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Use of pulse transit time to distinguish respiratory events from tidal breathing in sleeping children
Jong Yong A Foo1, Stephen J Wilson, Andrew P Bradley
1School of Information Technology and Electrical Engineering, University of Queensland, St. Lucia Campus, Brisbane, Australia 4072. jong@ieee.org
Insights
Pulse transit time (PTT) can noninvasively differentiate obstructive and central respiratory events in children during sleep. This method shows promise as a diagnostic tool for pediatric sleep studies.
Area of Science:
- Pediatric Sleep Medicine
- Cardiorespiratory Physiology
- Biomedical Engineering
Background:
- Esophageal pressure monitoring, the gold standard for inspiratory effort, is invasive and challenging for pediatric use.
- Pulse transit time (PTT) is a noninvasive technique that reflects arterial stiffness and blood pressure changes.
- PTT has shown potential in detecting inspiratory efforts through blood pressure fluctuations linked to pleural pressure swings.
Purpose of the Study:
- To investigate the capability of PTT to noninvasively classify respiratory events during sleep as central or obstructive in children.
- To evaluate PTT as a potential alternative to invasive monitoring methods for pediatric sleep studies.
Main Methods:
- PTT was measured in conjunction with routine overnight polysomnography in 33 children (mean age 6.7 years).
- The accuracy of PTT measurements was assessed against scored respiratory events identified during polysomnography.
- Analysis focused on PTT changes (mean and variance) during 334 valid respiratory events.
Main Results:
- Obstructive events (112) were characterized by a decrease in mean PTT (0.92 probability below baseline, p < 0.005).
- Central events (222) were identified by a decrease in PTT variance (0.94 probability below baseline, p < 0.005).
- PTT achieved 0.90 sensitivity for detecting obstructive events with 0.82 specificity, and 0.80 specificity for central events.
Conclusions:
- PTT effectively categorizes central and obstructive respiratory events in children, even with hypopneas and in the absence of motion artifacts.
- PTT demonstrates significant potential as a valuable, noninvasive diagnostic tool for pediatric respiratory sleep studies.
- This noninvasive method offers a promising alternative for assessing respiratory events in pediatric sleep evaluations.
Study Objectives:
Currently, esophageal pressure monitoring is the "gold standard" measure for inspiratory efforts, but its invasive nature necessitates a better tolerated and noninvasive method to be used on children. Pulse transit time (PTT) has demonstrated its potential as a noninvasive surrogate marker for inspiratory efforts. The principle velocity determinant of PTT is the change in stiffness of the arterial wall and is inversely correlated to BP. Moreover, PTT has been shown to identify changes in inspiratory effort via the BP fluctuations induced by negative pleural pressure swings. In this study, the capability of PTT to classify respiratory events during sleep as either central or obstructive in nature was investigated.
Setting And Participants:
PTT measure was used in adjunct to routine overnight polysomnographic studies performed on 33 children (26 boys and 7 girls; mean +/- SD age, 6.7 +/- 3.9 years). The accuracy of PTT measurements was then evaluated against scored corresponding respiratory events in the polysomnography recordings.
Results:
Three hundred thirty-four valid respiratory events occurred and were analyzed. One hundred twelve obstructive events (OEs) showed a decrease in mean PTT over a 10-sample window that had a probability of being correctly ranked below the baseline PTT during tidal breathing of 0.92 (p < 0.005); 222 central events (CEs) showed a decrease in the variance of PTT over a 10-sample window that had a probability of being ranked below the baseline PTT of 0.94 (p < 0.005). This indicates that, at a sensitivity of 0.90, OEs can be detected with a specificity of 0.82 and CEs can be detected with a specificity of 0.80.
Conclusions:
PTT is able to categorize CEs and OEs accordingly in the absence of motion artifacts, including hypopneas. Hence, PTT shows promise to differentiate respiratory events accordingly and can be an important diagnostic tool in pediatric respiratory sleep studies.
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