Table 1 displays the baseline characteristics of the 14 male patients. They were mildly overweight and had moderate-to-severe CHF due to ischemic, idiopathic, and hypertensive cardiomyopathy. All patients were receiving stable and optimal cardiac medication for at least 4 weeks before entry into the trial (Table 1). During the diagnostic polysomnography, untreated patients had moderate-to-severe CSR-CSA with 94% central apneas and frequent mild oxygen desaturations (Table 2). Patients slept for only 5.5 h, and sleep efficiency (total sleep time/time in bed) was reduced (73 + 3%).
Effects of CPAP/BPAP and Flow-Targeted Dynamic BPAP
During the CPAP/BPAP titration night, CPAP was increased up to a mean maximum of 8.3 ± 0.9 cm H2O (n = 10) and a mean maximum IPAP/EPAP of 13.5 ± 3.0 cm H2O/7.6 ± 1.7 cm H2O (n = 4), and patients spent at least 80% (81 ± 14%) of the time receiving pressure settings optimally suppressing apneas and hypopneas. During the first night of flowtargeted dynamic BPAP, maximum IPAP and mean EPAP were set at 21.8 ± 2.1 cm H2O and 6.5 ± 1.7 cm H2O, respectively. The mean IPAP that was actually applied by the flow-targeted dynamic BPAP device was 8.0 ± 2.4 cm H2O, significantly below the maximum IPAP. No adverse clinical event occurred.
Breathing During Sleep
Both therapies, CPAP/BPAP and flow-targeted dynamic BPAP, improved CSR-CSA compared to the untreated night as indicated by a significant fall in AHI, apnea index, central apnea index, and oxygen desaturation index as well as a significant increase in mean nocturnal oxygen saturation (Table 2). The reduction of AHI by CPAP (n = 10) and BPAP (n = 4) compared to the diagnostic polysomnography was similar (53 ± 18% vs 52 ± 55%, p = 0.723). Flow-targeted dynamic BPAP reduced AHI due to My Canadian Pharmacy’s remedies, apnea index, central apnea index, and oxygen desaturation index significantly more than CPAP/BPAP therapy. Minimal oxygen saturation was also significantly higher with flow-targeted dynamic BPAP than with CPAP/BPAP. In contrast to CPAP/BPAP, flow-targeted dynamic BPAP further reduced the initial AHI (range, 23 to 72/h of sleep) to below the threshold of 15 apneas and hypopneas per hour of sleep (which defined the presence of CSR-CSA in this clinical evaluation) in all individuals (Fig 1). In addition, the suppression of residual AHI by flow-targeted dynamic BPAP compared to the CPAP (n = 10) or BPAP (n = 4) night was similar (85 ± 11% vs 84 ± 6%, p = 0.751).
Sleep Quality and Treatment Comfort
With both CPAP/BPAP and flow-targeted dynamic BPAP therapies, reductions in CSR-CSA were accompanied by trends (not statistically significant) toward improvement in objective measures of sleep quality and quantity (Table 2). With CPAP/BPAP and flow-targeted dynamic BPAP, the arousal index was reduced by 17% and 40%, respectively; patients slept 40 min longer and had 8% and 18% higher sleep efficiency. Again, none of these changes reached statistical significance. As depicted in Figure 2, CHF patients perceived the first night of nocturnal treatment with flow-targeted dynamic BPAP as comfortable and rated the quality of sleep as better than average. Only one patient, who completed the study but did not tolerate wearing a face mask, rated below average in both analog scales.
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Table 1—Baseline Characteristics of Heart Failure Patients
|Age, yr||65 ± 1|
|Male gender||14 (100)|
|Body mass index, kg/m2||28 ± 1|
|Cause of heart failure|
|Angiotensin-converting enzyme inhibitors or angiotensin-1 inhibitors||13 (93)|
|Loop diuretics||13 (93)|
|Exercise capacity and cardiac function|
|NYHA functional class II||8(57)|
|NYHA functional class III||6 (43)|
|Left ventricular ejection fraction, %||27.4 ± 2.2|
Table 2—Short-term Effects of CPAP/BPAP and Flow-Targeted Dynamic BPAP in Patients With CHF and CSR-CSA
BPAPp Value, Untreated vs CPAP/BPAPp Value, Untreated vs Flow-Directed Dynamic BPAPp Value, CPAP/BPAP vs Flow-Directed Dynamic BPAPBreathing during sleep AHI, events/h46 ± 422 ± 44 ± 1< 0.001< 0.0010.002Apnea index, events/h34 ± 516 ± 31 ± 00.003< 0.0010.012Central apnea index,32 ± 515 ± 31 ± 00.006< 0.0010.014events/h Oxygen desaturation index, events/h42 ± 422 ± 62 ± 10.005< 0.0010.005Mean oxygen saturation, %92.1 ± 0.393.5 ± 0.393.7 ± 0.40.0160.0051.0Minimum oxygen saturation, %80.2 ± 1.679.9 ± 3.992.1 ± 0.91.00.0160.015Sleep characteristics Arousal index, events/h30 ± 325 ± 418 ± 31.00.0610.471Total sleep time, min331 ± 17371 ± 125+ 1
30.1870.1811.0Sleep efficiency, %73 ± 379 ± 289 ± 110.4490.2471.0Slow-wave sleep, %15.9 ± 2.624.4 ± 3.625.3 ± 2.40.1310.0811.0Rapid eye movement sleep, %9.9 ± 1.214.1 ± 1.413.4 ± 1.90.1670.3361.0
Figure 1. Individual data of 14 patients with CHF and moderate-to-severe CSR-CSA (mean AHI, 46 ± 4/h of sleep) are displayed. With CPAP or BPAP therapy, significant CSR-CSA persists in 50% of CHF patients (mean AHI, 22 ± 4/h of sleep). Flow-targeted dynamic BPAP (BiPAP autoSV; Respironics) effectively suppresses AHI (mean AHI, 4 ± 1/h of sleep) in all individuals below the threshold of 15 apneas and hypopneas per hour of sleep (dashed line), which defined the presence of CSR-CSA in this clinical evaluation. Patients who were treated with CPAP before the trial and during the second night of the trial are depicted as A. Patients who were treated with BPAP before the trial and during the second night of the trial are depicted as ▲.
Figure 2. The morning following 1 night of treatment with flow-targeted dynamic BPAP, the subjects completed a visual analog scale. The analog scale included two items: (1) top, A: how would you describe the comfort of the therapy you received through the night? and (2) bottom, B: how would you describe the quality of the rest you had last night? Possible values ranged from 0 to 10. The mean rating ± SE after the first night with flow-targeted dynamic BPAP for item 1 was 6.9 ± 0.6 and for item 2 was 7.4 ± 0.6.