Clinical characteristics and hemodynamic responses to head-up tilt test in children and adolescents with unexplained sighing.

Nitroglycerin-stimulated HUTT positive rate was higher in the study group than the control group (24.0% vs 10.1%, P = 0.014). In total, 32.3% of patients with sighing had positive responses to HUTT, which was higher than that of healthy individuals (32.3% vs 15.9%, P = 0.009). Among 62 cases with positive responses to HUTT in the study group, 48 cases were vasoinhibitory type vasovagal syncope (VVS), 5 cases were mixed type VVS, 3 cases were cardioinhibitory type VVS, 5 cases were postural tachycardia syndrome, and one case was orthostatic hypertension. Sighing patients with positive responses to HUTT had female dominance (54.8% vs39.2%, P = 0.045), older mean age (9.6 ± 2.8 vs 8.1 ± 2.7 years old, P = 0.001), higher basic systolic blood pressure (104.8 ± 10.4 vs 101.1 ± 9.9 mmHg, P = 0.019), and higher diastolic blood pressure (66.0 ± 7.5 vs 62.9 ± 9.2 mmHg, P = 0.021) compared with those of negative responses. CONCLUSIONS : Nearly one-third of children and adolescents with unexplained sighing had positive responses to HUTT, demonstrating that sighing was related to dysfunction of the autonomic nervous system. Elder female patients with higher systolic and diastolic blood pressure were more likely to have positive responses to HUTT.