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Ventilatory drive

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https://www.readbyqxmd.com/read/29890210/the-rostral-medulla-of-bullfrog-tadpoles-contains-critical-lung-rhythmogenic-and-chemosensitive-regions-across-metamorphosis
#1
Mitchell D Reed, Kimberly E Iceman, Michael B Harris, Barbara E Taylor
The development of amphibian breathing provides insight into vertebrate respiratory control mechanisms. Neural oscillators in the rostral and caudal medulla drive ventilation in amphibians, and previous reports describe ventilatory oscillators and CO2 sensitive regions arise during different stages of amphibian metamorphosis. However, inconsistent findings have been enigmatic, and make comparisons to potential mammalian counterparts challenging. In the current study we assessed amphibian central CO2 responsiveness and respiratory rhythm generation during two different developmental stages...
June 8, 2018: Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology
https://www.readbyqxmd.com/read/29859322/acute-hypercapnia-does-not-alter-voluntary-drive-to-the-diaphragm-in-healthy-humans
#2
Hsuan-Yu Wan, Jonathon L Stickford, Koichi Kitano, Wesley J Manz, David M Koceja, Robert F Chapman, Joel M Stager
Although systemic hypercapnia is a common outcome of pulmonary disease, the relationship between hypercapnia and voluntary diaphragmatic activation (VAdi ) is unclear. To examine whether hypercapnia independent of ventilatory work contributes to reduced central motor drive to the diaphragm in healthy humans, 14 subjects spontaneously breathed room air (NN) or a hypercapnic gas mixture (HH; 7% CO2 with air) while at rest. Thereafter, subjects volitionally hyperventilated room air (NH) matching the minute ventilation recorded during HH while maintained at eucapnic levels...
May 30, 2018: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/29789952/carotid-body-ablation-a-new-target-to-address-central-autonomic-dysfunction
#3
REVIEW
Rodrigo Iturriaga
PURPOSE OF REVIEW: An abnormal heightened carotid body (CB) chemoreflex, which produces autonomic dysfunction and sympathetic overactivation, is the common hallmark of obstructive sleep apnea (OSA), resistant hypertension, systolic heart failure (HF), and cardiometabolic diseases. Accordingly, it has been proposed that the elimination of the CB chemosensory input to the brainstem may reduce the autonomic and cardiorespiratory alterations in sympathetic-associated diseases in humans. RECENT FINDINGS: A growing body of evidence obtained in preclinical animal models support that an enhanced CB discharge produces sympathetic hyperactivity, baroreflex sensitivity and heart rate variability impairment, breathing instability, hypertension, and insulin resistance...
May 22, 2018: Current Hypertension Reports
https://www.readbyqxmd.com/read/29788047/haemodynamics-dyspnoea-and-pulmonary-reserve-in-heart-failure-with-preserved-ejection-fraction
#4
Masaru Obokata, Thomas P Olson, Yogesh N V Reddy, Vojtech Melenovsky, Garvan C Kane, Barry A Borlaug
Aims: Increases in left ventricular filling pressure are a fundamental haemodynamic abnormality in heart failure with preserved ejection fraction (HFpEF). However, very little is known regarding how elevated filling pressures cause pulmonary abnormalities or symptoms of dyspnoea. We sought to determine the relationships between simultaneously measured central haemodynamics, symptoms, and lung ventilatory and gas exchange abnormalities during exercise in HFpEF. Methods and results: Subjects with invasively-proven HFpEF (n = 50) and non-cardiac causes of dyspnoea (controls, n = 24) underwent cardiac catheterization at rest and during exercise with simultaneous expired gas analysis...
May 19, 2018: European Heart Journal
https://www.readbyqxmd.com/read/29779600/obesity-hypoventilation-syndrome
#5
REVIEW
Imran H Iftikhar, Joshua Roland
Obesity hypoventilation syndrome has been noted for centuries, yet we still are trying to uncover the exact mechanisms behind the disease and best treatment modalities for patients afflicted by the condition. The syndrome, which results in symptoms based on a diverse spectrum of interactions between obesity, ventilatory drive, and sleep's impact on respiration, has been shown to worsen morbidity and mortality far beyond that of more typical sleep-disordered breathing. In this article, the authors discuss current knowledge and research about the epidemiology, pathophysiology, and clinical features, along with treatment considerations of obesity hypoventilation syndrome...
