General characteristics of the included children
In total, 112 children were included (see flow chart in Figure 1). The
characteristics of the selected children are summarized in Table 1. The
population consisted of 59 girls (57.3%) and 53 boys (42.7%), with a
median age of 13.9 years [11.6 -16]. Among them, 84 children (75%)
had severe asthma (GINA 4 to 5) and 28 (25%) non-severe asthma (GINA 1
to 3).
The reason for carrying out the HVT was the presence of symptoms
suggestive of HVS for 53 children (47.3%), the persistence of asthma
symptoms despite good compliance with treatment for 21 (18.8%), and the
systematic search for HVS in the context of the exploration of
difficult-to-treat asthma for 38 (33.9%). The Nijmegen questionnaire
was performed for 103 children (92%) and the median Nijmegen score was
23 [15-29].
Among the 112 children, 108 underwent a HVT (96.4%), for which the
results are presented in Table 1.
The HVT was negative for 34 patients (31.5%) and positive for 74
(68.5%). The characteristics of children with a positive HVT and those
with a negative HVT are presented in Table 2. The baseline
PCO2 at the start of the HVT was lower for children with
a positive HVT than those with a negative test (35 mmHg [34-37] vs.
36 mmHg [35 -38], p < 0.01). The PCO2attained after the hyperventilation phase was also lower for children
with a positive HVT than those with a negative test (18 mmHg [17-20]
vs 22.5 mmHg [19-26.5], p < 0.01). Finally, the time to
return to baseline PCO2 was longer for children with a
positive HVT than those with a negative test (5 min [4-7] versus 1.5
min [1-2.1], p < 0.01). Symptoms reproduced during the HVT
are presented in Figure 2. The most frequently reproduced symptoms among
children with a positive HVT were dizziness for 58 children (78%),
headaches for 49 (66%), and palpitations for 33 (45%).
Girls had a positive HVT more frequently than boys (59 girls (57.3%) vs
53 boys (42.7%), p = 0.03). Children with a positive HVT were older
than those with a negative HVT (14.2 years [12.6-16.8] vs 12.7 years
[9.3-14.7], p < 0.01). The frequency of perennial allergic
rhinitis was higher among children with a positive HVT than those with a
negative test (35 [47.3%] vs 14 [41.2%], p = 0.04). Children
with a positive HVT had more IgE-mediated food allergies than those with
a negative test (26 [35.1%] vs 2 [5.9%], p < 0.01).