key: cord-0714153-3qpl8rbk
authors: Bottari, G.; Damiani, E.; Confalone, V.; Scorcella, C.; Casarotta, E.; Gandolfo, C.; Stoppa, F.; Cecchetti, C.; Donati, A.
title: Microvascular dysfunction in pediatric patients with SARS-COV-2 pneumonia: Report of three severe cases()()
date: 2022-01-10
journal: Microvasc Res
DOI: 10.1016/j.mvr.2022.104312
sha: 1b8830fbc3fe54ef7716c1c0f09bdd37a50bee92
doc_id: 714153
cord_uid: 3qpl8rbk

The coronavirus 19 (COVID-19) pandemic has affected hundreds of millions of people worldwide: in most of cases children and young people developed asymptomatic or pauci-symptomatic clinical pictures. However authors have showed that there are some categories of childhood more vulnerable to COVID-19 infection such as newborns or children with comorbidities. We report for the first time to the best of our knowledge about microvascular dysfunction in three pediatric clinical cases who developed COVID-19 infections with need of pediatric critical care. We found that sublingual microcirculation is altered in children with severe COVID-19 infection. Our findings confirmed most of data already observed by other authors in adult population affected by severe COVID-19 infection, but with distinct characteristics than microcirculation alterations previous observed in a clinical case of MIS-C. However we cannot establish direct correlation between microcirculation analysis and clinical or laboratory parameters in our series, by our experience we have found that sublingual microcirculation analysis allow clinicians to report directly about microcirculation dysfunction in COVID-19 patients and it could be a valuable bedside technique to monitor thrombosis complication in this population.

The coronavirus 19 pandemic has affected hundreds of millions of people worldwide so far and caused over 3 million deaths (1) . The existing evidence suggests that children generally have a milder disease course and better prognosis than adults, and deaths are extremely rare among the pediatric population (1) . Even if elevated inflammatory markers are less common in children with mild COVID-19 disease, those pediatric patients who develop severe COVID- 19 show not only a great increase in pro-inflammatory cytokines but also markers of endothelial dysfunction (2) .

COVID-19-related endothelitiis has been recently described in several organs by some authors (3) SMA has allowed the researchers to report directly about microcirculation dysfunction in COVID-19 patients (5)(6)(7) (8) showing some correlations between microvascular variables and clinical or laboratory parameters in this population.

We present the first clinical report about sublingual microcirculation analysis in three children with severe COVID-19 infection who required admission to the pediatric Intensive Care Unit (PICU).

Five videos per patients were recorded within a week from PICU admission with a single time-point assessment using handheld vital microscope based on incident dark field microscopy imaging (Braedius Medical, Huizen, The Netherlands). Three videos of the best quality were selected (9) .

Videos were analysed offline with dedicated software (Analysis Manager V2) (Braedius Medical, Huizen, The Netherlands) (10) by two independent operators (GB and VC) (11) (12) . The following parameters were calculated: De Backer score (12), total small vessel density (TVD); proportion of perfused vessels (PPV); perfused microvascular density (PVD). Semi-quantitative analysis of the J o u r n a l P r e -p r o o f Journal Pre-proof microcirculatory flow was performed as previously described by Boerma et al (13) . Each image was divided into four equal quadrants and for each one a quantification of flow was scored (no flow: 0; intermittent flow: 1; sluggish flow: 2; continuous flow: 3. MFI was determined by eye on the basis of the predominant type of flow in each quadrant and averaged over the values obtained in each one. We also calculated the heterogeneity index (HI), following the method of Trzeciak et al (14) based on MFI and PPV values. chest-X ray evidenced a basal pneumonia associated to a pleural effusion and diffuse thickening of the peri-broncovascular interstitium. He received dexamethasone (0.15 mg/kg/ day) and low molecular weight heparin 100 U/kg/bpd. Table 1 shows microvascular parameters together with ventilatory and hemodynamic variables and inflammatory biomarkers (measured at day 7). Figure 1 reports the sublingual microcirculation and chest X-ray performed at the same time point.

