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- Biselli, P. J. C., et al.
(författare)
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Nasal high-flow therapy reduces work of breathing compared with oxygen during sleep in COPD and smoking controls: a prospective observational study
- 2017
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Ingår i: Journal of Applied Physiology. - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 122:1, s. 82-88
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Tidskriftsartikel (refereegranskat)abstract
- Patients with chronic obstructive pulmonary disease (COPD) endure excessive resistive and elastic loads leading to chronic respiratory failure. Oxygen supplementation corrects hypoxemia but is not expected to reduce mechanical loads. Nasal high-flow (NHF) therapy supports breathing by reducing dead space, but it is unclear how it affects mechanical loads of patients with COPD. The objective of this study was to compare the effects of low-flow oxygen and NHF therapy on ventilation and work of breathing (WOB) in patients with COPD and controls during sleep. Patients with COPD (n = 12) and controls (n = 6) were recruited and submitted to polysomnography to measure sleep parameters and ventilation in response to administration of oxygen and NHF. A subset of six patients also had an esophageal catheter inserted for the purpose of measuring WOB. Patients with COPD had similar minute ventilation (V-E) but lower tidal volumes than matched controls. With oxygen, SaO(2) was increased and V-E was reduced in both controls and patients with COPD, but there was an increase in transcutaneous CO2 levels. NHF produced a greater reduction in V-E and was associated with a reduction in CO2 levels. Although NHF halved WOB, oxygen produced only a minor reduction in this parameter. We conclude that oxygen produced little change in WOB, which was associated with CO2 elevations. On the other hand, NHF produced a large reduction in V-E and WOB with a concomitant decrease in CO2 levels. Our data indicate that NHF improves alveolar ventilation during sleep compared with oxygen and room air in patients with COPD and therefore can decrease their cost of breathing. NEW & NOTEWORTHY Nasal high-flow (NHF) therapy can support ventilation in patients with chronic obstructive pulmonary disease during sleep by decreasing the work of breathing and improving CO2 levels. On the other hand, oxygen supplementation corrects hypoxemia, but it produces only a minimal reduction in work of breathing and is associated with increased CO2 levels. Therefore, NHF can be a useful method to assist ventilation in patients with increased respiratory mechanical loads.
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- Fricke, K., et al.
(författare)
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Nasal high flow, but not supplemental O-2, reduces peripheral vascular sympathetic activity during sleep in COPD patients
- 2018
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Ingår i: International Journal of Chronic Obstructive Pulmonary Disease. - 1178-2005. ; 13, s. 3635-3643
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Patients with COPD have increased respiratory loads and altered blood gases, both of which affect vascular function and sympathetic activity. Sleep, particularly rapid eye movement (REM) sleep, is known to exacerbate hypoxia and respiratory loads. Therefore, we hypothesize that nasal high flow (NHF), which lowers ventilatory loads, reduces sympathetic activity during sleep and that this effect depends on COPD severity. Methods: We performed full polysomnography in COPD patients (n=17; FEV1, 1.6 +/- 0.6 L) and in matched controls (n=8). Participants received room air (RA) at baseline and single night treatment with O-2 (2 L/min) and NHF (20 L/min) in a random order. Finger pulse wave amplitude (PWA), a measure of vascular sympathetic tone, was assessed by photoplethysmography. Autonomic activation (AA) events were defined as PWA attenuation >= 30% and indexed per hour for sleep stages (AA index [AAI]) at RA, NHF, and O-2). Results: In COPD, sleep apnea improved following O-2 (REM-apnea hypopnea index [AHI] with RA, O-2, and NHF: 18.6 +/- 20.9, 12.7 +/- 18.1, and 14.4 +/- 19.8, respectively; P=0.04 for O-2 and P=0.06 for NHF). REM-AAI was reduced only following NHF in COPD patients (AAI-RA, 21.5 +/- 18.4 n/h and AAI-NHF, 9.9 +/- 6.8 n/h, P=0.02) without changes following O-2 (NFIF-O-2 difference, P=0.01). REM-AAI reduction was associated with lung function expressed as FEV1 and FVC (FEV1: r=-0.59, P=0.001; FEV1/FVC: r=-0.52 and P=0.007). Conclusion: NHF but not elevated oxygenation reduces peripheral vascular sympathetic activity in COPD patients during REM sleep. Sympathetic off-loading by NHF, possibly related to improved breathing mechanics, showed a strong association with COPD severity.
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| 4. |
- Biselli, P., et al.
