Investigation of pulse transit time characteristics during single and recurrent obstructive respiratory events.

Conventional overnight polysomnography (PSG) used to determine the respiratory behaviour during sleep can be a complex and expensive procedure. Pulse transit time analysis (PTT) has shown potential to detect obstructive apnoeic and hypopnoeic events (OE) in adults. Due to abnormalities in central ventilatory control, recurring OE may occur. This study was undertaken to determine the potential of PTT to differentiate responses during upper airway obstruction in the paediatric population. This preliminary study included 11 children (10 male; aged 7.5 +/- 3.8 year) recruited to investigate PTT trend during single and recurrent OE. PTT measurements were evaluated against the corresponding PSG results pre-scored by two blinded observers. A total of 110 valid OE (47 single and 63 recurrent) were observed during these PSG studies. There were distinct PTT responses observed for these two types of OE with respect to those of tidal breathing (P < 0.05). For the tidal breathing events, the mean absolute standard deviation (SD) and maximal percentage (%) decrease (MAX) were 7.71 ms and 3.88% respectively. For the recurrent OE, the absolute SD, SD (%) and MAX were 52.21 ms, 8.52% and 55.08% accordingly while for the single OE, the absolute SD, SD (%) and MAX were 12.23 ms, 5.27% and 13.56% respectively. The findings herein can suggest that PTT can be a valuable clinical tool in the paediatric respiratory sleep studies.