Pulse Transit Time and Inspiratory Resistive Load as a Marker for Inspiratory Perception in Children

Inspiratory resistive load (IRL) has been used as part of clinical tools to evaluate respiratory responses of a child like depth of inspiratory efforts and perception of the inspiratory load. These responses have shown to be important to monitor the prognosis of asthma and sleep apnea. Minimally invasive instrumentations are generally preferred for children if extended monitoring is required. A parameter termed pulse transit time (PTT) has been suggested to be a surrogate marker of inspiratory efforts in respiratory sleep studies. In this study, 10 healthy children (8 male; aged 8.3 +/- 2.6yr) were recruited to breath through a customized facemask with four different inspiratory load settings in their wakeful state. PTT technique was used to determine its potential in assessing a child's perception of an inspiratory load. The results show that relative air pressure variations within the facemask can relate to changes observed in PTT in a significant manner (p < 0.05; R-2=0.627). The breathing frequency during each test activities also indicated that there was a general lower trend when a higher valued IRL is introduced. Essentially, a relative lower mean PTT value was observed with a higher inspiratory load (p < 0.05; R-2=0.643). The findings herein can suggest that this simple measure can be a suitable candidature for inspiratory effort monitor in the pediatrics population especially when prolonged monitoring is required.