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https://www.readbyqxmd.com/read/29123389/alveolar-capillary-reserve-during-exercise-in-patients-with-chronic-obstructive-pulmonary-disease
#1
Mehrdad Behnia, Courtney M Wheatley, Alberto Avolio, Bruce D Johnson
Background: Factors limiting exercise in patients with COPD are complex. With evidence for accelerated pulmonary vascular aging, destruction of alveolar-capillary bed, and hypoxic pulmonary vasoconstriction, the ability to functionally expand surface area during exercise may become a primary limitation. Purpose: To quantify measures of alveolar-capillary recruitment during exercise and the relationship to exercise capacity in a cohort of COPD patients. Methods: Thirty-two subjects gave consent (53% male, with mean ± standard deviation age 66±9 years, smoking 35±29 pack-years, and Global Initiative for Chronic Obstructive Lung Disease (GOLD) classification of 0-4: 2...
2017: International Journal of Chronic Obstructive Pulmonary Disease
https://www.readbyqxmd.com/read/29066588/effect-of-high-flow-nasal-cannula-on-expiratory-pressure-and-ventilation-in-infant-pediatric-and-adult-models
#2
Katie R Nielsen, Laura E Ellington, Alan J Gray, Larissa I Stanberry, Lincoln S Smith, Robert M DiBlasi
BACKGROUND: Heated and humidified high-flow nasal cannula (HFNC) is a widely used form of respiratory support; however, data regarding optimal flows for a given patient size or disease state are lacking. A comprehensive study of the physiologic effects of HFNC is needed to better understand the mechanisms of action. The objective of the current study was to quantify the effect of HFNC settings in age-specific, anatomically correct nasal airways and spontaneously breathing lung models...
October 24, 2017: Respiratory Care
https://www.readbyqxmd.com/read/29054325/use-of-ideal-alveolar-air-equations-and-corrected-end-tidal-pco2-to-estimate-arterial-pco2-and-physiological-dead-space-during-exercise-in-patients-with-heart-failure
#3
Erik H Van Iterson, Thomas P Olson
BACKGROUND: Arterial CO2 tension (PaCO2) and physiological dead space (VD) are not routinely measured during clinical cardiopulmonary exercise testing (CPET). Abnormal changes in PaCO2 accompanied by increased VD directly contribute to impaired exercise ventilatory function in heart failure (HF). Because arterial catheterization is not standard practice during CPET, this study tested the construct validity of PaCO2 and VD prediction models using 'ideal' alveolar air equations and basic ventilation and gas-exchangegas exchange measurements during CPET in HF...
October 7, 2017: International Journal of Cardiology
https://www.readbyqxmd.com/read/29051724/the-effect-of-low-frequency-physiological-correction-on-the-reproducibility-and-specificity-of-resting-state-fmri-metrics-functional-connectivity-alff-and-reho
#4
Ali M Golestani, Jonathan B Kwinta, Yasha B Khatamian, J Jean Chen
The resting-state fMRI (rs-fMRI) signal is affected by a variety of low-frequency physiological phenomena, including variations in cardiac-rate (CRV), respiratory-volume (RVT), and end-tidal CO2 (PETCO2). While these effects have become better understood in recent years, the impact that their correction has on the quality of rs-fMRI measurements has yet to be clarified. The objective of this paper is to investigate the effect of correcting for CRV, RVT and PETCO2 on the rs-fMRI measurements. Nine healthy subjects underwent a test-retest rs-fMRI acquisition using repetition times (TRs) of 2 s (long-TR) and 0...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/29051306/peripheral-chemosensitivity-is-not-blunted-during-2%C3%A2-h-of-thermoneutral-head-out-water-immersion-in-healthy-men-and-women
#5
James R Sackett, Zachary J Schlader, Suman Sarker, Christopher L Chapman, Blair D Johnson
Carbon dioxide (CO2) retention occurs during water immersion, but it is not known if peripheral chemosensitivity is altered during water immersion, which could contribute to CO2 retention. We tested the hypothesis that peripheral chemosensitivity to hypercapnia and hypoxia is blunted during 2 h of thermoneutral head out water immersion (HOWI) in healthy young adults. Peripheral chemosensitivity was assessed by the ventilatory, heart rate, and blood pressure responses to hypercapnia and hypoxia at baseline, 10, 60, 120 min, and post HOWI and a time-control visit (control)...
