OBJECTIVETo completely compare the risk factors, respiratory therapies and complications between respiratory distress syndrome (RDS) and transient tachypnea of newborn (TTN) in preterm infants.

METHODData were collected from preterm infants in Department of NICU, Peking University Third Hospital from January, 2013 to December, 2013. Components of clinical variables, including perinatal risk factors, ventilation therapies, pulmonary surfactant (PS) therapy, blood gas analysis and complications, were retrospectively analyzed. χ² test or Fisher's test or t test were used.

RESULTNinety-nine preterm infants mean gestational age was (31.9 ± 2.2) weeks and birth weight was (1 661 ± 501) g . Sixty-nine infants were diagnosed with TTN and 30 were diagnosed with RDS. There were significant differences in gestational age ((29.5 ± 2.5) vs. (32.0 ± 3.2) weeks, t = 6.046, P = 0.002), birth weight ((1 115 ± 415) vs. (1 660 ± 531) g, t = 5.916, P = 0.001). Nine cases in the RDS group had Apgar score ≤ 7 while four cases in the TTN group had Apgar score ≤ 7 (P = 0.001). Fourteen cases in RDS group were born through C-section while 55 cases of TTN group were born through C-section (P = 0.025). During 0-2 hours after birth, pH (7.25 ± 0.09 vs. 7.30 ± 0.01, t = -2.144, P = 0.046) was significantly lower in the RDS group. PaO₂((55 ± 20) vs. (41 ± 2) mmHg, 1 mmHg = 0.133 kPa, t = 2.963, P = 0.001) and oxigination index (OI) ((149 ± 58) vs.(100 ± 9) mmHg, t = 3.379, P = 0.003) were significantly lower in the TTN group. In the RDS group, all cases received PS therapy. Twenty-five cases received mechanical ventilation and five cases received noninvasive ventilation. In the TTN group, 12 cases received PS therapy. Forty-four cases received noninvasive ventilation and 25 cases received oxygen inhalation. The cases developing complications, including ventilator associated pneumonia (14(46.7%) vs.4(5.8%), P = 0.038), patent ductus arteriosus (19(63.3%) vs. 9(13.0%), P = 0.025), intraventricular hemorrhage (9(30.0%) vs. 2(2.9%), P = 0.041), bronchopulmonary dysplasia (12(40.0%) vs. 5(7.2%), P = 0.019), were significantly more in the RDS group.

CONCLUSIONRDS and TTN are common causes leading to early dyspnea in preterm infants. Preterm infants with RDS are characterized by younger gestational age, lower birth weight, severer acidosis and more complications. Preterm infants with TTN show lower hypoxemia and OI.