Ultrasound findings
The LUS findings of our patients were as follows: subpleural
consolidation in 70 (72.8%) patients, confluent B-lines in 19 (19.8%)
patients, focal multiple B-lines in 4 (4.1%) patients, and pleural
effusion in 3 (3.1%) patients. Table 1 shows the M-mode sonographic
findings of diaphragm thickness, TF, diaphragm excursion, IS, ES, and
total duration time of the respiratory cycle of the patients enrolled in
the study. Values of IS and ES were found to have significant positive
correlations with respiratory rate and length of stay in hospital and
negative correlations with SpO2 levels
evaluated at the time of admission to the emergency department. (Table
2). Additionally, TF values were negatively correlated with respiratory
rate (p : 0.022, r : -0.236) and length of stay in the
emergency department (p : 0.016, r : -0.256).
In order to obtain homogeneous numbers of patients in the clinical
severity groups, patients in the groups of PRESS grades 0–1 and grades
4–5 were merged, so four groups were evaluated for clinical severity
scores as follows: PRESS scores 0–1, 2, 3, and 4–5. The IS and ES
values differed significantly between these four groups; patients with
higher clinical scores had increased IS and ES values
(p <0.001) (Graphic 1). There was a positive correlation
between the clinical score and IS (p <0.01,r :0.541) and ES (p <0.01, r :0.429).
Thickening fraction values were also significantly different between
groups; patients with higher clinical scores had lower TF values
(p : 0.001) (Table 3, Graphic 2), and there was a negative
correlation between TF and clinical score (p <0.01,r : -0.318). Although there was no statistically significant
difference, diaphragm excursion was higher in the severe group (PRESS
4–5) than the mild and moderate (PRESS 0–3) group (2.2±0.56 vs.
2.2±0.59). Patients who required respiratory support (HFNC or BiPAP
therapy) had higher IS and ES measurements (p : 001, p :
0.004).
Analysis of ROC curves was performed and the value of the area under the
curve (AUC) for IS among patients of PRESS grades 4 and 5 was found to
be 0.805 (95% confidence interval (CI): 0.670–0.910). At a cut-off
level of 0.277 cm/s, the sensitivity and specificity of IS values for
PRESS grades 4 and 5 were 87.5% and 51.9%. For ES, the AUC value among
patients of PRESS grades 4 and 5 was 0.761 (95% CI: 0.650–0.890). At a
cut-off level of 0.248 cm/s, the sensitivity and specificity of ES
values for PRESS grades 4 and 5 were 87.5% and 58.2%, respectively
(Figure 2).