DISCUSSION:
Hemothorax is defined as a pleural fluid with a hematocrit level greater
than 50% of the patient’s blood. It is a clinical entity caused in most
cases by trauma or iatrogenic causes through procedures such as pleural
biopsies or central line insertion (3).
Spontaneous hemothorax (SH) involves the accumulation of blood within
the pleural space in the absence of trauma or iatrogenic causes(3). It
is extremely rare in the pediatric population with data limited to few
case reports (4).
Spontaneous hemothorax etiologies in children include connective tissue
disease, neoplasia, arteriovenous malformations, multiple exostosis and
coagulopathy (3).
Approximately 20%-50% of hospitalized patients with COVID-19 have
hematologic changes in coagulation tests (1).
Coagulopathy in Covid 19 infection is associated rather with
thromboembolic events than bleeding tendency.
The pathogenesis of SARS-CoV-2-induced coagulopathy is not yet fully
understood. It has been proven that the SARS-CoV-2 enters the host via
the angiotensin converting enzyme receptor 2, which is expressed in
cells including endothelial cells (5).
Recent evidence showed that the virus can induce endothelial activation
directly or by an immune-mediated mechanism in the presence of a locally
dysregulated inflammation. Activated endothelial cells release high
numbers of ultra large von Willebrand factor (vWF) multimers. Under
normal circumstances, vWF flows in intact vessels together with
platelets and erythrocytes without binding to any blood element.
Elevated microcirculatory shear stress due to endothelial cell
dysfunction leads the unfolding of vWF from a globular structure to an
extended chain structure exposing its binding sites. Long strands of vWF
multimers becoming functionally active. It has been proven that a
functional imbalance in vWF multimer sizes can lead to either
microcirculation bleeding or thrombosis (5).
While a meta-analysis comprising 28,173 patients with COVID-19 estimated
an in-hospital prevalence of venous thromboembolism of 14.1% (6),
Researchers reported a case of spontaneous retroperitoneal hematoma in a
47-year-old woman with a COVID-19 concurrent infection. She had no
medical priors and was not taking any medication(7).
Others reported 6 cases of abdominal bleeding associated with COVID-19
infection. Five of them used low/medium dosage heparin while the sixth
took a high dose for pulmonary embolism. Laboratory investigations
showed a normal PTT and PT, excluding a possible adverse effect from
anticoagulant therapy (8).
In addition, 2 cases of massive intracranial hemorrhage have been
reported in patients being treated with VV-ECMO for COVID-19, with
normal PTT and in the absence of other risk factors that could predict
such complication(9). Patients with chronic kidney disease (CKD) have a
paradoxical hemostatic potential with increased rates of bleeding
associated with a higher risk of thromboembolic events. Bleeding events
have been reported in 24–50% of patients on HD (10). Increased
bleeding is essentially due to platelet dysfunction and alterations in
the coagulation cascade with deranged vWF and platelet interactions
(10).
CKD was the major risk factor of bleeding in our patient. In the absence
other relevant findings, we concluded that the spontaneous hemothorax
was due to the covid 19 vasculopathy probably by rupture of small chest
wall vessels in a predisposed pediatric patient.