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https://www.readbyqxmd.com/read/28966145/how-important-is-the-co2-chemoreflex-for-the-control-of-breathing-environmental-and-evolutionary-considerations
#1
Joseph M Santin
Haldane and Priestley (1905) discovered that the ventilatory control system is highly sensitive to CO2. This "CO2 chemoreflex" has been interpreted to dominate control of resting arterial PCO2/pH (PaCO2/pHa) by monitoring PaCO2/pHa and altering ventilation through negative feedback. However, PaCO2/pHa varies little in mammals as ventilation tightly couples to metabolic demands, which may minimize chemoreflex control of PaCO2. The purpose of this synthesis is to (1) interpret data from experimental models with meager CO2 chemoreflexes to infer their role in ventilatory control of steady-state PaCO2, and (2) identify physiological causes of respiratory acidosis occurring normally across vertebrate classes...
September 28, 2017: Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology
https://www.readbyqxmd.com/read/28877974/exertional-dyspnoea-in-pulmonary-arterial-hypertension
#2
Daniel Dumitrescu, Olivier Sitbon, Jason Weatherald, Luke S Howard
Dyspnoea is a principal presenting symptom in pulmonary arterial hypertension (PAH), and often the most distressing. The pathophysiology of PAH is relatively well understood, with the primary abnormality of pulmonary vascular disease resulting in a combination of impaired cardiac output on exercise and abnormal gas exchange, both contributing to increased ventilatory drive. However, increased ventilatory drive is not the sole explanation for the complex neurophysiological and neuropsychological symptom of dyspnoea, with other significant contributions from skeletal muscle reflexes, respiratory muscle function, and psychological and emotional status...
September 30, 2017: European Respiratory Review: An Official Journal of the European Respiratory Society
https://www.readbyqxmd.com/read/28828362/tidal-volume-in-acute-respiratory-distress-syndrome-how-best-to-select-it
#3
REVIEW
Michele Umbrello, Antonella Marino, Davide Chiumello
Mechanical ventilation is the type of organ support most widely provided in the intensive care unit. However, this form of support does not constitute a cure for acute respiratory distress syndrome (ARDS), as it mainly works by buying time for the lungs to heal while contributing to the maintenance of vital gas exchange. Moreover, it can further damage the lung, leading to the development of a particular form of lung injury named ventilator-induced lung injury (VILI). Experimental evidence accumulated over the last 30 years highlighted the factors associated with an injurious form of mechanical ventilation...
July 2017: Annals of Translational Medicine
https://www.readbyqxmd.com/read/28808320/carotid-body-mediated-chemoreflex-drive-in-the-setting-of-low-and-high-output-heart-failure
#4
Rodrigo Del Rio, David C Andrade, Camilo Toledo, Hugo S Diaz, Claudia Lucero, Alexis Arce-Alvarez, Noah J Marcus, Harold D Schultz
Enhanced carotid body (CB) chemoreflex function is strongly related to cardiorespiratory disorders and disease progression in heart failure (HF). The mechanisms underlying CB sensitization during HF are not fully understood, however previous work indicates blood flow per se can affect CB function. Then, we hypothesized that the CB-mediated chemoreflex drive will be enhanced only in low output HF but not in high output HF. Myocardial infarcted rats and aorto-caval fistulated rats were used as a low output HF model (MI-CHF) and as a high output HF model (AV-CHF), respectively...
August 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28774953/cerebrovascular-and-ventilatory-responses-to-acute-normobaric-hypoxia-in-girls-and-women
#5
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/28757365/assessing-chemoreflexes-and-oxygenation-in-the-context-of-acute-hypoxia-implications-for-field-studies
#6
Jamie R Pfoh, Craig D Steinback, Emily R Vanden Berg, Christina D Bruce, Trevor A Day
Carotid chemoreceptors detect changes in PO2 and elicit a peripheral respiratory chemoreflex (PCR). The PCR can be tested through a transient hypoxic ventilatory response test (TT-HVR), which may not be safe nor feasible at altitude. We characterized a transient hyperoxic ventilatory withdrawal test in the setting of steady-state normobaric hypoxia (13.5-14% FIO2) and compared it to a TT-HVR and a steady-state poikilocapnic hypoxia test, within-individuals. No PCR test magnitude was correlated with any other test, nor was any test magnitude correlated with oxygenation while in steady-state hypoxia...
