[Value of pulse transit time in detecting respiratory drive].

Objective: To assess the accuracy of pulse transit time (PTT) in classification of apnea events, and collect data for clinical application reference.

Methods: Thirty-two obstructive sleep apnea-hypopnea syndrome (OSAHS) patients included in the research had Polysomnography (PSG), and 10 305 apnea events were recorded. All the events were analyzed by PTT and esophageal pressure (Pes) respectively. The results were analyzed to assess the accuracy of PTT and compare the accuracy of pulse transit time between REM stage and NREM stage, and analyze the correlation between age, body mass index (BMI), apnea hypopnea index (AHI) and concordance rate in every patient.

Results: The total concordance rate between PTT and Pes in classification of apnea was 96.7% (9970/10305). The sensitivities of PTT in detecting central, mixed and obstructive apnea were 88.0%, 91.3% and 97.8% respectively and the specificities were 99.8%, 97.8% and 92.8% respectively. The false determinations of apnea events mainly concentrated on the false determinations between the obstructive and mixed apnea. There was no statistical significant between the accuracy of PTT in different sleep stages. There was a negative relationship between the age, BMI, Lowest SaO2, AHI and the concordance rate.

Conclusions: There was good concordance between PTT and Pes in classification of apnea. PTT had very high sensitivity and specificity in detecting all kinds of apnea. This study showed that PTT can detect respiratory drive noninvasively with high accuracy.