November 2017: Physiological Reports
https://www.readbyqxmd.com/read/29040312/end-tidal-carbon-dioxide-measurement-in-preterm-infants-with-low-birth-weight
#6
Hsin-Ju Lin, Ching-Tzu Huang, Hsiu-Feng Hsiao, Ming-Chou Chiang, Mei-Jy Jeng
OBJECTIVE: There are conflicting data regarding the use of end-tidal carbon dioxide (PetCO2) measurement in preterm infants. The aim of this study was to evaluate the effects of different dead space to tidal volume ratios (VD/VT) on the correlation between PetCO2 and arterial carbon dioxide pressure (PaCO2) in ventilated preterm infants with respiratory distress syndrome (RDS). METHODS: We enrolled ventilated preterm infants (with assist control mode or synchronous intermittent mandatory mode) with RDS who were treated with surfactant in this prospective study...
2017: PloS One
https://www.readbyqxmd.com/read/29029284/the-influence-of-co2-on-genioglossus-muscle-after-discharge-following-arousal-from-sleep-hypocapnia-and-genioglossus-muscle-after-discharge
#7
Jennifer M Cori, Peter D Rochford, Fergal J O'Donoghue, John Trinder, Amy S Jordan
Objectives: Ventilatory after-discharge (sustained elevation of ventilation following stimulus removal), occurs during sleep but not when hypocapnia is present. Genioglossus after-discharge also occurs during sleep, but CO2 effects have not been assessed. The relevance is that post-arousal after-discharge may protect against upper airway collapse. This study aimed to determine whether arousal elicits genioglossus after-discharge that persists into sleep, and whether it is influenced by CO2...
October 6, 2017: Sleep
https://www.readbyqxmd.com/read/29025898/aging-is-associated-with-increased-propensity-for-central-apnea-during-nrem-sleep
#8
Susmita Chowdhuri, Sukanya Pranathiageswaran, Hillary Loomis-King, Anan Salloum, M Safwan Badr
The reason for increased sleep disordered breathing with predominance of central apneas in the elderly is unknown. We hypothesized that the propensity to central apneas is increased in older adults, manifested by a reduced carbon-dioxide (CO2) reserve in older compared to young adults during non-REM (NREM) sleep. METHODS: 10 elderly and 15 young healthy adults underwent multiple brief trials of nasal noninvasive positive pressure ventilation during stable NREM sleep. Cessation of mechanical ventilation (MV) resulted in hypocapnic central apnea or hypopnea...
October 12, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28982946/role-of-bronchodilation-and-pattern-of-breathing-in-increasing-expiratory-flow-during-progressive-hypercapnia-in-chronic-obstructive-pulmonary-disease
#9
Kevin E Finucane, Bhajan Singh
Hypercapnia (HC) in-vitro relaxes airway smooth muscle; in-vivo it increases respiratory effort, tidal expiratory flows (V'exp), and, by decreasing inspiratory duration (Ti), increases elastic recoil pressure (Pel) via lung visco-elasticity; however, its effect on airway resistance is uncertain. We examined the contributions of bronchodilation, Ti and expiratory effort to increasing V'exp ̇with progressive HC in 10 COPD subjects, mean FEV1 53% predicted. Lung volumes (Vl), V'exp, esophageal pressure (Pes), Ti and end tidal PCO2 (PetCO2) were measured during 6 tidal breaths followed by an inspiratory capacity (IC), breathing air and at 3 levels of HC...
October 5, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28967593/measurement-of-cerebrovascular-reactivity-as-blood-oxygen-level-dependent-magnetic-resonance-imaging-signal-response-to-a-hypercapnic-stimulus-in-mechanically-ventilated-patients
#10
Lashmi Venkatraghavan, Julien Poublanc, Jay S Han, Olivia Sobczyk, Casey Rozen, Kevin Sam, James Duffin, David J Mikulis, Joseph A Fisher
BACKGROUND: Impaired cerebrovascular reactivity (CVR) is an important prognostic marker of stroke. Most measures of CVR lack (1) a reproducible vasoactive stimulus and (2) a high time and spatial resolution measure of cerebral blood flow (CBF), particularly for mechanically ventilated patients. The aim of our study was to investigate the feasibility of measuring CVR using sequential gas delivery circuit and gas blender for precise targeting of end-tidal PCO2 (PetCO2), and blood oxygen level-dependent magnetic resonance imaging (BOLD-MRI) signal as a surrogate of CBF, in mechanically ventilated patients...
