Mark Norman

Noninvasive pressure preset ventilation for the treatment of Cheyne-Stokes respiration during sleep

Cheyne-Stokes respiration (CSR) during sleep is common in patients with congestive heart failure (CHF). This pattern of breathing fragments sleep, leading to daytime symptoms of sleepiness and fatigue. It was hypothesized that by controlling CSR with noninvasive pressure preset ventilation (NPPV), there would be a decrease in sleep fragmentation and an improvement in sleep quality. Nine patients (eight males, one female; mean +/- SD 65 +/- 11 yrs) with symptomatic CSR diagnosed on overnight polysomnography (apnoea/hypopnoea index (AHI) 49 +/- 10 x h(-1), minimum arterial oxygen saturation (Sa,O2, 77 +/- 7%) and CHF (left ventricular ejection fraction 25 +/- 8%) were studied. After a period of acclimatization to NPPV (variable positive airway pressure (VPAP) II ST, Sydney, NSW, Australia and bilevel positive airway pressure (BiPAP), Murraysville, PA, USA), sleep studies were repeated on therapy. NPPV almost completely abolished CSR in all patients with a reduction in AHI from 49 +/- 10 to 6 +/- 5 x h(-1) (p<0.001). Residual respiratory events were primarily due to upper airway obstruction at sleep on-set. Arousal index was markedly decreased from 42 +/- 6 to 17 +/- 7 x h(-1) (p <0.001). Sleep architecture showed a trend toward improvement with a reduction in stage 1 and 2 (79 +/- 7% during the diagnostic night versus 72 +/- 10% during NPPV, (p=0.057)), whilst sleep efficiency, slow-wave sleep (SWS), and rapid eye movement (REM) were not altered. Controlling Cheyne-Stokes respiration with noninvasive pressure preset ventilation resulted in reduced arousal and improved sleep quality in the patients with congestive heart failure. Noninvasive pressure preset ventilation should be considered a potential therapy for Cheyne-Stokes respiration in congestive heart failure in those patients who do not respond or fail to tolerate nasal continuous positive airway pressure therapy.

Nasal versus full face mask for noninvasive ventilation in chronic respiratory failure

This study was undertaken to determine the efficacy of nasal mask (NM) versus full face mask (FFM) for the delivery of noninvasive ventilation (NIV) in subjects with nocturnal hypoventilation. A total of 16 patients (11 males) were enrolled, all with nocturnal hypoventilation currently treated at home with NIV via pressure preset devices. Subjects underwent full polysomnography on three occasions; on the first night current therapy on NM was reviewed, followed by two experimental studies in randomised order using either NM or FFM. NIV settings and oxygen flow rate were the same under both conditions. Notably, 14 of the 16 subjects required the use of a chinstrap to minimise oral leak. Apnoea-hypopnoea indices were within normal limits under both conditions (1.7±3.4 NM versus 1.6±2.4 h FFM). The type of interface did not significantly affect gas exchange during sleep (minimum average arterial oxyhaemoglobin saturation total sleep time 93.4±2.1 NM versus 92.8±2.5% FFM, Delta transcutaneous carbon dioxide nonrapid eye movement sleep to rapid eye movement sleep (0.58±0.36 NM versus 0.50±0.40 kPa FFM). Sleep efficiency was significantly reduced on the FFM (78±9 NM versus 70±14% FFM), although arousal indices were comparable under both conditions (15.6±9.8 NM versus 15.8±8.8 h FFM). Full face masks appear to be as effective as nasal masks in the delivery of noninvasive ventilation to patients with nocturnal hypoventilation. However, a chinstrap was required to reduce oral leak in the majority of subjects using the nasal mask.