December 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28750686/carbon-dioxide-narcosis-due-to-inappropriate-oxygen-delivery-a-case-report
#7
Thomas Herren, Eva Achermann, Thomas Hegi, Adrian Reber, Max Stäubli
BACKGROUND: Oxygen delivery to patients with chronic obstructive pulmonary disease may be challenging because of their potential hypoxic ventilatory drive. However, some oxygen delivery systems such as non-rebreathing face masks with an oxygen reservoir bag require high oxygen flow for adequate oxygenation and to avoid carbon dioxide rebreathing. CASE PRESENTATION: A 72-year-old Caucasian man with severe chronic obstructive pulmonary disease was admitted to the emergency department because of worsening dyspnea and an oxygen saturation of 81% measured by pulse oximetry...
July 28, 2017: Journal of Medical Case Reports
https://www.readbyqxmd.com/read/28730724/dynamic-loop-gain-increases-upon-adopting-the-supine-body-position-during-sleep-in-patients-with-obstructive-sleep-apnoea
#8
Simon A Joosten, Shane A Landry, Scott A Sands, Philip I Terrill, Dwayne Mann, Christopher Andara, Elizabeth Skuza, Anthony Turton, Philip Berger, Garun S Hamilton, Bradley A Edwards
BACKGROUND AND OBJECTIVE: Obstructive sleep apnoea (OSA) is typically worse in the supine versus lateral sleeping position. One potential factor driving this observation is a decrease in lung volume in the supine position which is expected by theory to increase a key OSA pathogenic factor: dynamic ventilatory control instability (i.e. loop gain). We aimed to quantify dynamic loop gain in OSA patients in the lateral and supine positions, and to explore the relationship between change in dynamic loop gain and change in lung volume with position...
November 2017: Respirology: Official Journal of the Asian Pacific Society of Respirology
https://www.readbyqxmd.com/read/28687484/participation-of-locus-coeruleus-in-breathing-control-in-female-rats
#9
Débora de Carvalho, Luis Gustavo A Patrone, Danuzia A Marques, Mariane C Vicente, Raphael E Szawka, Janete A Anselmo-Franci, Kênia C Bícego, Luciane H Gargaglioni
Several evidences indicate that the locus coeruleus (LC) is involved in central chemoreception responding to CO2/pH and displaying a high percentage of chemosensitive neurons (>80%). However, there are no studies about the LC-mediated hypercapnic ventilation performed in females. Therefore, we assessed the role of noradrenergic LC neurons in non-ovariectomized (NOVX), ovariectomized (OVX) and estradiol (E2)-treated ovariectomized (OVX+E2) rats in respiratory response to hypercapnia, using a 6-hydroxydopamine (6-OHDA) - lesion model...
July 4, 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28683763/new-setting-of-neurally-adjusted-ventilatory-assist-for-noninvasive-ventilation-by-facial-mask-a-physiologic-study
#10
Federico Longhini, Chun Pan, Jianfeng Xie, Gianmaria Cammarota, Andrea Bruni, Eugenio Garofalo, Yi Yang, Paolo Navalesi, Haibo Qiu
BACKGROUND: Noninvasive ventilation (NIV) is generally delivered using pneumatically-triggered and cycled-off pressure support (PSP) through a mask. Neurally adjusted ventilatory assist (NAVA) is the only ventilatory mode that uses a non-pneumatic signal, i.e., diaphragm electrical activity (EAdi), to trigger and drive ventilator assistance. A specific setting to generate neurally controlled pressure support (PSN) was recently proposed for delivering NIV by helmet. We compared PSN with PSP and NAVA during NIV using a facial mask, with respect to patient comfort, gas exchange, and patient-ventilator interaction and synchrony...
July 7, 2017: Critical Care: the Official Journal of the Critical Care Forum
https://www.readbyqxmd.com/read/28673877/remifentanil-effects-on-respiratory-drive-and-timing-during-pressure-support-ventilation-and-neurally-adjusted-ventilatory-assist
#11
Roberta Costa, Paolo Navalesi, Gianmaria Cammarota, Federico Longhini, Giorgia Spinazzola, Flora Cipriani, Giuliano Ferrone, Olimpia Festa, Massimo Antonelli, Giorgio Conti
We assessed the effects of varying doses of remifentanil on respiratory drive and timing in patients receiving Pressure Support Ventilation (PSV) and Neurally Adjusted Ventilatory Assist (NAVA). Four incrementing remifentanil doses were randomly administered to thirteen intubated patients (0.03, 0.05, 0.08, and 0.1μg·Kg(-1)·min(-)1) during both PSV and NAVA. We measured the patient's (Ti/Ttotneu) and ventilator (Ti/Ttotmec) duty cycle, the Electrical Activity of the Diaphragm (EAdi), the inspiratory (Delaytrinsp) and expiratory (Delaytrexp) trigger delays and the Asynchrony Index (AI)...