September 26, 2017: Journal of Stroke and Cerebrovascular Diseases: the Official Journal of National Stroke Association
https://www.readbyqxmd.com/read/28912128/aging-modifies-the-effect-of-cardiac-output-on-middle-cerebral-artery-blood-flow-velocity
#11
Anne-Sophie G T Bronzwaer, Jasper Verbree, Wim J Stok, Mat J A P Daemen, Mark A van Buchem, Matthias J P van Osch, Johannes J van Lieshout
An association between cerebral blood flow (CBF) and cardiac output (CO) has been established in young healthy subjects. As of yet it is unclear how this association evolves over the life span. To that purpose, we continuously recorded mean arterial pressure (MAP; finger plethysmography), CO (pulse contour; CO-trek), mean blood flow velocity in the middle cerebral artery (MCAV; transcranial Doppler ultrasonography), and end-tidal CO2 partial pressure (PetCO2) in healthy young (19-27 years), middle-aged (51-61 years), and elderly subjects (70-79 years)...
September 2017: Physiological Reports
https://www.readbyqxmd.com/read/28855556/continuous-coloured-light-altered-human-brain-haemodynamics-and-oxygenation-assessed-by-systemic-physiology-augmented-functional-near-infrared-spectroscopy
#12
A J Metz, S D Klein, F Scholkmann, U Wolf
Exposure to artificial coloured light is unavoidable in our modern life, but we are only just beginning to understand the impact of coloured light on human physiology. The aim of the present study was to determine effects of coloured light exposure on human systemic and brain physiology using systemic physiology augmented functional near-infrared spectroscopy (SPA-fNIRS). We measured changes in haemoglobin concentrations and tissue oxygen saturation in the left and right prefrontal cortices (L-PFC, R-PFC) by fNIRS, and also recorded skin conductance (SC), partial pressure of end-tidal CO2 (PETCO2), and heart-rate variability variables...
August 30, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28843675/aerosol-furosemide-for-dyspnea-high-dose-controlled-delivery-does-not-improve-effectiveness
#13
Robert B Banzett, Richard M Schwartzstein, Robert W Lansing, Carl R O'Donnell
Published studies have shown great variability in response when aerosolized furosemide has been tested as a palliative treatment for dyspnea. We hypothesized that a higher furosemide dose with controlled aerosol administration would produce consistent dyspnea relief. We optimized deposition by controlling inspiratory flow (300-500mL/s) and tidal volume (15% predicted vital capacity) while delivering 3.4μm aerosol from either saline or 80mg of furosemide. We induced dyspnea in healthy subjects by varying inspired PCO2 while restricting minute ventilation...
August 24, 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28774953/cerebrovascular-and-ventilatory-responses-to-acute-normobaric-hypoxia-in-girls-and-women
#14
Laura E Morris, Daniela Flück, Philip N Ainslie, Ali M McManus
Physiological responses to hypoxia in children are incompletely understood. We aimed to characterize cerebrovascular and ventilatory responses to normobaric hypoxia in girls and women. Ten healthy girls (9.9 ± 1.7 years; mean ± SD; Tanner stage 1 and 2) and their mothers (43.9 ± 3.5 years) participated. Internal carotid (ICA) and vertebral artery (VA) velocity, diameter and flow (Duplex ultrasound) was recorded pre- and post-1 h of hypoxic exposure (FIO2 = 0.126;~4000 m) in a normobaric chamber...
August 2017: Physiological Reports
https://www.readbyqxmd.com/read/28760461/effect-of-dead-space-on-breathing-stability-at-exercise-in-hypoxia
#15
Eric Hermand, François J Lhuissier, Jean-Paul Richalet
Recent studies have shown that normal subjects exhibit periodic breathing when submitted to concomitant environmental (hypoxia) and physiological (exercise) stresses. A mathematical model including mass balance equations confirmed the short period of ventilatory oscillations and pointed out an important role of dead space in the genesis of these phenomena. Ten healthy subjects performed mild exercise on a cycloergometer in different conditions: rest/exercise, normoxia/hypoxia and no added dead space/added dead space (aDS)...
