RESUMEN
There are two recently completed large randomized clinical trials of blood transfusions in the preterm infants most at risk of requiring them. Liberal and restrictive strategies were compared with composite primary outcome measures of death and neurodevelopmental impairment. Infants managed under restrictive guidelines fared no worse in regard to mortality and neurodevelopment in early life. The studies had remarkably similar demographics and used similar transfusion guidelines. In both, there were fewer transfusions in the restrictive arm. Nevertheless, there were large differences between the studies in regard to transfusion exposure with almost 3 times the number of transfusions per participant in the transfusion of prematures (TOP) study. Associated with this, there were differences between the studies in various outcomes. For example, the combined primary outcome of death or neurodevelopmental impairment was more likely to occur in the TOP study and the mortality rate itself was considerably higher. Whilst the reasons for these differences are likely multifactorial, it does raise the question as to whether they could be related to the transfusions themselves? Clearly, every effort should be made to reduce exposure to transfusions and this was more successful in the Effects of Transfusion Thresholds on Neurocognitive Outcomes (ETTNO) study. In this review, we look at factors which may explain these transfusion differences and the differences in outcomes, in particular neurodevelopment at age 2 years. In choosing which guidelines to follow, centers using liberal guidelines should be encouraged to adopt more restrictive ones. However, should centers with more restrictive guidelines change to ones similar to those in the studies? The evidence for this is less compelling, particularly given the wide range of transfusion exposure between studies. Individual centers already using restrictive guidelines should assess the validity of the findings in light of their own transfusion experience. In addition, it should be remembered that the study guidelines were pragmatic and acceptable to a large number of centers. The major focus in these guidelines was on hemoglobin levels which do not necessarily reflect tissue oxygenation. Other factors such as the level of erythropoiesis should also be taken into account before deciding whether to transfuse.
RESUMEN
OBJECTIVE: The only guidance in the literature on which tidal volumes to use when ventilating babies with, or at high risk of, bronchopulmonary dysplasia (BPD) suggests using very large volume breaths of around 8-12 mL/kg and low rates (10-20 breaths per min) to achieve adequate gas exchange, whilst acknowledging there are no data to validate these strategies. The aim of this retrospective, observational, cohort study was to identify the mechanical ventilation settings that are used, and what carbon dioxide (CO2) levels were achieved, in neonates with ventilator-dependant evolving BPD. METHODS: This retrospective cohort study included neonates born <30 weeks GA admitted to the Grantley Stable Neonatal Unit between May 2014 and December 2018. Included ventilator-dependant neonates with evolving BPD ventilated on either or all days 28, 42 and 56 of life. RESULTS: A total of 105 neonates were included, all were between 23 and 28.5 weeks GA. The median (IQR) GA was 25.1 (24.2-26.5) weeks and BW 708 (608-809) grams. Neonates who required conventional mechanical ventilation (CMV) at each of the three time-points had median tidal volumes ranging between 4.5 and 4.7 mL/kg, median ventilator rates of 35-50 and MAPs of 10-11 cmH2O. For those neonates requiring HFOV, median MAPs ranged from 14 to 18 cmH2O and tidal volumes from 1.4 to 2.2 mL/kg to achieve adequate ventilation and oxygenation. CONCLUSIONS: Neonates with ventilator-dependant evolving BPD were ventilated either with CMV using tidal volumes of around 4-5 mL/kg, or HFOV using tidal volumes around 1-2 mL/kg, which achieves adequate ventilation and blood gas results.