Strengths and Limitations
To our best knowledge, this was the first study to develop initial fluid
treatment with HbV infusion for severe PPH. The resuscitative benefit of
HbV treatment in the initial hours led to maintenance of normal lactate
levels that in turn resulted in adequate oxygen supply. This indicates
that prompt HbV infusion might help stabilise the haemodynamics and
enable transport to secondary or tertiary facilities.
Our findings should be interpreted with caution in the context of the
principal limitations of the current study. First, the efficacy of HbVs
for severe PPH was evaluated in an animal model, and thus the
applicability of the findings in humans need to be further verified.
Second, this study did not investigate the long-term safety of HbVs
beyond the acute setting. Third, we did not precisely investigate the
effects of HbVs on the foetus, including intrauterine resuscitation in
this study. A previous study reported the efficacy of HbVs for chronic
placental hypoxia and improvement of foetal growth restriction in a rat
pre-eclampsia model36. However, there are no reports
on the efficacy of intrauterine resuscitation of foetuses for low
uteroplacental blood flow due to acute massive peripartum haemorrhage,
including placental abruption. In this study, the HbV group showed
dilutional coagulopathy due to lack of coagulation factors. Methods for
controlling coagulopathy using other blood substitutes with haemostatic
capacity, including PLT substitutes,23 should be
further investigated.
Furthermore, this study had methodological limitations. Measurement of
systemic NOx levels did not always reflect NO metabolism
at the cellular levels. Further studies are needed to validate our
findings and ultimately establish the use of HbVs for severe PPH in
clinical practice.