June 2018: Clinics in Chest Medicine
https://www.readbyqxmd.com/read/29698749/the-role-of-ca-2-and-bk-channels-of-locus-coeruleus-lc-neurons-as-a-brake-to-the-co-2-chemosensitivity-response-of-rats
#6
Ann N Imber, Luis G A Patrone, Ke-Yong Li, Luciane H Gargaglioni, Robert W Putnam
The cellular mechanisms by which LC neurons respond to hypercapnia are usually attributed to an "accelerator" whereby hypercapnic acidosis causes an inhibition of K+ channels or activation of Na+ and Ca+2 channels to depolarize CO2 -sensitive neurons. Nevertheless, it is still unknown if this "accelerator" mechanism could be controlled by a brake phenomenon. Whole-cell patch clamping, fluorescence imaging microscopy and plethysmography were used to study the chemosensitive response of the LC neurons...
April 24, 2018: Neuroscience
https://www.readbyqxmd.com/read/29667182/breathing-regulation-and-blood-gas-homeostasis-after-near-complete-lesions-of-the-retrotrapezoid-nucleus-in-adult-rats
#7
George M P R Souza, Roy Kanbar, Daniel S Stornetta, Stephen B G Abbott, Ruth L Stornetta, Patrice G Guyenet
The retrotrapezoid nucleus (RTN) is one of several CNS nuclei that contribute, in various capacities (e.g. CO2 detection, neuronal modulation) to the central respiratory chemoreflex (CRC). Here we test how important the RTN is to PCO2 homeostasis and breathing during sleep or wake. RTN Nmb positive neurons were killed with targeted microinjections of substance-P-saporin conjugate in adult rats. Under normoxia, rats with large RTN lesions (92 ± 4 % cell loss) had normal blood pressure (BP) and arterial pH but were hypoxic (-8 mmHg PaO2 ) and hypercapnic (+10 mmHg PaCO2 )...
April 18, 2018: Journal of Physiology
https://www.readbyqxmd.com/read/29575957/ventilator-induced-lung-injury-during-controlled-ventilation-in-patients-with-acute-respiratory-distress-syndrome-less-is-probably-better
#8
Fernanda Ferreira Cruz, Lorenzo Ball, Patricia Rieken Macedo Rocco, Paolo Pelosi
Mechanical ventilation is required to support respiratory function in the acute respiratory distress syndrome (ARDS), but it may promote lung damage, a phenomenon known as ventilator-induced lung injury (VILI). Areas covered: Several mechanisms of VILI have been described, such as: inspiratory and/or expiratory stress inducing overdistension (volutrauma); interfaces between collapsed or edema-filled alveoli with surrounding open alveoli, acting as stress raisers; alveoli that repetitively open and close during tidal breathing (atelectrauma); and peripheral airway dynamics...
May 2018: Expert Review of Respiratory Medicine
https://www.readbyqxmd.com/read/29566734/acute-exacerbation-of-idiopathic-pulmonary-fibrosis-lessons-learned-from-acute-respiratory-distress-syndrome
#9
REVIEW
Alessandro Marchioni, Roberto Tonelli, Lorenzo Ball, Riccardo Fantini, Ivana Castaniere, Stefania Cerri, Fabrizio Luppi, Mario Malerba, Paolo Pelosi, Enrico Clini
Idiopathic pulmonary fibrosis (IPF) is a fibrotic lung disease characterized by progressive loss of lung function and poor prognosis. The so-called acute exacerbation of IPF (AE-IPF) may lead to severe hypoxemia requiring mechanical ventilation in the intensive care unit (ICU). AE-IPF shares several pathophysiological features with acute respiratory distress syndrome (ARDS), a very severe condition commonly treated in this setting.A review of the literature has been conducted to underline similarities and differences in the management of patients with AE-IPF and ARDS...
March 23, 2018: Critical Care: the Official Journal of the Critical Care Forum
https://www.readbyqxmd.com/read/29564726/potentially-modifiable-respiratory-variables-contributing-to-outcome-in-icu-patients-without-ards-a-secondary-analysis-of-provent
#10
Fabienne D Simonis, Carmen S V Barbas, Antonio Artigas-Raventós, Jaume Canet, Rogier M Determann, James Anstey, Goran Hedenstierna, Sabrine N T Hemmes, Greet Hermans, Michael Hiesmayr, Markus W Hollmann, Samir Jaber, Ignacio Martin-Loeches, Gary H Mills, Rupert M Pearse, Christian Putensen, Werner Schmid, Paolo Severgnini, Roger Smith, Tanja A Treschan, Edda M Tschernko, Marcos F Vidal Melo, Hermann Wrigge, Marcelo Gama de Abreu, Paolo Pelosi, Marcus J Schultz, Ary Serpa Neto
BACKGROUND: The majority of critically ill patients do not suffer from acute respiratory distress syndrome (ARDS). To improve the treatment of these patients, we aimed to identify potentially modifiable factors associated with outcome of these patients. METHODS: The PRoVENT was an international, multicenter, prospective cohort study of consecutive patients under invasive mechanical ventilatory support. A predefined secondary analysis was to examine factors associated with mortality...
