Randomized trial of 'intelligent' autotitrating ventilation versus standard pressure support non-invasive ventilation: impact on adherence and physiological outcomes.

BACKGROUND AND OBJECTIVE: Effective non-invasive ventilation (NIV) therapy is dependent on optimal ventilator settings to maximize clinical benefit and patient tolerance. Intelligent volume-assured pressure support (iVAPS) is a hybrid mode of servoventilation, providing constant automatic adjustment of pressure support (PS) to achieve a target ventilation determined by the patient's requirements. In a randomized crossover trial, we tested the hypothesis that iVAPS, with automated selection of ventilator settings, was non-inferior to standard PS ventilation, with settings determined by an experienced health-care professional, for controlling nocturnal hypoventilation in patients naive to NIV. METHODS: Eighteen patients referred to a ventilator clinic with chronic obstructive or restrictive lung disease and newly diagnosed nocturnal hypoventilation (10 male, median (interquartile range): age 54(41-61) years, mean daytime PaO2 9.25(8.59-10.31) kPa, -PaCO2 6.38(5.93-6.65) kPa were randomized to iVAPS and standard PS. Polysomnography with transcutaneous CO2 monitoring was performed at baseline and 1 month after each treatment period. Nightly hours of therapy were recorded by the ventilator. RESULTS: iVAPS delivered a lower median PS compared with standard PS (8.3(5.6-10.4) vs 10.0(9.0-11.4) cmH2 O; P = 0.001) for the same ventilatory outcome (mean overnight: SpO2 96(95-98) vs 96(93-97)%; P = 0.13 and PtcCO2 6.5(5.8-6.8) vs 6.2(5.8-6.9); P = 0.54). There was no difference in outcome between ventilator modes for spirometry, respiratory muscle strength, sleep quality, arousals or O2 desaturation index. Adherence was greater with iVAPS (5:40(4:42-6:49) vs 4:20(2:27-6:17) hh:mm/night; P = 0.004). CONCLUSIONS: iVAPS servoventilation with automation of ventilation settings is as effective as PS ventilation initiated by a skilled health-care professional in controlling nocturnal hypoventilation and produced better overnight adherence in patients naive to NIV.

Patent foramen ovale in severe obstructive sleep apnea: clinical features and effects of closure.

BACKGROUND: Patent foramen ovale (PFO) may contribute to nocturnal desaturation in patients with obstructive sleep apnea (OSA), and the effect of PFO closure in OSA is unknown. Our study tested the hypotheses that: (1) patients with severe OSA have a higher prevalence of PFO compared with healthy control subjects, (2) patients with severe OSA with clinically significant PFO experience more nocturnal desaturation than those without, and (3) PFO closure reduces nocturnal desaturation. METHODS: Patients with severe OSA and healthy control subjects underwent contrast transthoracic echocardiography and transcranial Doppler to detect PFO and determine shunt size. A subgroup of patients with OSA with large shunts underwent percutaneous PFO closure. Polysomnography was performed at baseline and 1, 6, and 12 months postclosure. RESULTS: One hundred patients with OSA (mean [SD] age, 52 [10] years; apnea-hypopnea index [AHI], 54 [18] events/h) and 50 control subjects (age, 52 [11] years; AHI, 2 [2] events/h) were studied. PFO prevalence was 43% in patients with OSA and 30% in control subjects ( P = .16). Large shunts were detected in 18% of patients with OSA and 6% of control subjects ( P = .049). Patients with OSA with clinically significant shunts had higher oxygen-desaturation index (ODI)/AHI ratios than patients without (ratio, 1.05 [0.27] vs 0.86 [0.26], P = .004). Six patients with OSA underwent PFO closure, which was not associated with a reduction in ODI (baseline, 48 [18]; 12 months, 51 [19] events/h; P = .92) or percentage of the night with arterial oxygen saturation , 90% (baseline, 23% [16%]; 12 months, 20% [22%]; P = .35). CONCLUSIONS: Patients with severe OSA have a higher prevalence of PFO with large shunts compared with control subjects. The ODI/AHI ratio is increased in patients with OSA with clinically significant shunts. PFO closure does not reduce nocturnal desaturation.

Obstructive sleep apnea syndrome is associated with deficits in verbal but not visual memory.

RATIONALE: Although cognitive deficits are well documented in patients with sleep apnea, the impact on memory remains unclear. OBJECTIVES: To test the hypotheses that (1) patients with obstructive sleep apnea have memory impairment and (2) memory impairment is commensurate with disease severity. METHODS: Patients with obstructive sleep apnea and healthy volunteers (apnea-hypopnea index <5 events/h) completed a test battery specially designed to differentiate between aspects of memory (semantic, episodic, and working) versus attention. Sleepiness was measured on the basis of the Epworth Sleepiness Scale and Oxford Sleep Resistance test. Memory performance in patients versus control subjects was compared (Mann-Whitney U test; P < 0.01, Bonferroni corrected for multiple comparisons) and relationships between performance and disease severity were analyzed by linear regression. MEASUREMENTS AND MAIN RESULTS: Sixty patients and healthy control subjects matched for age (mean +/- SD: patients, 51 +/- 9 yr; control subjects, 50 +/- 9 yr) and education (patients, 14 +/- 3 yr; control subjects, 15 +/- 3 yr) participated. Patients demonstrated impaired Logical Memory Test results (immediate recall: patients, median [range], 36 [9-69]; control subjects, 43 [19-64], P = 0.0004; and delayed recall: patients, 22 [6-42]; control subjects, 27 [10-46]; P = 0.0001). There were minimal differences in attention, visual episodic, semantic, or working memory; patients performed better than control subjects on Spatial Span forward and backward. Regression analysis revealed that Logical Memory Test performance was not significantly related to disease severity after controlling for age, education, and sleepiness. CONCLUSIONS: Obstructive sleep apnea is associated with impairment in verbal, but not visual, memory. The impairment was present across a range of disease severity and was not explained by reduced attention. Such verbal memory impairment may affect daytime functioning and performance.