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Respiratory Effort Related Arousals

RESPIRATORY EFFORT RELATED AROUSALS ARE DETECTED BY NASAL FLOW MEASURED WITH CANNULA AND PRESSURE TRANSDUCER.

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Johnson PL 1, Edwards N 1, Burgess KR 2, Sullivan CE 1
1. David Read Laboratory, Department of Medicine, University of Sydney 2006 2. Peninsula Private Sleep Laboratory, Manly NSW

Respiratory effort related arousals (RERAs) were described by the American Academy of Sleep Medicine Task Force (AASM) and reported in the journal, SLEEP in 1999.The arousals from sleep associated with increased upper airway resistance that lead to excessive daytime sleepiness in the Upper Airway Resistance Syndrome were described by the AASM as being those arousals that are preceded by increasing negative esophageal pressure (Pes), lasting for at least ten seconds, terminating in arousal and a return to less negative Pes. Pes is an invasive and uncomfortable procedure that may cause disruption to sleep and refusal by patients to have the procedure performed. Our study aimed to compare several non invasive measures of increased upper airway resistance. Methods. Ten subjects with clinically minor degrees of OSAHS (reported snoring and/or witnessed apneas following alcohol ingestion) received overnight polysomnography which included Pes, nasal flow using cannula & pressure transducer, respiratory inductive plethysmography (RIP) and a stretch sensor placed in the supraclavicular fossa (OptiflexTM Upper Airway Resistance sensor) that detects increased respiratory effort. Alcohol was given 1-2 hours before the sleep studies to increase upper airway resistance. Results. Fifty RERAs were identified in the ten sleep studies i.e. arousals from sleep preceded by increasing negative Pes for at least one breath and return to less negative Pes following arousal. These 50 RERAs were distributed among the ten subjects. All fifty RERAs (100%) were preceded by flow limitation detected by the nasal flow signal using cannula & pressure transducer. 86% of RERAs were preceded by an increase in the size of the OptiflexTM UAR sensor signal and 53% of RERAs were preceded by an increase in the size of the RIP signal. Conclusion. Increased upper airway resistance, with increasing negative Pes, leading to arousal from sleep is reliably detectable by non invasive measurement using a cannula and pressure transducer.

Key words: respiratory effort related arousal, upper airway resistance, esophageal pressure, nasal flow/cannula with pressure transducer.

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