March 21, 2018: Annals of Intensive Care
https://www.readbyqxmd.com/read/29528526/minocycline-alters-expression-of-inflammatory-markers-in-autonomic-brain-areas-and-ventilatory-responses-induced-by-acute-hypoxia
#11
Talita M Silva, Laiali J Chaar, Reinaldo C Silva, Ana C Takakura, Niels O Câmara, Vagner R Antunes, Thiago S Moreira
NEW FINDINGS: What is the central question of this study? Microglia are presumed to be the source of inflammatory mediators that contribute to hypoxia-induced neuroinflammation. However, the relationship between microglial activity during hypoxia and inflammatory responses in specific autonomic brain regions is not well understood. Therefore, we hypothesized that acute hypoxia initiates an immune response in the central nervous system elicited by an increased expression of inflammatory mediators in specific brain areas related to autonomic control...
March 12, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29487747/extranodal-non-b-non-t-cell-lymphoma-with-bilateral-tympanic-bulla-involvement-in-a-cat
#12
Austin T Kerns, Kelsey A Brakel, Christopher Premanandan, Ashlie Saffire, Sarah A Moore
Case summary: A 9-year-old spayed female domestic shorthair cat with clinical signs suggestive of chronic recurrent otitis media and recent seizures was presented with multifocal nervous system disease, including bilateral central and/or peripheral vestibular, cerebellar and forebrain deficits. Prior to presentation, there was inadequate improvement after 6 weeks of treatment for bilateral middle ear effusion from which a highly susceptible Staphylococcus species was cultured. This was followed by the development of seizures...
January 2018: JFMS Open Reports
https://www.readbyqxmd.com/read/29474404/role-of-acid-sensing-ion-channels-in-hypoxia-and-hypercapnia-induced-ventilatory-responses
#13
Neil D Detweiler, Kenneth G Vigil, Thomas C Resta, Benjimen R Walker, Nikki L Jernigan
Previous reports indicate roles for acid-sensing ion channels (ASICs) in both peripheral and central chemoreception, but the contributions of ASICs to ventilatory drive in conscious, unrestrained animals remain largely unknown. We tested the hypotheses that ASICs contribute to hypoxic- and hypercapnic-ventilatory responses. Blood samples taken from conscious, unrestrained mice chronically instrumented with femoral artery catheters were used to assess arterial O2, CO2, and pH levels during exposure to inspired gas mixtures designed to cause isocapnic hypoxemia or hypercapnia...
2018: PloS One
https://www.readbyqxmd.com/read/29357505/chemoreflex-mediated-arrhythmia-during-apnea-at-5-050-m-in-low-but-not-high-altitude-natives
#14
Stephen A Busch, Hannah Davies, Sean van Diepen, Lydia L Simpson, Frances Sobierajski, Laurel Riske, Mike Stembridge, Philip N Ainslie, Christopher K Willie, Ryan Hoiland, Jonathan P Moore, Craig D Steinback
Peripheral chemoreflex mediated increases in both parasympathetic and sympathetic drive under chronic hypoxia may evoke bradyarrhythmias during apneic periods. We determined whether 1) voluntary apnea unmasks arrhythmia at low (344 m) and high (5,050 m) altitude, 2) high-altitude natives (Nepalese Sherpa) exhibit similar cardiovagal responses at altitude, and 3) bradyarrhythmias at altitude are partially chemoreflex mediated. Participants were grouped as Lowlanders ( n = 14; age = 27 ± 6 yr) and Nepalese Sherpa ( n = 8; age = 32 ± 11 yr)...
April 1, 2018: Journal of Applied Physiology
https://www.readbyqxmd.com/read/29327943/phenotyping-pharyngeal-pathophysiology-using-polysomnography-in-patients-with-obstructive-sleep-apnea
#15
Scott A Sands, Bradley A Edwards, Philip I Terrill, Luigi Taranto-Montemurro, Ali Azarbarzin, Melania Marques, Lauren Hess, David P White, Andrew Wellman
RATIONALE: Therapies for obstructive sleep apnea (OSA) could be administered based on a patient's own phenotypic causes ("traits") if a clinically-applicable approach were available. Here we present a novel approach to quantify two key contributors to OSA-pharyngeal collapsibility and compensatory muscle responsiveness-that is applicable to diagnostic polysomnography. METHODS: Based on physiological definitions, pharyngeal collapsibility determines the ventilation at normal (eupneic) ventilatory drive during sleep, and pharyngeal compensation determines the rise in ventilation accompanying a rising ventilatory drive...
