Ultrasound findings
The M-mode sonographic findings of diaphragm thickness, TF, EXC, IS, ES,
and total duration time of the respiratory cycle of the patients
enrolled in this study are shown in Table 1. The mRDAI scores and BUS
values had a significant positive correlation (p <
0.001, r : 0.760). There was a positive correlation between IS and
respiratory rate at admission (p < 0.001, r :
0.637). As the clinical score increased, IS (p < 0.001,r : 0.775), ES (p < 0.001, r: 0.444), and
EXC (p < 0.001, r : 0.200) measurements rose and
these were positively correlated (Table 2). Additionally, BUS values had
a correlation with both IS (p < 0.001, r : 0.562)
and ES (p : 0.012, r : 0.244) values. Because there were few
patients in the severe group according to mRDAI and BUS values, we
divided the patients into two groups for comparison as the mild and
moderate-severe groups. According to this classification, there were 71
(68.3%) patients in the mild and 27 (31.7%) patients in the
moderate-severe group for mRDAI scores and there were 55 (52.9%)
patients in the mild and 49 (47.1%) patients in the moderate-severe
group for BUS values. Furthermore, values of IS, ES, EXC, and total
duration time of the respiratory cycle were also higher in the
moderate-severe group than the mild group for both mRDAI scores (for IS
and ES: p < 0.001; for EXC: p : 0.003; for total
duration: p : 0.014) and BUS values (for IS: p <
0.001; for ES: p : 0.014; for EXC: p : 0.036). Patients who
received HFNC oxygen therapy had higher IS (p : 0.028) and TEE
(p : 0.023) measurements and, although not statistically
significant, higher EXC values (p : 0.053). We could repeat the
measurements of diaphragm parameters for 2 patients in 2 hours after
starting HFNC oxygen therapy; although we did not have enough patients
to statistically evaluate this, we observed that IS, ES, EXC, TEI, and
TEE were all decreased as the respiratory support reduced the work of
breathing. Values of IS were correlated with both the length of stay in
the emergency department (p : 0.002, r : 0.316) and the
total stay in the hospital (p < 0.001, r :
0.492).