Microbiological workup did not evidence other positive microbiological agents responsible for infection. During the PICU-stay the patient was hemodynamically stable and received only low dose of Noradrenaline 0.03-0.06 mcg/kg/min. He was weaned from VA-ECMO at day 10 and was discharged from the PICU at day 16. He survived to hospital discharge. Need for surgery had been excluded, but 48 hours after he showed a progressive respiratory failure with progressive hypercapnia not responsive to non-invasive mechanical ventilation, therefore he required oro-tracheal intubation (PaCO2 > 65 mmHg). At day 1 blood chemistry evidenced WBC 7.84 10 3 /uL , CRP 0.74 mg/dL, D-dimers 1.77 µg/ml. Thorax chest-X ray diffuse thickening of the J o u r n a l P r e -p r o o f Journal Pre-proof peri-broncovascular interstitium. He received hyper-immune plasma 15 ml/kg for three days, dexamethasone 0.15 mg/kg/ day, remdesivir 2.5-5 mg /kg/die and low molecular weight heparin 100 U/kg bpd. Table 1 shows microvascular, ventilatory and hemodynamic parameters and the most important biomarkers of inflammation (measured at day 6). Figure 1 reports the sublingual microcirculation and chest X-ray performed at the same time point. A first attempt of weaning from mechanical ventilation was made on day 7, but it failed for progressive respiratory distress and the baby required re-intubation. We performed MRI for an hypo-reactive baby during the mechanical ventilation weaning trial: MRI evidenced thrombosis of deep medullary veins with ischemic lesions in the related distribution areas. In Figure 2 we report the MRI images reporting thrombosis of deep medullary veins in association to a second report of the sublingual microcirculation where we have observed obstructed or sluggish flow. On day 18 he was successfully extubated and he was discharged from the PICU on day 22. He survived to hospital discharge.

Recently other authors (5)(6)(7) (8) Previous evidences suggest that COVID-19 in newborn induces more severe symptoms in comparison to older children (18) . In patient 3 we observed respiratory failure with need of mechanical ventilation associated with thrombotic complications. It is relevant to underline that in this patient we found images of obstructed blood flow in small and we have observed also J o u r n a l P r e -p r o o f Journal Pre-proof thrombotic complications involving central nervous system (Figure 2) . We can suppose that there is a relationship between these findings and COVID-19 infection and this is also a plausible hypothesis if we consider previously reported data in adults of an inverse relationship between PVD and D-dimers levels (7) .

Due to the small number of patients studied, we cannot establish correlations among microvascular parameters and laboratory values or mechanical ventilation variables. Our patients had severe and moderate ARDS, an increase of D-dimers and a mild increase in ferritin levels. Even if they were hemodynamically stable and two of them received only low doses of vasopressors, they showed sublingual microvascular alterations. Other markers of endothelial damage such as Il-8 ore C3a and C5a (2) (15) could better correlate with our sublingual microcirculation analysis, but unfortunately these were not measured in our patients.

The potential harmful role of viral agents against vascular endothelium has been already reported in scientific literature: Senchenkov and others have showed that persistent CMV infection induces adhesion molecules upregulation finally responsible of leukocyte and platelets recruitment and microvascular dysfunction (19) (20) . However our patients had not evidence of CMV infections, a similiar model could be hypothesized to explain the potential mechanisms of microvascular dysfunction COVID-19 related.

Although we are aware that we cannot draw definitive conclusions, some important observations could be done based on these clinical cases. The three patients had very different severity of clinical conditions and also a different prognosis. Our experience confirms that children with comorbidity, in particular with congenital and acquired immunodeficiencies could show a higher risk of severe COVID-19 infections (21) . At present, limited evidences exist on the impact of COVID-19 in newborns, although a higher vulnerability has been described by some authors (18) . We confirmed that, in children affected by COVID-19, the sublingual TVD is normal or increased, whereas flow parameters (convective) MFI and PPV are decreased and may be correlated with the outcome. A limitation of this report is that we performed a single time point evaluation: evaluating the evolution 

Children affected by COVID 19 with need of PICU show a wide spectrum of clinical pictures. Preexisting comorbidities can impact of the clinical course of this infection which is mild in the most healthy children (21) . In children with severe COVID-19 microvascular parameters are altereted. 

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