Characteristic alteration in the second derivative of photoplethysmogram in children

BACKGROUND: The second derivative of the photoplethysmogram (SDPTG) has been verified as a useful method for analyzing pulse wave form in adults; however, there have been few studies on the SDPTG in children. METHODS: We examined age-related alteration of SDPTG (study 1) and the SDPTG response to a vasodilator (study 2). The subjects in study 1 were 36 healthy children aged 0.9-16.0 years. The subjects in study 2 were 13 children aged 5.4-18.9 years with a history of Kawasaki disease. Subjects received an i.v. infusion of 0.568 mg/kg dipyridamole. We assessed the SDPTG by d/a ratio, b/a ratio and aging index (AGI). RESULTS: The d/a ratio increased with advance of age (r= 0.636, P < 0.001), and the b/a ratio and AGI decreased with advance of age (r=-0.343, P < 0.05 and r=-0.678, P < 0.001, respectively). The d/a ratio and AGI were correlated with height (r= 0.523, P < 0.01 and r=-0.623, P < 0.001, respectively), but the b/a ratio was not significantly correlated with height. In study 2, the d/a ratio increased significantly (P≤ 0.05), but the b/a ratio and AGI did not alter. CONCLUSIONS: The SDPTG indices in children show characteristic alterations with advance of age and react to a vasodilator.