Materials and Methods
This prospective observational study was conducted between January 2022
and December 2022 in a 61-bed NICU. The ethical approval was obtained
from the ethics board of the hospital. The written informed consent was
obtained from the parents of each participant before lung USG.
Newborns who were hospitalized in the NICU during the study period and
treated with HFOV for any cause (as primary or rescue therapy) and for
whom parental consent was obtained were included in the study. The study
did not include those without parental consent and those with chest
deformities, congenital lung malformation, or diaphragmatic pathology.
Weeks of gestation, birth weights, and postnatal ages of the patients
were recorded.
The patients were followed on HFOV using Leoni Plus devices (Courtesy of
Löwenstein Medical Technology, Bad Ems, Germany). Generally CXR is
obtained to assess lung aeration after mechanical ventilator adjustments
in accordance with procedures.
Lung USG was performed right before CXR, using pre-warmed gel on the
linear probe (13 MHz) of a portable ultrasonography device (Esaote,
Mylab Seven, 201236) while the baby was in the supine position within
the incubator. The linear probe was placed in the longitudinal plane on
the right mid-clavicular line, and the ribs were counted by advancing in
the craniocaudal axis without lifting the probe from the chest until the
right hemidiaphragm was observed (Picture 1). In order to avoid
alterations in lung mechanics due to positional changes, we evaluated
the ribs on anterior aspect. Each patient had a single measurement.
Throughout the examination, the optimal blood oxygenation and body
temperature are maintained.
To minimize variability, all USG measurements were performed by a single
neonatologist who had received two weeks of training from a radiologist
on the use of the equipment and anatomical landmarks of the chest before
the onset of the study.
CXR was performed in an anterior-posterior position immediately after
lung USG using a portable X-ray device (Siemens, Mobilet Miramax, 3638,
1015544537) by the radiology technician. The CXR image, which had been
digitized in the hospital system, was examined by another neonatologist
who was blinded to the thorax USG findings. To assess lung aeration, the
posterior costae in the right hemithorax were counted in the
craniocaudal direction, until the level of the hemidiaphragm and
recorded. The localization of the posterior part of the right diaphragm
positioned at the level of the 9th costa was
considered as the landmark for optimal lung expansion during HFOV[8]. Following validation with CXR, which is still
regarded as the gold standard, corrective steps for HFOV were performed.