December 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28715240/the-effect-of-inspiratory-muscle-training-on-respiratory-variables-in-a-patient-with-ankylosing-spondylitis-a-case-report
#16
Marlon L Wong, Rachael G Anderson, Kelsey Garcia, Elissa M Housmann, Erin McHale, Gregory S Goldberger, Lawrence P Cahalin
Ankylosing Spondylitis (AS) presents with both musculoskeletal and cardiorespiratory pathophysiological manifestations. Inspiratory muscle training (IMT) may be a useful intervention to address deficits in respiratory and functional status. CASE DESCRIPTION: A 25-year-old male with AS initially sought treatment for low back and right hip pain, but 7 weeks of IMT was also provided due to abnormal respiratory performance. OUTCOMES: At baseline, the patient presented with a resting respiratory rate (RR) of 14...
July 17, 2017: Physiotherapy Theory and Practice
https://www.readbyqxmd.com/read/28705998/is-normobaric-hypoxia-an-effective-treatment-for-sustaining-previously-acquired-altitude-acclimatization
#17
Beth A Beidleman, Charles S Fulco, Bruce S Cadarette, Allen Cymerman, Mark J Buller, Roy M Salgado, Alexander M Posch, Janet E Staab, Ingrid V Sils, Beau R Yurkevicius, Adam J Luippold, Alexander P Welles, Stephen R Muza
This study examined whether normobaric hypoxia (NH) treatment is more efficacious for sustaining high altitude (HA) acclimatization during re-introduction to altitude (RA) than no treatment at all. Seventeen sea level (SL) residents (age=23±6yrs; mean±SE) completed in the following order: 1)4d of SL testing, 2)12d of high altitude (HA) acclimatization at 4300m, 3)12d at SL post HA acclimatization (Post) where each received either NH (n=9;FiO2=0.122) or Sham (n=8;FiO2=0.207) treatment, and 4)24-h re-introduction to 4300m altitude (RA) in a hypobaric chamber...
July 13, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28684586/exposure-to-intermittent-hypoxia-and-sustained-hypercapnia-reduces-therapeutic-cpap-in-participants-with-obstructive-sleep-apnea
#18
Mohamad El-Chami, Sukhesh Sudan, Ho-Sheng Lin, Jason H Mateika
Our purpose was to determine whether exposure to mild intermittent hypoxia leads to a reduction in the therapeutic continuous positive airway pressure required to eliminate breathing events. Ten male participants were treated with twelve 2-min episodes of hypoxia ([Formula: see text] ≈50 mmHg) separated by 2-min intervals of normoxia in the presence of [Formula: see text] that was sustained 3 mmHg above baseline. During recovery from the last episode, the positive airway pressure was reduced in a stepwise fashion until flow limitation was evident...
October 1, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28656353/effect-of-low-tidal-volume-with-peep-on-respiratory-function-in-infants-undergoing-one-lung-ventilation
#19
Jing Liu, Xinfang Liao, Yongle Li, Hui Luo, Weijian Huang, Lingli Peng, Qin Fang, Zurong Hu
BACKGROUND: An increasing number of studies have shown that low tidal volume (TV) with positive end-expiratory pressure (PEEP) offers lung protection during one-lung ventilation (OLV). Considering the unique physiological characteristics of infants, we aimed to determine the feasibility and effect of low TV with PEEP in infants undergoing OLV during thoracoscopy. PATIENTS AND METHODS: We randomized 60 infants to a conventional group (group I: TV, 8-10 ml/kg; RR, 23-45 bpm; PEEP, 0 cmH2O) or a low TV with PEEP group (group II: TV, 5-7 ml/kg; RR, 23-45 bpm; PEEP, 4-6 cmH2O)...
June 27, 2017: Der Anaesthesist
https://www.readbyqxmd.com/read/28642340/cardiovascular-and-cerebral-hemodynamics-during-exercise-and-recovery-in-obese-individuals-as-a-function-of-their-fitness-status
#20
Mathieu Gayda, Gabriel Lapierre, Olivier Dupuy, Sarah Fraser, Louis Bherer, Martin Juneau, Vincent Gremeaux, Anil Nigam
The aim of this study was to compare cardiovascular hemodynamics and cerebral oxygenation/perfusion (COP) during and after maximal incremental exercise in obese individuals according to their aerobic fitness versus age-matched healthy controls (AMHC). Fifty-four middle-aged obese (OB) and 16 AMHC were recruited. Maximal cardiopulmonary function (gas exchange analysis), cardiac hemodynamics (impedance cardiography), and left frontal COP (near-infrared spectroscopy: NIRS) were measured continuously during a maximal incremental ergocycle test...
June 2017: Physiological Reports
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