Mean platelet volume and risk of BPD and IVH in extremely preterm infants

Mean platelet volume (MPV) is an important risk factor for cardiovascular disease and is considered an indicator of platelet function: larger platelets are more reactive and associated with a shortened bleeding time. MPV has been poorly investigated in preterm infants and only few studies are available which showed that MPV can be similar or lower in preterm than in term infants. In addition, low MPV is associated with more frequent oxygen therapy or need for mechanical ventilation at 48 hours of life and pH<7.20 at umbilical blood gas analysis in preterm infants from mothers with abnormal blood flow velocity in uterine arteries. Furthermore, MPV is higher in preterm infants with respiratory distress syndrome (RDS) than in controls. Therefore, high MPV could represent a risk factor for the development of bronchopulmonary dysplasia (BPD) in preterm infants by two different mechanisms: (a) more frequent need for mechanical ventilation, and (b) pathological deposition of fibrin in the lung microcirculation and alveolar spaces of preterm infants with severe RDS through activation of the coagulation system and/or concomitant insufficient fibrinolysis. Moreover, coagulation and platelet function might be involved in the pathogenesis of intraventricular hemorrhage (IVH).
On these bases, an Italian group has performed a retrospective study to assess the possible correlation between MPV and the occurrence of BPD and IVH in a cohort of extremely preterm infants (gestational age <30 weeks). Enrolled infants were divided into BPD and no-BPD groups and IVH and no-IVH groups. MPV was evaluated at birth and at 24 to 48 hours of life.
MPV measured at birth was similar in BPD and no-BPD groups, but at 24 to 48 hours of life it was higher in the BPD than in the no-BPD group (11.1±0.9 versus 10.8±0.9 fL, p=0.033). Multivariate analysis showed that MPV >11 fL is an independent factor increasing the risk of developing BPD (relative risk 1.40, 95% confidence interval: 1.08-1.80). MPV was similar in infants with or without IVH.
In conclusion, this study suggests that a high MPV value at 24 to 48 hours of life is an independent risk factor for the development of BPD in extremely preterm infants. This may occur because larger platelets can induce a worsening of RDS and consequent inflammatory and oxidative lung damage due to the greater need for mechanical ventilation and oxygen therapy. On the other hand, these data indicate that MPV is not associated with the development of IVH.

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