Sitting-induced hemodynamic changes and association with sitting intolerance in children and adolescents: a cross-sectional study

Abstract

Hemodynamic alteration with postural change from supine to sitting has been unclear in the young. In the cross-sectional study, 686 participants (371 boys and 315 girls, aged 6-18 years) were recruited from 4 schools in Kaifeng city, the central area of China. The active sitting test was performed to obtain heart rate (HR) and blood pressure (BP) changes from supine to sitting in children and adolescents. Hemodynamic change-associated sitting intolerance was analyzed. In the study participants, the 95th percentile (P 95) values of changes in HR and BP within 3 min from supine to sitting were 25 beats/min and 18/19 mm Hg, respectively. Sixty-six participants had sitting intolerance symptoms. Compared with participants without sitting intolerance symptoms, those with symptoms more frequently had HR increase ≥ P 95 or BP increase ≥ P 95 within 3 min from supine to sitting (P < 0.001). Risk factors for sitting intolerance were age (odds ratio 1.218, 95% confidence interval 1.072-1.384, P = 0.002) and changes in HR or BP ≥ P 95 within 3 min after sitting (odds ratio 2.902, 95% confidence interval 1.572-5.357, P = 0.001). We firstly showed hemodynamic changing profiles from supine to sitting and their association with sitting intolerance in children and adolescents. Sitting tachycardia is likely suggested with a change in HR ≥ 25 beats/min and sitting hypertension with a change in BP ≥ 20/20 mm Hg when changing from supine to sitting within 3 min. The age and changes in HR or BP were independent risk factors for sitting intolerance. Lying, sitting and standing are inevitable postures in daily life, and blood distribution changes are accompanied by postural changes. Physiologically, changing from the supine to the orthostatic position induces an instantaneous and large shift of 10% to 25% of blood volume from the thorax to the lower extremities and splanchnic organs and a transfer from the vasculature to the interstitial tissues. This redistribution causes an immediate decrease in venous return to the heart, resulting in a transient decline in cardiac filling and blood pressure. Then, positive chronotropic and inotropic cardiac effects are stimulated by activation of the sympathetic nervous system and withdrawal of the parasympathetic nervous system to maintain a relatively stable circulatory condition,

Spectrum of underlying diseases in syncope and treatment of neurally-mediated syncope in children and adolescents over the past 30 years: A single center study

“…We also established the diagnostic criteria for POTS according to the epidemiological investigation in China in 2015 ( 19 ), contributing to POTS diagnosis and management in children worldwide. Recently, we proposed SI in children for the first time in 2020, including STS and SHT ( 8 ). Therefore, the syncope spectrum was gradually enlarged, and the proportion of unexplained syncope in children decreased over this period (χ 2 = 128.839, P < 0.01).…”

“…During this period, HR, BP, and intolerance symptoms of children and adolescents were noted. The sitting-up test assisted in diagnosing STS and SHT ( 8 ).…”

“…The positive criteria of STS were as follows: HR increased by ≥25 beats/min within the initial 3 min of the sitting position. The positive criteria of STS were as follows: BP increased by ≥20/20 mmHg within the initial 3 min of sitting ( 8 ).…”

“…NMS includes vasovagal syncope (VVS) and postural orthostatic tachycardia syndrome (POTS) as its main underlying diseases ( 7 ). In 2020, our team reported sitting intolerance (SI) in children for the first time, including sitting tachycardia syndrome (STS) and sitting hypertension (SHT) ( 8 ), expanding the spectrum of syncope in children and adolescents. This study retrospectively analyzed the spectrum of underlying diseases in syncope in children and adolescents and described the treatment options for children and adolescents with NMS to increase the understanding and awareness of pediatric syncope and provide help for NMS treatment in children and adolescents.…”

Sitting intolerance: A new disease entity in children and adolescents

“…On the basis of those findings, Tao et al. 5 proposed the first set of diagnostic criteria for STS and sitting hypertension. For children and adolescents who exhibited symptoms of orthostatic intolerance within 3 min after shifting from a supine position to a sitting position during an active sitting test, STS should be suspected when the heart rate is increased by ≥25 beats/min, whereas sitting hypertension should be suspected when the blood pressure is elevated by ≥ 20/20 mmHg.…”