July 1, 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28665692/excess-ventilation-in-copd-heart-failure-overlap-implications-for-dyspnea-and-exercise-intolerance
#12
Alcides Rocha, Flavio F Arbex, Priscilla A Sperandio, Aline Souza, Ligia Biazzim, Frederico Mancuso, Danilo C Berton, Bruno Hochhegger, Maria Clara N Alencar, Luiz E Nery, Denis E O'Donnell, J Alberto Neder
BACKGROUND: An increased ventilatory response to exertional metabolic demand (high ventilation (⩒E)-carbon dioxide output (⩒CO2) relationship) is a common finding in patients with coexistent COPD-heart failure. We aimed to determine the mechanisms underlying high ⩒E-⩒CO2 and its impact on operating lung volumes, dyspnea and exercise tolerance in these patients. METHODS: Twenty-two ex-smokers with combined COPD and heart failure with reduced left ventricular ejection fraction (LVEF) undertook, after careful treatment optimization, a progressive cycle exercise test with capillary (c) blood gas collection...
June 30, 2017: American Journal of Respiratory and Critical Care Medicine
https://www.readbyqxmd.com/read/28623885/monitoring-the-electric-activity-of-the-diaphragm-during-noninvasive-positive-pressure-ventilation-a-case-report
#13
Fabia Diniz-Silva, Anna Miethke-Morais, Adriano M Alencar, Henrique T Moriya, Pedro Caruso, Eduardo L V Costa, Juliana C Ferreira
BACKGROUND: In patients with post-extubation respiratory distress, delayed reintubation may worsen clinical outcomes. Objective measures of extubation failure at the bedside are lacking, therefore clinical parameters are currently used to guide the need of reintubation. Electrical activity of the diaphragm (EAdi) provides clinicians with valuable, objective information about respiratory drive and could be used to monitor respiratory effort. CASE PRESENTATION: We describe the case of a patient with Chronic Obstructive Pulmonary Disease (COPD), from whom we recorded EAdi during four different ventilatory conditions: 1) invasive mechanical ventilation, 2) spontaneous breathing trial (SBT), 3) unassisted spontaneous breathing, and 4) Noninvasive Positive Pressure Ventilation (NPPV)...
June 17, 2017: BMC Pulmonary Medicine
https://www.readbyqxmd.com/read/28587125/equine-welfare-during-exercise-an-evaluation-of-breathing-breathlessness-and-bridles
#14
REVIEW
David J Mellor, Ngaio J Beausoleil
Horses engaged in strenuous exercise display physiological responses that approach the upper functional limits of key organ systems, in particular their cardiorespiratory systems. Maximum athletic performance is therefore vulnerable to factors that diminish these functional capacities, and such impairment might also lead to horses experiencing unpleasant respiratory sensations, i.e., breathlessness. The aim of this review is to use existing literature on equine cardiorespiratory physiology and athletic performance to evaluate the potential for various types of breathlessness to occur in exercising horses...
May 26, 2017: Animals: An Open Access Journal From MDPI
https://www.readbyqxmd.com/read/28569280/respiratory-dysfunction-in-parkinson-s-disease
#15
D Forsyth, K M Torsney
Respiratory dysfunction has been associated with Parkinson's disease since it was first described in 1817. The respiratory symptoms observed in Parkinson's disease patients vary greatly. Most patients remain asymptomatic, whereas others present with acute shortness of breath and even stridor. In August 2016, an electronic literature search was conducted using PubMed and Google Scholar. Results were screened and studies reporting on respiratory dysfunction associated with Parkinson's disease were included. Respiratory dysfunction is due to a combination of factors including restrictive changes, upper airway obstruction, abnormal ventilatory drive and response to medications...
March 2017: Journal of the Royal College of Physicians of Edinburgh
https://www.readbyqxmd.com/read/28554331/outcome-of-acute-respiratory-distress-syndrome-in-university-and-non-university-hospitals-in-germany
#16
Konstantinos Raymondos, Tamme Dirks, Michael Quintel, Ulrich Molitoris, Jörg Ahrens, Thorben Dieck, Kai Johanning, Dietrich Henzler, Rolf Rossaint, Christian Putensen, Hermann Wrigge, Ralph Wittich, Maximilian Ragaller, Thomas Bein, Martin Beiderlinden, Maxi Sanmann, Christian Rabe, Jörn Schlechtweg, Monika Holler, Fernando Frutos-Vivar, Andres Esteban, Hartmut Hecker, Simone Rosseau, Vera von Dossow, Claudia Spies, Tobias Welte, Siegfried Piepenbrock, Steffen Weber-Carstens
BACKGROUND: This study investigates differences in treatment and outcome of ventilated patients with acute respiratory distress syndrome (ARDS) between university and non-university hospitals in Germany. METHODS: This subanalysis of a prospective, observational cohort study was performed to identify independent risk factors for mortality by examining: baseline factors, ventilator settings (e.g., driving pressure), complications, and care settings-for example, case volume of ventilated patients, size/type of intensive care unit (ICU), and type of hospital (university/non-university hospital)...
