DISCUSSION
Thoracic CT is prevalently used to determine the diagnosis, follow-up
and prognosis of COVID-19 pneumonia. As the stage of pneumonia in
COVID-19 increases, disease-related mortality
increases10,13. Different studies have reported
varying rates of pulmonary involvement14. In this
study, while the thoracic CT findings of 18 patients in Group 1 were
normal, 8 patients had Stage 2 pneumonia, and 6 had Stage 3 pneumonia.
None of the patients in this study who were diagnosed with COVID-19 had
a comorbid condition, and no mortality occurred.
In addition to parameters that explain the characteristics and severity
of lung parenchyma involvement, vascular measurements can also be
analyzed on thoracic CT images. Enlarged PA diameters on CT images were
studied as a method of screening and diagnosing PH15.
PH can develop in relation to many causes such as idiopathic, genetic,
cardiac, pulmonary, vascular and medication-related
causes16. CT is suitable for evaluating interstitial
lung disease, vascular anomalies and thromboembolic factors, which are
among the secondary causes of PH17. In this study, it
was found that the PA diameters of the pediatric children who had
COVID-19 infection on their thoracic CT images were larger. A single CT
examination in pediatric COVID-19 patients might not provide clear
information about the etiology of PA expansion. However, the demographic
characteristics of the patients and the absence of comorbid diseases
suggested that the cause of the PA expansion was an acute complication
developing secondarily to the COVID-19 infection. Still, COVID-19
pneumonia can present in the form of hypoxemia as a result of
ventilation-perfusion mismatch, increased PVR and expansion in the
diameter of PA.
The morphology of IVC is frequently used to estimate right atrial
pressure; however,the relationship between IVC morphology and RV
outcomes has not been clarified completely18. Dilated
IVC cases were found to be associated with RV dysfunction, high central
venous pressure, and high pulmonary artery pressure19.
High PVR can lead to IVC dilatation along with PH and RV deficiency.
Some studies showed that IVC dilatation was one of the early indicators
of disrupted hemodynamics in shock patients19. The
mechanism of RV dilatation is multifactorial, and it involves thrombotic
events, hypoxemic vasoconstriction, cytokines and direct viral damage.
In COVID-19 patients, RV dilatation was determined to be associated with
a poor prognosis20. In this study, the diameter of IVC
was significantly larger in the COVID-19 patients, but no significant
finding was detected about RV dilatation.
In pediatric patients, the laboratory findings of COVID-19 are
non-specific. Leukocyte and platelet counts may be normal, increased, or
decreased4,21. Severe infection is frequently
accompanied by lymphopenia22. In this study, in Group
1, 12 patients (40%) had leukopenia, and 3 (9.3%) had lymphopenia.
While the leukocyte counts in Group 2 were significantly higher, there
was no significant difference between Groups 1 and 2 in terms of the
other whole blood parameters. Likewise, in most COVID-19 patients, CRP,
ferritin, fibrinogen, D-dimer, LDH, CPK, ALT and AST levels may be found
higher in proportion to the severity of the
infection4. There was no significant difference
between the two groups in this study regarding their CRP, ferritin,
D-dimer, fibrinogen, LDH, CPK or AST values among biochemical
parameters. The finding that clinical symptoms of COVID-19 emerged in
Group 1 without a noticeable increase in acute phase reactants may be an
indicator that different immune and inflammatory mechanisms are in place
in children. Although these findings could partly explain the milder
course of COVID-19 in children than in adults, they suggested that the
mechanism is more complex. Liver damage can be seen in COVID-19
infections. The mechanisms of this damage may include direct
cholangiocyte and hepatocyte damage or accompanying conditions such as
hypoxia, sepsis and multiorgan dysfunction caused by antiviral
medication use, systemic inflammatory response and respiratory distress
syndrome23. Temporary disruptions in liver function
tests may be encountered in COVID-19 infection cases, and these might
not affect liver-related morbidity and mortality23. In
this study, the ALT levels of Group 1 were significantly higher than
those of Group 2. Anomalies in liver function tests are usually
encountered alongside increased enzyme activities in muscles and the
heart. In COVID-19 cases, myocardial injury defined by increased
troponin levels occurs especially due to hypoxia, sepsis, systemic
inflammation, pulmonary thrombosis and embolism, in addition to severe
respiratory airway infection and non-ischemic myocardial processes like
cardiac adrenergic hyperstimulation during a cytokine
storm24. In this study, the troponin I levels were
higher in Group 1 than Group 2, but the difference was not statistically
significant.There was no significant difference between the groups
regarding their D-dimer levels. Many studies have demonstrated that
increased D-dimer levels in adult COVID-19 patients are an indicator of
PTE25,26. COVID-19-related PTE cases in the pediatric
population are very rare27. This suggests that there
was no increased risk of PTE in the patients in Group 1, and their high
troponin I levels could be associated with hypoxia and systemic
inflammatory response.
Consequently, the results of this study indicated that increased
diameters of PA and IVC as a result of increased inflammation, high
vascular resistance and hypoxemia in pediatric COVID-19 patients may be
an early warning sign related to potential cardiopulmonary
complications. To propose an exact explanation on this topic, there is a
need for more comprehensive studies supported by larger datasets.