Point-of-care lung ultrasound predicts hyperferritinemia and hospitalization, but not elevated troponin in SARS-CoV-2 viral pneumonitis in children

Abstract

SARS-CoV-2 often causes viral pneumonitis, hyperferritinemia, elevations in D-dimer, lactate dehydrogenase (LDH), transaminases, troponin, CRP, and other inflammatory markers. Lung ultrasound is increasingly used to diagnose and stratify viral pneumonitis severity. We retrospectively reviewed 427 visits in patients aged 14 days to 21 years who had had a point-of-care lung ultrasound in our pediatric emergency department from 30/November/2019 to 14/August/2021. Lung ultrasounds were categorized using a 6-point ordinal scale. Lung ultrasound abnormalities predicted increased hospitalization with a threshold effect. Increasingly abnormal laboratory values were associated with decreased discharge from the ED and increased admission to the ward and ICU. Among patients SARS-CoV-2 positive patients ferritin, LDH, and transaminases, but not CRP or troponin were significantly associated with abnormalities on lung ultrasound and also with threshold effects. This effect was not demonstrated in SARS-CoV-2 negative patients. D-Dimer, CRP, and troponin were sometimes elevated even when the lung ultrasound was normal.

Figure 1

Representative sample of images for each category.

Figure 2

The predicted probability of admission is calculated from the logistic regression model estimating the relationship between the severity of lung ultrasound findings and hospital admission at different triage categories. The whiskers represent 95% confidence intervals. The left panel includes only those patients with a positive SARS-CoV-2 nasal or nasopharyngeal test. ESI, emergency severity index.

Figure 3

Laboratory findings and disease severity. Plots of the probability of discharge from the ED, admission to the ward, or admission to the PICU for selected laboratory tests. Troponin-I and D-dimer were categorized as positive or negative and are presented as box-plots. The graphs reflect adjustment for ESI triage category. All were statistically significant at the p < 0.05 level except for Hematocrit (p = 0.067) and AST (p = 0.052).

Figure 4

Boxplots of lung ultrasound and disease severity overlaid with inverse probability weighted regression model predicted values. Except for the D-Dimer, important abnormalities in the markers shown are observed only for more than moderately severe lung disease. The top row shows all-comers, and the bottom row: SARS-CoV-2 positive only. AST aspartate aminotransferase, ALT alanine transaminase.

Figure 5

Bar graphs showing elevated D-dimer and troponin-I by SARS-CoV-2 status and severity of lung ultrasound findings.

Figure 6

Raw pairwise correlations between laboratory tests.

Figure 7

SQL extraction from the electronic medical record.