Scoring respiratory events in paediatric patients: evaluation of nasal pressure and thermistor recordings separately and in combination.

BACKGROUND

In children both nasal pressure (NP) and thermistor (Th) technologies are commonly used to assess airflow measurement during routine polysomnography (PSG) for the assessment of sleep disordered breathing. We aimed to compare NP and Th measurement techniques when scoring central and obstructive respiratory events during PSG.

METHODS

Sleep, arousal and respiratory scoring was performed manually by a single experienced scorer (NV) on 10 patients. Respiratory scoring was repeated using three different montages for each patient, including as the airflow measurement: NP only, Th only and both NP+Th (gold standard). The respiratory disturbance index (RDI), central apnoea index (CnAI), obstructive apnoea index (OAI), obstructive apnoea hypopnoea index (OAHI) and respiratory arousal index (RespArI) were calculated. Percent of sleep time with uninterpretable NP and Th signal was also assessed.

RESULTS

The difference in CnAI for the different montages was clinically acceptable. But differences in the montages were clinically unacceptable for RDI, OAI, OAHI and RespArI. Using Th alone typically underestimated the number of obstructive events and respiratory arousals. Using NP alone resulted in an overestimation of obstructive apnoeas. NP signal was uninterpretable for a significantly greater percentage of the study than was the Th signal (mean 22+/-19% vs 2+/-2%, p<0.05), with no effect of age or OAHI on % uninterpretable signal.

CONCLUSIONS

To maximise available airflow information and the inclusion of clinically significant obstructive events in respiratory event indices, the use of both NP and Th should be routine for clinical paediatric PSG. Further studies to determine normative values for children using combined NP and Th should be conducted.