Scoring polysomnography respiratory events: the utility of nasal pressure and oro-nasal thermal sensor recordings

Objective: To evaluate the clinical utility of nasal cannula/pressure (NP) and oro-nasal thermal sensor (Th) recordings, alone and in combination for scoring respiratory events during routine diagnostic polysomnography (PSG). Background: The use of Th devices to measure airflow during PSG is not recommended because Th are insensitive to airflow changes other then complete airflow cessation. It has been suggested that NP recording is a better measure of airflow and can also detect increased upper airway resistance during PSG. Methods: Thirty consecutive PSG's were examined using 13 standard channels including Th and NP recordings. Respiratory events were scored separately utilizing NP + Th, Th alone and NP alone in a blinded fashion using modified AASM criteria. Respiratory events were time matched to within 5 s for each of the recording methods. Results: NP + Th detected more events than Th alone (P < 0.0001); NP + Th detected more events than NP alone (P < 0.0001) and NP alone detected more events than Th alone (P < 0.0001). For AHI > 50, NP alone and Th alone each detected 90% of matched NP + Th events. However, for AHI < 50, NP alone detects 54% and Th alone detects 42% (P < 0.005) of matched NP + Th events. For AHI > 50, NP alone scored 97% of matched Th alone scored respiratory events, and Th alone scored 94% of NP alone scored respiratory events (P > 0.05). However, for AHI < 50, NP alone scored 90% of matched Th alone scored respiratory events, whereas Th alone scored 62% of matched NP alone scored events (P < 0.0001). Conclusions: In severe sleep disordered breathing (AHI > 50), NP + Th, NP alone and Th alone have similar ability to detect respiratory events. When AHI < 50, NP + Th appears better for detecting respiratory events than NP or Th alone. If only one measure of airflow is used, NP detects more events than Th. (C) 2003 Elsevier B.V. All rights reserved.