The concentration changes of β-endorphin in full-term newborns with respiratory failure

Objective To explore the role of β-endorphin (β-EP) in neonatal respiratory failure. Methods Plasma β-EP levels of 46 full-term newborns with the neonatal respiratory failure, which including 31cases as asphyxia group and 15 cases as pneumonia group, were measured by radioimmunoassay at the time of admission to the hospital, 72 hours after admission or before the death, and in recovery phase. Seventeen newborns without the respiratory failure (9 with asphyxia and 8 with pneumonia) and 20 healthy neonates were included as controls. Results Plasma β-EP levels of respiratory failure group were significantly higher than those of control group and healthy group at the time of admission to the hospital (P < 0.01) . Plasma β-EP levels were remarkably higher in the patients with severe respiratory failure (n = 29) than those with mild respiratory failure group (n =17, P < 0.01) . Plasma β-EP levels were also higher in respiratory failure newborns with the asphyxia than those in respiratory failure newborns with pneumonia. Plasma β-EP levels of the dead patients (n = 22) in respiratory failure group were significantly higher than those of the survivors (n = 24) 72 hours after the hospitalization. The concentration of plasma β-EP showed a negative correlation with pH and PaO2 ( P < 0.05) and a positive correlation with PaCO2 (P < 0.05) in the group of asphyxia newborns with the respiratory failure. Newborns with severe hypoxia (PaO2 ≤35 mm Hg) or severe acidosis (pH≤7.0) presented much higher plasma β-EP levels (P <0.05) . Conclusion β-EP may play some roles in respiratory failure of newborns. Key words: Infant, newborn; Respiratory insufficiency; Beta-endorphin