May 30, 2017: Critical Care: the Official Journal of the Critical Care Forum
https://www.readbyqxmd.com/read/28515334/central-acting-therapeutics-alleviate-respiratory-weakness-caused-by-heart-failure-induced-ventilatory-overdrive
#17
Andrew J Foster, Mathew J Platt, Jason S Huber, Ashley L Eadie, Alicia M Arkell, Nadya Romanova, David C Wright, Todd E Gillis, Coral L Murrant, Keith R Brunt, Jeremy A Simpson
Diaphragmatic weakness is a feature of heart failure (HF) associated with dyspnea and exertional fatigue. Most studies have focused on advanced stages of HF, leaving the cause unresolved. The long-standing theory is that pulmonary edema imposes a mechanical stress, resulting in diaphragmatic remodeling, but stable HF patients rarely exhibit pulmonary edema. We investigated how diaphragmatic weakness develops in two mouse models of pressure overload-induced HF. As in HF patients, both models had increased eupneic respiratory pressures and ventilatory drive...
May 17, 2017: Science Translational Medicine
https://www.readbyqxmd.com/read/28493943/open-lung-approach-versus-standard-protective-strategies-effects-on-driving-pressure-and-ventilatory-efficiency-during-anesthesia-a-pilot-randomized-controlled-trial
#18
RANDOMIZED CONTROLLED TRIAL
Carlos Ferrando, Fernando Suarez-Sipmann, Gerardo Tusman, Irene León, Esther Romero, Estefania Gracia, Ana Mugarra, Blanca Arocas, Natividad Pozo, Marina Soro, Francisco J Belda
BACKGROUND: Low tidal volume (VT) during anesthesia minimizes lung injury but may be associated to a decrease in functional lung volume impairing lung mechanics and efficiency. Lung recruitment (RM) can restore lung volume but this may critically depend on the post-RM selected PEEP. This study was a randomized, two parallel arm, open study whose primary outcome was to compare the effects on driving pressure of adding a RM to low-VT ventilation, with or without an individualized post-RM PEEP in patients without known previous lung disease during anesthesia...
2017: PloS One
https://www.readbyqxmd.com/read/28487387/different-determinants-of-ventilatory-inefficiency-at-different-stages-of-reduced-ejection-fraction-chronic-heart-failure-natural-history
#19
Alessandro Mezzani, Andrea Giordano, Klara Komici, Ugo Corrà
BACKGROUND: It is not known whether determinants of ventilation (VE)/volume of exhaled carbon dioxide (VCO2) slope during incremental exercise may differ at different stages of reduced ejection fraction chronic heart failure natural history. METHODS AND RESULTS: VE/VCO2 slope was fitted up to lowest VE/VCO2 ratio, that is, a proxy of the VE/perfusion ratio devoid of nonmetabolic stimuli to ventilatory drive. VE/VCO2 slope tertiles were generated from our database (<27...
May 9, 2017: Journal of the American Heart Association
https://www.readbyqxmd.com/read/28485314/effects-of-propofol-on-respiratory-drive-and-patient-ventilator-synchrony-during-pressure-support-ventilation-in-postoperative-patients-a-prospective-study
#20
Ling Liu, Ai-Ping Wu, Yi Yang, Song-Qiao Liu, Ying-Zi Huang, Jian-Feng Xie, Chun Pan, Cong-Shan Yang, Hai-Bo Qiu
BACKGROUND: Propofol is increasingly used during partial support mechanical ventilation such as pressure support ventilation (PSV) in postoperative patients. However, breathing pattern, respiratory drive, and patient-ventilator synchrony are affected by the sedative used and the sedation depth. The present study aimed to evaluate the physiologic effects of varying depths of propofol sedation on respiratory drive and patient-ventilator synchrony during PSV in postoperative patients. METHODS: Eight postoperative patients receiving PSV for <24 h were enrolled...
May 20, 2017: Chinese Medical Journal
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