Materials and Methods
Study Population
This retrospective study enrolled all patients aged between 1 month and
14 years of age who were diagnosed with PARDS in the PICU of Shengjing
Hospital between January 2013 and January 2020. Data were collected by
searching the Health Information System (HIS) database for the PARDS
diagnostic and clinical codes “principal diagnosis” and “all listed
diagnoses,” yielding the final list of patients included in the study.
In addition, patients’ diagnoses were confirmed from their medical
records. Patients meeting the following criteria were included: 1) age
between 1 month and 14 years; and 2) ARDS diagnosis and treatment with
invasive mechanical ventilation. ARDS was defined in accordance with the
Pediatric Acute Lung Injury Consensus Conference (PALICC) criteria
[11]. Patients meeting the following criteria were excluded: 1)
noninvasive ventilation treatment was received during the first 24 h
following ARDS diagnosis; 2) missing data for any included variables;
and 3) PICU admission lasting <24 h.
Data Collection
The following demographic and clinical data were retrospectively
collected from electronic medical records (HIS records): 1) age and sex;
2) mortality and FSS scores upon admission and at hospital discharge; 3)
data pertaining to treatment regimens following ARDS diagnosis,
including inhaled nitric oxide, neuromuscular blockers, continuous renal
replacement therapy, and extracorporeal membrane oxygenation (ECMO); 4)
measurement data for the worst peak inspiratory pressure (PIP), positive
end-expiratory pressure (PEEP), and inhaled oxygen concentration within
the first 24 h after ARDS diagnosis (collected from blood tests); and 5)
mechanical ventilation parameters. FSS scores upon admission and at
discharge were determined retrospectively based on data recorded in the
medical charts to assess and compare clinical and functional outcomes at
those time points. The initial FSS score reflected each child’s
functional status upon hospital/PICU admission with critical illness and
chronic comorbid conditions, both of which contribute to impaired
functional status. The FSS is based on symptomology scores, such as
those of the Pediatric Overall Performance Category Scale, Pediatric
Cerebral Performance Category Scale, and Glasgow Coma Scale [12]. It
comprises six domains (mental, sensory, communication, motor, feeding,
and respiratory), with domain scores ranging from 1 (normal) to 5 (very
severe dysfunction), and total scores ranging from 6–30, with scores of
6‒7, 8‒9, 10‒15, 16‒21, and >21 indicating good, mildly
abnormal, moderately abnormal, severely abnormal, and very severely
abnormal functional status, respectively [3].
Definitions
In-hospital mortality was defined as in-hospital death following PICU
admission. FSS dysfunction was defined as a change in FSS score ≥3
between baseline and discharge. PARDS severity was determined according
to the worst oxygenation index
(OI) in the first 24 h following diagnosis, according to the PALICC
categories [11]. Patients were stratified into two groups based on
severity, with an OI <16 defined as mild/moderate PARDS and an
OI ≥16 as severe PARDS. The partial pressure of arterial oxygen
(PaO2)/fraction of inspired oxygen
(FiO2) (P/F) ratio was based on the Berlin definition
issued by the European Society of Critical Care Medicine, where severity
was graded as follows: mild/moderate, P/F >100, and severe,
P/F ≤100 [13]. The Pediatric Logistic Organ Dysfunction-2 (PELOD-2)
score was used to assess disease criticality in all patients upon
admission [14]. The neuromuscular blocking agents used included
rocuronium and vecuronium. Hemopurification refers to continuous renal
replacement therapy. Direct and indirect PARDS were defined as ARDS
caused by pneumonia, aspiration, or lung contusion and ARDS caused by
non-pulmonary sepsis, leukemia, or pancreatitis, respectively.
Statistical Analysis
Categorical and continuous variables are presented as counts
(percentages) and medians (interquartile ranges [IQRs]),
respectively. Logistic regression analyses were conducted to evaluate
the relationships between patient characteristics and PARDS outcomes.
Any variables with a P <0.2 in the univariate logistic
regression analysis were included in a subsequent multivariate logistic
regression analysis. Survival curves were generated to analyze the
survival outcomes of the direct and indirect PARDS groups. The log-rank
test was utilized to compare the survival curves between the two groups.
Statistical analyses were performed using Stata software (v13.0;
StataCorp, College Station, TX, USA). Statistical significance was
defined as P <0.05 (two-tailed test).
Ethical Approval
Statement
All procedures were conducted in accordance with the ethical standards
of the responsible committees on human experimentation, both
institutional and national, and conformed with the 1975 principles of
the Helsinki Declaration, as revised in 2008. This study was approved by
the Institute of Research Medical Ethics Committee of Shengjing Hospital
(approval number: 2022PS489K). As this was a retrospective study, the
requirement for informed consent was waived.