Definition of respiratory support need
Respiratory need in our study includes hood oxygen support, CPAP,
mechanical ventilation(MV) and pulmonary surfactant(PS). In this study,
we defined ”hood oxygen support need” as over 6-hour support after birth
that still can not relief infants’ respiratory difficulty. Different
from temperary usage, this prolonged hood oxygen support is high likely
a harbinger of severe TTN, RDS or other lung diseases according to our
experience. As our policy, pure oxygen with pressure of 6 cm H2O was
lead into a hood covered the head of infants completely, so it mixed
with air and provide him/her oxygen of approxmate 30% oxygen with
atmospheric pressure. The CPAP applied when hood oxygen support can not
stabilize infants’ oxygen saturation, or severe lung diseases were
confirmed by chest X-ray. The CPAP using a mask with a starting pressure
of about 6-8 cm H2O and positive end-expiratory pressure (PEEP) was
individualized depending on clinical condition, oxygenation and
perfusion. MV was used in infants with RDS or when other methods of
respiratory support have failed. Pulmonary surfactant use depends on a
combination of clinical evidence(e.g. FiO2 to maintain normal
saturations, work of breathing) and appearance on chest X-ray. Usually,
FiO2 >0.30 in infants on CPAP is regarded as a
threshold22. All infants received respiratory support
were confirmed with certain lung diseases later, and the diagnosis was
made according to integrating evidence of prenatal and postnatal
clinical data (such as GA, inflammatory markers, microbiological test
results, and physical examination findings) and X-ray
inspection(RDS22-23,TTN24,
pneumonia23, MAS25).
Statistical Analysis
Data were tested for normality with Kolmogorov-Smirnov test and
expressed as mean (standard deviation) or median (interquartile range)
as appropriate. Receiver operating characteristic (ROC) analysis was
used to evaluate the reliability of the LUS to predict all kinds of
respiratory support need(comprehensively and respectively). Areas under
the curves (AUCs) and cutoff values showing the highest sensitivity were
reported. The AUCs were compared using the method by Hanley and
McNeil26 .p< .05 was considered
statistically significant. Analyses were performed using SPSS version
15.0 (SPSS Inc) and MedCalc version 13.3 (MedCalc bvba) statistical
software.