Simultaneous laboratory-based comparison of ResMed Autoset with polysomnography in the diagnosis of sleep apnoea/hypopnoea syndrome

Abstract

ResMed Autoset (AS) is a simplified diagnosis system for obstructive sleep apnoea/hypopnoea syndrome (OSAS) based on the respiratory flow/time relationship by pressure variation measured through simple nasal prongs. A multicentre prospective trial was used to compare AS and polysomnography (PSG) for diagnosing 95 patients, with suspected OSAS. Physicians gave a pretest probability of the patient having OSAS. The apnoea/hypopnoea index (AHI) was compared between the two methods of diagnosis for the whole population and for subgroups according to the pretest probability. Twenty-four patients had AHI < 15 events x h(-1) on PSG and 19 AHI 15-30, and 52 patients had AHI > or = 30. Correlation between AHI assessed by AS and PSG was r=0.87 for total sleep time (TST), p<0.0001. A Bland and Altman plot gave an agreement between the two methods of +/-40%. For a threshold of AHI > or = 15 events x h(-1) to diagnose OSAS, AS has a sensitivity of 92%, specificity of 79%, positive predictive value of 93% and negative predictive value of 76%. With a pretest probability > or = 80%, sensitivity and positive predictive value were 98 and 100% respectively. Of six false negative, four had a high pretest probability (> 80%) or Epworth score > or = 10. Using these parameters as a criterion for proceeding to PSG after a negative AS study would mean that two apnoeic patients (AHI 20 and 17 events x h(-1) by PSG) would escape detection. The Autoset is useful for the detection of obstructive sleep apnoea but with high pretest probability and a negative Autoset result polysomnography should be performed.

In-Home, Self-Assembled Sleep Studies Are Useful in Diagnosing Sleep Apnea in the Elderly

“…13,20,21 This device has been tested in comparison with in-laboratory PSG and found to have a sensitivity of 92% and specificity of 79% in middle-aged patients for detection of sleep apnea. 20 All unattended studies were done within 2 mo before PSG; 99% were done within 1 day of PSG. The unit was delivered to the home and study participants were provided instruction and assistance regarding assembly on the night of the study.…”

Residual sleep-disordered breathing during autotitrating continuous positive airway pressure therapy

“…Earlier studies reported strong correlations between the device-and polysomnography-measured respiratory indices, a tendency of autoCPAP to over-score events, and an underestimation of AHI at higher values [24][25][26]. These early studies were limited in that the devices were evaluated in diagnostic mode and autoCPAP devices are neither intended nor recommended for diagnostic purposes [10].…”

Positive effect of CPAP treatment on the control of difficult-to-treat hypertension

“…The AS is an auto-CPAP model in which the diagnostic mode allows the recording of different respiratory variables and patient's cardiac frequency. The system has been described and validated by several studies [17][18][19][20]. The AS provided a semi-quantitative reading of nasal ventilation.…”

“…First, the AS system does not allow quantification of the hours of sleep and it has not been validated in populations with a low pre-test probability of suffering obstructive sleep apnoea syndrome. In any case, the studies that have validated this technique versus polysomnography report that the AS system offers good correlation values in patients with a high AHI cut-off point, even with a low ESS score value, as is the case in the current population [18][19][20]. Secondly, a nonrandomised placebo controlled trial was used in an attempt to maximise the number of patients receiving effective CPAP treatment and exceeding the estimated sample size, as the percentage of patients with truly refractory AHT was small.…”