Objectives: To compare nocturnal polysomnography (PSG) with pulse transit time (PTT) recordings and structured clinical assessments and assess the reliability of these methods as a surrogate for the apnea-hypopnea index (AHI; calculated as the number of apneas/hypopneas per hour of total sleep time) and to test the associations between the clinical assessments and sleep disordered breathing (SDB).
Design: Prospective observational study. The parents of 51 children and adolescents filled out a questionnaire on SDB and the participants underwent examination. Scores from questionnaire and examination items were weighted according to their association with SDB. A total clinical score was assigned combining questionnaire and examination scores.
Setting: Hospital pediatrics department.
Patients: Children and adolescents aged 5 to 17 years undergoing standard PSG with the addition of PTT as part of a clinical investigation for SDB.
Main outcome measures: The AHI and associations between the AHI and PTT arousal index (PTT-AI) and questionnaire, examination, and total clinical scores.
Results: We found a significant correlation between the AHI and PTT-AI (r = 0.55; P < .001). The relationship between the AHI and PTT-AI was stronger when the AHI was greater than 3. We also found significant correlations between the PTT-AI and the total clinical score (r = 0.38; P = .008) and the examination score (r = 0.44; P = .002) but not the questionnaire score (r = 0.23; P = .12). There was an association between the AHI and examination score in particular when the AHI was greater than 3.
Conclusions: Pulse transit time shows promise as a screening test for SDB associated with an AHI greater than 3. For less severe SDB, the validity of using the PTT to separate these conditions from primary snoring has not been demonstrated in a clinical setting.