Respiratory physiology & neurobiology
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Respir Physiol Neurobiol · Jun 2020
Endogenous glutamatergic inputs to the Parabrachial Nucleus/Kölliker-Fuse Complex determine respiratory rate.
The Kölliker-Fuse Nucleus (KF) has been widely investigated for its contribution to "inspiratory off-switch" while more recent studies showed that activation of the Parabrachial Nucleus (PBN) shortened expiratory duration. This study used an adult, in vivo, decerebrate rabbit model to delineate the contribution of each site to inspiratory and expiratory duration through sequential block of glutamatergic excitation with the receptor antagonists 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo[f]quinoxaline-2,3-dione (NBQX) and d(-)-2-amino-5-phosphonopentanoic acid (AP5). ⋯ The contribution of PBN activity to inspiratory and expiratory duration was equal while block of the KF affected inspiratory duration more than expiratory. We conclude that in the in vivo preparation respiratory rate greatly depends on PBN/KF activity, which contributes to the "inspiratory on- "and "off-switch", but is of minor importance for the magnitude of phrenic motor output.
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Respir Physiol Neurobiol · Feb 2021
Observational StudyDiaphragmatic thickening fraction as a potential predictor of response to continuous positive airway pressure ventilation in Covid-19 pneumonia: A single-center pilot study.
In a variable number of Covid-19 patients with acute respiratory failure, non-invasive breathing support strategies cannot provide adequate oxygenation, thus making invasive mechanical ventilation necessary. Factors predicting this unfavorable outcome are unknown, but we hypothesized that diaphragmatic weakness may contribute. ⋯ In critically ill patients with Covid-19 respiratory failure admitted to ICU, a reduced DTF could be a potential predictor of CPAP failure and requirement of invasive ventilation.
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Respir Physiol Neurobiol · Sep 2020
Activation of μ-opioid receptors differentially affects the preBötzinger Complex and neighbouring regions of the respiratory network in the adult rabbit.
The role of the different components of the respiratory network in the mediation of opioid-induced respiratory depression is still unclear. We investigated the contribution of the preBötzinger Complex (preBötC) and the neighbouring Bötzinger Complex (BötC) and inspiratory portion of the ventral respiratory group (iVRG) in anesthetized, vagotomized, paralyzed and artificially ventilated adult rabbits making use of bilateral microinjections (30-50 nl) of the μ-opioid receptor agonist [D-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin (DAMGO). Dose-dependent effects were observed. ⋯ In the iVRG DAMGO provoked decreases in amplitude and frequency of phrenic bursts at 0.1 mM and apnea at 0.5 mM. Local 5 mM naloxone reversed the apneic effects. The results imply that different components of the respiratory network may contribute to opioid-induced respiratory disorders.
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Respir Physiol Neurobiol · Sep 2018
Randomized Controlled Trial Multicenter Study Comparative Study Observational StudyPressure support ventilation vs Continuous positive airway pressure for treating of acute cardiogenic pulmonary edema: A pilot study.
Non-invasive ventilation is usually adopted as a support to medical therapy in patients with acute pulmonary edema, but which modality between Pressure Support Ventilation (PSV) and Continuous Positive Airway Pressure (CPAP) has better favourable effects is not been yet well known. Aim of this observational study was to provide data on these different non-invasive ventilation modalities in the management of acute cardiogenic pulmonary edema. ⋯ Furthermore, there were no significant differences regarding mortality in the two groups, but patients treated with PSV had a significant lower rate of endotracheal intubation and a higher improvement of blood gas analyses parameters. In conclusion, our data support only a slight advantage in favour to PSV versus CPAP.
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Respir Physiol Neurobiol · Jun 2020
Evidence for the emergence of an opioid-resistant respiratory rhythm following fentanyl overdose.
Breathing resumes within one to two minutes following fentanyl overdose induced apnea in spontaneously breathing rats. As this regular rhythm is produced at a time wherein fentanyl concentrations and receptor occupancy are likely to be extremely high, the mechanisms initiating and sustaining such a respiratory activity remain unclear. Forty-four un-anesthetized adult rats were studied in an open-flow plethysmograph. ⋯ When a second injection of the highest dose of fentanyl (300 μg.kg-1) was performed at 10 min, ventilation was not significantly affected and no apnea was produced in major contrast to the first injection. When a similar injection was performed 30 min after the first injection, in a separate group of rats, an apnea and breathing depression was produced in 30 % of the animals, while in the other rats, ventilation was unaffected. We conclude that the depressed regular respiratory activity emerging during and following fentanyl overdose is uniquely resistant to fentanyl.