Nasal prongs in the detection of sleep-related disordered breathing in the sleep apnoea/hypopnoea syndrome

Conventional systems to monitor oronasal how in sleep studies have traditionally relied on a thermistor signal. Our study was designed to verify whether nasal prongs (NP) connected to a pressure transducer could improve respiratory events detection in patients with sleep apnoea/hypopnoea syndrome (SAHS) compared to traditional systems, Sleep episodes from a 2 h conventional polysomnographic record plus NP signal obtained at random from eight patients (age: mean(+/-SD) 53(+/-12) yrs; body mass index (BMI): 29(+/-6) kg.m(-2); apnoea/hypopnoea index (AHI): 27(+/-20) events.h(-1)) were identified and used for analysis, An abnormal change in the pattern of any of the respiratory or neurological variables occurring during the observation period was defined as an episode, Each episode was registered and scored with concomitant scoring of the remaining variables, According to the episode definition three different profiles were established: 1) periods of reduction of ventilation in either variable without an arousal or cyclical desaturation, named nonpathological episode (NPE); 2) an idiopathic or nonrespiratory arousal (IA); and 3) a true respiratory event (TRE) defined as reduction or absence of how demonstrated by either thermistor, thoraco-abdominal bands or NP accompanied by cyclical desaturation and/or arousal. For each TRE, its detection by thermistor, thoraco-abdominal bands or NP was established, A total of 877 sleep episodes were observed (42 NPE, 30 IA and 805 TRE), When compared to single or combined thermistor and bands approach, NP had the highest respiratory events detection rate, 779 (98.8%) versus 673 events (83.6%), respectively. Detection of respiratory-related arousals was also improved by NP and only 3% could account for mouth breathing respiration, It is concluded that nasal prongs improve the detection of respiratory events in patients with sleep respiratory disorders.