January 12, 2018: American Journal of Respiratory and Critical Care Medicine
https://www.readbyqxmd.com/read/29228393/quantifying-the-arousal-threshold-using-polysomnography-in-obstructive-sleep-apnea
#16
Scott A Sands, Philip I Terrill, Bradley A Edwards, Luigi Taranto Montemurro, Ali Azarbarzin, Melania Marques, Camila M de Melo, Stephen H Loring, James P Butler, David P White, Andrew Wellman
Study Objectives: Precision medicine for obstructive sleep apnea (OSA) requires noninvasive estimates of each patient's pathophysiological "traits." Here, we provide the first automated technique to quantify the respiratory arousal threshold-defined as the level of ventilatory drive triggering arousal from sleep-using diagnostic polysomnographic signals in patients with OSA. Methods: Ventilatory drive preceding clinically scored arousals was estimated from polysomnographic studies by fitting a respiratory control model (Terrill et al...
January 1, 2018: Sleep
https://www.readbyqxmd.com/read/29184292/cardiopulmonary-rehabilitation-program-impact-on-prognostic-markers-in-selected-patients-with-resting-and-exercise-induced-ventilatory-inefficiency-a-clinical-trial
#17
Sherin Hassan M Mehani, Heba Ahmed A Abdeen
[Purpose] Ventilatory limitation is a common problem in patients with chronic heart failure and pulmonary hypertension. Excess ventilation may arise from augmented ventilatory drive, over activity of chemoreceptors and muscle ergoreceptors, or premature onset of lactic acidosis. Exertional dyspnea can cause limitations in the activities of daily living and as a result, reduced quality of life for these patients. The aim of the present study was to evaluate the effect of cardiopulmonary rehabilitation program on ventilatory efficiency for these patients...
October 2017: Journal of Physical Therapy Science
https://www.readbyqxmd.com/read/29150452/a-metabolic-hypothesis-for-the-evolution-of-temperature-effects-on-the-arterial-p-co-2-and-ph-of-vertebrate-ectotherms
#18
Stanley S Hillman, Michael S Hedrick
Body temperature increases in ectothermic vertebrates characteristically lead to both increases in arterial P CO2  ( P aCO2 ) and declines in resting arterial pH (pHa) of about 0.017 pH units per 1°C increase in temperature. This 'alphastat' pH pattern has previously been interpreted as being evolutionarily driven by the maintenance of a constant protonation state on the imidazole moiety of histidine protein residues, hence stabilizing protein structure-function. Analysis of the existing data for interclass responses of ectothermic vertebrates shows different degrees of P aCO2  increases and pH declines with temperature between the classes, with reptiles>amphibians>fish...
January 4, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/29135500/association-of-driving-pressure-with-mortality-among-ventilated-patients-with-acute-respiratory-distress-syndrome-a-systematic-review-and-meta-analysis
#19
Hiroko Aoyama, Tommaso Pettenuzzo, Kazuyoshi Aoyama, Ruxandra Pinto, Marina Englesakis, Eddy Fan
OBJECTIVES: A recent post hoc analysis suggested that driving pressure may be more important than traditional ventilatory variables in determining outcome in mechanically ventilated patients with acute respiratory distress syndrome. We conducted a systematic review and meta-analysis to summarize the risk of mortality for higher versus lower driving pressure. DATA SOURCES: MEDLINE, EMBASE, PubMed, CINAHL, and Cochrane CENTRAL from inception to February 10, 2017. STUDY SELECTION: Studies including mechanically ventilated adult patients with acute respiratory distress syndrome, reporting driving pressure and mortality...
February 2018: Critical Care Medicine
https://www.readbyqxmd.com/read/29114876/translating-carotid-body-function-into-clinical-medicine
#20
Rodrigo Iturriaga
The carotid body (CB) is considered the main O2 chemoreceptor, which contributes to the cardiorespiratory homeostasis and ventilatory acclimatization. In clinical medicine, the most common pathology associated with the CB are tumours. However, a growing body of evidences supports the novel idea that an enhanced CB chemosensory discharge contributes to the autonomic dysfunction and pathological consequences in obstructive sleep apnoea (OSA), hypertension, systolic heart failure (HF) and cardiometabolic diseases...
November 8, 2017: Journal of Physiology
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