Publications by authors named "J Alberto Neder"

253 Publications

Exertional ventilation/carbon dioxide output relationship in COPD: from physiological mechanisms to clinical applications.

Eur Respir Rev 2021 Sep 15;30(161). Epub 2021 Sep 15.

Respiratory Investigation Unit and Laboratory of Clinical Exercise Physiology, Queen's University and Kingston General Hospital, Kingston, ON, Canada.

There is well established evidence that the minute ventilation (')/carbon dioxide output (' ) relationship is relevant to a number of patient-related outcomes in COPD. In most circumstances, an increased '/' reflects an enlarged physiological dead space ("wasted" ventilation), although alveolar hyperventilation (largely due to increased chemosensitivity) may play an adjunct role, particularly in patients with coexistent cardiovascular disease. The '/' nadir, in particular, has been found to be an important predictor of dyspnoea and poor exercise tolerance, even in patients with largely preserved forced expiratory volume in 1 s. As the disease progresses, a high nadir might help to unravel the cause of disproportionate breathlessness. When analysed in association with measurements of dynamic inspiratory constraints, a high '/' is valuable to ascertain a role for the "lungs" in limiting dyspnoeic patients. Regardless of disease severity, cardiocirculatory (heart failure and pulmonary hypertension) and respiratory (lung fibrosis) comorbidities can further increase '/' A high '/' is a predictor of poor outcome in lung resection surgery, adding value to resting lung hyperinflation in predicting all-cause and respiratory mortality across the spectrum of disease severity. Considering its potential usefulness, the '/' should be valued in the clinical management of patients with COPD.
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http://dx.doi.org/10.1183/16000617.0190-2020DOI Listing
September 2021

Mechanisms of Exertional Dyspnea in Patients with Mild COPD and a Low Resting DL.

COPD 2021 Sep 8:1-10. Epub 2021 Sep 8.

Respiratory Investigation Unit, Department of Medicine, Queen's University, and Kingston Health Sciences Centre, Kingston, Ontario, Canada.

Patients with mild chronic obstructive pulmonary disease (COPD) and lower resting diffusing capacity for carbon monoxide (DL) often report troublesome dyspnea during exercise although the mechanisms are not clear. We postulated that in such individuals, exertional dyspnea is linked to relatively high inspiratory neural drive (IND) due, in part, to the effects of reduced ventilatory efficiency. This cross-sectional study included 28 patients with GOLD I COPD stratified into two groups with ( = 15) and without ( = 13) DL less than the lower limit of normal (
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http://dx.doi.org/10.1080/15412555.2021.1932782DOI Listing
September 2021

Sleep quality and architecture in COPD: the relationship with lung function abnormalities.

J Bras Pneumol 2021 19;47(3):e20200612. Epub 2021 Jul 19.

. Division of Respiratory & Sleep Medicine, Department of Medicine, Queen's University, Kingston (ON) Canada.

Objective: Impaired respiratory mechanics and gas exchange may contribute to sleep disturbance in patients with COPD. We aimed to assess putative associations of different domains of lung function (airflow limitation, lung volumes, and gas exchange efficiency) with polysomnography (PSG)-derived parameters of sleep quality and architecture in COPD.

Methods: We retrospectively assessed data from COPD 181 patients ≥ 40 years of age who underwent spirometry, plethysmography, and overnight PSG. Univariate and multivariate linear regression models predicted sleep efficiency (total sleep time/total recording time) and other PSG-derived parameters that reflect sleep quality.

Results: The severity of COPD was widely distributed in the sample (post-bronchodilator FEV1 ranging from 25% to 128% of predicted): mild COPD (40.3%), moderate COPD (43.1%), and severe-very severe COPD (16.6%). PSG unveiled a high proportion of obstructive sleep apnea (64.1%) and significant nocturnal desaturation (mean pulse oximetry nadir = 82.2% ± 6.9%). After controlling for age, sex, BMI, apnea-hypopnea index, nocturnal desaturation, comorbidities, and psychotropic drug prescription, FEV1/FVC was associated with sleep efficiency (β = 25.366; R2 = 14%; p < 0.001), whereas DLCO predicted sleep onset latency (β = -0.314; R2 = 13%; p < 0.001) and rapid eye movement sleep time/total sleep time in % (β = 0.085; R2 = 15%; p = 0.001).

Conclusions: Pulmonary function variables reflecting severity of airflow and gas exchange impairment, adjusted for some potential confounders, were weakly related to PSG outcomes in COPD patients. The direct contribution of the pathophysiological hallmarks of COPD to objectively measured parameters of sleep quality seems to be less important than it was previously assumed.
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http://dx.doi.org/10.36416/1806-3756/e20200612DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8332731PMC
August 2021

Editorial: Clinical Cardiopulmonary Exercise Testing.

Front Physiol 2021 28;12:711505. Epub 2021 Jun 28.

Respiratory Investigation Unit and the Laboratory of Clinical Exercise Physiology, Queen's University and Kingston Health Sciences Centre, Kingston, ON, Canada.

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http://dx.doi.org/10.3389/fphys.2021.711505DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8273375PMC
June 2021

Proportional Assist Ventilation Improves Leg Muscle Reoxygenation After Exercise in Heart Failure With Reduced Ejection Fraction.

Front Physiol 2021 21;12:685274. Epub 2021 Jun 21.

Pulmonary Function and Clinical Exercise Physiology Unit, Division of Respiratory Diseases, Department of Medicine, Federal University of Sao Paulo (UNIFESP), São Paulo, Brazil.

Background: Respiratory muscle unloading through proportional assist ventilation (PAV) may enhance leg oxygen delivery, thereby speeding off-exercise oxygen uptake ( ) kinetics in patients with heart failure with reduced left ventricular ejection fraction (HFrEF).

Methods: Ten male patients (HFrEF = 26 ± 9%, age 50 ± 13 years, and body mass index 25 ± 3 kg m) underwent two constant work rate tests at 80% peak of maximal cardiopulmonary exercise test to tolerance under PAV and sham ventilation. Post-exercise kinetics of , vastus lateralis deoxyhemoglobin ([deoxy-Hb + Mb]) by near-infrared spectroscopy, and cardiac output (Q ) by impedance cardiography were assessed.

Results: PAV prolonged exercise tolerance compared with sham (587 ± 390 s vs. 444 ± 296 s, respectively; = 0.01). PAV significantly accelerated recovery ( = 56 ± 22 s vs. 77 ± 42 s; < 0.05), being associated with a faster decline in Δ[deoxy-Hb + Mb] and Q compared with sham ( = 31 ± 19 s vs. 42 ± 22 s and 39 ± 22 s vs. 78 ± 46 s, < 0.05). Faster off-exercise decrease in Q with PAV was related to longer exercise duration ( = -0.76; < 0.05).

Conclusion: PAV accelerates the recovery of central hemodynamics and muscle oxygenation in HFrEF. These beneficial effects might prove useful to improve the tolerance to repeated exercise during cardiac rehabilitation.
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http://dx.doi.org/10.3389/fphys.2021.685274DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8255967PMC
June 2021
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