23/06/2005
Surfactant administration combined with nCPAP reduces the need for mechanical ventilation
A Swedish study on preterm rabbits indicates the beneficial effects of spontaneous breathing with early nCPAP instead of prolonged intubation.

In newborn babies with respiratory distress syndrome (RDS), exogenous surfactant is administered into the airways through intubation, which implies mechanical ventilation.
Due to the effects of mechanical ventilation which are known to be detrimental on the immature lung, alternative treatment approaches are needed.

It was clinically observed that with the administration of exogenous surfactant during a short intubation, followed by immediate extubation to spontaneous breathing with early nasal continuous positive airway pressure (nCPAP) the need for mechanical ventilation is reduced in preterm babies with RDS. Early nCPAP has in fact shown to be beneficial as initial treatment of RDS also in very low birth weight infants.

This treatment approach showed that repeated doses of surfactant are rarely required to reverse the clinical course of RDS. On the basis of these observations a Swedish study hypothesized that initial treatment response to exogenous surfactant therapy could be better and more sustained if infants were allowed to breathe spontaneously after receiving surfactant instead of being subjected to prolonged mechanical ventilation.

A series of experiments based on a rabbit model was designed to test whether treatment response patterns, including tissue association, function and inactivation of exogenous surfactant in the first 4h of postnatal life would differ after spontaneous breathing or mechanical ventilation.

The experiments were performed on 54 preterm rabbits at a gestional age of 28.5 d (term 31). The treatment administered was 200mg/kg radiolabeled surfactant (14C-Curosurf) and the rabbits were randomised to 4 h of spontaneous breathing or mechanical ventilation or to a control group.

The study showed that the dynamic lung-thorax compliance was higher in spontaneously breathing compared with mechanically ventilated animals and that the relative distribution of 14C-Curosurf in Broncho Alveolar Lavage (BAL) fluid and in lung tissue has a greater tissue association in the spontaneously breathing animals. In the mechanical ventilated animals a higher degree of lipid peroxidation and fewer microbubbles in BAL fluid was observed.

The study concluded that the initial lung tissue association of exogenous surfactant is impaired by mechanical ventilation compared with spontaneous breathing. This is associated with a lower dynamic compliance and evidence of surfactant inactivation. Spontaneous breathing seems to allow the exogenous surfactant to enter more effectively the metabolic pathways of endogenous surfactant and therefore reducing the need for repeated dosing. This study supports the growing evidence of the beneficial effects of surfactant treatment combined with early nCPAP in preterm infants.

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