Night-to-night variability in sleep in cystic fibrosis

OBJECTIVES The impact of night-to-night variability (NNV) on polysomnography (PSG) has been reported mainly in normal subjects, the elderly and patients with obstructive sleep apnea with focus on changes in the apnea/hypopnea index, rather than measures of nocturnal oxygenation. There is very limited data on NNV in patients with cystic fibrosis (CF). The goal of this study was to assess for first-night effect and reliability of PSG measurements on nocturnal oxygenation and respiratory disturbance in CF. METHODS A prospective observational study was performed in patients with CF who consented to PSG on two consecutive nights. Paired t-tests and intra-class correlation coefficients (ICCs) were calculated for repeated measures of sleep stage time, sleep efficiency, arousal indices, measures of nocturnal oxygenation, and respiratory events in all sleep stages. RESULTS Thirty-one patients with CF were studied, aged 27+/-8 (mean+/-1 SD) years and forced expiratory volume in 1 s (FEV(1)) of 37+/-11% of predicted. Relative to the first-night PSG, on the second PSG, we observed the following: shorter latency to rapid eye movement (REM) sleep (P<0.001), increased sleep efficiency (P<0.01), decreased wake after sleep onset (WASO) time (P<0.01), decreased percentage of non-REM time with oxyhemoglobin saturation by pulse oximetry (SpO(2))< or =90% (P<0.05), decreased number of central apneas per hour (P<0.05) and reduced respiratory rate in stage 2 sleep on night 2 (P<0.05). Despite these changes, the ICCs between night 1 and night 2 showed good repeatability/reliability for measures of nocturnal oxygenation and indices of respiratory disturbance, including the percentage of total sleep time with SpO(2)< or =90% (ICC=0.85) and apnea-hypopnea index (ICC=0.75). Likewise, the ICCs were extremely high for respiratory rate in stage 2 (ICC=0.94), slow wave sleep (ICC=0.97), and REM sleep (ICC=0.96). CONCLUSION Although a first-night effect is seen with sleep efficiency, REM latency, and WASO, a single-night PSG in patients with CF yields reliable information on nocturnal oxygenation and respiratory disturbance.

Validation of the Sonomat: a contactless monitoring system used for the diagnosis of sleep disordered breathing.

STUDY OBJECTIVES To evaluate the ability of the Sonomat to diagnose obstructive sleep apnea (OSA). DESIGN Prospective and randomized. SETTING Sleep laboratory and home. PARTICIPANTS 62 subjects; 54 with a clinical history of OSA and 8 normal control subjects. INTERVENTIONS N/A. MEASUREMENTS AND RESULTS Simultaneous PSG and Sonomat recordings were made in 62 subjects; 2 were excluded due to a poor nasal flow recording in PSG. There were positive correlations between the two devices for measures of sleep time, respiratory events, and the AHI (all correlations > 0.89). Bland-Altman analysis of the AHI showed positive agreement between devices, particularly at levels around common diagnostic thresholds. The mean difference in AHI values was 1.4 events per hour, and at a diagnostic threshold of 15 events per hour, sensitivity and specificity were 88% and 91%. More than 93% of PSG defined respiratory events were identified by the Sonomat and the absence of respiratory events was correctly identified in 91% of occasions. Gender, obesity, and body position did not influence the accuracy of the Sonomat. PSG snore sensors differed in how much snoring was detected when compared to the Sonomat. CONCLUSION These data indicate that the Sonomat was reliable and accurate for the diagnosis of OSA. The provision of audible breath sound/snoring replay permits more accurate quantification of snoring. It requires no patient attachment and can be performed in the home with minimal training.

Validation of the Sonomat Against PSG and Quantitative Measurement of Partial Upper Airway Obstruction in Children With Sleep-Disordered Breathing

Study Objectives To validate the Sonomat against polysomnography (PSG) metrics in children and to objectively measure snoring and stertor to produce a quantitative indicator of partial upper airway obstruction that accurately reflects the pathology of pediatric sleep-disordered breathing (SDB). Methods Simultaneous PSG and Sonomat recordings were performed in 76 children (46 male, age 5.8 ± 2.8, BMI = 18.5 ± 3.8 kg/m2). Sleep time, individual respiratory events and the apnea/hypopnea index (AHI) were compared. Obstructed breathing sounds were measured from the unobtrusive non-contact experimental device. Results There was no significant difference in total sleep time (TST), respiratory events or AHI values, the latter over-estimated by 0.3 events hr-1 by the Sonomat. Poor signal quality was minimal and gender, BMI, and body position did not adversely influence event detection. Obstructive and central events were classified correctly. The number of runs and duration of snoring (13 399 events, 20% TST) and stertor (5748 events, 24% TST) were an order of magnitude greater than respiratory events (1367 events, 1% TST). Many children defined as normal by PSG had just as many or more runs of snoring and stertor as those with mild, moderate and severe obstructive sleep apnea (OSA). Conclusions The Sonomat accurately diagnoses SDB in children using current metrics. In addition, it permits quantification of partial airway obstruction that can be used to better describe pediatric SDB. Its non-contact design makes it ideal for use in children.