Methods
This is a retrospective case
control study of preterm newborns with MAS admitted to the NICU of
Children’s Hospital of Chongqing Medical University, between Jan 1, 2010
and Jan 1, 2020. Preterm infants
born through MSAF grade Ⅲ and need mechanical ventilation support due to
respiratory distress onset within first 24 hours of life were included.
Preterm neonates with no need of ventilator support or/and with
incomplete data were excluded.
Data from electronic medical records were procured, and were recorded
using a standardized form: 1)maternal information (gestational age,
delivery mode, disorders complicating pregnancy, antenatal steroid
therapy); 2)neonatal data (weight, gender, 1-min and 5-min Apgar score,
required resuscitation, duration of hospitalization, outcome);
3)treatment and complications (mechanical ventilation, persistent
pulmonary hypertension, neonatal sepsis, shock, necrotizing
enterocolitis, pneumothorax, pulmonary hemorrhage, intracranial
hemorrhage, myocardial injury, renal dysfunction, anemia, hypoglycemia).
MAS was defined as respiratory distress in an infant born through MSAF
whose symptoms cannot be otherwise explained [1].
Persistent pulmonary hypertension of the newborn (PPHN) was defined as
elevated pulmonary vascular resistance and right-to-left shunting at the
ductus arteriosus based on echocardiography[11].
Pulmonary hemorrhage was defined as a nontraumatic gush of bloody
secretion from the endotracheal tube associated with clinical
deterioration as well as requiring increased ventilatory
support[12]. Intracranial hemorrhage was depended
on imaging manifestations, including intraventricular hemorrhage and
intraparenchymal hemorrhage. Arterial blood gas analysis was done at the
time of admission to the NICU. This study was approved by the Ethics
Committee of the Children’s Hospital of Chongqing Medical University
(No: 2020-09).
Data analysis was performed using SPSS version 26 (IBM Corp., Armonk,
NY, USA). Chi-square test or Fisher’s exact test were used to analyze
categorical variables, as appropriate, and T- Student test or
Mann–Whitney U test were used to analyze continuous variables, as
appropriate. Categorical variables were expressed as
number of cases and percentages
while continuous variables were expressed as mean ± standard deviation
(SD) or median (range). A p value
below 0.05 was considered as statistically significant. Variables that
were statistically significant in the univariate analysis were entered
into the logistic regression analysis to identify risk factors for
mortality of MAS in preterm infants.