLUSION

Exchange transfusion in neonates can result in perinatal transmission of CMV infection in low birth weight neonates. Such transmission does not result in any immediate manifestations. Data are not sufficient to warrant routine CMV screening of donor blood for exchange transfusion in our setting.

Effectiveness of WBC reduction in neonates: what is the evidence of benefit?

BACKGROUND

The presence of WBCs in RBCs is thought to be associated with a number of significant adverse effects in recipients. In adults, WBC reduction has been shown to reduce the frequency of HLA alloimmunization, CMV and HTLV infections, and febrile nonhemolytic transfusion reactions. However, neonates are unique, given that they have an immature immune system and are frequently transfused with RBCs. Thus, the aims of this systematic review were to determine whether WBC reduction of RBCs transfused to neonates decreases the transmission of CMV, reduces the ability to develop HLA antibodies, or reduces the risk of immunomodulation. In addition, nosocomial infection, mortality, and duration of stay were identified and analyzed.

STUDY DESIGN AND METHODS

All studies of WBC reduction were identified by a systematic review of the literature. Studies meeting the inclusion criteria were grouped based on study outcome. Where appropriate, studies were pooled to obtain an overall measure of effect.

RESULTS

Nine eligible studies were identified from the systematic literature search, and six were deemed evaluable. Two studies evaluated WBC reduction and the development of CMV, with different results. The pooled OR was 0.19 (95% Cl, 0.01-3.41), suggesting a clinical but nonsignificant effect. Two studies evaluated WBC reduction and HLA antibody development. As with CMV, the two studies were not congruent in their results. The pooled OR was 0.17 (95% Cl, 0.01-2.43). As for immunomodulation, two small studies presented evidence of a statistically significant change in lymphocyte subsets. No studies were identified with a primary objective of evaluating the impact of WBC reduction on nosocomial infection, mortality, or duration of stay.

CONCLUSION

Current evidence suggests that WBC reduction may be effective in neonates; however, further studies are needed. The lack of convincing data and the significant cost of WBC reduction mandate evaluations to determine the clinical and economic impact.