(författare)
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Reductions in dead space ventilation with nasal high flow depend on physiological dead space volume: metabolic hood measurements during sleep in patients with COPD and controls
- 2018
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Ingår i: European Respiratory Journal. - : European Respiratory Society (ERS). - 0903-1936 .- 1399-3003. ; 51:5
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Tidskriftsartikel (refereegranskat)abstract
- Nasal high flow (NHF) reduces minute ventilation and ventilatory loads during sleep but the mechanisms are not clear. We hypothesised NHF reduces ventilation in proportion to physiological but not anatomical dead space. 11 subjects (five controls and six chronic obstructive pulmonary disease (COPD) patients) underwent polysomnography with transcutaneous carbon dioxide (CO2) monitoring under a metabolic hood. During stable non-rapid eye movement stage 2 sleep, subjects received NHF (20 L center dot min(-1)) intermittently for periods of 5-10 min. We measured CO2 production and calculated dead space ventilation. Controls and COPD patients responded similarly to NHF. NHF reduced minute ventilation (from 5.6 +/- 0.4 to 4.8 +/- 0.4 L center dot min(-1); p< 0.05) and tidal volume (from 0.34 +/- 0.03 to 0.3 +/- 0.03 L; p< 0.05) without a change in energy expenditure, transcutaneous CO2 or alveolar ventilation. There was a significant decrease in dead space ventilation (from 2.5 +/- 0.4 to 1.6 +/- 0.4 L center dot min(-1); p< 0.05), but not in respiratory rate. The reduction in dead space ventilation correlated with baseline physiological dead space fraction (r(2)=0.36; p< 0.05), but not with respiratory rate or anatomical dead space volume. During sleep, NHF decreases minute ventilation due to an overall reduction in dead space ventilation in proportion to the extent of baseline physiological dead space fraction.
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- Villalaín, C., et al.
(författare)
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Diagnostic accuracy of prenatal ultrasound in coarctation of aorta : systematic review and individual participant data meta-analysis
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Ingår i: Ultrasound in Obstetrics and Gynecology. - 0960-7692.
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Forskningsöversikt (refereegranskat)abstract
- Objective: To determine the diagnostic accuracy of prenatal ultrasound in detecting coarctation of the aorta (CoA). Methods: An individual participant data meta-analysis was performed to report on the strength of association and diagnostic accuracy of different ultrasound signs in detecting CoA prenatally. MEDLINE, EMBASE and CINAHL were searched for studies published between January 2000 and November 2021. Inclusion criteria were fetuses with suspected isolated CoA, defined as ventricular and/or great vessel disproportion with right dominance on ultrasound assessment. Individual participant-level data were obtained by two leading teams. PRISMA-IPD and PRISMA-DTA guidelines were used for extracting data, and the QUADAS-2 tool was used for assessing quality and applicability. The reference standard was CoA, defined as narrowing of the aortic arch, diagnosed after birth. The most commonly evaluated parameters on ultrasound, both in B-mode and on Doppler, constituted the index test. Summary estimates of sensitivity, specificity, diagnostic odds ratio (DOR) and likelihood ratios were computed using the hierarchical summary receiver-operating-characteristics model. Results: The initial search yielded 72 studies, of which 25 met the inclusion criteria. Seventeen studies (640 fetuses) were included. On random-effects logistic regression analysis, tricuspid valve/mitral valve diameter ratio > 1.4 and > 1.6, aortic isthmus/arterial duct diameter ratio < 0.7, hypoplastic aortic arch (all P < 0.001), aortic isthmus diameter Z-score of < −2 in the sagittal (P = 0.003) and three-vessel-and-trachea (P < 0.001) views, pulmonary artery/ascending aorta diameter ratio > 1.4 (P = 0.048) and bidirectional flow at the foramen ovale (P = 0.012) were independently associated with CoA. Redundant foramen ovale was inversely associated with CoA (P = 0.037). Regarding diagnostic accuracy, tricuspid valve/mitral valve diameter ratio > 1.4 had a sensitivity of 72.6% (95% CI, 48.2–88.3%), specificity of 65.4% (95% CI, 46.9–80.2%) and DOR of 5.02 (95% CI, 1.82–13.9). The sensitivity and specificity values were, respectively, 75.0% (95% CI, 61.1–86.0%) and 39.7% (95% CI, 27.0–53.4%) for pulmonary artery/ascending aorta diameter ratio > 1.4, 47.8% (95% CI, 14.6–83.0%) and 87.6% (95% CI, 27.3–99.3%) for aortic isthmus diameter Z-score of < –2 in the sagittal view and 74.1% (95% CI, 58.0–85.6%) and 62.0% (95% CI, 41.6–78.9%) for aortic isthmus diameter Z-score of < –2 in the three-vessel-and-trachea view. Hypoplastic aortic arch had a sensitivity of 70.0% (95% CI, 42.0–88.6%), specificity of 91.3% (95% CI, 78.6–96.8%) and DOR of 24.9 (95% CI, 6.18–100). The diagnostic yield of prenatal ultrasound in detecting CoA did not change significantly when considering multiple categorical parameters. Five of the 11 evaluated continuous parameters were independently associated with CoA (all P < 0.001) but all had low-to-moderate diagnostic yield. Conclusions: Several prenatal ultrasound parameters are associated with an increased risk for postnatal CoA. However, diagnostic accuracy is only moderate, even when combinations of parameters are considered.
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